#!/usr/bin/env python3
## Purges all branches that have been squashed and merged to a target branch (defaults to branches merged to master). Requires pygithub.
## Source: git-extra-commands

# -*- coding: utf-8 -*-

# https://github.com/paulirish/dotfiles
#
# prereqs:
#
#     pip3 install pygithub
#

# usage:
#     git delete-squashed-and-merged-branches --dry-run  # won't actually delete shit
#     git delete-squashed-and-merged-branches            # probably will delete shit

# get a github personal access token and put it in ~/.githubtoken

# thanks!
# this script is a bit of a combo from:
#   danvk   https://gist.github.com/danvk/a715357444ff3c1a05c4cff730eea8e1
#   larsks  https://github.com/larsks/github-tools/blob/master/git-is-merged
#   paulirish

from glob import glob
import os.path

import sys
import github
import subprocess
import time

yellow = '\033[93m'
brightblack = '\u001b[30;1m'
reset = '\033[0m'
DRY_RUN = len(sys.argv) > 1 and sys.argv[1] == '--dry-run'

tokenpath = os.path.expanduser('~/.githubtoken')
tokenfile = open(tokenpath)
token = tokenfile.read().strip();


def get_branch_heads():
    '''Returns an Array<[branchname, SHA]> of local branches.'''
    branch_to_sha = []
    # %09 is a tab, which we later split on
    refsoutput = subprocess.check_output(["git", "for-each-ref", "--sort=-committerdate", "refs/heads/", "--format=%(refname)%09%(objectname)"])
    lines = refsoutput.decode().split('\n')

    for line in lines:
        if not line:
            continue
        objectname,sha = line.split('\t')
        branch_name = objectname.replace('refs/heads/', '')
        if branch_name != 'master':
            branch_to_sha.append([branch_name, sha])
    return branch_to_sha


def main():
    G = github.Github(login_or_token=token)

    retval = 0
    items = get_branch_heads()

    print(f"Looking at {len(items)} total local heads, from newest to oldest.")

    for [branch, sha] in items:
        print('\n')
        time.sleep(2) # search only allows 30 req/min. https://developer.github.com/v3/search/#rate-limit
        res = G.search_issues(sha)
        shortsha = sha[0:7]
        issue_closed_states = [issue.state == 'closed' for issue in res]
        open_issues = [issue for issue in res if issue.state != 'closed']

        # todo: filter found issues to see if they are from remotes that we care about.
        # eg not this shit https://github.com/DrippingFuture/lighthouse/pull/1

        if not issue_closed_states:
            msg = '🔃  No PRs found'
            retval = 4
        elif all(issue_closed_states):
            msg = '💀  All PRs are closed. Ready to 🗑'
            retval = 0
        elif any(issue_closed_states):
            msg = '🌀  Some (BUT not all) PRs are closed'
            retval = 1
        else:
            msg = '🔃  All PRs still open'
            retval = 2

        print('{}{}{} ({}):\n{}'.format(yellow, branch, reset, shortsha, msg))
        for issue in open_issues:
            print('    · "{}" {}{}{}'.format(issue.title, brightblack, issue.html_url, reset))

        if retval == 0:
            if DRY_RUN:
                print('❎  Without --dry-run, would delete branch %s' % branch)
            else:
                print('❌  Deleting local branch %s' % branch)
                subprocess.check_call(['git', 'branch', '-D', branch])

    sys.exit(retval)

if __name__ == '__main__':
    main()