#!/usr/bin/env python


__license__   = 'GPL v3'
__copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
__docformat__ = 'restructuredtext en'

# Imports {{{
import apsw
import errno
import hashlib
import json
import os
import shutil
import sys
import time
import uuid
from contextlib import closing, suppress
from functools import partial

from calibre import as_unicode, force_unicode, isbytestring, prints
from calibre.constants import (
    filesystem_encoding, iswindows, plugins, preferred_encoding,
)
from calibre.db import SPOOL_SIZE, FTSQueryError
from calibre.db.annotations import annot_db_data, unicode_normalize
from calibre.db.delete_service import delete_service
from calibre.db.errors import NoSuchFormat
from calibre.db.schema_upgrades import SchemaUpgrade
from calibre.db.tables import (
    AuthorsTable, CompositeTable, FormatsTable, IdentifiersTable, ManyToManyTable,
    ManyToOneTable, OneToOneTable, PathTable, RatingTable, SizeTable, UUIDTable,
)
from calibre.ebooks.metadata import author_to_author_sort, title_sort
from calibre.library.field_metadata import FieldMetadata
from calibre.ptempfile import PersistentTemporaryFile, TemporaryFile
from calibre.utils import pickle_binary_string, unpickle_binary_string
from calibre.utils.config import from_json, prefs, to_json, tweaks
from calibre.utils.date import EPOCH, parse_date, utcfromtimestamp, utcnow
from calibre.utils.filenames import (
    WindowsAtomicFolderMove, ascii_filename, atomic_rename, copyfile_using_links,
    copytree_using_links, hardlink_file, is_case_sensitive, is_fat_filesystem,
    remove_dir_if_empty, samefile,
)
from calibre.utils.formatter_functions import (
    compile_user_template_functions, formatter_functions, load_user_template_functions,
    unload_user_template_functions,
)
from calibre.utils.icu import lower as icu_lower, sort_key
from calibre.utils.resources import get_path as P
from polyglot.builtins import (
    cmp, iteritems, itervalues, native_string_type, reraise, string_or_bytes,
)

# }}}


BOOK_ID_PATH_TEMPLATE = ' ({})'
CUSTOM_DATA_TYPES = frozenset(('rating', 'text', 'comments', 'datetime',
    'int', 'float', 'bool', 'series', 'composite', 'enumeration'))
WINDOWS_RESERVED_NAMES = frozenset('CON PRN AUX NUL COM1 COM2 COM3 COM4 COM5 COM6 COM7 COM8 COM9 LPT1 LPT2 LPT3 LPT4 LPT5 LPT6 LPT7 LPT8 LPT9'.split())


class DynamicFilter:  # {{{

    'No longer used, present for legacy compatibility'

    def __init__(self, name):
        self.name = name
        self.ids = frozenset()

    def __call__(self, id_):
        return int(id_ in self.ids)

    def change(self, ids):
        self.ids = frozenset(ids)
# }}}


class DBPrefs(dict):  # {{{

    'Store preferences as key:value pairs in the db'

    def __init__(self, db):
        dict.__init__(self)
        self.db = db
        self.defaults = {}
        self.disable_setting = False
        self.load_from_db()

    def load_from_db(self):
        self.clear()
        for key, val in self.db.conn.get('SELECT key,val FROM preferences'):
            try:
                val = self.raw_to_object(val)
            except:
                prints('Failed to read value for:', key, 'from db')
                continue
            dict.__setitem__(self, key, val)

    def raw_to_object(self, raw):
        if not isinstance(raw, str):
            raw = raw.decode(preferred_encoding)
        return json.loads(raw, object_hook=from_json)

    def to_raw(self, val):
        # sort_keys=True is required so that the serialization of dictionaries is
        # not random, which is needed for the changed check in __setitem__
        return json.dumps(val, indent=2, default=to_json, sort_keys=True)

    def has_setting(self, key):
        return key in self

    def __getitem__(self, key):
        try:
            return dict.__getitem__(self, key)
        except KeyError:
            return self.defaults[key]

    def __delitem__(self, key):
        dict.__delitem__(self, key)
        self.db.execute('DELETE FROM preferences WHERE key=?', (key,))

    def __setitem__(self, key, val):
        if not self.disable_setting:
            raw = self.to_raw(val)
            do_set = False
            with self.db.conn:
                try:
                    dbraw = next(self.db.execute('SELECT id,val FROM preferences WHERE key=?', (key,)))
                except StopIteration:
                    dbraw = None
                if dbraw is None or dbraw[1] != raw:
                    if dbraw is None:
                        self.db.execute('INSERT INTO preferences (key,val) VALUES (?,?)', (key, raw))
                    else:
                        self.db.execute('UPDATE preferences SET val=? WHERE id=?', (raw, dbraw[0]))
                    do_set = True
            if do_set:
                dict.__setitem__(self, key, val)

    def set(self, key, val):
        self.__setitem__(key, val)

    def get_namespaced(self, namespace, key, default=None):
        key = 'namespaced:%s:%s'%(namespace, key)
        try:
            return dict.__getitem__(self, key)
        except KeyError:
            return default

    def set_namespaced(self, namespace, key, val):
        if ':' in key:
            raise KeyError('Colons are not allowed in keys')
        if ':' in namespace:
            raise KeyError('Colons are not allowed in the namespace')
        key = 'namespaced:%s:%s'%(namespace, key)
        self[key] = val

    def write_serialized(self, library_path):
        try:
            to_filename = os.path.join(library_path, 'metadata_db_prefs_backup.json')
            data = json.dumps(self, indent=2, default=to_json)
            if not isinstance(data, bytes):
                data = data.encode('utf-8')
            with open(to_filename, 'wb') as f:
                f.write(data)
        except:
            import traceback
            traceback.print_exc()

    @classmethod
    def read_serialized(cls, library_path, recreate_prefs=False):
        from_filename = os.path.join(library_path,
                'metadata_db_prefs_backup.json')
        with open(from_filename, 'rb') as f:
            return json.load(f, object_hook=from_json)
# }}}

# Extra collators {{{


def pynocase(one, two, encoding='utf-8'):
    if isbytestring(one):
        try:
            one = one.decode(encoding, 'replace')
        except:
            pass
    if isbytestring(two):
        try:
            two = two.decode(encoding, 'replace')
        except:
            pass
    return cmp(one.lower(), two.lower())


def _author_to_author_sort(x):
    if not x:
        return ''
    return author_to_author_sort(x.replace('|', ','))


def icu_collator(s1, s2):
    return cmp(sort_key(force_unicode(s1, 'utf-8')),
               sort_key(force_unicode(s2, 'utf-8')))

# }}}

# Unused aggregators {{{


def Concatenate(sep=','):
    '''String concatenation aggregator for sqlite'''

    def step(ctxt, value):
        if value is not None:
            ctxt.append(value)

    def finalize(ctxt):
        try:
            if not ctxt:
                return None
            return sep.join(ctxt)
        except Exception:
            import traceback
            traceback.print_exc()
            raise

    return ([], step, finalize)


def SortedConcatenate(sep=','):
    '''String concatenation aggregator for sqlite, sorted by supplied index'''

    def step(ctxt, ndx, value):
        if value is not None:
            ctxt[ndx] = value

    def finalize(ctxt):
        try:
            if len(ctxt) == 0:
                return None
            return sep.join(map(ctxt.get, sorted(ctxt)))
        except Exception:
            import traceback
            traceback.print_exc()
            raise

    return ({}, step, finalize)


def IdentifiersConcat():
    '''String concatenation aggregator for the identifiers map'''

    def step(ctxt, key, val):
        ctxt.append('%s:%s'%(key, val))

    def finalize(ctxt):
        try:
            return ','.join(ctxt)
        except Exception:
            import traceback
            traceback.print_exc()
            raise

    return ([], step, finalize)


def AumSortedConcatenate():
    '''String concatenation aggregator for the author sort map'''

    def step(ctxt, ndx, author, sort, link):
        if author is not None:
            ctxt[ndx] = ':::'.join((author, sort, link))

    def finalize(ctxt):
        try:
            keys = list(ctxt)
            l = len(keys)
            if l == 0:
                return None
            if l == 1:
                return ctxt[keys[0]]
            return ':#:'.join([ctxt[v] for v in sorted(keys)])
        except Exception:
            import traceback
            traceback.print_exc()
            raise

    return ({}, step, finalize)

# }}}


# Annotations {{{
def annotations_for_book(cursor, book_id, fmt, user_type='local', user='viewer'):
    for (data,) in cursor.execute(
        'SELECT annot_data FROM annotations WHERE book=? AND format=? AND user_type=? AND user=?',
        (book_id, fmt.upper(), user_type, user)
    ):
        try:
            yield json.loads(data)
        except Exception:
            pass


def save_annotations_for_book(cursor, book_id, fmt, annots_list, user_type='local', user='viewer'):
    data = []
    fmt = fmt.upper()
    for annot, timestamp_in_secs in annots_list:
        atype = annot['type'].lower()
        aid, text = annot_db_data(annot)
        if aid is None:
            continue
        data.append((book_id, fmt, user_type, user, timestamp_in_secs, aid, atype, json.dumps(annot), text))
    cursor.execute('INSERT OR IGNORE INTO annotations_dirtied (book) VALUES (?)', (book_id,))
    cursor.execute('DELETE FROM annotations WHERE book=? AND format=? AND user_type=? AND user=?', (book_id, fmt, user_type, user))
    cursor.executemany(
        'INSERT OR REPLACE INTO annotations (book, format, user_type, user, timestamp, annot_id, annot_type, annot_data, searchable_text)'
        ' VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)', data)
# }}}


class Connection(apsw.Connection):  # {{{

    BUSY_TIMEOUT = 10000  # milliseconds

    def __init__(self, path):
        from calibre.utils.localization import get_lang
        from calibre_extensions.sqlite_extension import set_ui_language
        set_ui_language(get_lang())
        super().__init__(path)
        plugins.load_apsw_extension(self, 'sqlite_extension')
        self.fts_dbpath = None

        self.setbusytimeout(self.BUSY_TIMEOUT)
        self.execute('pragma cache_size=-5000')
        self.execute('pragma temp_store=2')

        encoding = next(self.execute('pragma encoding'))[0]
        self.createcollation('PYNOCASE', partial(pynocase,
            encoding=encoding))

        self.createscalarfunction('title_sort', title_sort, 1)
        self.createscalarfunction('author_to_author_sort',
                _author_to_author_sort, 1)
        self.createscalarfunction('uuid4', lambda: str(uuid.uuid4()),
                0)

        # Dummy functions for dynamically created filters
        self.createscalarfunction('books_list_filter', lambda x: 1, 1)
        self.createcollation('icucollate', icu_collator)

        # Legacy aggregators (never used) but present for backwards compat
        self.createaggregatefunction('sortconcat', SortedConcatenate, 2)
        self.createaggregatefunction('sortconcat_bar',
                partial(SortedConcatenate, sep='|'), 2)
        self.createaggregatefunction('sortconcat_amper',
                partial(SortedConcatenate, sep='&'), 2)
        self.createaggregatefunction('identifiers_concat',
                IdentifiersConcat, 2)
        self.createaggregatefunction('concat', Concatenate, 1)
        self.createaggregatefunction('aum_sortconcat',
                AumSortedConcatenate, 4)

    def create_dynamic_filter(self, name):
        f = DynamicFilter(name)
        self.createscalarfunction(name, f, 1)

    def get(self, *args, **kw):
        ans = self.cursor().execute(*args)
        if kw.get('all', True):
            return ans.fetchall()
        with suppress(StopIteration, IndexError):
            return next(ans)[0]

    def get_dict(self, *args, all=True):
        ans = self.cursor().execute(*args)
        desc = ans.getdescription()
        field_names = tuple(x[0] for x in desc)

        def as_dict(row):
            return dict(zip(field_names, row))

        if all:
            return tuple(map(as_dict, ans))
        ans = ans.fetchone()
        if ans is not None:
            ans = as_dict(ans)
        return ans

    def execute(self, sql, bindings=None):
        cursor = self.cursor()
        return cursor.execute(sql, bindings)

    def executemany(self, sql, sequence_of_bindings):
        with self:  # Disable autocommit mode, for performance
            return self.cursor().executemany(sql, sequence_of_bindings)

# }}}


def set_global_state(backend):
    load_user_template_functions(
        backend.library_id, (), precompiled_user_functions=backend.get_user_template_functions())


def rmtree_with_retry(path, sleep_time=1):
    try:
        shutil.rmtree(path)
    except OSError as e:
        if e.errno == errno.ENOENT and not os.path.exists(path):
            return
        time.sleep(sleep_time)  # In case something has temporarily locked a file
        shutil.rmtree(path)


class DB:

    PATH_LIMIT = 40 if iswindows else 100
    WINDOWS_LIBRARY_PATH_LIMIT = 75

    # Initialize database {{{

    def __init__(self, library_path, default_prefs=None, read_only=False,
                 restore_all_prefs=False, progress_callback=lambda x, y:True,
                 load_user_formatter_functions=True):
        self.is_closed = False
        if isbytestring(library_path):
            library_path = library_path.decode(filesystem_encoding)
        self.field_metadata = FieldMetadata()

        self.library_path = os.path.abspath(library_path)
        self.dbpath = os.path.join(library_path, 'metadata.db')
        self.dbpath = os.environ.get('CALIBRE_OVERRIDE_DATABASE_PATH',
                self.dbpath)

        if iswindows and len(self.library_path) + 4*self.PATH_LIMIT + 10 > 259:
            raise ValueError(_(
                'Path to library ({0}) too long. It must be less than'
                ' {1} characters.').format(self.library_path, 259-4*self.PATH_LIMIT-10))
        exists = self._exists = os.path.exists(self.dbpath)
        if not exists:
            # Be more strict when creating new libraries as the old calculation
            # allowed for max path lengths of 265 chars.
            if (iswindows and len(self.library_path) > self.WINDOWS_LIBRARY_PATH_LIMIT):
                raise ValueError(_(
                    'Path to library too long. It must be less than'
                    ' %d characters.')%self.WINDOWS_LIBRARY_PATH_LIMIT)

        if read_only and os.path.exists(self.dbpath):
            # Work on only a copy of metadata.db to ensure that
            # metadata.db is not changed
            pt = PersistentTemporaryFile('_metadata_ro.db')
            pt.close()
            shutil.copyfile(self.dbpath, pt.name)
            self.dbpath = pt.name

        if not os.path.exists(os.path.dirname(self.dbpath)):
            os.makedirs(os.path.dirname(self.dbpath))

        self._conn = None
        if self.user_version == 0:
            self.initialize_database()

        if not os.path.exists(self.library_path):
            os.makedirs(self.library_path)
        self.is_case_sensitive = is_case_sensitive(self.library_path)
        self.is_fat_filesystem = is_fat_filesystem(self.library_path)

        SchemaUpgrade(self, self.library_path, self.field_metadata)

        # Guarantee that the library_id is set
        self.library_id

        # Fix legacy triggers and columns
        self.execute('''
        DROP TRIGGER IF EXISTS author_insert_trg;
        CREATE TEMP TRIGGER author_insert_trg
            AFTER INSERT ON authors
            BEGIN
            UPDATE authors SET sort=author_to_author_sort(NEW.name) WHERE id=NEW.id;
        END;
        DROP TRIGGER IF EXISTS author_update_trg;
        CREATE TEMP TRIGGER author_update_trg
            BEFORE UPDATE ON authors
            BEGIN
            UPDATE authors SET sort=author_to_author_sort(NEW.name)
            WHERE id=NEW.id AND name <> NEW.name;
        END;
        UPDATE authors SET sort=author_to_author_sort(name) WHERE sort IS NULL;
        ''')

        # Initialize_prefs must be called before initialize_custom_columns because
        # icc can set a pref.
        self.initialize_prefs(default_prefs, restore_all_prefs, progress_callback)
        self.initialize_custom_columns()
        self.initialize_tables()
        self.set_user_template_functions(compile_user_template_functions(
                                 self.prefs.get('user_template_functions', [])))
        if load_user_formatter_functions:
            set_global_state(self)

    def get_template_functions(self):
        return self._template_functions

    def get_user_template_functions(self):
        return self._user_template_functions

    def set_user_template_functions(self, user_formatter_functions):
        self._user_template_functions = user_formatter_functions
        self._template_functions = formatter_functions().get_builtins_and_aliases().copy()
        self._template_functions.update(user_formatter_functions)

    def initialize_prefs(self, default_prefs, restore_all_prefs, progress_callback):  # {{{
        self.prefs = DBPrefs(self)

        if default_prefs is not None and not self._exists:
            progress_callback(None, len(default_prefs))
            # Only apply default prefs to a new database
            for i, key in enumerate(default_prefs):
                # be sure that prefs not to be copied are listed below
                if restore_all_prefs or key not in frozenset(['news_to_be_synced']):
                    self.prefs[key] = default_prefs[key]
                    progress_callback(_('restored preference ') + key, i+1)
            if 'field_metadata' in default_prefs:
                fmvals = [f for f in default_prefs['field_metadata'].values()
                                if f['is_custom']]
                progress_callback(None, len(fmvals))
                for i, f in enumerate(fmvals):
                    progress_callback(_('creating custom column ') + f['label'], i)
                    self.create_custom_column(f['label'], f['name'],
                            f['datatype'],
                            (f['is_multiple'] is not None and len(f['is_multiple']) > 0),
                            f['is_editable'], f['display'])

        defs = self.prefs.defaults
        defs['gui_restriction'] = defs['cs_restriction'] = ''
        defs['categories_using_hierarchy'] = []
        defs['column_color_rules'] = []
        defs['column_icon_rules'] = []
        defs['cover_grid_icon_rules'] = []
        defs['grouped_search_make_user_categories'] = []
        defs['similar_authors_search_key'] = 'authors'
        defs['similar_authors_match_kind'] = 'match_any'
        defs['similar_publisher_search_key'] = 'publisher'
        defs['similar_publisher_match_kind'] = 'match_any'
        defs['similar_tags_search_key'] = 'tags'
        defs['similar_tags_match_kind'] = 'match_all'
        defs['similar_series_search_key'] = 'series'
        defs['similar_series_match_kind'] = 'match_any'
        defs['book_display_fields'] = [
        ('title', False), ('authors', True), ('series', True),
        ('identifiers', True), ('tags', True), ('formats', True),
        ('path', True), ('publisher', False), ('rating', False),
        ('author_sort', False), ('sort', False), ('timestamp', False),
        ('uuid', False), ('comments', True), ('id', False), ('pubdate', False),
        ('last_modified', False), ('size', False), ('languages', False),
        ]
        defs['popup_book_display_fields'] = [('title', True)] + [(f[0], True) for f in defs['book_display_fields'] if f[0] != 'title']
        defs['qv_display_fields'] = [('title', True), ('authors', True), ('series', True)]
        defs['virtual_libraries'] = {}
        defs['virtual_lib_on_startup'] = defs['cs_virtual_lib_on_startup'] = ''
        defs['virt_libs_hidden'] = defs['virt_libs_order'] = ()
        defs['update_all_last_mod_dates_on_start'] = False
        defs['field_under_covers_in_grid'] = 'title'
        defs['cover_browser_title_template'] = '{title}'
        defs['cover_browser_subtitle_field'] = 'rating'
        defs['styled_columns'] = {}
        defs['edit_metadata_ignore_display_order'] = False
        defs['fts_enabled'] = False

        # Migrate the bool tristate tweak
        defs['bools_are_tristate'] = \
                tweaks.get('bool_custom_columns_are_tristate', 'yes') == 'yes'
        if self.prefs.get('bools_are_tristate') is None:
            self.prefs.set('bools_are_tristate', defs['bools_are_tristate'])

        # Migrate column coloring rules
        if self.prefs.get('column_color_name_1', None) is not None:
            from calibre.library.coloring import migrate_old_rule
            old_rules = []
            for i in range(1, 6):
                col = self.prefs.get('column_color_name_%d' % i, None)
                templ = self.prefs.get('column_color_template_%d' % i, None)
                if col and templ:
                    try:
                        del self.prefs['column_color_name_%d' % i]
                        rules = migrate_old_rule(self.field_metadata, templ)
                        for templ in rules:
                            old_rules.append((col, templ))
                    except:
                        pass
            if old_rules:
                self.prefs['column_color_rules'] += old_rules

        # Migrate saved search and user categories to db preference scheme
        def migrate_preference(key, default):
            oldval = prefs[key]
            if oldval != default:
                self.prefs[key] = oldval
                prefs[key] = default
            if key not in self.prefs:
                self.prefs[key] = default

        migrate_preference('user_categories', {})
        migrate_preference('saved_searches', {})

        # migrate grouped_search_terms
        if self.prefs.get('grouped_search_terms', None) is None:
            try:
                ogst = tweaks.get('grouped_search_terms', {})
                ngst = {}
                for t in ogst:
                    ngst[icu_lower(t)] = ogst[t]
                self.prefs.set('grouped_search_terms', ngst)
            except:
                pass

        # migrate the gui_restriction preference to a virtual library
        gr_pref = self.prefs.get('gui_restriction', None)
        if gr_pref:
            virt_libs = self.prefs.get('virtual_libraries', {})
            virt_libs[gr_pref] = 'search:"' + gr_pref + '"'
            self.prefs['virtual_libraries'] = virt_libs
            self.prefs['gui_restriction'] = ''
            self.prefs['virtual_lib_on_startup'] = gr_pref

        # migrate the cs_restriction preference to a virtual library
        gr_pref = self.prefs.get('cs_restriction', None)
        if gr_pref:
            virt_libs = self.prefs.get('virtual_libraries', {})
            virt_libs[gr_pref] = 'search:"' + gr_pref + '"'
            self.prefs['virtual_libraries'] = virt_libs
            self.prefs['cs_restriction'] = ''
            self.prefs['cs_virtual_lib_on_startup'] = gr_pref

        # Rename any user categories with names that differ only in case
        user_cats = self.prefs.get('user_categories', [])
        catmap = {}
        for uc in user_cats:
            ucl = icu_lower(uc)
            if ucl not in catmap:
                catmap[ucl] = []
            catmap[ucl].append(uc)
        cats_changed = False
        for uc in catmap:
            if len(catmap[uc]) > 1:
                prints('found user category case overlap', catmap[uc])
                cat = catmap[uc][0]
                suffix = 1
                while icu_lower(cat + str(suffix)) in catmap:
                    suffix += 1
                prints('Renaming user category %s to %s'%(cat, cat+str(suffix)))
                user_cats[cat + str(suffix)] = user_cats[cat]
                del user_cats[cat]
                cats_changed = True
        if cats_changed:
            self.prefs.set('user_categories', user_cats)
    # }}}

    def initialize_custom_columns(self):  # {{{
        self.custom_columns_deleted = False
        with self.conn:
            # Delete previously marked custom columns
            for record in self.conn.get(
                    'SELECT id FROM custom_columns WHERE mark_for_delete=1'):
                num = record[0]
                table, lt = self.custom_table_names(num)
                self.execute('''\
                        DROP INDEX   IF EXISTS {table}_idx;
                        DROP INDEX   IF EXISTS {lt}_aidx;
                        DROP INDEX   IF EXISTS {lt}_bidx;
                        DROP TRIGGER IF EXISTS fkc_update_{lt}_a;
                        DROP TRIGGER IF EXISTS fkc_update_{lt}_b;
                        DROP TRIGGER IF EXISTS fkc_insert_{lt};
                        DROP TRIGGER IF EXISTS fkc_delete_{lt};
                        DROP TRIGGER IF EXISTS fkc_insert_{table};
                        DROP TRIGGER IF EXISTS fkc_delete_{table};
                        DROP VIEW    IF EXISTS tag_browser_{table};
                        DROP VIEW    IF EXISTS tag_browser_filtered_{table};
                        DROP TABLE   IF EXISTS {table};
                        DROP TABLE   IF EXISTS {lt};
                        '''.format(table=table, lt=lt)
                )
                self.prefs.set('update_all_last_mod_dates_on_start', True)
            self.execute('DELETE FROM custom_columns WHERE mark_for_delete=1')

        # Load metadata for custom columns
        self.custom_column_label_map, self.custom_column_num_map = {}, {}
        self.custom_column_num_to_label_map = {}
        triggers = []
        remove = []
        custom_tables = self.custom_tables
        for record in self.conn.get(
                'SELECT label,name,datatype,editable,display,normalized,id,is_multiple FROM custom_columns'):
            data = {
                    'label':record[0],
                    'name':record[1],
                    'datatype':record[2],
                    'editable':bool(record[3]),
                    'display':json.loads(record[4]),
                    'normalized':bool(record[5]),
                    'num':record[6],
                    'is_multiple':bool(record[7]),
                    }
            if data['display'] is None:
                data['display'] = {}
            # set up the is_multiple separator dict
            if data['is_multiple']:
                if data['display'].get('is_names', False):
                    seps = {'cache_to_list': '|', 'ui_to_list': '&', 'list_to_ui': ' & '}
                elif data['datatype'] == 'composite':
                    seps = {'cache_to_list': ',', 'ui_to_list': ',', 'list_to_ui': ', '}
                else:
                    seps = {'cache_to_list': '|', 'ui_to_list': ',', 'list_to_ui': ', '}
            else:
                seps = {}
            data['multiple_seps'] = seps

            table, lt = self.custom_table_names(data['num'])
            if table not in custom_tables or (data['normalized'] and lt not in
                    custom_tables):
                remove.append(data)
                continue

            self.custom_column_num_map[data['num']] = \
                self.custom_column_label_map[data['label']] = data
            self.custom_column_num_to_label_map[data['num']] = data['label']

            # Create Foreign Key triggers
            if data['normalized']:
                trigger = 'DELETE FROM %s WHERE book=OLD.id;'%lt
            else:
                trigger = 'DELETE FROM %s WHERE book=OLD.id;'%table
            triggers.append(trigger)

        if remove:
            with self.conn:
                for data in remove:
                    prints('WARNING: Custom column %r not found, removing.' %
                            data['label'])
                    self.execute('DELETE FROM custom_columns WHERE id=?',
                            (data['num'],))

        if triggers:
            with self.conn:
                self.execute('''\
                    CREATE TEMP TRIGGER custom_books_delete_trg
                        AFTER DELETE ON books
                        BEGIN
                        %s
                    END;
                    '''%(' \n'.join(triggers)))

        # Setup data adapters
        def adapt_text(x, d):
            if d['is_multiple']:
                if x is None:
                    return []
                if isinstance(x, (str, bytes)):
                    x = x.split(d['multiple_seps']['ui_to_list'])
                x = [y.strip() for y in x if y.strip()]
                x = [y.decode(preferred_encoding, 'replace') if not isinstance(y,
                    str) else y for y in x]
                return [' '.join(y.split()) for y in x]
            else:
                return x if x is None or isinstance(x, str) else \
                        x.decode(preferred_encoding, 'replace')

        def adapt_datetime(x, d):
            if isinstance(x, (str, bytes)):
                if isinstance(x, bytes):
                    x = x.decode(preferred_encoding, 'replace')
                x = parse_date(x, assume_utc=False, as_utc=False)
            return x

        def adapt_bool(x, d):
            if isinstance(x, (str, bytes)):
                if isinstance(x, bytes):
                    x = x.decode(preferred_encoding, 'replace')
                x = x.lower()
                if x == 'true':
                    x = True
                elif x == 'false':
                    x = False
                elif x == 'none':
                    x = None
                else:
                    x = bool(int(x))
            return x

        def adapt_enum(x, d):
            v = adapt_text(x, d)
            if not v:
                v = None
            return v

        def adapt_number(x, d):
            if x is None:
                return None
            if isinstance(x, (str, bytes)):
                if isinstance(x, bytes):
                    x = x.decode(preferred_encoding, 'replace')
                if x.lower() == 'none':
                    return None
            if d['datatype'] == 'int':
                return int(x)
            return float(x)

        self.custom_data_adapters = {
                'float': adapt_number,
                'int': adapt_number,
                'rating':lambda x,d: x if x is None else min(10., max(0., float(x))),
                'bool': adapt_bool,
                'comments': lambda x,d: adapt_text(x, {'is_multiple':False}),
                'datetime': adapt_datetime,
                'text':adapt_text,
                'series':adapt_text,
                'enumeration': adapt_enum
        }

        # Create Tag Browser categories for custom columns
        for k in sorted(self.custom_column_label_map):
            v = self.custom_column_label_map[k]
            if v['normalized']:
                is_category = True
            else:
                is_category = False
            is_m = v['multiple_seps']
            tn = 'custom_column_{}'.format(v['num'])
            self.field_metadata.add_custom_field(label=v['label'],
                    table=tn, column='value', datatype=v['datatype'],
                    colnum=v['num'], name=v['name'], display=v['display'],
                    is_multiple=is_m, is_category=is_category,
                    is_editable=v['editable'], is_csp=False)

    # }}}

    def initialize_tables(self):  # {{{
        tables = self.tables = {}
        for col in ('title', 'sort', 'author_sort', 'series_index', 'comments',
                'timestamp', 'pubdate', 'uuid', 'path', 'cover',
                'last_modified'):
            metadata = self.field_metadata[col].copy()
            if col == 'comments':
                metadata['table'], metadata['column'] = 'comments', 'text'
            if not metadata['table']:
                metadata['table'], metadata['column'] = 'books', ('has_cover'
                        if col == 'cover' else col)
            if not metadata['column']:
                metadata['column'] = col
            tables[col] = (PathTable if col == 'path' else UUIDTable if col == 'uuid' else OneToOneTable)(col, metadata)

        for col in ('series', 'publisher'):
            tables[col] = ManyToOneTable(col, self.field_metadata[col].copy())

        for col in ('authors', 'tags', 'formats', 'identifiers', 'languages', 'rating'):
            cls = {
                    'authors':AuthorsTable,
                    'formats':FormatsTable,
                    'identifiers':IdentifiersTable,
                    'rating':RatingTable,
                  }.get(col, ManyToManyTable)
            tables[col] = cls(col, self.field_metadata[col].copy())

        tables['size'] = SizeTable('size', self.field_metadata['size'].copy())

        self.FIELD_MAP = {
            'id':0, 'title':1, 'authors':2, 'timestamp':3, 'size':4,
            'rating':5, 'tags':6, 'comments':7, 'series':8, 'publisher':9,
            'series_index':10, 'sort':11, 'author_sort':12, 'formats':13,
            'path':14, 'pubdate':15, 'uuid':16, 'cover':17, 'au_map':18,
            'last_modified':19, 'identifiers':20, 'languages':21,
        }

        for k,v in iteritems(self.FIELD_MAP):
            self.field_metadata.set_field_record_index(k, v, prefer_custom=False)

        base = max(itervalues(self.FIELD_MAP))

        for label_ in sorted(self.custom_column_label_map):
            data = self.custom_column_label_map[label_]
            label = self.field_metadata.custom_field_prefix + label_
            metadata = self.field_metadata[label].copy()
            link_table = self.custom_table_names(data['num'])[1]
            self.FIELD_MAP[data['num']] = base = base+1
            self.field_metadata.set_field_record_index(label_, base,
                    prefer_custom=True)
            if data['datatype'] == 'series':
                # account for the series index column. Field_metadata knows that
                # the series index is one larger than the series. If you change
                # it here, be sure to change it there as well.
                self.FIELD_MAP[str(data['num'])+'_index'] = base = base+1
                self.field_metadata.set_field_record_index(label_+'_index', base,
                            prefer_custom=True)

            if data['normalized']:
                if metadata['is_multiple']:
                    tables[label] = ManyToManyTable(label, metadata,
                            link_table=link_table)
                else:
                    tables[label] = ManyToOneTable(label, metadata,
                            link_table=link_table)
                    if metadata['datatype'] == 'series':
                        # Create series index table
                        label += '_index'
                        metadata = self.field_metadata[label].copy()
                        metadata['column'] = 'extra'
                        metadata['table'] = link_table
                        tables[label] = OneToOneTable(label, metadata)
            else:
                if data['datatype'] == 'composite':
                    tables[label] = CompositeTable(label, metadata)
                else:
                    tables[label] = OneToOneTable(label, metadata)

        self.FIELD_MAP['ondevice'] = base = base+1
        self.field_metadata.set_field_record_index('ondevice', base, prefer_custom=False)
        self.FIELD_MAP['marked'] = base = base+1
        self.field_metadata.set_field_record_index('marked', base, prefer_custom=False)
        self.FIELD_MAP['series_sort'] = base = base+1
        self.field_metadata.set_field_record_index('series_sort', base, prefer_custom=False)
        self.FIELD_MAP['in_tag_browser'] = base = base+1
        self.field_metadata.set_field_record_index('in_tag_browser', base, prefer_custom=False)

    # }}}

    def initialize_fts(self, dbref):
        self.fts = None
        if not self.prefs['fts_enabled']:
            return
        from .fts.connect import FTS
        self.fts = FTS(dbref)
        return self.fts

    def enable_fts(self, dbref=None):
        enabled = dbref is not None
        self.prefs['fts_enabled'] = enabled
        self.initialize_fts(dbref)
        if self.fts is not None:
            self.fts.dirty_existing()
        return self.fts

    @property
    def fts_enabled(self):
        return getattr(self, 'fts', None) is not None

    @property
    def fts_has_idle_workers(self):
        return self.fts_enabled and self.fts.pool.num_of_idle_workers > 0

    @property
    def fts_num_of_workers(self):
        return self.fts.pool.num_of_workers if self.fts_enabled else 0

    @fts_num_of_workers.setter
    def fts_num_of_workers(self, num):
        if self.fts_enabled:
            self.fts.pool.num_of_workers = num

    def get_next_fts_job(self):
        return self.fts.get_next_fts_job()

    def reindex_fts(self):
        if self.conn.fts_dbpath:
            self.conn.execute('DETACH fts_db')
            os.remove(self.conn.fts_dbpath)
            self.conn.fts_dbpath = None

    def remove_dirty_fts(self, book_id, fmt):
        return self.fts.remove_dirty(book_id, fmt)

    def queue_fts_job(self, book_id, fmt, path, fmt_size, fmt_hash, start_time):
        return self.fts.queue_job(book_id, fmt, path, fmt_size, fmt_hash, start_time)

    def commit_fts_result(self, book_id, fmt, fmt_size, fmt_hash, text, err_msg):
        if self.fts is not None:
            return self.fts.commit_result(book_id, fmt, fmt_size, fmt_hash, text, err_msg)

    def fts_unindex(self, book_id, fmt=None):
        self.fts.unindex(book_id, fmt=fmt)

    def reindex_fts_book(self, book_id, *fmts):
        return self.fts.dirty_book(book_id, *fmts)

    def fts_search(self,
        fts_engine_query, use_stemming, highlight_start, highlight_end, snippet_size, restrict_to_book_ids, return_text, process_each_result
    ):
        yield from self.fts.search(
            fts_engine_query, use_stemming, highlight_start, highlight_end, snippet_size, restrict_to_book_ids, return_text, process_each_result)

    def shutdown_fts(self):
        if self.fts_enabled:
            self.fts.shutdown()

    def join_fts(self):
        if self.fts:
            self.fts.pool.join()
            self.fts = None

    def get_connection(self):
        return self.conn

    @property
    def conn(self):
        if self._conn is None:
            self._conn = Connection(self.dbpath)
            self.is_closed = False
            if self._exists and self.user_version == 0:
                self._conn.close()
                os.remove(self.dbpath)
                self._conn = Connection(self.dbpath)
        return self._conn

    def execute(self, sql, bindings=None):
        try:
            return self.conn.cursor().execute(sql, bindings)
        except apsw.IOError:
            # This can happen if the computer was suspended see for example:
            # https://bugs.launchpad.net/bugs/1286522. Try to reopen the db
            if not self.conn.getautocommit():
                raise  # We are in a transaction, re-opening the db will fail anyway
            self.reopen(force=True)
            return self.conn.cursor().execute(sql, bindings)

    def executemany(self, sql, sequence_of_bindings):
        try:
            with self.conn:  # Disable autocommit mode, for performance
                return self.conn.cursor().executemany(sql, sequence_of_bindings)
        except apsw.IOError:
            # This can happen if the computer was suspended see for example:
            # https://bugs.launchpad.net/bugs/1286522. Try to reopen the db
            if not self.conn.getautocommit():
                raise  # We are in a transaction, re-opening the db will fail anyway
            self.reopen(force=True)
            with self.conn:  # Disable autocommit mode, for performance
                return self.conn.cursor().executemany(sql, sequence_of_bindings)

    def get(self, *args, **kw):
        ans = self.execute(*args)
        if kw.get('all', True):
            return ans.fetchall()
        try:
            return next(ans)[0]
        except (StopIteration, IndexError):
            return None

    def last_insert_rowid(self):
        return self.conn.last_insert_rowid()

    def custom_field_name(self, label=None, num=None):
        if label is not None:
            return self.field_metadata.custom_field_prefix + label
        return self.field_metadata.custom_field_prefix + self.custom_column_num_to_label_map[num]

    def custom_field_metadata(self, label=None, num=None):
        if label is not None:
            return self.custom_column_label_map[label]
        return self.custom_column_num_map[num]

    def set_custom_column_metadata(self, num, name=None, label=None, is_editable=None, display=None):
        changed = False
        if name is not None:
            self.execute('UPDATE custom_columns SET name=? WHERE id=?', (name, num))
            changed = True
        if label is not None:
            self.execute('UPDATE custom_columns SET label=? WHERE id=?', (label, num))
            changed = True
        if is_editable is not None:
            self.execute('UPDATE custom_columns SET editable=? WHERE id=?', (bool(is_editable), num))
            self.custom_column_num_map[num]['is_editable'] = bool(is_editable)
            changed = True
        if display is not None:
            self.execute('UPDATE custom_columns SET display=? WHERE id=?', (json.dumps(display), num))
            changed = True
        # Note: the caller is responsible for scheduling a metadata backup if necessary
        return changed

    def create_custom_column(self, label, name, datatype, is_multiple, editable=True, display={}):  # {{{
        import re
        if not label:
            raise ValueError(_('No label was provided'))
        if re.match(r'^\w*$', label) is None or not label[0].isalpha() or label.lower() != label:
            raise ValueError(_('The label must contain only lower case letters, digits and underscores, and start with a letter'))
        if datatype not in CUSTOM_DATA_TYPES:
            raise ValueError('%r is not a supported data type'%datatype)
        normalized  = datatype not in ('datetime', 'comments', 'int', 'bool',
                'float', 'composite')
        is_multiple = is_multiple and datatype in ('text', 'composite')
        self.execute(
                ('INSERT INTO '
                'custom_columns(label,name,datatype,is_multiple,editable,display,normalized)'
                'VALUES (?,?,?,?,?,?,?)'),
                (label, name, datatype, is_multiple, editable, json.dumps(display), normalized))
        num = self.conn.last_insert_rowid()

        if datatype in ('rating', 'int'):
            dt = 'INT'
        elif datatype in ('text', 'comments', 'series', 'composite', 'enumeration'):
            dt = 'TEXT'
        elif datatype in ('float',):
            dt = 'REAL'
        elif datatype == 'datetime':
            dt = 'timestamp'
        elif datatype == 'bool':
            dt = 'BOOL'
        collate = 'COLLATE NOCASE' if dt == 'TEXT' else ''
        table, lt = self.custom_table_names(num)
        if normalized:
            if datatype == 'series':
                s_index = 'extra REAL,'
            else:
                s_index = ''
            lines = [
                '''\
                CREATE TABLE %s(
                    id    INTEGER PRIMARY KEY AUTOINCREMENT,
                    value %s NOT NULL %s,
                    link TEXT NOT NULL DEFAULT "",
                    UNIQUE(value));
                '''%(table, dt, collate),

                'CREATE INDEX %s_idx ON %s (value %s);'%(table, table, collate),

                '''\
                CREATE TABLE %s(
                    id INTEGER PRIMARY KEY AUTOINCREMENT,
                    book INTEGER NOT NULL,
                    value INTEGER NOT NULL,
                    %s
                    UNIQUE(book, value)
                    );'''%(lt, s_index),

                'CREATE INDEX %s_aidx ON %s (value);'%(lt,lt),
                'CREATE INDEX %s_bidx ON %s (book);'%(lt,lt),

                '''\
                CREATE TRIGGER fkc_update_{lt}_a
                        BEFORE UPDATE OF book ON {lt}
                        BEGIN
                            SELECT CASE
                                WHEN (SELECT id from books WHERE id=NEW.book) IS NULL
                                THEN RAISE(ABORT, 'Foreign key violation: book not in books')
                            END;
                        END;
                CREATE TRIGGER fkc_update_{lt}_b
                        BEFORE UPDATE OF author ON {lt}
                        BEGIN
                            SELECT CASE
                                WHEN (SELECT id from {table} WHERE id=NEW.value) IS NULL
                                THEN RAISE(ABORT, 'Foreign key violation: value not in {table}')
                            END;
                        END;
                CREATE TRIGGER fkc_insert_{lt}
                        BEFORE INSERT ON {lt}
                        BEGIN
                            SELECT CASE
                                WHEN (SELECT id from books WHERE id=NEW.book) IS NULL
                                THEN RAISE(ABORT, 'Foreign key violation: book not in books')
                                WHEN (SELECT id from {table} WHERE id=NEW.value) IS NULL
                                THEN RAISE(ABORT, 'Foreign key violation: value not in {table}')
                            END;
                        END;
                CREATE TRIGGER fkc_delete_{lt}
                        AFTER DELETE ON {table}
                        BEGIN
                            DELETE FROM {lt} WHERE value=OLD.id;
                        END;

                CREATE VIEW tag_browser_{table} AS SELECT
                    id,
                    value,
                    (SELECT COUNT(id) FROM {lt} WHERE value={table}.id) count,
                    (SELECT AVG(r.rating)
                     FROM {lt},
                          books_ratings_link as bl,
                          ratings as r
                     WHERE {lt}.value={table}.id and bl.book={lt}.book and
                           r.id = bl.rating and r.rating <> 0) avg_rating,
                    value AS sort
                FROM {table};

                CREATE VIEW tag_browser_filtered_{table} AS SELECT
                    id,
                    value,
                    (SELECT COUNT({lt}.id) FROM {lt} WHERE value={table}.id AND
                    books_list_filter(book)) count,
                    (SELECT AVG(r.rating)
                     FROM {lt},
                          books_ratings_link as bl,
                          ratings as r
                     WHERE {lt}.value={table}.id AND bl.book={lt}.book AND
                           r.id = bl.rating AND r.rating <> 0 AND
                           books_list_filter(bl.book)) avg_rating,
                    value AS sort
                FROM {table};

                '''.format(lt=lt, table=table),

            ]
        else:
            lines = [
                '''\
                CREATE TABLE %s(
                    id    INTEGER PRIMARY KEY AUTOINCREMENT,
                    book  INTEGER,
                    value %s NOT NULL %s,
                    UNIQUE(book));
                '''%(table, dt, collate),

                'CREATE INDEX %s_idx ON %s (book);'%(table, table),

                '''\
                CREATE TRIGGER fkc_insert_{table}
                        BEFORE INSERT ON {table}
                        BEGIN
                            SELECT CASE
                                WHEN (SELECT id from books WHERE id=NEW.book) IS NULL
                                THEN RAISE(ABORT, 'Foreign key violation: book not in books')
                            END;
                        END;
                CREATE TRIGGER fkc_update_{table}
                        BEFORE UPDATE OF book ON {table}
                        BEGIN
                            SELECT CASE
                                WHEN (SELECT id from books WHERE id=NEW.book) IS NULL
                                THEN RAISE(ABORT, 'Foreign key violation: book not in books')
                            END;
                        END;
                '''.format(table=table),
            ]
        script = ' \n'.join(lines)
        self.execute(script)
        self.prefs.set('update_all_last_mod_dates_on_start', True)
        return num
    # }}}

    def delete_custom_column(self, label=None, num=None):
        data = self.custom_field_metadata(label, num)
        self.execute('UPDATE custom_columns SET mark_for_delete=1 WHERE id=?', (data['num'],))

    def close(self, force=False, unload_formatter_functions=True):
        if getattr(self, '_conn', None) is not None:
            if unload_formatter_functions:
                try:
                    unload_user_template_functions(self.library_id)
                except Exception:
                    pass
            self._conn.close(force)
            del self._conn
            self.is_closed = True

    def reopen(self, force=False):
        self.close(force=force, unload_formatter_functions=False)
        self._conn = None
        self.conn

    def dump_and_restore(self, callback=None, sql=None):
        import codecs
        from apsw import Shell
        if callback is None:
            def callback(x):
                return x
        uv = int(self.user_version)

        with TemporaryFile(suffix='.sql') as fname:
            if sql is None:
                callback(_('Dumping database to SQL') + '...')
                with codecs.open(fname, 'wb', encoding='utf-8') as buf:
                    shell = Shell(db=self.conn, stdout=buf)
                    shell.process_command('.dump')
            else:
                with open(fname, 'wb') as buf:
                    buf.write(sql if isinstance(sql, bytes) else sql.encode('utf-8'))

            with TemporaryFile(suffix='_tmpdb.db', dir=os.path.dirname(self.dbpath)) as tmpdb:
                callback(_('Restoring database from SQL') + '...')
                with closing(Connection(tmpdb)) as conn:
                    shell = Shell(db=conn, encoding='utf-8')
                    shell.process_command('.read ' + fname.replace(os.sep, '/'))
                    conn.execute('PRAGMA user_version=%d;'%uv)

                self.close(unload_formatter_functions=False)
                try:
                    atomic_rename(tmpdb, self.dbpath)
                finally:
                    self.reopen()

    def vacuum(self, include_fts_db):
        self.execute('VACUUM')
        if self.fts_enabled and include_fts_db:
            self.fts.vacuum()

    @property
    def user_version(self):
        '''The user version of this database'''
        return self.conn.get('pragma user_version;', all=False)

    @user_version.setter
    def user_version(self, val):
        self.execute('pragma user_version=%d'%int(val))

    def initialize_database(self):
        metadata_sqlite = P('metadata_sqlite.sql', data=True,
                allow_user_override=False).decode('utf-8')
        cur = self.conn.cursor()
        cur.execute('BEGIN EXCLUSIVE TRANSACTION')
        try:
            cur.execute(metadata_sqlite)
        except:
            cur.execute('ROLLBACK')
            raise
        else:
            cur.execute('COMMIT')
        if self.user_version == 0:
            self.user_version = 1
    # }}}

    def normpath(self, path):
        path = os.path.abspath(os.path.realpath(path))
        if not self.is_case_sensitive:
            path = os.path.normcase(path).lower()
        return path

    def is_deletable(self, path):
        return path and not self.normpath(self.library_path).startswith(self.normpath(path))

    def rmtree(self, path):
        if self.is_deletable(path):
            rmtree_with_retry(path)

    def construct_path_name(self, book_id, title, author):
        '''
        Construct the directory name for this book based on its metadata.
        '''
        book_id = BOOK_ID_PATH_TEMPLATE.format(book_id)
        l = self.PATH_LIMIT - (len(book_id) // 2) - 2
        author = ascii_filename(author)[:l]
        title  = ascii_filename(title.lstrip())[:l].rstrip()
        if not title:
            title = 'Unknown'[:l]
        try:
            while author[-1] in (' ', '.'):
                author = author[:-1]
        except IndexError:
            author = ''
        if not author:
            author = ascii_filename(_('Unknown'))
        if author.upper() in WINDOWS_RESERVED_NAMES:
            author += 'w'
        return f'{author}/{title}{book_id}'

    def construct_file_name(self, book_id, title, author, extlen):
        '''
        Construct the file name for this book based on its metadata.
        '''
        extlen = max(extlen, 14)  # 14 accounts for ORIGINAL_EPUB
        # The PATH_LIMIT on windows already takes into account the doubling
        # (it is used to enforce the total path length limit, individual path
        # components can be much longer than the total path length would allow on
        # windows).
        l = (self.PATH_LIMIT - (extlen // 2) - 2) if iswindows else ((self.PATH_LIMIT - extlen - 2) // 2)
        if l < 5:
            raise ValueError('Extension length too long: %d' % extlen)
        author = ascii_filename(author)[:l]
        title  = ascii_filename(title.lstrip())[:l].rstrip()
        if not title:
            title = 'Unknown'[:l]
        name   = title + ' - ' + author
        while name.endswith('.'):
            name = name[:-1]
        if not name:
            name = ascii_filename(_('Unknown'))
        return name

    # Database layer API {{{

    def custom_table_names(self, num):
        return 'custom_column_%d'%num, 'books_custom_column_%d_link'%num

    @property
    def custom_tables(self):
        return {x[0] for x in self.conn.get(
            'SELECT name FROM sqlite_master WHERE type=\'table\' AND '
            '(name GLOB \'custom_column_*\' OR name GLOB \'books_custom_column_*\')')}

    @classmethod
    def exists_at(cls, path):
        return path and os.path.exists(os.path.join(path, 'metadata.db'))

    @property
    def library_id(self):
        '''The UUID for this library. As long as the user only operates  on libraries with calibre, it will be unique'''

        if getattr(self, '_library_id_', None) is None:
            ans = self.conn.get('SELECT uuid FROM library_id', all=False)
            if ans is None:
                ans = str(uuid.uuid4())
                self.library_id = ans
            else:
                self._library_id_ = ans
        return self._library_id_

    @library_id.setter
    def library_id(self, val):
        self._library_id_ = str(val)
        self.execute('''
                DELETE FROM library_id;
                INSERT INTO library_id (uuid) VALUES (?);
                ''', (self._library_id_,))

    def last_modified(self):
        ''' Return last modified time as a UTC datetime object '''
        return utcfromtimestamp(os.stat(self.dbpath).st_mtime)

    def read_tables(self):
        '''
        Read all data from the db into the python in-memory tables
        '''

        with self.conn:  # Use a single transaction, to ensure nothing modifies the db while we are reading
            for table in itervalues(self.tables):
                try:
                    table.read(self)
                except:
                    prints('Failed to read table:', table.name)
                    import pprint
                    pprint.pprint(table.metadata)
                    raise

    def find_path_for_book(self, book_id):
        q = BOOK_ID_PATH_TEMPLATE.format(book_id)
        for author_dir in os.scandir(self.library_path):
            if not author_dir.is_dir():
                continue
            try:
                book_dir_iter = os.scandir(author_dir.path)
            except OSError:
                pass
            else:
                for book_dir in book_dir_iter:
                    if book_dir.name.endswith(q) and book_dir.is_dir():
                        return book_dir.path

    def format_abspath(self, book_id, fmt, fname, book_path):
        path = os.path.join(self.library_path, book_path)
        fmt = ('.' + fmt.lower()) if fmt else ''
        fmt_path = os.path.join(path, fname+fmt)
        if os.path.exists(fmt_path):
            return fmt_path
        if not fmt:
            return
        candidates = ()
        with suppress(OSError):
            candidates = os.listdir(path)
        q = fmt.lower()
        for x in candidates:
            if x.lower().endswith(q):
                x = os.path.join(path, x)
                with suppress(OSError):
                    atomic_rename(x, fmt_path)
                    return fmt_path
                try:
                    shutil.move(x, fmt_path)
                except (shutil.SameFileError, OSError):
                    # some other process synced in the file since the last
                    # os.path.exists()
                    return x
                return fmt_path

    def cover_abspath(self, book_id, path):
        path = os.path.join(self.library_path, path)
        fmt_path = os.path.join(path, 'cover.jpg')
        if os.path.exists(fmt_path):
            return fmt_path

    def apply_to_format(self, book_id, path, fname, fmt, func, missing_value=None):
        path = self.format_abspath(book_id, fmt, fname, path)
        if path is None:
            return missing_value
        with open(path, 'r+b') as f:
            return func(f)

    def format_hash(self, book_id, fmt, fname, path):
        path = self.format_abspath(book_id, fmt, fname, path)
        if path is None:
            raise NoSuchFormat('Record %d has no fmt: %s'%(book_id, fmt))
        sha = hashlib.sha256()
        with open(path, 'rb') as f:
            while True:
                raw = f.read(SPOOL_SIZE)
                sha.update(raw)
                if len(raw) < SPOOL_SIZE:
                    break
        return sha.hexdigest()

    def format_metadata(self, book_id, fmt, fname, path):
        path = self.format_abspath(book_id, fmt, fname, path)
        ans = {}
        if path is not None:
            stat = os.stat(path)
            ans['path'] = path
            ans['size'] = stat.st_size
            ans['mtime'] = utcfromtimestamp(stat.st_mtime)
        return ans

    def has_format(self, book_id, fmt, fname, path):
        return self.format_abspath(book_id, fmt, fname, path) is not None

    def is_format_accessible(self, book_id, fmt, fname, path):
        fpath = self.format_abspath(book_id, fmt, fname, path)
        return fpath and os.access(fpath, os.R_OK | os.W_OK)

    def rename_format_file(self, book_id, src_fname, src_fmt, dest_fname, dest_fmt, path):
        src_path = self.format_abspath(book_id, src_fmt, src_fname, path)
        dest_path = self.format_abspath(book_id, dest_fmt, dest_fname, path)
        atomic_rename(src_path, dest_path)
        return os.path.getsize(dest_path)

    def remove_formats(self, remove_map):
        paths = []
        for book_id, removals in iteritems(remove_map):
            for fmt, fname, path in removals:
                path = self.format_abspath(book_id, fmt, fname, path)
                if path is not None:
                    paths.append(path)
        try:
            delete_service().delete_files(paths, self.library_path)
        except:
            import traceback
            traceback.print_exc()

    def cover_last_modified(self, path):
        path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
        try:
            return utcfromtimestamp(os.stat(path).st_mtime)
        except OSError:
            pass  # Cover doesn't exist

    def copy_cover_to(self, path, dest, windows_atomic_move=None, use_hardlink=False, report_file_size=None):
        path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
        if windows_atomic_move is not None:
            if not isinstance(dest, string_or_bytes):
                raise Exception('Error, you must pass the dest as a path when'
                        ' using windows_atomic_move')
            if os.access(path, os.R_OK) and dest and not samefile(dest, path):
                windows_atomic_move.copy_path_to(path, dest)
                return True
        else:
            if os.access(path, os.R_OK):
                try:
                    f = open(path, 'rb')
                except OSError:
                    time.sleep(0.2)
                    try:
                        f = open(path, 'rb')
                    except OSError as e:
                        # Ensure the path that caused this error is reported
                        raise Exception(f'Failed to open {path!r} with error: {e}')

                with f:
                    if hasattr(dest, 'write'):
                        if report_file_size is not None:
                            f.seek(0, os.SEEK_END)
                            report_file_size(f.tell())
                            f.seek(0)
                        shutil.copyfileobj(f, dest)
                        if hasattr(dest, 'flush'):
                            dest.flush()
                        return True
                    elif dest and not samefile(dest, path):
                        if use_hardlink:
                            try:
                                hardlink_file(path, dest)
                                return True
                            except:
                                pass
                        with open(dest, 'wb') as d:
                            shutil.copyfileobj(f, d)
                        return True
        return False

    def cover_or_cache(self, path, timestamp):
        path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
        try:
            stat = os.stat(path)
        except OSError:
            return False, None, None
        if abs(timestamp - stat.st_mtime) < 0.1:
            return True, None, None
        try:
            f = open(path, 'rb')
        except OSError:
            time.sleep(0.2)
        f = open(path, 'rb')
        with f:
            return True, f.read(), stat.st_mtime

    def compress_covers(self, path_map, jpeg_quality, progress_callback):
        cpath_map = {}
        if not progress_callback:
            def progress_callback(book_id, old_sz, new_sz):
                return None
        for book_id, path in path_map.items():
            path = os.path.abspath(os.path.join(self.library_path, path, 'cover.jpg'))
            try:
                sz = os.path.getsize(path)
            except OSError:
                progress_callback(book_id, 0, 'ENOENT')
            else:
                cpath_map[book_id] = (path, sz)
        from calibre.db.covers import compress_covers
        compress_covers(cpath_map, jpeg_quality, progress_callback)

    def set_cover(self, book_id, path, data, no_processing=False):
        path = os.path.abspath(os.path.join(self.library_path, path))
        if not os.path.exists(path):
            os.makedirs(path)
        path = os.path.join(path, 'cover.jpg')
        if callable(getattr(data, 'save', None)):
            from calibre.gui2 import pixmap_to_data
            data = pixmap_to_data(data)
        elif callable(getattr(data, 'read', None)):
            data = data.read()
        if data is None:
            if os.path.exists(path):
                try:
                    os.remove(path)
                except OSError:
                    time.sleep(0.2)
                    os.remove(path)
        else:
            if no_processing:
                with open(path, 'wb') as f:
                    f.write(data)
            else:
                from calibre.utils.img import save_cover_data_to
                try:
                    save_cover_data_to(data, path)
                except OSError:
                    time.sleep(0.2)
                    save_cover_data_to(data, path)

    def copy_format_to(self, book_id, fmt, fname, path, dest,
                       windows_atomic_move=None, use_hardlink=False, report_file_size=None):
        path = self.format_abspath(book_id, fmt, fname, path)
        if path is None:
            return False
        if windows_atomic_move is not None:
            if not isinstance(dest, string_or_bytes):
                raise Exception('Error, you must pass the dest as a path when'
                        ' using windows_atomic_move')
            if dest:
                if samefile(dest, path):
                    # Ensure that the file has the same case as dest
                    try:
                        if path != dest:
                            os.rename(path, dest)
                    except:
                        pass  # Nothing too catastrophic happened, the cases mismatch, that's all
                else:
                    windows_atomic_move.copy_path_to(path, dest)
        else:
            if hasattr(dest, 'write'):
                with open(path, 'rb') as f:
                    if report_file_size is not None:
                        f.seek(0, os.SEEK_END)
                        report_file_size(f.tell())
                        f.seek(0)
                    shutil.copyfileobj(f, dest)
                if hasattr(dest, 'flush'):
                    dest.flush()
            elif dest:
                if samefile(dest, path):
                    if not self.is_case_sensitive and path != dest:
                        # Ensure that the file has the same case as dest
                        try:
                            os.rename(path, dest)
                        except:
                            pass  # Nothing too catastrophic happened, the cases mismatch, that's all
                else:
                    if use_hardlink:
                        try:
                            hardlink_file(path, dest)
                            return True
                        except:
                            pass
                    with open(path, 'rb') as f, open(dest, 'wb') as d:
                        shutil.copyfileobj(f, d)
        return True

    def windows_check_if_files_in_use(self, paths):
        '''
        Raises an EACCES IOError if any of the files in the folder of book_id
        are opened in another program on windows.
        '''
        if iswindows:
            for path in paths:
                spath = os.path.join(self.library_path, *path.split('/'))
                wam = None
                if os.path.exists(spath):
                    try:
                        wam = WindowsAtomicFolderMove(spath)
                    finally:
                        if wam is not None:
                            wam.close_handles()

    def add_format(self, book_id, fmt, stream, title, author, path, current_name, mtime=None):
        fmt = ('.' + fmt.lower()) if fmt else ''
        fname = self.construct_file_name(book_id, title, author, len(fmt))
        path = os.path.join(self.library_path, path)
        dest = os.path.join(path, fname + fmt)
        if not os.path.exists(path):
            os.makedirs(path)
        size = 0
        if current_name is not None:
            old_path = os.path.join(path, current_name + fmt)
            if old_path != dest:
                # Ensure that the old format file is not orphaned, this can
                # happen if the algorithm in construct_file_name is changed.
                try:
                    # rename rather than remove, so that if something goes
                    # wrong in the rest of this function, at least the file is
                    # not deleted
                    os.rename(old_path, dest)
                except OSError as e:
                    if getattr(e, 'errno', None) != errno.ENOENT:
                        # Failing to rename the old format will at worst leave a
                        # harmless orphan, so log and ignore the error
                        import traceback
                        traceback.print_exc()

        if (not getattr(stream, 'name', False) or not samefile(dest, stream.name)):
            with open(dest, 'wb') as f:
                shutil.copyfileobj(stream, f)
                size = f.tell()
            if mtime is not None:
                os.utime(dest, (mtime, mtime))
        elif os.path.exists(dest):
            size = os.path.getsize(dest)
            if mtime is not None:
                os.utime(dest, (mtime, mtime))

        return size, fname

    def update_path(self, book_id, title, author, path_field, formats_field):
        path = self.construct_path_name(book_id, title, author)
        current_path = path_field.for_book(book_id, default_value='')
        formats = formats_field.for_book(book_id, default_value=())
        try:
            extlen = max(len(fmt) for fmt in formats) + 1
        except ValueError:
            extlen = 10
        fname = self.construct_file_name(book_id, title, author, extlen)
        # Check if the metadata used to construct paths has changed
        changed = False
        for fmt in formats:
            name = formats_field.format_fname(book_id, fmt)
            if name and name != fname:
                changed = True
                break
        if path == current_path and not changed:
            return
        spath = os.path.join(self.library_path, *current_path.split('/'))
        tpath = os.path.join(self.library_path, *path.split('/'))

        source_ok = current_path and os.path.exists(spath)
        wam = WindowsAtomicFolderMove(spath) if iswindows and source_ok else None
        format_map = {}
        original_format_map = {}
        try:
            if not os.path.exists(tpath):
                os.makedirs(tpath)

            if source_ok:  # Migrate existing files
                dest = os.path.join(tpath, 'cover.jpg')
                self.copy_cover_to(current_path, dest,
                        windows_atomic_move=wam, use_hardlink=True)
                for fmt in formats:
                    dest = os.path.join(tpath, fname+'.'+fmt.lower())
                    format_map[fmt] = dest
                    ofmt_fname = formats_field.format_fname(book_id, fmt)
                    original_format_map[fmt] = os.path.join(spath, ofmt_fname+'.'+fmt.lower())
                    self.copy_format_to(book_id, fmt, ofmt_fname, current_path,
                                        dest, windows_atomic_move=wam, use_hardlink=True)
            # Update db to reflect new file locations
            with self.conn:
                for fmt in formats:
                    formats_field.table.set_fname(book_id, fmt, fname, self)
                path_field.table.set_path(book_id, path, self)

            # Delete not needed files and directories
            if source_ok:
                if os.path.exists(spath):
                    if samefile(spath, tpath):
                        # The format filenames may have changed while the folder
                        # name remains the same
                        for fmt, opath in iteritems(original_format_map):
                            npath = format_map.get(fmt, None)
                            if npath and os.path.abspath(npath.lower()) != os.path.abspath(opath.lower()) and samefile(opath, npath):
                                # opath and npath are different hard links to the same file
                                os.unlink(opath)
                    else:
                        if wam is not None:
                            wam.delete_originals()
                        self.rmtree(spath)
                        parent = os.path.dirname(spath)
                        if len(os.listdir(parent)) == 0:
                            self.rmtree(parent)
        finally:
            if wam is not None:
                wam.close_handles()

        curpath = self.library_path
        c1, c2 = current_path.split('/'), path.split('/')
        if not self.is_case_sensitive and len(c1) == len(c2):
            # On case-insensitive systems, title and author renames that only
            # change case don't cause any changes to the directories in the file
            # system. This can lead to having the directory names not match the
            # title/author, which leads to trouble when libraries are copied to
            # a case-sensitive system. The following code attempts to fix this
            # by checking each segment. If they are different because of case,
            # then rename the segment. Note that the code above correctly
            # handles files in the directories, so no need to do them here.
            for oldseg, newseg in zip(c1, c2):
                if oldseg.lower() == newseg.lower() and oldseg != newseg:
                    try:
                        os.rename(os.path.join(curpath, oldseg),
                                os.path.join(curpath, newseg))
                    except:
                        break  # Fail silently since nothing catastrophic has happened
                curpath = os.path.join(curpath, newseg)

    def write_backup(self, path, raw):
        path = os.path.abspath(os.path.join(self.library_path, path, 'metadata.opf'))
        try:
            with open(path, 'wb') as f:
                f.write(raw)
        except OSError:
            exc_info = sys.exc_info()
            try:
                os.makedirs(os.path.dirname(path))
            except OSError as err:
                if err.errno == errno.EEXIST:
                    # Parent directory already exists, re-raise original exception
                    reraise(*exc_info)
                raise
            finally:
                del exc_info
            with open(path, 'wb') as f:
                f.write(raw)

    def read_backup(self, path):
        path = os.path.abspath(os.path.join(self.library_path, path, 'metadata.opf'))
        with open(path, 'rb') as f:
            return f.read()

    def remove_books(self, path_map, permanent=False):
        self.executemany(
            'DELETE FROM books WHERE id=?', [(x,) for x in path_map])
        paths = {os.path.join(self.library_path, x) for x in itervalues(path_map) if x}
        paths = {x for x in paths if os.path.exists(x) and self.is_deletable(x)}
        if permanent:
            for path in paths:
                self.rmtree(path)
                remove_dir_if_empty(os.path.dirname(path), ignore_metadata_caches=True)
        else:
            delete_service().delete_books(paths, self.library_path)

    def add_custom_data(self, name, val_map, delete_first):
        if delete_first:
            self.execute('DELETE FROM books_plugin_data WHERE name=?', (name, ))
        self.executemany(
            'INSERT OR REPLACE INTO books_plugin_data (book, name, val) VALUES (?, ?, ?)',
            [(book_id, name, json.dumps(val, default=to_json))
                    for book_id, val in iteritems(val_map)])

    def get_custom_book_data(self, name, book_ids, default=None):
        book_ids = frozenset(book_ids)

        def safe_load(val):
            try:
                return json.loads(val, object_hook=from_json)
            except:
                return default

        if len(book_ids) == 1:
            bid = next(iter(book_ids))
            ans = {book_id:safe_load(val) for book_id, val in
                   self.execute('SELECT book, val FROM books_plugin_data WHERE book=? AND name=?', (bid, name))}
            return ans or {bid:default}

        ans = {}
        for book_id, val in self.execute(
            'SELECT book, val FROM books_plugin_data WHERE name=?', (name,)):
            if not book_ids or book_id in book_ids:
                val = safe_load(val)
                ans[book_id] = val
        return ans

    def delete_custom_book_data(self, name, book_ids):
        if book_ids:
            self.executemany('DELETE FROM books_plugin_data WHERE book=? AND name=?',
                                  [(book_id, name) for book_id in book_ids])
        else:
            self.execute('DELETE FROM books_plugin_data WHERE name=?', (name,))

    def dirtied_books(self):
        for (book_id,) in self.execute('SELECT book FROM metadata_dirtied'):
            yield book_id

    def dirty_books(self, book_ids):
        self.executemany('INSERT OR IGNORE INTO metadata_dirtied (book) VALUES (?)', ((x,) for x in book_ids))

    def mark_book_as_clean(self, book_id):
        self.execute('DELETE FROM metadata_dirtied WHERE book=?', (book_id,))

    def get_ids_for_custom_book_data(self, name):
        return frozenset(r[0] for r in self.execute('SELECT book FROM books_plugin_data WHERE name=?', (name,)))

    def annotations_for_book(self, book_id, fmt, user_type, user):
        yield from annotations_for_book(self.conn, book_id, fmt, user_type, user)

    def search_annotations(self,
        fts_engine_query, use_stemming, highlight_start, highlight_end, snippet_size, annotation_type,
        restrict_to_book_ids, restrict_to_user, ignore_removed=False
    ):
        fts_engine_query = unicode_normalize(fts_engine_query)
        fts_table = 'annotations_fts_stemmed' if use_stemming else 'annotations_fts'
        text = 'annotations.searchable_text'
        if highlight_start is not None and highlight_end is not None:
            if snippet_size is not None:
                text = "snippet({fts_table}, 0, '{highlight_start}', '{highlight_end}', '…', {snippet_size})".format(
                        fts_table=fts_table, highlight_start=highlight_start, highlight_end=highlight_end,
                        snippet_size=max(1, min(snippet_size, 64)))
            else:
                text = f"highlight({fts_table}, 0, '{highlight_start}', '{highlight_end}')"
        query = 'SELECT {0}.id, {0}.book, {0}.format, {0}.user_type, {0}.user, {0}.annot_data, {1} FROM {0} '
        query = query.format('annotations', text)
        query += ' JOIN {fts_table} ON annotations.id = {fts_table}.rowid'.format(fts_table=fts_table)
        query += f' WHERE {fts_table} MATCH ?'
        data = [fts_engine_query]
        if restrict_to_user:
            query += ' AND annotations.user_type = ? AND annotations.user = ?'
            data += list(restrict_to_user)
        if annotation_type:
            query += ' AND annotations.annot_type = ? '
            data.append(annotation_type)
        query += f' ORDER BY {fts_table}.rank '
        ls = json.loads
        try:
            for (rowid, book_id, fmt, user_type, user, annot_data, text) in self.execute(query, tuple(data)):
                if restrict_to_book_ids is not None and book_id not in restrict_to_book_ids:
                    continue
                try:
                    parsed_annot = ls(annot_data)
                except Exception:
                    continue
                if ignore_removed and parsed_annot.get('removed'):
                    continue
                yield {
                    'id': rowid,
                    'book_id': book_id,
                    'format': fmt,
                    'user_type': user_type,
                    'user': user,
                    'text': text,
                    'annotation': parsed_annot,
                }
        except apsw.SQLError as e:
            raise FTSQueryError(fts_engine_query, query, e)

    def all_annotations_for_book(self, book_id, ignore_removed=False):
        for (fmt, user_type, user, data) in self.execute(
            'SELECT format, user_type, user, annot_data FROM annotations WHERE book=?', (book_id,)
        ):
            try:
                annot = json.loads(data)
            except Exception:
                pass
            if not ignore_removed or not annot.get('removed'):
                yield {'format': fmt, 'user_type': user_type, 'user': user, 'annotation': annot}

    def delete_annotations(self, annot_ids):
        replacements = []
        removals = []
        now = utcnow()
        ts = now.isoformat()
        timestamp = (now - EPOCH).total_seconds()
        for annot_id in annot_ids:
            for (raw_annot_data, annot_type) in self.execute(
                'SELECT annot_data, annot_type FROM annotations WHERE id=?', (annot_id,)
            ):
                try:
                    annot_data = json.loads(raw_annot_data)
                except Exception:
                    removals.append((annot_id,))
                    continue
                now = utcnow()
                new_annot = {'removed': True, 'timestamp': ts, 'type': annot_type}
                uuid = annot_data.get('uuid')
                if uuid is not None:
                    new_annot['uuid'] = uuid
                else:
                    new_annot['title'] = annot_data['title']
                replacements.append((json.dumps(new_annot), timestamp, annot_id))
        if replacements:
            self.executemany("UPDATE annotations SET annot_data=?, timestamp=?, searchable_text='' WHERE id=?", replacements)
        if removals:
            self.executemany('DELETE FROM annotations WHERE id=?', removals)

    def update_annotations(self, annot_id_map):
        now = utcnow()
        ts = now.isoformat()
        timestamp = (now - EPOCH).total_seconds()
        with self.conn:
            for annot_id, annot in annot_id_map.items():
                atype = annot['type']
                aid, text = annot_db_data(annot)
                if aid is not None:
                    annot['timestamp'] = ts
                    self.execute('UPDATE annotations SET annot_data=?, timestamp=?, annot_type=?, searchable_text=?, annot_id=? WHERE id=?',
                        (json.dumps(annot), timestamp, atype, text, aid, annot_id))

    def all_annotations(self, restrict_to_user=None, limit=None, annotation_type=None, ignore_removed=False, restrict_to_book_ids=None):
        ls = json.loads
        q = 'SELECT id, book, format, user_type, user, annot_data FROM annotations'
        data = []
        restrict_clauses = []
        if restrict_to_user is not None:
            data.extend(restrict_to_user)
            restrict_clauses.append(' user_type = ? AND user = ?')
        if annotation_type:
            data.append(annotation_type)
            restrict_clauses.append(' annot_type = ? ')
        if restrict_clauses:
            q += ' WHERE ' + ' AND '.join(restrict_clauses)
        q += ' ORDER BY timestamp DESC '
        count = 0
        for (rowid, book_id, fmt, user_type, user, annot_data) in self.execute(q, tuple(data)):
            if restrict_to_book_ids is not None and book_id not in restrict_to_book_ids:
                continue
            try:
                annot = ls(annot_data)
                atype = annot['type']
            except Exception:
                continue
            if ignore_removed and annot.get('removed'):
                continue
            text = ''
            if atype == 'bookmark':
                text = annot['title']
            elif atype == 'highlight':
                text = annot.get('highlighted_text') or ''
            yield {
                'id': rowid,
                'book_id': book_id,
                'format': fmt,
                'user_type': user_type,
                'user': user,
                'text': text,
                'annotation': annot,
            }
            count += 1
            if limit is not None and count >= limit:
                break

    def all_annotation_users(self):
        return self.execute('SELECT DISTINCT user_type, user FROM annotations')

    def all_annotation_types(self):
        for x in self.execute('SELECT DISTINCT annot_type FROM annotations'):
            yield x[0]

    def set_annotations_for_book(self, book_id, fmt, annots_list, user_type='local', user='viewer'):
        try:
            with self.conn:  # Disable autocommit mode, for performance
                save_annotations_for_book(self.conn.cursor(), book_id, fmt, annots_list, user_type, user)
        except apsw.IOError:
            # This can happen if the computer was suspended see for example:
            # https://bugs.launchpad.net/bugs/1286522. Try to reopen the db
            if not self.conn.getautocommit():
                raise  # We are in a transaction, re-opening the db will fail anyway
            self.reopen(force=True)
            with self.conn:  # Disable autocommit mode, for performance
                save_annotations_for_book(self.conn.cursor(), book_id, fmt, annots_list, user_type, user)

    def dirty_books_with_dirtied_annotations(self):
        with self.conn:
            self.execute('INSERT or IGNORE INTO metadata_dirtied(book) SELECT book FROM annotations_dirtied;')
            changed = self.conn.changes() > 0
            if changed:
                self.execute('DELETE FROM annotations_dirtied')
        return changed

    def annotation_count_for_book(self, book_id):
        for (count,) in self.execute('''
                 SELECT count(id) FROM annotations
                 WHERE book=? AND json_extract(annot_data, '$.removed') IS NULL
                 ''', (book_id,)):
            return count
        return 0

    def reindex_annotations(self):
        self.execute('''
            INSERT INTO {0}({0}) VALUES('rebuild');
            INSERT INTO {1}({1}) VALUES('rebuild');
        '''.format('annotations_fts', 'annotations_fts_stemmed'))

    def conversion_options(self, book_id, fmt):
        for (data,) in self.conn.get('SELECT data FROM conversion_options WHERE book=? AND format=?', (book_id, fmt.upper())):
            if data:
                try:
                    return unpickle_binary_string(bytes(data))
                except Exception:
                    pass

    def has_conversion_options(self, ids, fmt='PIPE'):
        ids = frozenset(ids)
        with self.conn:
            self.execute('DROP TABLE IF EXISTS conversion_options_temp; CREATE TEMP TABLE conversion_options_temp (id INTEGER PRIMARY KEY);')
            self.executemany('INSERT INTO conversion_options_temp VALUES (?)', [(x,) for x in ids])
            for (book_id,) in self.conn.get(
                'SELECT book FROM conversion_options WHERE format=? AND book IN (SELECT id FROM conversion_options_temp)', (fmt.upper(),)):
                return True
            return False

    def delete_conversion_options(self, book_ids, fmt):
        self.executemany('DELETE FROM conversion_options WHERE book=? AND format=?',
            [(book_id, fmt.upper()) for book_id in book_ids])

    def set_conversion_options(self, options, fmt):
        def map_data(x):
            if not isinstance(x, string_or_bytes):
                x = native_string_type(x)
            x = x.encode('utf-8') if isinstance(x, str) else x
            x = pickle_binary_string(x)
            return x
        options = [(book_id, fmt.upper(), map_data(data)) for book_id, data in iteritems(options)]
        self.executemany('INSERT OR REPLACE INTO conversion_options(book,format,data) VALUES (?,?,?)', options)

    def get_top_level_move_items(self, all_paths):
        items = set(os.listdir(self.library_path))
        paths = set(all_paths)
        paths.update({'metadata.db', 'full-text-search.db', 'metadata_db_prefs_backup.json'})
        path_map = {x:x for x in paths}
        if not self.is_case_sensitive:
            for x in items:
                path_map[x.lower()] = x
            items = {x.lower() for x in items}
            paths = {x.lower() for x in paths}
        items = items.intersection(paths)
        return items, path_map

    def move_library_to(self, all_paths, newloc, progress=(lambda item_name, item_count, total: None), abort=None):
        if not os.path.exists(newloc):
            os.makedirs(newloc)
        old_dirs, old_files = set(), set()
        items, path_map = self.get_top_level_move_items(all_paths)
        total = len(items) + 1
        for i, x in enumerate(items):
            if abort is not None and abort.is_set():
                return
            src = os.path.join(self.library_path, x)
            dest = os.path.join(newloc, path_map[x])
            if os.path.isdir(src):
                if os.path.exists(dest):
                    shutil.rmtree(dest)
                copytree_using_links(src, dest, dest_is_parent=False)
                old_dirs.add(src)
            else:
                if os.path.exists(dest):
                    os.remove(dest)
                copyfile_using_links(src, dest, dest_is_dir=False)
                old_files.add(src)
            x = path_map[x]
            if not isinstance(x, str):
                x = x.decode(filesystem_encoding, 'replace')
            progress(x, i+1, total)

        dbpath = os.path.join(newloc, os.path.basename(self.dbpath))
        odir = self.library_path
        self.conn.close()
        self.library_path, self.dbpath = newloc, dbpath
        if self._conn is not None:
            self._conn.close()
        self._conn = None
        for loc in old_dirs:
            try:
                rmtree_with_retry(loc)
            except OSError as e:
                if os.path.exists(loc):
                    prints('Failed to delete:', loc, 'with error:', as_unicode(e))
        for loc in old_files:
            try:
                os.remove(loc)
            except OSError as e:
                if e.errno != errno.ENOENT:
                    prints('Failed to delete:', loc, 'with error:', as_unicode(e))
        try:
            os.rmdir(odir)
        except OSError:
            pass
        self.conn  # Connect to the moved metadata.db
        progress(_('Completed'), total, total)

    def restore_book(self, book_id, path, formats):
        self.execute('UPDATE books SET path=? WHERE id=?', (path.replace(os.sep, '/'), book_id))
        vals = [(book_id, fmt, size, name) for fmt, size, name in formats]
        self.executemany('INSERT INTO data (book,format,uncompressed_size,name) VALUES (?,?,?,?)', vals)

    def backup_database(self, path):
        with closing(apsw.Connection(path)) as dest_db:
            with dest_db.backup('main', self.conn, 'main') as b:
                while not b.done:
                    with suppress(apsw.BusyError):
                        b.step(128)
            dest_db.cursor().execute('DELETE FROM metadata_dirtied; VACUUM;')

    def backup_fts_database(self, path):
        with closing(apsw.Connection(path)) as dest_db:
            with dest_db.backup('main', self.conn, 'fts_db') as b:
                while not b.done:
                    with suppress(apsw.BusyError):
                        b.step(128)
    # }}}
