#!/usr/bin/python3
# Copyright (C) 2019 Jelmer Vernooij
#
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Utility functions for dealing with rules files."""

import os
import re
from typing import Iterator, Optional, List

from .reformatting import Editor


def wildcard_to_re(wildcard: str):
    wc = []
    for c in wildcard:
        if c == '%':
            wc.append('.*')
        else:
            wc.append(re.escape(c))
    return re.compile(''.join(wc))


def matches_wildcard(text: str, wildcard: str) -> bool:
    wc = wildcard_to_re(wildcard)
    return bool(wc.fullmatch(text))


class Rule(object):
    """A make rule."""

    def __init__(self, target: Optional[bytes] = None,
                 commands: Optional[List[bytes]] = None,
                 prereq_targets: Optional[List[bytes]] = None,
                 precomment: Optional[List[bytes]] = None):
        self.precomment = precomment or []
        self.target = target
        self.components = prereq_targets or []
        if self.components:
            self._component_str = b' ' + b' '.join(self.components)
        else:
            self._component_str = b''
        if target:
            self.lines = (
                [b'%s:%s' % (target, self._component_str)] +
                [b'\t' + cmd for cmd in (commands or [])])
        else:
            self.lines = []

    @classmethod
    def _from_first_line(
            cls, firstline: bytes,
            precomment: Optional[List[bytes]] = None) -> 'Rule':
        self = cls(precomment=precomment)
        self.lines = [firstline]
        # TODO(jelmer): What if there are multiple targets?
        self.target, self._component_str = firstline.split(b':', 1)
        self.components = self._component_str.split()
        return self

    def __repr__(self):
        return "<%s(%r)>" % (type(self).__name__, self.target)

    @property
    def targets(self):
        return self.target.split(b' ')

    def has_target(self, target: bytes, exact: bool = True) -> bool:
        if exact:
            return target in self.targets
        else:
            return any(
                [matches_wildcard(
                    target.decode(), t.decode()) for t in self.targets])

    def rename_target(self, oldname: bytes, newname: bytes) -> bool:
        # TODO(jelmer): Handle multiple targets
        if self.target == oldname:
            self.target = newname
            firstline = b':'.join([self.target, self._component_str])
            self.lines = [firstline] + self.lines[1:]
            return True
        return False

    def commands(self) -> List[bytes]:
        return [line[1:] for line in self.lines if line.startswith(b'\t')]

    def append_line(self, line: bytes) -> None:
        self.lines.append(line)

    def append_command(self, command: bytes) -> None:
        self.lines.append(b'\t' + command)

    def append_component(self, component: bytes) -> None:
        self.components.append(component)
        self._component_str = b' ' + b' '.join(self.components)
        self.lines[0] = b'%s:%s' % (self.target, self._component_str)

    def remove_component(self, component: bytes) -> None:
        self.components.remove(component)
        self._component_str = b' ' + b' '.join(self.components)
        self.lines[0] = b'%s:%s' % (self.target, self._component_str)

    def dump_lines(self) -> Iterator[bytes]:
        for line in self.precomment:
            yield line + b'\n'
        for line in self.lines:
            yield line + b'\n'

    def __eq__(self, other) -> bool:
        if not isinstance(other, type(self)):
            return False
        return list(self.dump_lines()) == list(other.dump_lines())

    def __bool__(self) -> bool:
        return bool(self.lines)

    def clear(self) -> None:
        self.precomment = []
        self.lines = []

    def _finish(self):
        rest = [self]
        while self.lines and (
                not self.lines[-1] or self.lines[-1].startswith(b'#')):
            rest.insert(1, self.lines.pop(-1))
        return rest


def _is_conditional(line):
    line = line.lstrip(b' ')
    return (
        line.startswith(b'ifeq') or
        line.startswith(b'ifneq') or
        line.startswith(b'else') or
        line.startswith(b'endif') or
        line.startswith(b'include') or
        line.startswith(b'-include'))


def _is_rule(line):
    before, sep, after = line.partition(b':')
    if sep != b':':
        return False
    if b'=' in before:
        return False
    if after.startswith(b'='):
        return False
    return True


class Makefile(object):

    def __init__(self, contents: Optional[bytes] = None):
        self.contents = list(contents or [])

    @classmethod
    def from_path(cls, path: str) -> 'Makefile':
        with open(path, 'rb') as f:
            original_contents = f.read()
        return cls.from_bytes(original_contents)

    def iter_all_rules(self) -> Iterator[Rule]:
        for entry in self.contents:
            if isinstance(entry, Rule):
                yield entry

    def iter_rules(self, target: bytes, exact: bool = True) -> Iterator[Rule]:
        for rule in self.iter_all_rules():
            if rule.has_target(target, exact):
                yield rule

    def get_variable(self, desired_key: bytes) -> bytes:
        for line in self.contents:
            if not isinstance(line, bytes):
                continue
            m = re.fullmatch(
                br'(export\s)?([A-Za-z0-9_]+)\s*[:?]?=\s*(.*)', line)
            if not m:
                continue
            if m.group(2).strip() == desired_key:
                return m.group(3).strip()
        raise KeyError(desired_key)

    @classmethod
    def from_bytes(cls, contents):
        mf = cls()
        keep = b''
        rule = None
        joinedlines = []
        for line in contents.splitlines():
            line = keep + line
            keep = b''
            if line.endswith(b'\\'):
                keep = line + b'\n'
                continue
            joinedlines.append(line)

        if keep:
            # file ends with continuation line..
            joinedlines.append(keep)

        for line in joinedlines:
            if line.startswith(b'\t') and rule:
                rule.append_line(line)
            elif _is_conditional(line) or line.lstrip(b' ').startswith(b'#'):
                if rule:
                    rule.append_line(line)
                else:
                    mf.contents.append(line)
            elif _is_rule(line):
                if rule:
                    mf.contents.extend(rule._finish())
                precomment = []
                while (len(mf.contents) > 1 and
                        isinstance(mf.contents[-1], bytes) and
                        mf.contents[-1].startswith(b'#')):
                    precomment.insert(0, mf.contents.pop(-1))
                rule = Rule._from_first_line(line, precomment=precomment)
            elif not line.strip():
                if rule:
                    rule.append_line(line)
                else:
                    mf.contents.append(line)
            else:
                if rule:
                    mf.contents.extend(rule._finish())
                rule = None
                mf.contents.append(line)

        if rule:
            mf.contents.extend(rule._finish())

        return mf

    def dump_lines(self):
        lines = []
        contents = self.contents[:]
        while contents and contents[-1] == b'':
            del contents[-1]
        for entry in contents:
            if isinstance(entry, Rule):
                if entry.lines == []:
                    if lines[-1] == b'\n':
                        lines.pop(-1)
                else:
                    lines.extend(entry.dump_lines())
            else:
                lines.append(entry + b'\n')
        return lines

    def dump(self):
        return b''.join(self.dump_lines())

    def add_rule(self, target, components=None, precomment=None):
        if self.contents:
            if isinstance(self.contents[-1], Rule):
                self.contents.append(b'')
        if isinstance(target, list):
            target = b' '.join(target)
        line = b'%s:' % target
        if components:
            line += b' ' + b' '.join(components)
        rule = Rule._from_first_line(line, precomment=precomment)
        self.contents.append(rule)
        return rule

    def mark_phony(self, rule):
        for r in self.iter_rules(b'.PHONY'):
            if rule in r.components:
                return
        try:
            phony_rule = list(self.iter_rules(b'.PHONY'))[-1]
        except IndexError:
            self.add_rule(b'.PHONY', [rule])
        else:
            phony_rule.append_component(rule)

    def add_phony(self, rule):
        try:
            phony_rule = list(self.iter_rules(b'.PHONY'))[-1]
        except IndexError:
            return

        phony_rule.append_component(rule)

    def drop_phony(self, rule):
        for r in self.iter_rules(b'.PHONY'):
            if rule in r.components:
                r.remove_component(rule)
            if not r.components:
                r.clear()


class MakefileEditor(Editor):

    def __init__(self, path):
        super(MakefileEditor, self).__init__(path, mode='b')

    def _parse(self, content):
        return Makefile.from_bytes(content)

    def _format(self, parsed):
        return parsed.dump()

    @property
    def makefile(self):
        return self._parsed


class RulesEditor(MakefileEditor):

    def __init__(self, path='debian/rules'):
        super(RulesEditor, self).__init__(path)

    def legacy_update(self, command_line_cb=None, global_line_cb=None,
                      rule_cb=None, makefile_cb=None):
        """Update a debian/rules file.

        Args:
          command_line_cb: Callback to call on every rule command line
          global_line_cb: Callback to call on every global line
          rule_cb: Callback to call on every rule
        Returns:
          boolean indicating whether any changes were made
        """
        newcontents = []
        for entry in self.makefile.contents:
            if isinstance(entry, Rule):
                rule = entry
                newlines = []
                for line in list(rule.lines[1:]):
                    if line.startswith(b'\t'):
                        ret = line[1:]
                        if callable(command_line_cb):
                            ret = command_line_cb(ret, rule.target)
                        elif isinstance(command_line_cb, list):
                            for fn in command_line_cb:
                                ret = fn(ret, rule.target)
                        if isinstance(ret, bytes):
                            newlines.append(b'\t' + ret)
                        elif isinstance(ret, list):
                            for otherl in ret:
                                newlines.append(b'\t' + otherl)
                        else:
                            raise TypeError(ret)
                    else:
                        newlines.append(line)

                rule.lines = [rule.lines[0]] + newlines

                if rule_cb:
                    rule_cb(rule)
                if rule:
                    newcontents.append(rule)
                else:
                    if newcontents and newcontents[-1] == b'':
                        newcontents.pop(-1)
            else:
                line = entry
                if global_line_cb:
                    line = global_line_cb(line)
                if line is None:
                    pass
                elif isinstance(line, list):
                    newcontents.extend(line)
                elif isinstance(line, bytes):
                    newcontents.append(line)
                else:
                    raise TypeError(line)

        self.makefile.contents = newcontents
        if makefile_cb:
            makefile_cb(self.makefile)
        if self.has_changed():
            discard_pointless_overrides(self.makefile)
            return True
        else:
            return False


def discard_pointless_overrides(makefile, ignore_comments=False):
    for rule in makefile.iter_all_rules():
        discard_pointless_override(
            makefile, rule, ignore_comments=ignore_comments)


def discard_pointless_override(makefile, rule, ignore_comments=False):
    if not rule.target.startswith(b'override_'):
        return
    command = rule.target[len(b'override_'):]
    if ignore_comments:
        effective_lines = [
            line for line in rule.lines[1:]
            if line.split(b'#', 1)[0].strip()]
    else:
        effective_lines = [
            line for line in rule.lines[1:]
            if line.strip()]
    if effective_lines != [b'\t' + command]:
        return
    if rule.components:
        return
    rule.clear()
    makefile.drop_phony(rule.target)


def update_rules(command_line_cb=None, global_line_cb=None,
                 rule_cb=None,
                 makefile_cb=None, path='debian/rules'):
    """Update a debian/rules file.

    Args:
      command_line_cb: Callback to call on every rule command line
      global_line_cb: Callback to call on every global line
      rule_cb: Callback to call on every rule
      path: Path to the debian/rules file to edit
    Returns:
      boolean indicating whether any changes were made
    """
    if not os.path.exists(path):
        return False
    with RulesEditor(path) as updater:
        updater.legacy_update(
            command_line_cb=command_line_cb,
            global_line_cb=global_line_cb,
            rule_cb=rule_cb,
            makefile_cb=makefile_cb)
    return updater.changed


def dh_invoke_add_with(line, with_argument):
    """Add a particular value to a with argument."""
    if with_argument in line:
        return line
    if b' --with' not in line:
        return line + b' --with=' + with_argument
    return re.sub(
        b'([ \t])--with([ =])([^ \t]+)', b'\\1--with\\2\\3,' + with_argument,
        line)


def dh_invoke_get_with(line):
    ret = []
    for m in re.finditer(b'[ \t]--with[ =]([^ \t]+)', line):
        ret.extend(m.group(1).decode('utf-8').split(','))
    return ret


def dh_invoke_drop_with(line, with_argument):
    """Drop a particular value from a with argument."""
    if with_argument not in line:
        return line
    # It's the only with argument
    line = re.sub(
        b"[ \t]--with[ =]" + with_argument + b"( .+|)$",
        b"\\1", line)
    # It's at the beginning of the line
    line = re.sub(
        b"([ \t])--with([ =])" + with_argument + b",",
        b"\\1--with\\2", line)
    # It's somewhere in the middle or the end
    line = re.sub(
        b"([ \t])--with([ =])(.+)," + with_argument + b"([ ,])",
        b"\\1--with\\2\\3\\4", line)
    # It's at the end
    line = re.sub(
        b"([ \t])--with([ =])(.+)," + with_argument + b"$",
        b"\\1--with\\2\\3", line)
    return line


def dh_invoke_drop_argument(line, argument):
    """Drop a particular argument from a dh invocation."""
    if argument not in line:
        return line
    line = re.sub(b'[ \t]+' + argument + b'$', b'', line)
    line = re.sub(b'([ \t])' + argument + b'[ \t]', b'\\1', line)
    return line


def dh_invoke_replace_argument(line, old, new):
    if old not in line:
        return line
    line = re.sub(b'([ \t])' + old + b'$', b'\\1' + new, line)
    line = re.sub(
        b'([ \t])' + old + b'([ \t])', b'\\1' + new + b'\\2', line)
    return line


def check_cdbs(path='debian/rules'):
    if not os.path.exists(path):
        return False
    with open(path, 'rb') as f:
        for line in f:
            if line.lstrip(b'-').startswith(b'include /usr/share/cdbs/'):
                return True
    return False
