#!/usr/bin/env python
# coding: utf-8

import argparse
import os
import re

import requests

COMMIT_API = 'https://api.github.com/repos/hpcaitech/ColossalAI/commits'
TAGS_API = 'https://api.github.com/repos/hpcaitech/ColossalAI/tags'


def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('--out', type=str, help='output path for the release draft', required=True)
    parser.add_argument('--version', type=str, help='current version to release', required=True)
    return parser.parse_args()


def get_latest_tag_commit(headers=None):
    res = requests.get(url=TAGS_API, headers=headers)
    data = res.json()
    commit_hash = data[0]['commit']['sha']
    version = data[0]['name']
    return commit_hash, version


def get_commit_info(commit_hash, headers=None):
    api = f'{COMMIT_API}/{commit_hash}'
    res = requests.get(url=api, headers=headers)
    return res.json()


def get_all_commit_info(since, headers=None):
    page = 1
    results = []

    while True:
        api = f'{COMMIT_API}?since={since}&per_page=100&page={page}'
        resp = requests.get(url=api, headers=headers)
        data = resp.json()

        # exit when no more data
        if len(data) == 0:
            break

        results.extend(data)
        page += 1

    return results


def collate_release_info(commit_info_list):
    results = dict()
    pattern = pattern = r'\[.*\]'

    for commit_info in commit_info_list:
        author = commit_info['commit']['author']['name']

        try:
            author_url = commit_info['author']['url']
        except:
            # author can be None
            author_url = None
        msg = commit_info['commit']['message']
        match = re.search(pattern, msg)

        if match:
            tag = match.group().lstrip('[').rstrip(']').capitalize()
            if tag not in results:
                results[tag] = []
            results[tag].append((msg, author, author_url))

    return results


def generate_release_post_markdown(current_version, last_version, release_info):
    text = []

    # add highlights
    highlights = "## What's Changed \n\n"
    text.append(highlights)

    # add items
    for k, v in release_info.items():
        topic = f"### {k} \n"
        text.append(topic)

        for msg, author, author_url in v:
            # only keep the first line
            msg = msg.split('\n')[0]

            if author_url:
                item = f'{msg} by [{author}]({author_url})\n'
            else:
                item = f'{msg} by {author}\n'
            text.append(f'- {item}')

        text.append('\n')

    # add full change log
    text.append(
        f'**Full Changelog**: https://github.com/hpcaitech/ColossalAI/compare/{current_version}...{last_version}')

    return text


if __name__ == '__main__':
    args = parse_args()
    token = os.environ['GITHUB_API_TOKEN']
    headers = {'Authorization': token}

    # get previous release tag
    last_release_commit, last_version = get_latest_tag_commit(headers)
    last_release_commit_info = get_commit_info(last_release_commit, headers=headers)
    last_release_date = last_release_commit_info['commit']['author']['date']

    # get the commits since last release
    commit_info = get_all_commit_info(since=last_release_date, headers=headers)
    commit_info = commit_info[:-1]    # remove the release commit

    # collate into markdown
    release_info = collate_release_info(commit_info)
    markdown_text = generate_release_post_markdown(args.version, last_version, release_info)

    # write into a file
    with open(args.out, 'w') as f:
        for line in markdown_text:
            f.write(line)
