import os
import sys
import json
import re
import subprocess
import requests

github_token = os.environ['GITHUB_TOKEN']
auth = (github_token, 'x-oauth-basic')
repo = 'getredash/redash'

def _github_request(method, path, params=None, headers={}):
    if not path.startswith('https://api.github.com'):
        url = "https://api.github.com/{}".format(path)
    else:
        url = path

    if params is not None:
        params = json.dumps(params)

    response = requests.request(method, url, data=params, auth=auth)
    return response

def exception_from_error(message, response):
    return Exception("({}) {}: {}".format(response.status_code, message, response.json().get('message', '?')))

def rc_tag_name(version):
    return "v{}-rc".format(version)

def get_rc_release(version):
    tag = rc_tag_name(version)
    response = _github_request('get', 'repos/{}/releases/tags/{}'.format(repo, tag))

    if response.status_code == 404:
        return None
    elif response.status_code == 200:
        return response.json()

    raise exception_from_error("Unknown error while looking RC release: ", response)

def create_release(version, commit_sha):
    tag = rc_tag_name(version)

    params = {
        'tag_name': tag,
        'name': "{} - RC".format(version),
        'target_commitish': commit_sha,
        'prerelease': True
    }

    response = _github_request('post', 'repos/{}/releases'.format(repo), params)

    if response.status_code != 201:
        raise exception_from_error("Failed creating new release", response)

    return response.json()

def upload_asset(release, filepath):
    upload_url = release['upload_url'].replace('{?name,label}', '')
    filename = filepath.split('/')[-1]

    with open(filepath) as file_content:
        headers = {'Content-Type': 'application/gzip'}
        response = requests.post(upload_url, file_content, params={'name': filename}, headers=headers, auth=auth, verify=False)

    if response.status_code != 201:  # not 200/201/...
        raise exception_from_error('Failed uploading asset', response)

    return response

def remove_previous_builds(release):
    for asset in release['assets']:
        response = _github_request('delete', asset['url'])
        if response.status_code != 204:
            raise exception_from_error("Failed deleting asset", response)

def get_changelog(commit_sha):
    latest_release = _github_request('get', 'repos/{}/releases/latest'.format(repo))
    if latest_release.status_code != 200:
        raise exception_from_error('Failed getting latest release', latest_release)

    latest_release = latest_release.json()
    previous_sha = latest_release['target_commitish']

    args = ['git', '--no-pager', 'log', '--merges', '--grep', 'Merge pull request', '--pretty=format:"%h|%s|%b|%p"', '{}...{}'.format(previous_sha, commit_sha)]
    log = subprocess.check_output(args)
    changes = ["Changes since {}:".format(latest_release['name'])]

    for line in log.split('\n'):
        try:
            sha, subject, body, parents = line[1:-1].split('|')
        except ValueError:
            continue

        try:
            pull_request = re.match("Merge pull request #(\d+)", subject).groups()[0]
            pull_request = " #{}".format(pull_request)
        except Exception, ex:
            pull_request = ""

        author = subprocess.check_output(['git', 'log', '-1', '--pretty=format:"%an"', parents.split(' ')[-1]])[1:-1]

        changes.append("{}{}: {} ({})".format(sha, pull_request, body.strip(), author))

    return "\n".join(changes)

def update_release_commit_sha(release, commit_sha):
    params = {
        'target_commitish': commit_sha,
    }

    response = _github_request('patch', 'repos/{}/releases/{}'.format(repo, release['id']), params)

    if response.status_code != 200:
        raise exception_from_error("Failed updating commit sha for existing release", response)

    return response.json()

def update_release(version, build_filepath, commit_sha):
    try:
        release = get_rc_release(version)
        if release:
            release = update_release_commit_sha(release, commit_sha)
        else:
            release = create_release(version, commit_sha)

        print "Using release id: {}".format(release['id'])

        remove_previous_builds(release)
        response = upload_asset(release, build_filepath)

        changelog = get_changelog(commit_sha)

        response = _github_request('patch', release['url'], {'body': changelog})
        if response.status_code != 200:
            raise exception_from_error("Failed updating release description", response)

    except Exception, ex:
        print ex

if __name__ == '__main__':
    commit_sha = sys.argv[1]
    version = sys.argv[2]
    filepath = sys.argv[3]

    # TODO: make sure running from git directory & remote = repo
    update_release(version, filepath, commit_sha)