#!/usr/bin/env python3

import argparse
import subprocess
import re
import sys

left  = "master"
right = "OpenSSL_1_1_1-stable"


def parse_arguments():
    parser = argparse.ArgumentParser(
        description = """Shows the commits in '{left}...{right}'
        which are eligible for cherry-picking. A commit is considered
        cherry-picked, if there is another commit on the "other side"
        which introduces an equivalent patch.
        For details, see the documentation of the '--cherry-mark' option
        in the git-log(1) manpage.
        """.format(left=left, right=right))

    parser.add_argument(
        '-a', '--all',
        action = 'store_true',
        help = "Show all commits, also those which have been cherry-picked."\
        )

    parser.add_argument(
        '-s', '--sort',
        action = 'store_true',
        help = "Sort commits w.r.t. pull request number and author date."\
        )

    parser.add_argument(
        '-r', '--remote',
        action = 'store_true',
        help = "Compare the remote branches instead of the local ones."\
        )

    args = parser.parse_args()

    return args


def check_openssl_git_repo():
    """Checks whether we're inside a openssl.git downstrem repository"""
    try:
        if "/openssl.git" in subprocess.check_output(
                ["git", "remote", "-v"]
        ).decode():
            return True;
    except:
        pass

    return False


def get_remote():
    try:
        return subprocess.check_output(
            ["git", "config", "branch.master.remote"]
            ).decode().trim()
    except:
        return "origin"


def pick_cherries(left, right, all = False):
    """Lists all commits from the symmetric difference of left and right

    By default, all commits are omitted which have an 'equivalent' commit
    on the other side, unless 'all' == True.
    """

    git_command = [
        "git", "log", "--oneline", "--cherry-mark", "--left-right",
        left + "..." + right, "--pretty=%at;%m;%h;%s"
    ]

    prnum_regex   = re.compile("|".join([
        # The standard pull request annotation
        "\(Merged from https://github.com/openssl/openssl/pull/([0-9]+)\)",
        # @kroeck's special pull request annotation ;-)
        "GH: #([0-9]+)"
    ]))

    fixes_regex   = re.compile(
        "Fixes[:]?\s+(#|https://github.com/openssl/openssl/pull/)([0-9]+)")

    for line in subprocess.check_output(git_command).decode().splitlines():

        timestamp, branch, commit, subject = line.split(";", maxsplit=3)

        if branch == '=' and not all:
            continue

        # shorten overlong subject lines
        if len(subject) > 70:
            subject = subject[:70] + "..."

        # search commit message for pull request number
        message = subprocess.check_output(
            ["git", "show", "--no-patch", commit]
        ).decode()

        match = prnum_regex.search(message)
        if match:
            if match.group(1):
                prnum = match.group(1)
            else:
                prnum = match.group(2)
        else:
            prnum = "????"

        match = fixes_regex.search(message)
        if match:
            fixes = "#" + match.group(2)
        else:
            fixes = ""

        yield prnum, fixes, timestamp, branch, commit, subject



if __name__ == '__main__':
    args = parse_arguments()

    if not check_openssl_git_repo():
        print("cherry-checker: Not inside an openssl git repository.", file=sys.stderr)
        sys.exit(1)


    if args.remote:
        remote = get_remote()
        left  = remote+"/"+left
        right = remote+"/"+right

    commits = pick_cherries(left, right, args.all)

    if args.sort:
        commits = sorted(commits, reverse=True)

    print("""These cherries are hanging on the git-tree:

  <-  {left}
  ->  {right}
  ==  both

 prnum  | fixes  | br |   commit   |   subject
------- | ------ | -- | ---------- | -------------------------------------------""".format(
         left = left,
         right = right))

    branch_marker = { '<': '<-', '>': '->', '=' : '==' }

    try:
        for prnum, fixes, _, branch, commit, subject in commits:
            print(' {:>6} | {:>6} | {} | {} | {} '.format(
                '#'+prnum, fixes, branch_marker[branch], commit, subject
            ))
    except subprocess.CalledProcessError as e:
        print(e, file=sys.stderr)