#!/usr/bin/env python3
"""Cherry pick and backport a PR"""
from __future__ import print_function

from builtins import input
import sys
import os
import argparse
from os.path import expanduser
import re
from subprocess import check_call, call, check_output
import requests
import json

usage = """
    Example usage:
        ./devtools/label <pr_number>
"""


def main():
    """Main"""
    parser = argparse.ArgumentParser(
        description="Adds a label to a pull request",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog=usage)
    parser.add_argument("pr_number",
                        help="The PR number being merged (e.g. 2345)")
    args = parser.parse_args()

    print(args)

    create_label(parser, args)

def create_label(parser, args):
    info("Checking if GitHub API token is available in `~/.elastic/github.token`")
    token = get_github_token()

    if not token:
        info("GitHub API token not available.")
    else:
        # initialize github
        session = github_session(token)
        base = "https://api.github.com/repos/elastic/logstash"

        # add labels
        labels = []

        # get the version (vX.Y.Z) we are merging to
        version = get_version(os.getcwd())
        if version:
            labels.append(version)

        session.post(
            base + "/issues/{}/labels".format(args.pr_number), json=labels)

def get_version(base_dir):
    with open(os.path.join(base_dir, "versions.yml"), "r") as f:
        for line in f:
            if line.startswith('logstash:'):
                return "v" + line.split(':')[-1].strip()

def get_github_token():
    try:
        token = open(expanduser("~/.elastic/github.token"), "r").read().strip()
    except:
        token = False
    return token

def github_session(token):
    session = requests.Session()
    session.headers.update({"Authorization": "token " + token})
    return session

def info(msg):
    print("\nINFO: {}".format(msg))

if __name__ == "__main__":
    sys.exit(main())