#!/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

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

--no-topic
    Do not push the topic HEAD.

--no-upstream
    Do not set an upstream branch (i.e. tracking) for the topic
'
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

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

remote=''
refspecs=''
force=''
lease=false
lease_flag=''
no_topic=''
no_default=''
dry_run=''
set_upstream=true

# Parse the command line options.
while test $# != 0; do
	case "$1" in
		-f|--force)    force='+'; lease=true ;;
		--no-topic)    no_topic=1; set_upstream=false ;;
		--dry-run)     dry_run=--dry-run ;;
		--no-default)  no_default=1 ;;
		--no-upstream) set_upstream=false ;;
		--) shift; break ;;
		-*) usage ;;
		*) test -z "$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

	if $lease; then
		have_ref=false
		remoteref="refs/remotes/$remote/$topic"
		if git rev-parse --verify -q "$remoteref" > /dev/null; then
			have_ref=true
		else
			die "It seems that a local ref for the branch is
missing; forcing a push is dangerous and may overwrite
previous work.  Fetch from the $remote remote first or
push without '-f' or '--force'."
		fi

		have_lease_flag=false
		# Note: on Windows 'git push --help' will open a browser, and
		# the check will fail, so use the flag by default.
		if git --version | egrep_q -e 'windows'; then
			have_lease_flag=true
		elif git push --help | egrep_q -e '--force-with-lease'; then
			have_lease_flag=true
		fi

		if $have_lease_flag && $have_ref; then
			# Set the lease flag.
			lease_flag="--force-with-lease=$topic:$remoteref"
			# Clear the force string.
			force=''
		fi
	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

# 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 $lease_flag --porcelain $dry_run "$remote" $refspecs); push_exit=$?
echo "$push_stdout"

if test "$push_exit" -ne 0 && test -z "$force"; then
	# Advise the user to fetch if needed.
	if echo "$push_stdout" | egrep_q 'stale info'; then
		echo "
You have pushed to your branch from another machine; you may be overwriting
commits unintentionally.  Fetch from the $remote remote and check that you are
not pushing an outdated branch."
	fi

	# Advise the user to force-push if needed.
	if echo "$push_stdout" | egrep_q 'non-fast-forward'; then
		echo '
Add "-f" or "--force" to push a rewritten topic.'
	fi
elif $set_upstream && test -n "$topic"; then
	git branch -u "$remote/$topic"
fi

# Reproduce the push exit code.
exit $push_exit
