#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# git-phab - git subcommand to integrate with phabricator
#
# Copyright (C) 2008  Owen Taylor
# Copyright (C) 2015  Xavier Claessens <xavier.claessens@collabora.com>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, If not, see
# http://www.gnu.org/licenses/.

import subprocess
import argparse
import git
import os
import re
import sys
import json


repo = git.Repo(os.getcwd())


# Copied from git-bz
def die(message):
    print(message, file=sys.stderr)
    sys.exit(1)


# Copied from git-bz
def prompt(message):
    try:
        while True:
            # Using print here could result in Python adding a stray space
            # before the next print
            sys.stdout.write(message + " [yn] ")
            sys.stdout.flush()
            line = sys.stdin.readline().strip()
            if line == 'y' or line == 'Y':
                return True
            elif line == 'n' or line == 'N':
                return False
    except KeyboardInterrupt:
        # Ctrl+C doesn’t cause a newline
        sys.stdout.write("\n")
        return False


def get_commits(commit_or_revision_range):
    try:
        # See if the argument identifies a single revision
        commits = [repo.rev_parse(commit_or_revision_range)]
    except:
        # If not, assume the argument is a range
        try:
            commits = list(repo.iter_commits(commit_or_revision_range))
        except:
            # If not again, the argument must be invalid — perhaps the user has
            # accidentally specified a bug number but not a revision.
            commits = []

    if len(commits) == 0:
        die(("'%s' does not name any commits. Use HEAD to specify just the "
             "last commit") % commit_or_revision_range)

    return commits


def get_differential_link(commit):
    m = re.search('(^Differential Revision: )(.*)$',
                  commit.message, re.MULTILINE)
    return None if m is None else m.group(2)


def format_commit(commit):
    link = get_differential_link(commit)
    d = "N/A" if link is None else link[link.rfind('/') + 1:]
    return u"%s %s — %s" % (commit.hexsha[:7], d, commit.summary)


def print_commit(commit):
    print(format_commit(commit))


def conduit(cmd, args):
    output = subprocess.check_output('arc call-conduit ' + cmd,
                                     input=bytes(json.dumps(args), 'utf-8'),
                                     shell=True)
    return json.loads(output.decode('utf-8'))


def get_wip_branch(args, fetch=False):
    remote = args.remote
    branch = "wip/phab/" + args.task

    if fetch and not remote:
        try:
            reply = conduit('maniphest.query', {
                "ids": [int(args.task[1:])]
            })
            props = list(reply['response'].values())[0]
            uri = props['auxiliary']['std:maniphest:git:uri-branch']
            remote, branch = uri.split('#')
            print("Git URI: %s, branch: %s" % (remote, branch))
        except:
            print("Couldn't get git URI from Maniphest")

    if not remote:
        remote = repo.config_reader().get_value('phab', 'remote')

    return branch, remote


def validate_args(args):
    if args.task and not re.fullmatch('T[0-9]+', args.task):
        die(("Task '%s' is not in the correct format. "
             "Expecting 'T123'." % args.task))


def parse_commit_msg(msg):
    subject = None
    body = []
    fields = []

    for line in msg.split('\n'):
        if not subject:
            subject = line
        elif line.startswith('Differential Revision: '):
            fields.append(line)
        else:
            body.append(line)

    return subject, body, fields


def do_attach(args):
    if repo.is_dirty():
        die("Repository is dirty. Aborting.")

    validate_args(args)

    # Oldest commit is last in the list
    commits = get_commits(args.revision_range)
    all_commits = list(repo.iter_commits(commits[-1].hexsha + "^..HEAD"))

    # Sanity checks
    for c in commits:
        if c not in all_commits:
            die("'%s' is not in current tree. Aborting." % c.hexsha)
        if len(c.parents) > 1:
            die("'%s' is a merge commit. Aborting." % c.hexsha)

    # Try to guess the task from branch name
    if not args.task:
        name = str(repo.head.reference)
        m = re.search('(^T[0-9]+)($|-.*)', name)
        if m is not None:
            args.task = m.group(1)

    # Ask confirmation before doing any harm
    for c in commits:
        print_commit(c)
    if not prompt("Attach above commits?" if not args.task else
                  "Attach above commits to task %s?" % args.task):
        print("Aborting")
        sys.exit(0)

    orig_commit = repo.head.commit
    orig_branch = repo.head.reference

    options = ['--allow-untracked',
               '--config history.immutable=false',
               '--verbatim']
    if args.reviewers:
        options.append('--reviewers ' + args.reviewers)
    if args.message:
        options.append('--message "' + args.message + '"')
    arc_cmd = 'arc diff %s HEAD~1' % (' '.join(options))

    summary = ""

    try:
        # Detach HEAD from the branch; this gives a cleaner reflog for the
        # branch
        print("Moving to starting point")
        repo.head.reference = commits[-1].parents[0]
        repo.head.reset(index=True, working_tree=True)

        last_revision_id = None
        for commit in reversed(all_commits):
            repo.git.cherry_pick(commit.hexsha)

            if commit in commits:
                # Add extra info in the commit msg. It is important that
                # phabricator fields are last, after all common git fields like
                # 'Reviewed-by:', etc. Note that "Depends on" is not a field
                # and is parsed from the body part.
                subject, body, fields = parse_commit_msg(commit.message)
                if last_revision_id:
                    body.append("Depends on %s" % last_revision_id)
                if args.task:
                    fields.append("Maniphest Tasks: %s" % args.task)

                msg = '\n\n'.join([subject,
                                   '\n'.join(body),
                                   '\n'.join(fields)])

                repo.head.commit = repo.head.commit.parents[0]
                repo.head.commit = repo.index.commit(msg)

                print("attach " + commit.hexsha)
                try:
                    subprocess.check_call(arc_cmd, shell=True)
                except:
                    print("Command '%s' failed. Continuing." % arc_cmd)
                    summary += "Failed: %s\n" % format_commit(commit)
                    repo.head.commit = commit
                    continue

                # arc diff modified our commit message. Re-commit it with the
                # original message, adding only the "Differential Revision:"
                # line.
                msg = commit.message
                orig_link = get_differential_link(commit)
                new_link = get_differential_link(repo.head.commit)
                if orig_link is None and new_link is not None:
                    msg = msg + '\nDifferential Revision: ' + new_link
                    summary += "New: "
                else:
                    summary += "Updated: "

                repo.head.commit = repo.head.commit.parents[0]
                repo.head.commit = repo.index.commit(msg)
                last_revision_id = new_link.split("/")[-1]

                summary += format_commit(repo.head.commit) + "\n"
            else:
                print("pick " + commit.hexsha)
                summary += "Picked: %s\n" % format_commit(commit)

        if orig_branch is not None:
            orig_branch.commit = repo.head.commit
            repo.head.reference = orig_branch
    except:
        print("Cleaning up back to original state on error")
        repo.head.commit = orig_commit
        if orig_branch is not None:
            orig_branch.commit = orig_commit
            repo.head.reference = orig_branch
        repo.head.reset(index=True, working_tree=True)
        raise

    if args.task:
        try:
            branch, remote_name = get_wip_branch(args)
            remote = repo.remote(remote_name)
            if prompt('Push HEAD to %s/%s?' % (remote, branch)):
                remote.push('HEAD:refs/heads/' + branch, force=True)
                summary += "Branch pushed to %s/%s\n" % (remote, branch)

            try:
                uri = "%s#%s" % (remote.config_reader.get('url'), branch)
                conduit('maniphest.update', {
                    "id": int(args.task[1:]),
                    "auxiliary": {
                        "std:maniphest:git:uri-branch": uri
                    }
                })
            except:
                print("Failed to set std:maniphest:git:uri-branch")

        except Exception as e:
            summary += "Failed: push wip branch: %s\n" % e

    print("\n\nSummary:")
    print(summary)


def do_log(args):
    commits = get_commits(args.revision_range)
    for c in commits:
        print_commit(c)


def do_fetch(args):
    validate_args(args)

    branch, remote = get_wip_branch(args, fetch=True)
    if not remote:
        die("No remote location defined. Aborting.")

    repo.git.fetch(remote, "%s:%s" % (branch, args.task), force=True)
    print("Branch %s created." % args.task)


parser = argparse.ArgumentParser(description='Phabricator integration.')
subparsers = parser.add_subparsers()

attach_parser = subparsers.add_parser(
    'attach', help="Generate a Differential for each commit")
attach_parser.add_argument(
    '--reviewers', '-r', metavar='<username1,username2,...>',
    help="A list of reviewers")
attach_parser.add_argument(
    '--message', '-m', metavar='<message>',
    help=("When updating a revision, use the specified message instead of "
          "prompting"))
attach_parser.add_argument(
    '--task', '-t', metavar='<T123>',
    help=("Set the task this Differential refers to"))
attach_parser.add_argument(
    '--remote', metavar='<remote>',
    help=("A remote repository to push to. "
          "Overrides 'phab.remote' configuration."))
attach_parser.add_argument(
    'revision_range', metavar='<revision range>',
    nargs='?', default='origin/master..',
    help="commit or revision range to attach (Default: 'origin/master..')")
attach_parser.set_defaults(func=do_attach)

log_parser = subparsers.add_parser(
    'log', help="Show commit logs with their differential ID")
log_parser.add_argument(
    'revision_range', metavar='<revision range>',
    nargs='?', default='origin/master..',
    help="commit or revision range to show (Default: 'origin/master..')")
log_parser.set_defaults(func=do_log)

fetch_parser = subparsers.add_parser(
    'fetch', help="Fetch a task's branch")
fetch_parser.add_argument(
    '--remote', metavar='<remote>',
    help=("A remote repository to fetch from. "
          "Overrides 'phab.remote' configuration."))
fetch_parser.add_argument(
    'task', metavar='<T123>',
    help="The task to fetch")
fetch_parser.set_defaults(func=do_fetch)

args = parser.parse_args()
args.func(args)