#!/usr/bin/env python3

import argparse
import os
import sys

import pygit2

from flake8.api import legacy as flake8_legacy


def is_git_repo(abspath):
    """
    True of abspath points to a git repo, False otherwise
    """
    if not os.path.isdir(abspath):
        return False
    try:
        pygit2.Repository(abspath)
        return True
    except pygit2.GitError:
        return False


def modifications_exist(abspath):
    """
    True if modifications exist for git repo representing abspath
    False if no modifications exist

    pygit2.GitError raised if abspath points to illegal repo
    """
    repo = pygit2.Repository(abspath)
    status = repo.status()
    for gfile, state in status.items():
        if (
                state in (pygit2.GIT_STATUS_WT_MODIFIED,
                          pygit2.GIT_STATUS_WT_NEW,
                          pygit2.GIT_STATUS_INDEX_NEW,
                          pygit2.GIT_STATUS_INDEX_MODIFIED)
        ):
            return True
    return False


def print_modification_status(abspath, status, args):
    """
    Prints the modification status for the give abspath
    """
    if status:
        if args.verbose:
            print(f'{abspath} -> modified')
        else:
            print(abspath)
        return status
    if args.verbose:
        print(f'{abspath} -> unchanged')
    return status


def fetch_git_repos(abspath):
    """
    Returns a list of git repo paths under abspath
    """
    repo_list = list()
    for root, dirs, files in os.walk(abspath):
        if '.git' in dirs:
            try:
                pygit2.Repository(root)
                repo_list.append(root)
            except pygit2.GitError:
                continue
    return repo_list


def fetch_git_files(args):
    """
    Fetches new and modified .py-files using pygit2
    """
    git_files_list = list()
    try:
        repo = pygit2.Repository(args.repo_path)
        status = repo.status()
    except pygit2.GitError:
        print('{repo_path} is not a valid git repository'.format(
            repo_path=args.repo_path),
              file=sys.stderr,
              flush=True)
        sys.exit(1)
    if not status:
        return git_files_list
    for gfile, state in status.items():
        if (
                state in (pygit2.GIT_STATUS_WT_MODIFIED,
                          pygit2.GIT_STATUS_WT_NEW,
                          pygit2.GIT_STATUS_INDEX_NEW,
                          pygit2.GIT_STATUS_INDEX_MODIFIED) and
                gfile.lower().endswith('.py')
        ):
            if args.verbose:
                print(gfile)
            git_files_list.append(gfile)
    return git_files_list


if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description='The following options are available')
    parser.add_argument(
        'repo_path',
        metavar='REPO',
        default=os.getcwd(),
        type=str,
        help='Git repo path (default: cwd)')
    parser.add_argument(
        '-m', '--modifications-only',
        action='store_true',
        dest='mod_only',
        default=False,
        help='Only check for git modifications')
    parser.add_argument(
        '-r', '--recursive',
        action='store_true',
        dest='recursive',
        default=False,
        help='Look for several repos recursively')
    parser.add_argument(
        '-v', '--verbose',
        action='store_true',
        dest='verbose',
        default=False,
        help='Verbosity')
    args = parser.parse_args()
    abs_repo_path = os.path.abspath(os.path.expanduser(args.repo_path))
    if args.mod_only:
        if not args.recursive:
            if not is_git_repo(abs_repo_path):
                print(f'{abs_repo_path} is not a valid git repository',
                      file=sys.stderr,
                      flush=True)
                sys.exit(1)
            print_modification_status(abs_repo_path,
                                      modifications_exist(abs_repo_path),
                                      args)
            sys.exit(0)
        # resursive
        repo_list = fetch_git_repos(abs_repo_path)
        if not repo_list:
            print('No git-repos found')
            sys.exit(0)
        repo_list.sort()
        for repo_path in repo_list:
            print_modification_status(repo_path,
                                      modifications_exist(repo_path),
                                      args)
        sys.exit(0)
    git_files = fetch_git_files(args)
    if not git_files:
        print('No modifications')
        sys.exit(0)
    report = flake8_legacy.get_style_guide().check_files(git_files)
    if report.total_errors:
        print('Total errors: {errors}'.format(errors=report.total_errors))