#!/usr/bin/env bash
#=============================================================================
# Copyright 2010-2015 Kitware, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#=============================================================================

USAGE='[<remote>] [<options>...] [--]

OPTIONS

--dry-run
    Show what would be pushed without actually updating the destination

-f,--force
    Force-push the topic HEAD to rewrite the destination branch

--keep-data
    Do not erase local data refs after pushing

--no-data
    Do not push any data refs that may normally go with the topic

--no-default
    Do not push the default branch (e.g. master)

--no-topic
    Do not push the topic HEAD.
'
OPTIONS_SPEC=
SUBDIRECTORY_OK=Yes
. "$(git --exec-path)/git-sh-setup"

egrep-q() {
	egrep "$@" >/dev/null 2>/dev/null
}

# Load the project configuration.
gitlab_upstream='' &&
gitlab_configured='' &&
config="${BASH_SOURCE%/*}/config" &&
protocol=$(git config -f "$config" --get gitlab.protocol ||
	   echo "https") &&
host=$(git config -f "$config" --get gitlab.host) &&
site=$(git config -f "$config" --get gitlab.site ||
       echo "$protocol://$host") &&
group_path=$(git config -f "$config" --get gitlab.group-path) &&
project_path=$(git config -f "$config" --get gitlab.project-path) &&
gitlab_upstream="$site/$group_path/$project_path.git" &&
gitlab_pushurl=$(git config --get remote.gitlab.pushurl ||
		 git config --get remote.gitlab.url) &&
gitlab_configured=1

data_report_and_remove() {
	data="$1" &&
	if test -n "$keep_data"; then
		action="kept"
	else
		action="removed"
		if test -z "$dry_run"; then
			git update-ref -d "$1" 2>/dev/null || true
		fi
	fi &&
	echo "Pushed $data and $action local ref."
}

data_refs() {
	git rev-list "$@" |
	git diff-tree --no-commit-id --root -c -r --diff-filter=AM --stdin |
	egrep '\.(md5)$' |
	#     read :srcmode dstmode srcobj dstobj status file
	while read  _       _       _      obj    _      file; do
		# Identify the hash algorithm used.
		case "$file" in
			*.md5) algo=MD5 ; validate="^[0-9a-fA-F]{32}$" ;;
			*) continue ;;
		esac

		# Load and validate the hash.
		if hash=$(git cat-file blob $obj 2>/dev/null) &&
				echo "$hash" | egrep-q "$validate"; then
			# Use this data ref if it exists.
			git for-each-ref --format='%(refname)' "refs/data/$algo/$hash"
		fi
	done |
	sort |
	uniq
}

#-----------------------------------------------------------------------------

remote=''
refspecs=''
force=''
keep_data=''
no_topic=''
no_default=''
no_data=''
dry_run=''

# Parse the command line options.
while test $# != 0; do
	case "$1" in
		-f|--force)   force='+' ;;
		--keep-data)  keep_data=1 ;;
		--no-topic)   no_topic=1 ;;
		--no-data)    no_data=1 ;;
		--dry-run)    dry_run=--dry-run ;;
		--no-default) no_default=1 ;;
		--) shift; break ;;
		-*) usage ;;
		*) test -z "$remote" || usage ; remote="$1" ;;
	esac
	shift
done
test $# = 0 || usage

# Default remote.
test -n "$remote" || remote="gitlab"

if test -z "$no_topic"; then
	# Identify and validate the topic branch name.
	head="$(git symbolic-ref HEAD)" && topic="${head#refs/heads/}" || topic=''
	if test -z "$topic" -o "$topic" = "master"; then
		die 'Please name your topic:
		git checkout -b descriptive-name'
	fi
	# The topic branch will be pushed by name.
	refspecs="${force}HEAD:refs/heads/$topic $refspecs"
fi

# Fetch the current remote master branch head.
# This helps computation of a minimal pack to push.
echo "Fetching $remote master"
fetch_out=$(git fetch "$remote" master 2>&1) || die "$fetch_out"
gitlab_head=$(git rev-parse FETCH_HEAD) || exit

# Fetch the current upstream master branch head.
if origin_fetchurl=$(git config --get remote.origin.url) &&
   test "$origin_fetchurl" = "$gitlab_upstream"; then
	upstream_remote='origin'
else
	upstream_remote="$gitlab_upstream"
fi
echo "Fetching $upstream_remote master"
fetch_out=$(git fetch "$upstream_remote" master 2>&1) || die "$fetch_out"
upstream_head=$(git rev-parse FETCH_HEAD) || exit

# Collect refspecs for each data object referenced by the topic.
if test -z "$no_data"; then
	data_refs=$(data_refs $upstream_head..) &&
	for data in $data_refs; do
		refspecs="+$data:$data $refspecs"
	done
else
	data_refs=''
fi

# Add a refspec to keep the remote master up to date if possible.
if test -z "$no_default" &&
   base=$(git merge-base "$gitlab_head" "$upstream_head") &&
   test "$base" = "$gitlab_head"; then
	refspecs="$upstream_head:refs/heads/master $refspecs"
fi

# Exit early if we have nothing to push.
if test -z "$refspecs"; then
	echo 'Nothing to push!'
	exit 0
fi

# Push.  Save output and exit code.
echo "Pushing to $remote"
push_config='-c advice.pushUpdateRejected=false'
push_stdout=$(git $push_config push --porcelain $dry_run "$remote" $refspecs); push_exit=$?
echo "$push_stdout"

# Advise the user to force-push if needed.
if test "$push_exit" -ne 0 && test -z "$force" &&
   echo "$push_stdout" | egrep-q 'non-fast-forward'; then
	echo '
Add "-f" or "--force" to push a rewritten topic.'
fi

# Check if data were pushed successfully.
for data in $data_refs; do
	if echo "$push_stdout" | egrep-q "^[*=+]	$data"; then
		data_report_and_remove "$data"
	fi
done

# Tell the user what to do next with the topic in GitLab.
if test -z "$no_topic" &&
   test "$push_exit" -eq 0 &&
   test "$remote" = "gitlab" &&
   test -n "$gitlab_configured" &&
   echo "$gitlab_pushurl" | egrep-q "$host[^/:]*[/:][^/]*/$project_path\\.git$"; then
	userpath="${gitlab_pushurl%/*.git}" &&
	username="${userpath##*[/:]}" &&
	echo '
The topic has been pushed to your fork in GitLab.  Visit

  '"$site/$username/$project_path/tree/$topic"'

to see the files.  Visit

  '"$site/$username/$project_path/merge_requests/new"'

to create a Merge Request if there is not one already.'
fi

# Reproduce the push exit code.
exit $push_exit