# utils/update_checkout.py - Utility to update local checkouts --*- python -*-
#
# This source file is part of the Swift.org open source project
#
# Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
# Licensed under Apache License v2.0 with Runtime Library Exception
#
# See https://swift.org/LICENSE.txt for license information
# See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors

from __future__ import print_function

import argparse
import json
import os
import re
import sys
import traceback

from functools import reduce
from multiprocessing import freeze_support

from swift_build_support.swift_build_support import shell
from swift_build_support.swift_build_support.SwiftBuildSupport import \
    SWIFT_SOURCE_ROOT


SCRIPT_FILE = os.path.abspath(__file__)
SCRIPT_DIR = os.path.dirname(SCRIPT_FILE)


def confirm_tag_in_repo(tag, repo_name):
    tag_exists = shell.capture(['git', 'ls-remote', '--tags',
                                'origin', tag], echo=False)
    if not tag_exists:
        print("Tag '" + tag + "' does not exist for '" +
              repo_name + "', just updating regularly")
        tag = None
    return tag


def find_rev_by_timestamp(timestamp, repo_name, refspec):
    base_args = ["git", "log", "-1", "--format=%H",
                 '--before=' + timestamp]
    # Prefer the most-recent change _made by swift-ci_ before the timestamp,
    # falling back to most-recent in general if there is none by swift-ci.
    rev = shell.capture(base_args + ['--author', 'swift-ci', refspec]).strip()
    if rev:
        return rev
    rev = shell.capture(base_args + [refspec]).strip()
    if rev:
        return rev
    else:
        raise RuntimeError('No rev in %s before timestamp %s' %
                           (repo_name, timestamp))


def get_branch_for_repo(config, repo_name, scheme_name, scheme_map,
                        cross_repos_pr):
    cross_repo = False
    repo_branch = scheme_name
    if scheme_map:
        scheme_branch = scheme_map[repo_name]
        repo_branch = scheme_branch
        remote_repo_id = config['repos'][repo_name]['remote']['id']
        if remote_repo_id in cross_repos_pr:
            cross_repo = True
            pr_id = cross_repos_pr[remote_repo_id]
            repo_branch = "ci_pr_{0}".format(pr_id)
            shell.run(["git", "checkout", scheme_branch],
                      echo=True)
            shell.capture(["git", "branch", "-D", repo_branch],
                          echo=True, allow_non_zero_exit=True)
            shell.run(["git", "fetch", "origin",
                       "pull/{0}/merge:{1}"
                       .format(pr_id, repo_branch)], echo=True)
    return repo_branch, cross_repo


def update_single_repository(args):
    config, repo_name, scheme_name, scheme_map, tag, timestamp, \
        reset_to_remote, should_clean, cross_repos_pr = args
    repo_path = os.path.join(SWIFT_SOURCE_ROOT, repo_name)
    if not os.path.isdir(repo_path):
        return

    try:
        print("Updating '" + repo_path + "'")
        with shell.pushd(repo_path, dry_run=False, echo=False):
            cross_repo = False
            checkout_target = None
            if tag:
                checkout_target = confirm_tag_in_repo(tag, repo_name)
            elif scheme_name:
                checkout_target, cross_repo = get_branch_for_repo(
                    config, repo_name, scheme_name, scheme_map, cross_repos_pr)
                if timestamp:
                    checkout_target = find_rev_by_timestamp(timestamp,
                                                            repo_name,
                                                            checkout_target)
            elif timestamp:
                checkout_target = find_rev_by_timestamp(timestamp, repo_name,
                                                        "HEAD")

            # The clean option restores a repository to pristine condition.
            if should_clean:
                shell.run(['git', 'clean', '-fdx'], echo=True)
                shell.run(['git', 'submodule', 'foreach', '--recursive', 'git',
                           'clean', '-fdx'], echo=True)
                shell.run(['git', 'submodule', 'foreach', '--recursive', 'git',
                           'reset', '--hard', 'HEAD'], echo=True)
                shell.run(['git', 'reset', '--hard', 'HEAD'], echo=True)
                # It is possible to reset --hard and still be mid-rebase.
                try:
                    shell.run(['git', 'rebase', '--abort'], echo=True)
                except Exception:
                    pass

            if checkout_target:
                shell.run(['git', 'status', '--porcelain', '-uno'],
                          echo=False)
                shell.run(['git', 'checkout', checkout_target], echo=True)

            # It's important that we checkout, fetch, and rebase, in order.
            # .git/FETCH_HEAD updates the not-for-merge attributes based on
            # which branch was checked out during the fetch.
            shell.run(["git", "fetch", "--recurse-submodules=yes"], echo=True)

            # If we were asked to reset to the specified branch, do the hard
            # reset and return.
            if checkout_target and reset_to_remote and not cross_repo:
                shell.run(['git', 'reset', '--hard',
                           "origin/%s" % checkout_target], echo=True)
                return

            # Query whether we have a "detached HEAD", which will mean that
            # we previously checked out a tag rather than a branch.
            detached_head = False
            try:
                # This git command returns error code 1 if HEAD is detached.
                # Otherwise there was some other error, and we need to handle
                # it like other command errors.
                shell.run(["git", "symbolic-ref", "-q", "HEAD"], echo=False)
            except Exception as e:
                if e.ret == 1:
                    detached_head = True
                else:
                    raise  # Pass this error up the chain.

            # If we have a detached HEAD in this repository, we don't want
            # to rebase. With a detached HEAD, the fetch will have marked
            # all the branches in FETCH_HEAD as not-for-merge, and the
            # "git rebase FETCH_HEAD" will try to rebase the tree from the
            # default branch's current head, making a mess.

            # Prior to Git 2.6, this is the way to do a "git pull
            # --rebase" that respects rebase.autostash.  See
            # http://stackoverflow.com/a/30209750/125349
            if not cross_repo and not detached_head:
                shell.run(["git", "rebase", "FETCH_HEAD"], echo=True)
            elif detached_head:
                print(repo_path,
                      "\nDetached HEAD; probably checked out a tag. No need "
                      "to rebase.\n")

            shell.run(["git", "submodule", "update", "--recursive"], echo=True)
    except Exception:
        (type, value, tb) = sys.exc_info()
        print('Error on repo "%s": %s' % (repo_path, traceback.format_exc()))
        return value


def get_timestamp_to_match(args):
    if not args.match_timestamp:
        return None
    with shell.pushd(os.path.join(SWIFT_SOURCE_ROOT, "swift"),
                     dry_run=False, echo=False):
        return shell.capture(["git", "log", "-1", "--format=%cI"],
                             echo=False).strip()


def update_all_repositories(args, config, scheme_name, cross_repos_pr):
    scheme_map = None
    if scheme_name:
        # This loop is only correct, since we know that each alias set has
        # unique contents. This is checked by validate_config. Thus the first
        # branch scheme data that has scheme_name as one of its aliases is
        # the only possible correct answer.
        for v in config['branch-schemes'].values():
            if scheme_name in v['aliases']:
                scheme_map = v['repos']
                break
    pool_args = []
    timestamp = get_timestamp_to_match(args)
    for repo_name in config['repos'].keys():
        if repo_name in args.skip_repository_list:
            print("Skipping update of '" + repo_name + "', requested by user")
            continue
        my_args = [config,
                   repo_name,
                   scheme_name,
                   scheme_map,
                   args.tag,
                   timestamp,
                   args.reset_to_remote,
                   args.clean,
                   cross_repos_pr]
        pool_args.append(my_args)

    return shell.run_parallel(update_single_repository, pool_args,
                              args.n_processes)


def obtain_additional_swift_sources(pool_args):
    (args, repo_name, repo_info, repo_branch, remote, with_ssh, scheme_name,
     skip_history, skip_repository_list) = pool_args

    with shell.pushd(SWIFT_SOURCE_ROOT, dry_run=False, echo=False):

        print("Cloning '" + repo_name + "'")

        if skip_history:
            shell.run(['git', 'clone', '--recursive', '--depth', '1',
                       remote, repo_name], echo=True)
        else:
            shell.run(['git', 'clone', '--recursive', remote,
                       repo_name], echo=True)
        if scheme_name:
            src_path = os.path.join(SWIFT_SOURCE_ROOT, repo_name, ".git")
            shell.run(['git', '--git-dir', src_path, '--work-tree',
                       os.path.join(SWIFT_SOURCE_ROOT, repo_name),
                       'checkout', repo_branch], echo=False)
    with shell.pushd(os.path.join(SWIFT_SOURCE_ROOT, repo_name),
                     dry_run=False, echo=False):
        shell.run(["git", "submodule", "update", "--recursive"],
                  echo=False)


def obtain_all_additional_swift_sources(args, config, with_ssh, scheme_name,
                                        skip_history, skip_repository_list):

    pool_args = []
    with shell.pushd(SWIFT_SOURCE_ROOT, dry_run=False, echo=False):
        for repo_name, repo_info in config['repos'].items():
            if repo_name in skip_repository_list:
                print("Skipping clone of '" + repo_name + "', requested by "
                      "user")
                continue

            if os.path.isdir(os.path.join(repo_name, ".git")):
                print("Skipping clone of '" + repo_name + "', directory "
                      "already exists")
                continue

            # If we have a url override, use that url instead of
            # interpolating.
            remote_repo_info = repo_info['remote']
            if 'url' in remote_repo_info:
                remote = remote_repo_info['url']
            else:
                remote_repo_id = remote_repo_info['id']
                if with_ssh is True or 'https-clone-pattern' not in config:
                    remote = config['ssh-clone-pattern'] % remote_repo_id
                else:
                    remote = config['https-clone-pattern'] % remote_repo_id

            repo_branch = None
            if scheme_name:
                for v in config['branch-schemes'].values():
                    if scheme_name not in v['aliases']:
                        continue
                    repo_branch = v['repos'][repo_name]
                    break
                else:
                    repo_branch = scheme_name

            pool_args.append([args, repo_name, repo_info, repo_branch, remote,
                              with_ssh, scheme_name, skip_history,
                              skip_repository_list])

    if not pool_args:
        print("Not cloning any repositories.")
        return

    return shell.run_parallel(obtain_additional_swift_sources, pool_args,
                              args.n_processes)


def dump_repo_hashes(config):
    max_len = reduce(lambda acc, x: max(acc, len(x)),
                     config['repos'].keys(), 0)
    fmt = "{:<%r}{}" % (max_len + 5)
    for repo_name, repo_info in sorted(config['repos'].items(),
                                       key=lambda x: x[0]):
        with shell.pushd(os.path.join(SWIFT_SOURCE_ROOT, repo_name),
                         dry_run=False,
                         echo=False):
            h = shell.capture(["git", "log", "--oneline", "-n", "1"],
                              echo=False).strip()
            print(fmt.format(repo_name, h))


def dump_hashes_config(args, config):
    branch_scheme_name = args.dump_hashes_config
    new_config = {}
    config_copy_keys = ['ssh-clone-pattern', 'https-clone-pattern', 'repos']
    for config_copy_key in config_copy_keys:
        new_config[config_copy_key] = config[config_copy_key]