# vim: set fileencoding=utf-8 :
#
# (C) 2011,2015,2017 Guido Günther <agx@sigxcpu.org>
# (C) 2012 Intel Corporation <markus.lehtonen@linux.intel.com>
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, please see
#    <http://www.gnu.org/licenses/>
#
"""Common functionality for Debian and RPM patchqueue management"""

import re
import os
import datetime
import time
from email.message import Message
from email.header import Header
from email.charset import Charset, QP
from email.policy import Compat32

from gbp.git import GitRepositoryError
from gbp.git.modifier import GitModifier, GitTz
from gbp.errors import GbpError
import gbp.log

PQ_BRANCH_PREFIX = "patch-queue/"


def is_pq_branch(branch):
    """
    is branch a patch-queue branch?

    >>> is_pq_branch("foo")
    False
    >>> is_pq_branch("patch-queue/foo")
    True
    """
    return [False, True][branch.startswith(PQ_BRANCH_PREFIX)]


def pq_branch_name(branch):
    """
    get the patch queue branch corresponding to branch

    >>> pq_branch_name("patch-queue/master")
    'patch-queue/master'
    >>> pq_branch_name("foo")
    'patch-queue/foo'
    """
    if not is_pq_branch(branch):
        return PQ_BRANCH_PREFIX + branch
    else:
        return branch


def pq_branch_base(branch):
    """
    get the branch corresponding to the given patch queue branch

    >>> pq_branch_base("patch-queue/master")
    'master'
    >>> pq_branch_base("foo")
    'foo'
    """
    if is_pq_branch(branch):
        return branch[len(PQ_BRANCH_PREFIX):]
    else:
        return branch


def parse_gbp_commands(info, cmd_tag, noarg_cmds, arg_cmds, filter_cmds=None):
    """
    Parses gbp commands from commit message. Args with and wthout
    arguments are supported as is filtering out of commands from the
    commit body.

    @param info: the commit into to parse for commands
    @param cmd_tag: the command tag
    @param noarg_cmds: commands without an argument
    @type  noarg_cmds: C{list} of C{str}
    @param arg_cmds: command with an argumnt
    @type  arg_cmds: C{list} of C{str}
    @param filter_cmds: commands to filter out of the passed in info
    @type  filter_cmds: C{list} of C{str}
    @returns: the parsed commands and the filtered commit body.
    """
    body = []
    cmd_re = re.compile(r'^%s:\s*(?P<cmd>[a-z-]+)(\s+(?P<args>\S.*))?' %
                        cmd_tag, flags=re.I)
    commands = {}
    for line in info['body'].splitlines():
        match = re.match(cmd_re, line)
        if match:
            cmd = match.group('cmd').lower()
            if arg_cmds and cmd in arg_cmds:
                if match.group('args'):
                    commands[cmd] = match.group('args')
                else:
                    gbp.log.warn("Ignoring gbp-command '%s' in commit %s: "
                                 "missing cmd arguments" % (line, info['id']))
            elif noarg_cmds and cmd in noarg_cmds:
                commands[cmd] = match.group('args')
            else:
                gbp.log.warn("Ignoring unknown gbp-command '%s' in commit %s"
                             % (line, info['id']))
            if filter_cmds is None or cmd not in filter_cmds:
                body.append(line)
        else:
            body.append(line)
    msg = '\n'.join(body)
    return (commands, msg)


def patch_path_filter(file_status, exclude_regex=None):
    """
    Create patch include paths, i.e. a "negation" of the exclude paths.
    """
    if exclude_regex:
        include_paths = []
        for file_list in file_status.values():
            for fname in file_list:
                if not re.match(exclude_regex, fname):
                    include_paths.append(fname)
    else:
        include_paths = ['.']

    return include_paths


def write_patch_file(filename, commit_info, diff):
    """Write patch file"""
    if not diff:
        gbp.log.debug("I won't generate empty diff %s" % filename)
        return None
    try:
        with open(filename, 'wb') as patch:
            msg = Message()
            charset = Charset('utf-8')
            charset.body_encoding = None
            charset.header_encoding = QP

            # Write headers
            name = commit_info['author']['name']
            email = commit_info['author']['email']
            # Git compat: put name in quotes if special characters found
            if re.search(r'[,.@()\[\]\\\:;]', name):
                name = '"%s"' % name
            from_header = Header(header_name='from')
            try:
                from_header.append(name, 'us-ascii')
            except UnicodeDecodeError:
                from_header.append(name, charset)
            from_header.append('<%s>' % email)
            msg['From'] = from_header
            date = commit_info['author'].datetime
            datestr = date.strftime('%a, %-d %b %Y %H:%M:%S %z')
            msg['Date'] = Header(datestr, 'us-ascii', 'date')
            subject_header = Header(header_name='subject')
            try:
                subject_header.append(commit_info['subject'], 'us-ascii')
            except UnicodeDecodeError:
                subject_header.append(commit_info['subject'], charset)
            msg['Subject'] = subject_header
            # Write message body
            if commit_info['body']:
                # Strip extra linefeeds
                body = commit_info['body'].rstrip() + '\n'
                try:
                    msg.set_payload(body.encode('us-ascii'))
                except (UnicodeEncodeError):
                    msg.set_payload(body, charset)
            policy = Compat32(max_line_length=77)
            patch.write(msg.as_bytes(unixfrom=False, policy=policy))

            # Write diff
            patch.write(b'---\n')
            patch.write(diff)
    except IOError as err:
        raise GbpError('Unable to create patch file: %s' % err)
    return filename


DEFAULT_PATCH_NUM_PREFIX_FORMAT = "%04d-"


def format_patch(outdir, repo, commit_info, series, abbrev, numbered=True,
                 path_exclude_regex=None, topic='', name=None, renumber=False,
                 patch_num_prefix_format=DEFAULT_PATCH_NUM_PREFIX_FORMAT):
    """Create patch of a single commit"""

    # Determine filename and path
    outdir = os.path.join(outdir, topic)
    if not os.path.exists(outdir):
        os.makedirs(outdir)

    try:
        num_prefix = str(patch_num_prefix_format) % (len(series) + 1) \
            if numbered else ''
    except Exception:
        gbp.log.warn("Bad format format string '%s', "
                     "falling back to default '%s'" %
                     (str(patch_num_prefix_format),
                      DEFAULT_PATCH_NUM_PREFIX_FORMAT))
        num_prefix = DEFAULT_PATCH_NUM_PREFIX_FORMAT % (len(series) + 1)

    if name is not None:
        if renumber:
            # Remove any existing numeric prefix if the patch
            # should be renumbered
            name = re.sub(r'^\d+[-_]*', '', name)
        else:
            # Otherwise, clear proposed prefix
            num_prefix = ''
        (base, suffix) = os.path.splitext(name)
    else:
        suffix = '.patch'
        base_maxlen = 63 - len(num_prefix) - len(suffix)
        base = commit_info['patchname'][:base_maxlen]

    filename = num_prefix + base + suffix
    filepath = os.path.join(outdir, filename)
    # Make sure that we don't overwrite existing patches in the series
    if filepath in series:
        presuffix = '-%d' % len([p for p in series
                                 if p.startswith(os.path.splitext(filepath)[0])])
        filename = num_prefix + base + presuffix + suffix
        filepath = os.path.join(outdir, filename)

    # Determine files to include
    paths = patch_path_filter(commit_info['files'], path_exclude_regex)

    # Finally, create the patch
    patch = None
    if paths:
        diff = repo.diff('%s^!' % commit_info['id'], paths=paths, stat=80,
                         summary=True, text=True, abbrev=abbrev, renames=False)
        patch = write_patch_file(filepath, commit_info, diff)
        if patch:
            series.append(patch)
    return patch


def format_diff(outdir, filename, repo, start, end, abbrev, path_exclude_regex=None):
    """Create a patch of diff between two repository objects"""

    info = {'author': repo.get_author_info()}
    now = datetime.datetime.now().replace(tzinfo=GitTz(-time.timezone))
    info['author'].set_date(now)
    info['subject'] = "Raw diff %s..%s" % (start, end)
    info['body'] = ("Raw diff between %s '%s' and\n%s '%s'\n" %
                    (repo.get_obj_type(start), start,
                     repo.get_obj_type(end), end))
    if not filename:
        filename = '%s-to-%s.diff' % (start, end)
    filename = os.path.join(outdir, filename)

    file_status = repo.diff_status(start, end)
    paths = patch_path_filter(file_status, path_exclude_regex)
    if paths:
        diff = repo.diff(start, end, paths=paths, stat=80, summary=True,
                         text=True, abbrev=abbrev, renames=False)
        return write_patch_file(filename, info, diff)
    return None


def get_maintainer_from_control(repo):
    """Get the maintainer from the control file"""
    control = os.path.join(repo.path, 'debian', 'control')

    maint_re = re.compile('Maintainer: +(?P<name>.*[^ ]) *<(?P<email>.*)>')
    try:
        with open(control, encoding='utf-8') as f:
            for line in f:
                m = maint_re.match(line)
                if m:
                    return GitModifier(m.group('name'), m.group('email'))
    except FileNotFoundError:
        raise GbpError("Debian control file {} not found".format(control))
    return GitModifier()


def switch_to_pq_branch(repo, branch):
    """
    Switch to patch-queue branch if not already on it.
    doesn't exist yet
    """
    if is_pq_branch(branch):
        return

    pq_branch = pq_branch_name(branch)
    if not repo.has_branch(pq_branch):
        raise GbpError("Branch '%s' does not exist, try "
                       "'import' instead" % pq_branch)

    gbp.log.info("Switching to '%s'" % pq_branch)
    repo.set_branch(pq_branch)


def apply_single_patch(repo, branch, patch, fallback_author, topic=None):
    switch_to_pq_branch(repo, branch)
    apply_and_commit_patch(repo, patch, fallback_author, topic)
    gbp.log.info("Applied %s" % os.path.basename(patch.path))


def apply_and_commit_patch(repo, patch, fallback_author, topic=None, name=None):
    """apply a single patch 'patch', add topic 'topic' and commit it"""
    author = {'name': patch.author,
              'email': patch.email,
              'date': patch.date}

    patch_fn = os.path.basename(patch.path)
    if not (author['name'] and author['email']):
        if fallback_author and fallback_author['name']:
            author = {}
            for key in 'name', 'email', 'date':
                author[key] = fallback_author.get(key)
            gbp.log.warn("Patch '%s' has no authorship information, using "
                         "'%s <%s>'" % (patch_fn, author['name'],
                                        author['email']))
        else:
            gbp.log.warn("Patch '%s' has no authorship information" % patch_fn)

    try:
        repo.apply_patch(patch.path, strip=patch.strip)
    except GitRepositoryError:
        gbp.log.warn("Patch %s failed to apply, retrying with whitespace fixup" % patch_fn)
        repo.apply_patch(patch.path, strip=patch.strip, fix_ws=True)
    tree = repo.write_tree()
    msg = "%s\n\n%s" % (patch.subject, patch.long_desc)
    if topic:
        msg += "\nGbp-Pq: Topic %s" % topic
    if name:
        msg += "\nGbp-Pq: Name %s" % name
    if author['name']:
        author['name'] = author['name'].encode('utf-8')
    commit = repo.commit_tree(tree, msg, [repo.head], author=author)
    repo.update_ref('HEAD', commit, msg="gbp-pq import %s" % patch.path)


def drop_pq(repo, branch):
    repo.checkout(pq_branch_base(branch))
    pq_branch = pq_branch_name(branch)
    if repo.has_branch(pq_branch):
        repo.delete_branch(pq_branch)
        gbp.log.info("Dropped branch '%s'." % pq_branch)
    else:
        gbp.log.info("No patch queue branch found - doing nothing.")
