""" Identify bugfixes in Bugzilla repository given a list of issues """
__author__ = "Justin Tracey and Kristian Berg"
__copyright__ = "Copyright (c) 2018 Axis Communications AB"
__license__ = "MIT"

import os
import json
import argparse
import subprocess
import datetime
from get_bugzilla_patches import get_title_lines


class Commit:
    def __init__(self, git_path=None, git_hash=None, author_date=None):
        self.git_path = git_path
        self.git_hash = git_hash
        self.author_date = author_date

    def files(self):
        return subprocess.check_output(['git', '-C', self.git_path,
                                        'diff-tree', '--no-commit-id',
                                        '--name-only', '-r', self.git_hash],
                                       universal_newlines=True)


def find_bug_fixes(issue_path, git_path):
    """ Identify bugfixes in Bugzilla repository given a list of issues """

    progress = 0
    no_matches = []
    matches_per_issue = {}
    total_matches = 0

    issue_list = build_issue_list(issue_path)

    for key in issue_list:
        nbr = key.split('-')[1]
        matches = []

        patterns = list(get_title_lines(nbr))

        for pattern in patterns:
            commits = subprocess.check_output(['git', '-C', git_path, 'log',
                                               '--date=iso',
                                               '--format=format:%H|%ad',
                                               '--grep={}'.format(pattern),
                                               '-F'],
                                              universal_newlines=True).strip()
            for commit in commits.splitlines():
                if commit:
                    commit = Commit(git_path, *(commit.split('|')))
                    matches.append(commit)
        total_matches += len(matches)
        matches_per_issue[key] = len(matches)

        if matches:
            selected_commit = commit_selector_heuristic(matches)
            if not selected_commit:
                no_matches.append(key)
            else:
                issue_list[key]['hash'] = selected_commit.git_hash
                issue_list[key]['commitdate'] = selected_commit.author_date
        else:
            no_matches.append(key)

        progress += 1
        if progress % 10 == 0:
            print(progress, end='\r')

    print('Total issues: ' + str(len(issue_list)))
    print('Issues matched to a bugfix: ' +
          str(len(issue_list) - len(no_matches)))
    print('Percent of issues matched to a bugfix: ' +
          str((len(issue_list) - len(no_matches)) / len(issue_list)))
    for key in no_matches:
        issue_list.pop(key)

    return issue_list


def build_issue_list(path):
    """ Helper method for find_bug_fixes """
    issue_list = {}
    for filename in os.listdir(path):
        with open(path + '/' + filename) as f:
            for issue in json.loads(f.read())['issues']:
                issue_list[issue['key']] = {}

                created_date = issue['fields']['created'].replace('T', ' ')
                created_date = created_date.replace('.000', ' ')
                issue_list[issue['key']]['creationdate'] = created_date

                res_date = issue['fields']['resolutiondate'].replace('T', ' ')
                res_date = res_date.replace('.000', ' ')
                issue_list[issue['key']]['resolutiondate'] = res_date
    return issue_list


suffixes = ["c", "C", "cc", "cpp", "cxx", "c++",
            "h", ".H", "hh", "hpp", "hxx", "h++"]


def commit_selector_heuristic(commits):
    """ SZZUnleashed only allows one fix commit per issue.
        We follow its norm of using the most recent associated commit.
        We also filter on commits touching C/C++ files.
    """
    def touches_c_file(commit):
        return any(filename for filename in commit.files().splitlines()
                   if filename.split('.')[-1] in suffixes)
    commits = [c for c in commits if touches_c_file(c)]
    # the weird string manipulation is to fix timezones formatted as +0000
    # (that git produces) to +00:00 (that python wants)
    return min(commits, key=lambda x:
               datetime.datetime.fromisoformat(x.author_date[:-2] + ':' +
                                               x.author_date[-2:]),
               default=None)


def main():
    """ Main method """
    parser = argparse.ArgumentParser(
        description="Identify bugfixes. Use this script together with a git "
        "repo and a path with issues. The issue directory is created and "
        "populated using the fetch-bugzilla.py script.")
    parser.add_argument('--git-path', type=str,
                        help='Path to local git repository')
    parser.add_argument('--issue-list', type=str,
                        help='Path to directory containing issue json files')
    args = parser.parse_args()

    issue_list = find_bug_fixes(args.issue_list, args.git_path)
    with open('issue_list.json', 'w') as f:
        f.write(json.dumps(issue_list))


if __name__ == '__main__':
    main()