#!/usr/bin/env python3
# git config linker (gcl) v1.0
# Written by Martin Fischer <martin@push-f.com> and licensed under MIT.
import sys
import os
import configparser
import subprocess
import shutil

GITCONFIGS = 'gitconfigs/'


class colors:
    WARNING = '\033[93m'
    FAIL = '\033[91m'
    ENDC = '\033[0m'


def print_usage():
    print(
        '''git config linker (gcl):

 gcl status            check the status of the directories in .

 gcl link <repo>...    move <repo>/.git/config to gitconfigs/<repo>
                       (leaving a symlink behind)

 gcl clone             list all configs that are not cloned

 gcl clone <config>... clone a repository using gitconfigs/<config>

 gcl mv <src> <dest>   rename a repo and its config and update the symlink

 gcl unlink <repo>...  undo "gcl link <repo>"
                       (only needed if you want to stop using gcl)
'''
    )
    sys.exit()


args = sys.argv[1:]
if len(args) == 0:
    print_usage()

if not os.path.exists(GITCONFIGS + '/.git/config'):
    sys.exit(f'expected {GITCONFIGS} to be a git repository')


def get_link_error(path):
    configpath = path + '/.git/config'
    if not os.path.exists(configpath):
        missing = os.path.relpath(os.path.realpath(configpath))
        return (
            colors.FAIL + 'BROKEN LINK' + colors.ENDC + f' ({missing} does not exist)'
        )
    elif (
        os.path.islink(configpath)
        and os.path.relpath(os.path.realpath(configpath)) != GITCONFIGS + path
    ):
        missing = os.path.relpath(os.path.realpath(configpath))
        return colors.WARNING + 'LINK MISMATCH' + colors.ENDC + f' ({missing})'


def get_repo_status(path):
    errors = []
    link_error = get_link_error(path)
    if link_error:
        errors.append(link_error)

    if hasremote(path + '/.git/config'):
        try:
            if (
                subprocess.check_output(
                    ['git', 'branch', '-r', '--contains', 'HEAD'],
                    cwd=path,
                    stderr=subprocess.DEVNULL,
                )
                == b''
            ):
                errors.append(colors.WARNING + 'UNPUSHED' + colors.ENDC)
        except subprocess.CalledProcessError as err:
            if (
                subprocess.run(
                    ['git', 'rev-parse', 'HEAD'],
                    cwd=path,
                    stderr=subprocess.DEVNULL,
                    stdout=subprocess.DEVNULL,
                )
                == 0
            ):
                # the first command did not just fail because there are no commits yet
                raise err
    else:
        errors.append(colors.FAIL + 'NO REMOTE' + colors.ENDC)

    if subprocess.check_output(['git', 'status', '--porcelain'], cwd=path) != b'':
        errors.append(colors.WARNING + 'DIRTY' + colors.ENDC)
    return ', '.join(errors)


def print_repo_table(reponames):
    maxlen = max([len(s) for s in reponames])
    for reponame in reponames:
        print(f'\t{reponame.ljust(maxlen)} {get_repo_status(reponame)}')
    print()


linked = []
unlinked = []
not_a_repo = []


def hasremote(path):
    config = configparser.ConfigParser()
    config.read(path)
    return any(
        [
            ':' in config[s].get('url', '')
            for s in config.sections()
            if s.startswith('remote')
        ]
    )


def scan():
    for filename in sorted(os.listdir()):
        if not os.path.isdir(filename):
            continue

        configpath = filename + '/.git/config'
        if os.path.islink(configpath):
            linked.append(filename)
        elif not os.path.exists(configpath):
            not_a_repo.append(filename)
        else:
            unlinked.append(filename)


cmd = args.pop(0)

if cmd == 'status':
    scan()
    if not_a_repo:
        print(f"non-repositories:\n")
        print('\t' + '\n\t'.join(not_a_repo))
        print()
    if unlinked:
        print('unlinked repos:\n    (link with "gcl link <name>...")\n')
        print_repo_table(unlinked)
    if linked:
        print('linked repos:\n')
        print_repo_table(linked)

elif cmd == 'link':
    if len(args) == 0:
        sys.exit('Nothing specified, nothing linked.')

    for repo in args:
        configpath = repo + '/.git/config'
        if not os.path.isfile(configpath):
            print(
                f"skipping '{repo}' because {configpath} is not a file (maybe already linked?)"
            )
            continue
        if os.path.exists(GITCONFIGS + repo):
            sys.exit(f"aborting since {GITCONFIGS + repo} already exists")
        os.rename(configpath, GITCONFIGS + repo)
        os.symlink('../../' + GITCONFIGS + repo, configpath)

elif cmd == 'unlink':
    if len(args) == 0:
        sys.exit('Nothing specified, nothing unlinked.')

    for repo in args:
        configpath = repo + '/.git/config'
        if not os.path.islink(configpath):
            continue
        if not os.path.isfile(configpath):
            print(f"skipping '{repo}' because {config} is not a file")
            continue

        os.unlink(configpath)
        shutil.copyfile(GITCONFIGS + repo, configpath)
        os.unlink(GITCONFIGS + repo)

elif cmd == 'clone':
    if len(args) == 0:
        scan()
        available = set(os.listdir(GITCONFIGS)) - set(linked) - set(['.git'])
        if available:
            print('uncloned configs:\n    (clone with "gcl clone <name>...")\n')
            for l in sorted(available):
                print('    ' + l)
            print()
    for arg in args:
        if os.path.exists(arg):
            print(f"skipping '{arg}' because the directory already exists")
            continue
        if not os.path.isfile(GITCONFIGS + arg):
            print(f"skipping '{arg}' because {GITCONFIGS}/{arg} doesn't exist")
            continue
        subprocess.run(['git', 'init', arg])
        os.unlink(arg + '/.git/config')
        os.symlink('../../' + GITCONFIGS + arg, arg + '/.git/config')
        subprocess.run(['git', 'pull'], cwd=arg)

elif cmd == 'mv':
    if len(args) != 2:
        print_usage()
    src, dest = args
    if '/' in src or '/' in dest:
        sys.exit('fatal: src and dest may not contain slashes')
    if src == 'gitconfigs':
        sys.exit('fatal: cannot move gitconfigs')
    link_error = get_link_error(src)
    if link_error:
        sys.exit('aborting because src is not properly linked: ' + link_error)
    if os.path.exists(dest):
        sys.exit(f"fatal: repo destination '{dest}' already exists")
    if os.path.exists(GITCONFIGS + dest):
        sys.exit(f"fatal: config destination '{GITCONFIGS + dest}' already exists")

    os.rename(src, dest)
    os.rename(GITCONFIGS + src, GITCONFIGS + dest)
    os.unlink(dest + '/.git/config')
    os.symlink('../../' + GITCONFIGS + dest, dest + '/.git/config')
else:
    print_usage()