# vim: set fileencoding=utf-8 :
#
# (C) 2011,2014,2017 Guido Günther <agx@sigxcpu.org>
#    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/>
#
"""Manage Debian patches on a patch queue branch"""

import errno
import os
import shutil
import sys
import tempfile
import re
from gbp.config import GbpOptionParserDebian
from gbp.deb.source import DebianSource
from gbp.deb.git import DebianGitRepository
from gbp.git import GitRepositoryError
from gbp.command_wrappers import (GitCommand, CommandExecFailed)
from gbp.errors import GbpError
import gbp.log
from gbp.patch_series import (PatchSeries, Patch)
from gbp.scripts.common.pq import (is_pq_branch, pq_branch_name, pq_branch_base,
                                   parse_gbp_commands, format_patch,
                                   apply_single_patch,
                                   apply_and_commit_patch,
                                   drop_pq, get_maintainer_from_control,
                                   switch_to_pq_branch)
from gbp.scripts.common import ExitCodes
from gbp.dch import extract_bts_cmds

PATCH_DIR = "debian/patches/"
SERIES_FILE = os.path.join(PATCH_DIR, "series")


def parse_old_style_topic(commit_info):
    """Parse 'gbp-pq-topic:' line(s) from commit info"""

    commit = commit_info['id']
    topic_regex = r'gbp-pq-topic:\s*(?P<topic>\S.*)'
    mangled_body = ''
    topic = ''
    # Parse and filter commit message body
    for line in commit_info['body'].splitlines():
        match = re.match(topic_regex, line, flags=re.I)
        if match:
            topic = match.group('topic')
            gbp.log.debug("Topic %s found for %s" % (topic, commit))
            gbp.log.warn("Deprecated 'gbp-pq-topic: <topic>' in %s, please "
                         "use 'Gbp[-Pq]: Topic <topic>' instead" % commit)
            continue
        mangled_body += line + '\n'
    commit_info['body'] = mangled_body
    return topic


def generate_patches(repo, start, end, outdir, options):
    """
    Generate patch files from git
    """
    gbp.log.info("Generating patches from git (%s..%s)" % (start, end))
    patches = []
    for treeish in [start, end]:
        if not repo.has_treeish(treeish):
            raise GbpError('%s not a valid tree-ish' % treeish)

    # Generate patches
    rev_list = reversed(repo.get_commits(start, end))
    for commit in rev_list:
        info = repo.get_commit_info(commit)
        # Parse 'gbp-pq-topic:'
        topic = parse_old_style_topic(info)
        cmds = {'topic': topic} if topic else {}
        # Parse 'Gbp: ' style commands
        (cmds_gbp, info['body']) = parse_gbp_commands(info, 'gbp',
                                                      ('ignore'),
                                                      ('topic', 'name'),
                                                      ('topic', 'name'))
        cmds.update(cmds)
        # Parse 'Gbp-Pq: ' style commands
        (cmds_gbp_pq, info['body']) = parse_gbp_commands(info,
                                                         'gbp-pq',
                                                         ('ignore'),
                                                         ('topic', 'name'),
                                                         ('topic', 'name'))
        cmds.update(cmds_gbp_pq)
        if 'ignore' not in cmds:
            if 'topic' in cmds:
                topic = cmds['topic']
            name = cmds.get('name', None)
            format_patch(outdir, repo, info, patches, options.abbrev,
                         numbered=options.patch_numbers,
                         topic=topic, name=name,
                         renumber=options.renumber,
                         patch_num_prefix_format=options.patch_num_format)
        else:
            gbp.log.info('Ignoring commit %s' % info['id'])

    return patches


def compare_series(old, new):
    """
    Compare new pathes to lists of patches already exported

    >>> compare_series(['# comment', 'a', 'b'], ['b', 'c'])
    (['c'], ['a'])
    >>> compare_series([], [])
    ([], [])
    """
    added = set(new).difference(old)
    removed = [l for l in set(old).difference(new) if not l.startswith('#')]
    return (list(added), removed)


def format_series_diff(added, removed, options):
    """
    Format the patch differences into a suitable commit message

    >>> format_series_diff(['a'], ['b'], None)
    'Rediff patches\\n\\nAdd a: <REASON>\\nDrop b: <REASON>\\n'
    """
    if len(added) == 1 and not removed:
        # Single patch added, create a more thorough commit message
        patch = Patch(os.path.join('debian', 'patches', added[0]))
        msg = patch.subject
        bugs, dummy = extract_bts_cmds(patch.long_desc.split('\n'), options)
        if bugs:
            msg += '\n'
            for k, v in bugs.items():
                msg += '\n%s: %s' % (k, ', '.join(v))
    else:
        msg = "Rediff patches\n\n"
        for p in added:
            msg += 'Add %s: <REASON>\n' % p
        for p in removed:
            msg += 'Drop %s: <REASON>\n' % p
    return msg


def commit_patches(repo, branch, patches, options, patch_dir):
    """
    Commit chanages exported from patch queue
    """
    clean, dummy = repo.is_clean()
    if clean:
        return ([], [])

    vfs = gbp.git.vfs.GitVfs(repo, branch)
    try:
        with vfs.open('debian/patches/series') as oldseries:
            oldpatches = [p.strip() for p in oldseries.readlines()]
    except IOError:
        # No series file yet
        oldpatches = []
    newpatches = [p[len(patch_dir):] for p in patches]

    # FIXME: handle case were only the contents of the patches changed
    added, removed = compare_series(oldpatches, newpatches)
    msg = format_series_diff(added, removed, options)

    if not repo.is_clean(paths='debian/patches')[0]:
        repo.add_files(PATCH_DIR, force=True)
        repo.commit_staged(msg=msg)
    return added, removed


def find_upstream_commit(repo, branch, upstream_tag):
    """
    Find commit corresponding to upstream version based on changelog
    """
    vfs = gbp.git.vfs.GitVfs(repo, pq_branch_base(branch))
    cl = DebianSource(vfs).changelog
    upstream_commit = repo.find_version(upstream_tag, cl.upstream_version)
    if not upstream_commit:
        raise GbpError("Couldn't find upstream version %s" %
                       cl.upstream_version)
    return upstream_commit


def pq_on_upstream_tag(pq_from):
    """Return True if the patch queue is based on the uptream tag,
    False if its based on the debian packaging branch"""
    return True if pq_from.upper() == 'TAG' else False


def export_patches(repo, branch, options):
    """Export patches from the pq branch into a patch series"""
    patch_dir = os.path.join(repo.path, PATCH_DIR)
    series_file = os.path.join(repo.path, SERIES_FILE)
    if is_pq_branch(branch):
        base = pq_branch_base(branch)
        gbp.log.info("On '%s', switching to '%s'" % (branch, base))
        branch = base
        repo.set_branch(branch)

    pq_branch = pq_branch_name(branch)
    try:
        shutil.rmtree(patch_dir)
    except OSError as e:
        if e.errno != errno.ENOENT:
            raise GbpError("Failed to remove patch dir: %s" % e.strerror)
        else:
            gbp.log.debug("%s does not exist." % patch_dir)

    if pq_on_upstream_tag(options.pq_from):
        base = find_upstream_commit(repo, branch, options.upstream_tag)
    else:
        base = branch

    patches = generate_patches(repo, base, pq_branch, patch_dir, options)

    if patches:
        with open(series_file, 'w') as seriesfd:
            for patch in patches:
                seriesfd.write(os.path.relpath(patch, patch_dir) + '\n')
    else:
        gbp.log.info("No patches on '%s' - nothing to export." % pq_branch)

    if options.commit:
        added, removed = commit_patches(repo, branch, patches, options, patch_dir)
        if added:
            what = 'patches' if len(added) > 1 else 'patch'
            gbp.log.info("Added %s %s to patch series" % (what, ', '.join(added)))
        if removed:
            what = 'patches' if len(removed) > 1 else 'patch'
            gbp.log.info("Removed %s %s from patch series" % (what, ', '.join(removed)))
        else:
            gbp.log.info("Updated existing patches.")

    if options.drop:
        drop_pq(repo, branch)


def safe_patches(series, repo):
    """
    Safe the current patches in a temporary directory
    below .git/

    @param series: path to series file
    @return: tmpdir and path to safed series file
    @rtype: tuple
    """

    src = os.path.dirname(series)
    name = os.path.basename(series)

    tmpdir = tempfile.mkdtemp(dir=repo.git_dir, prefix='gbp-pq')
    patches = os.path.join(tmpdir, 'patches')
    series = os.path.join(patches, name)

    gbp.log.debug("Saving patches '%s' in '%s'" % (src, tmpdir))
    shutil.copytree(src, patches)

    return (tmpdir, series)


def import_quilt_patches(repo, branch, series, tries, force, pq_from,
                         upstream_tag):
    """
    apply a series of quilt patches in the series file 'series' to branch
    the patch-queue branch for 'branch'

    @param repo: git repository to work on
    @param branch: branch to base patch queue on
    @param series: series file to read patches from
    @param tries: try that many times to apply the patches going back one
                  commit in the branches history after each failure.
    @param force: import the patch series even if the branch already exists
    @param pq_from: what to use as the starting point for the pq branch.
                    DEBIAN indicates the current branch, TAG indicates that
                    the corresponding upstream tag should be used.
    @param upstream_tag: upstream tag template to use
    """
    tmpdir = None
    series = os.path.join(repo.path, series)

    if is_pq_branch(branch):
        if force:
            branch = pq_branch_base(branch)
            pq_branch = pq_branch_name(branch)
            repo.checkout(branch)
        else:
            raise GbpError("Already on a patch-queue branch '%s' - doing nothing." % branch)
    else:
        pq_branch = pq_branch_name(branch)

    if repo.has_branch(pq_branch):
        if force:
            drop_pq(repo, branch)
        else:
            raise GbpError("Patch queue branch '%s'. already exists. Try 'rebase' or 'switch' instead."
                           % pq_branch)

    maintainer = get_maintainer_from_control(repo)
    if pq_on_upstream_tag(pq_from):
        commits = [find_upstream_commit(repo, branch, upstream_tag)]
    else:  # pq_from == 'DEBIAN'
        commits = repo.get_commits(num=tries, first_parent=True)
    # If we go back in history we have to safe our pq so we always try to apply
    # the latest one
    # If we are using the upstream_tag, we always need a copy of the patches
    if len(commits) > 1 or pq_on_upstream_tag(pq_from):
        if os.path.exists(series):
            tmpdir, series = safe_patches(series, repo)

    queue = PatchSeries.read_series_file(series)

    i = len(commits)
    for commit in commits:
        if len(commits) > 1:
            gbp.log.info("%d %s left" % (i, 'tries' if i > 1 else 'try'))
        try:
            gbp.log.info("Trying to apply patches at '%s'" % commit)
            repo.create_branch(pq_branch, commit)
        except GitRepositoryError:
            raise GbpError("Cannot create patch-queue branch '%s'." % pq_branch)

        repo.set_branch(pq_branch)
        for patch in queue:
            gbp.log.debug("Applying %s" % patch.path)
            try:
                name = os.path.basename(patch.path)
                apply_and_commit_patch(repo, patch, maintainer, patch.topic, name)
            except (GbpError, GitRepositoryError) as e:
                gbp.log.err("Failed to apply '%s': %s" % (patch.path, e))
                repo.force_head('HEAD', hard=True)
                repo.set_branch(branch)
                repo.delete_branch(pq_branch)
                break
        else:
            # All patches applied successfully
            break
        i -= 1
    else:
        raise GbpError("Couldn't apply patches")

    if tmpdir:
        gbp.log.debug("Remove temporary patch safe '%s'" % tmpdir)
        shutil.rmtree(tmpdir)

    return len(queue)


def rebase_pq(repo, branch, options):
    maybe_import_pq(repo, branch, options)
    # Make sure we're on the pq branch
    switch_to_pq_branch(repo, branch)
    if pq_on_upstream_tag(options.pq_from):
        base = find_upstream_commit(repo, branch, options.upstream_tag)
    else:
        base = pq_branch_base(repo.branch)

    GitCommand("rebase", cwd=repo.path)([base])


def import_pq(repo, branch, options):
    """Import quilt patches onto pq branch"""
    series = SERIES_FILE
    tries = options.time_machine if (options.time_machine > 0) else 1
    num = import_quilt_patches(repo, branch, series, tries,
                               options.force, options.pq_from,
                               options.upstream_tag)
    gbp.log.info("%d patches listed in '%s' imported on '%s'" %
                 (num, series, repo.get_branch()))


def maybe_import_pq(repo, branch, options):
    """Import quilt patches onto pq branch if pq branch does not exist yet"""
    if not repo.has_branch(pq_branch_name(branch)):
        gbp.log.info("No pq branch found, importing patches")
        import_pq(repo, branch, options)
        return True
    return False


def switch_pq(repo, branch, options):
    """Switch to patch-queue branch if on base branch and vice versa"""
    if is_pq_branch(branch):
        base = pq_branch_base(branch)
        gbp.log.info("Switching to %s" % base)
        repo.checkout(base)
    else:
        maybe_import_pq(repo, branch, options)
        switch_to_pq_branch(repo, branch)


def usage_msg():
    return """%prog [options] action - maintain patches on a patch queue branch
Actions:
  export         export the patch queue associated to the current branch
                 into a quilt patch series in debian/patches/ and update the
                 series file.
  import         create a patch queue branch from quilt patches in debian/patches.
  rebase         switch to patch queue branch associated to the current
                 branch and rebase against current branch.
  drop           drop (delete) the patch queue associated to the current branch.
  apply          apply a patch
  switch         switch to patch-queue branch and vice versa"""


def build_parser(name):
    try:
        parser = GbpOptionParserDebian(command=os.path.basename(name),
                                       usage=usage_msg())
    except GbpError as err:
        gbp.log.err(err)
        return None

    parser.add_boolean_config_file_option(option_name="patch-numbers", dest="patch_numbers")
    parser.add_config_file_option(option_name="patch-num-format", dest="patch_num_format")
    parser.add_boolean_config_file_option(option_name="renumber", dest="renumber")
    parser.add_option("-v", "--verbose", action="store_true", dest="verbose", default=False,
                      help="verbose command execution")
    parser.add_option("--topic", dest="topic", help="in case of 'apply' topic (subdir) to put patch into")
    parser.add_config_file_option(option_name="time-machine", dest="time_machine", type="int")
    parser.add_boolean_config_file_option("drop", dest='drop')
    parser.add_boolean_config_file_option(option_name="commit", dest="commit")
    parser.add_config_file_option(option_name="abbrev", dest="abbrev", type="int")
    parser.add_option("--force", dest="force", action="store_true", default=False,
                      help="in case of import even import if the branch already exists")
    parser.add_config_file_option(option_name="color", dest="color", type='tristate')
    parser.add_config_file_option(option_name="color-scheme",
                                  dest="color_scheme")
    parser.add_config_file_option(option_name="meta-closes", dest="meta_closes")
    parser.add_config_file_option(option_name="meta-closes-bugnum", dest="meta_closes_bugnum")
    parser.add_config_file_option(option_name="pq-from", dest="pq_from", choices=['DEBIAN', 'TAG'])
    parser.add_config_file_option(option_name="upstream-tag", dest="upstream_tag")
    return parser


def parse_args(argv):
    parser = build_parser(argv[0])
    if not parser:
        return None, None
    return parser.parse_args(argv)


def main(argv):
    retval = 0

    (options, args) = parse_args(argv)
    if not options:
        return ExitCodes.parse_error

    gbp.log.setup(options.color, options.verbose, options.color_scheme)

    if len(args) < 2:
        gbp.log.err("No action given.")
        return 1
    else:
        action = args[1]

    if args[1] in ["export", "import", "rebase", "drop", "switch"]:
        pass
    elif args[1] in ["apply"]:
        if len(args) != 3:
            gbp.log.err("No patch name given.")
            return 1
        else:
            patchfile = args[2]
    else:
        gbp.log.err("Unknown action '%s'." % args[1])
        return 1

    try:
        repo = DebianGitRepository(os.path.curdir)
    except GitRepositoryError:
        gbp.log.err("%s is not a git repository" % (os.path.abspath('.')))
        return 1

    try:
        current = repo.get_branch()
        if action == "export":
            export_patches(repo, current, options)
        elif action == "import":
            import_pq(repo, current, options)
        elif action == "drop":
            drop_pq(repo, current)
        elif action == "rebase":
            rebase_pq(repo, current, options)
        elif action == "apply":
            patch = Patch(patchfile)
            maintainer = get_maintainer_from_control(repo)
            apply_single_patch(repo, current, patch, maintainer, options.topic)
        elif action == "switch":
            switch_pq(repo, current, options)
    except KeyboardInterrupt:
        retval = 1
        gbp.log.err("Interrupted. Aborting.")
    except CommandExecFailed:
        retval = 1
    except (GbpError, GitRepositoryError) as err:
        if str(err):
            gbp.log.err(err)
        retval = 1

    return retval


if __name__ == '__main__':
    sys.exit(main(sys.argv))