#!/usr/bin/env python3

import argparse
from os import path, makedirs, walk, listdir, remove
from shutil import copy, rmtree
from subprocess import run


def folder(default_search, user_input):
    if path.sep in user_input:
        return user_input
    else:
        the_path = path.dirname(path.dirname(path.abspath(__file__)))
        the_path = path.join(the_path, default_search, user_input)
        return the_path


parser = argparse.ArgumentParser(description='''
    Expand a patchset into a git repository (based on git-am)
''')

parser.add_argument('patchset', metavar='PATCHSET', action='store', type=lambda x: folder('patchset', x), help='Patchset (assumed in ../patchset/)')
parser.add_argument('worktree', metavar='WORKTREE', action='store', type=lambda x: folder('worktree', x), help='Destination worktree (assumed in ../worktree/)')
group = parser.add_mutually_exclusive_group()
group.add_argument('--base', metavar='SRC', action='store', default='SuperMarioProj.1994-02-09', type=lambda x: folder('base', x), help='Base source tree (default=SuperMarioProj.1994-02-09, assumed in ../base/)')
group.add_argument('--base-commit', metavar='REV', action='store', help='Base commit')
parser.add_argument('--branch', metavar='BRANCH', action='store', default='master', help='Destination branch')

args = parser.parse_args()


assert path.exists(args.patchset)
assert not path.exists(path.join(args.patchset, '.git')) # protect against argument swap


horst = ['-c', 'user.name=Horst Beepmanh', '-c', 'user.email=<>']


makedirs(args.worktree, exist_ok=True)
run(['git', 'init'], cwd=args.worktree, check=True)
run(['git', 'checkout', '--orphan', args.branch], cwd=args.worktree, check=True)

# This cleans the working directory, because the manpage's suggestion `git rm -rf .` does not work
run(['git', 'reset'], cwd=args.worktree, check=True)
for do_delete in listdir(args.worktree):
    if do_delete != '.git':
        do_delete = path.join(args.worktree, do_delete)
        try:
            rmtree(do_delete)
        except NotADirectoryError:
            remove(do_delete)

if args.base_commit is not None:
    run(['git', 'reset', '--hard', args.base_commit], cwd=args.worktree, check=True)
else:
    for walk_base, walk_dirs, walk_files in walk(args.base):
        walk_dirs[:] = [x for x in walk_dirs if not x.startswith('.')]
        walk_files[:] = [x for x in walk_files if not x.startswith('.')]

        other_dir = path.join(args.worktree, path.relpath(walk_base, args.base))

        makedirs(other_dir, exist_ok=True)

        for this_file in walk_files:
            copy(path.join(walk_base, this_file), other_dir)

    run(['git', 'add', '.'], cwd=args.worktree, check=True)
    run(['git', *horst, 'commit', '-m', path.basename(args.base)], cwd=args.worktree, check=True)

with open(path.join(args.worktree, '.gitignore'), 'a') as f:
    f.write('Build*\n')
run(['git', 'add', '.gitignore'], cwd=args.worktree, check=True)
run(['git', *horst, 'commit', '-m', 'auto-gitignore (do not rebase)'], cwd=args.worktree, check=True)

run(['git', 'tag', args.branch+'-patchset-base'], cwd=args.worktree, check=True)

patchfiles = [path.join(args.patchset, x) for x in sorted(listdir(args.patchset)) if path.splitext(x)[1].lower() == '.patch']
run(['git', *horst, 'am', *patchfiles], cwd=args.worktree, check=True)