#!/usr/bin/python3

import io
import os
import os.path
import re
import subprocess
import sys


def main(repo, range='torvalds/master..dhowells/efi-lock-down'):
    patch_dir = 'debian/patches'
    lockdown_patch_dir = 'features/all/lockdown'
    series_name = 'series'

    # Only replace patches in this subdirectory and starting with a digit
    # - the others are presumably Debian-specific for now
    lockdown_patch_name_re = re.compile(
        r'^' + re.escape(lockdown_patch_dir) + r'/\d')
    series_before = []
    series_after = []

    old_series = set()
    new_series = set()

    try:
        with open(os.path.join(patch_dir, series_name), 'r') as series_fh:
            for line in series_fh:
                name = line.strip()
                if lockdown_patch_name_re.match(name):
                    old_series.add(name)
                elif len(old_series) == 0:
                    series_before.append(line)
                else:
                    series_after.append(line)
    except FileNotFoundError:
        pass

    with open(os.path.join(patch_dir, series_name), 'w') as series_fh:
        for line in series_before:
            series_fh.write(line)

        # Add directory prefix to all filenames.
        # Add Origin to all patch headers.
        def add_patch(name, source_patch, origin):
            name = os.path.join(lockdown_patch_dir, name)
            path = os.path.join(patch_dir, name)
            try:
                os.unlink(path)
            except FileNotFoundError:
                pass
            with open(path, 'w') as patch:
                in_header = True
                for line in source_patch:
                    if in_header and re.match(r'^(\n|[^\w\s]|Index:)', line):
                        patch.write('Origin: %s\n' % origin)
                        if line != '\n':
                            patch.write('\n')
                        in_header = False
                    patch.write(line)
            series_fh.write(name)
            series_fh.write('\n')
            new_series.add(name)

        # XXX No signature to verify

        env = os.environ.copy()
        env['GIT_DIR'] = os.path.join(repo, '.git')
        args = ['git', 'format-patch', '--subject-prefix=', range]
        format_proc = subprocess.Popen(args,
                                       cwd=os.path.join(patch_dir,
                                                        lockdown_patch_dir),
                                       env=env, stdout=subprocess.PIPE)
        with io.open(format_proc.stdout.fileno(), encoding='utf-8') as pipe:
            for line in pipe:
                name = line.strip('\n')
                with open(os.path.join(patch_dir, lockdown_patch_dir, name)) \
                     as source_patch:
                    patch_from = source_patch.readline()
                    match = re.match(r'From ([0-9a-f]{40}) ', patch_from)
                    assert match
                    origin = ('https://git.kernel.org/pub/scm/linux/kernel/'
                              'git/dhowells/linux-fs.git/commit?id=%s' %
                              match.group(1))
                    add_patch(name, source_patch, origin)

        for line in series_after:
            series_fh.write(line)

    for name in new_series:
        if name in old_series:
            old_series.remove(name)
        else:
            print('Added patch', os.path.join(patch_dir, name))

    for name in old_series:
        print('Obsoleted patch', os.path.join(patch_dir, name))


if __name__ == '__main__':
    if not (2 <= len(sys.argv) <= 3):
        sys.stderr.write('''\
Usage: %s REPO [REVISION-RANGE]
REPO is a git repo containing the REVISION-RANGE.  The default range is
torvalds/master..dhowells/efi-lock-down.
''' % sys.argv[0])
        print('BASE is the base branch (default: torvalds/master).')
        sys.exit(2)
    main(*sys.argv[1:])