#!/usr/bin/env bash
#
# @license Apache-2.0
#
# Copyright (c) 2023 The Stdlib Authors.
#
# 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.

# A Git hook called after a developer writes a commit message. If this scripts exits with a non-zero status, the commit will be aborted.
#
# This hook is called with the following arguments:
#
# -   `$1`: path to temporary file containing the commit message written by the developer

# shellcheck disable=SC2181


# VARIABLES #

# Resolve environment variables:
skip_lint="${SKIP_LINT_COMMIT}"

# Get the path to a file containing the commit message:
commit_message="$1"

# Determine root directory:
root=$(git rev-parse --show-toplevel)

# Define the path to a report generated during the pre-commit hook:
pre_commit_report="${root}/.git/hooks-cache/pre_commit_report.yml"


# FUNCTIONS #

# Defines an error handler.
#
# $1 - error status
on_error() {
	cleanup
	exit "$1"
}

# Runs clean-up tasks.
cleanup() {
	echo '' >&2
}

# Runs initialization tasks.
init() {
	return 0
}

# Lints a commit message.
lint() {
	if [[ -z "${skip_lint}" ]]; then
		make FILES="${commit_message}" lint-commit-files > /dev/null >&2
		if [[ "$?" -ne 0 ]]; then
			echo '' >&2
			echo 'Git commit message lint errors.' >&2
			return 1
		fi
	fi

	return 0
}

# Appends a report generated during the pre-commit hook.
append_pre_commit_report() {
	# Check whether the commit is a merge commit:
	head -n 1 "${commit_message}" | grep -q '^Merge branch';

	# For merge commits, no need to append a report...
	if [[ "$?" -eq 0 ]]; then
		return 0
	fi

	# Check whether the commit message already contains a report (e.g., as may be the case when amending a commit message via git commit --amend):
	grep -q 'type: pre_commit_static_analysis_report' "${commit_message}"

	# If a message already includes a report, skip appending a report...
	if [[ "$?" -eq 0 ]]; then
		return 0
	fi

	# Append the report:
	echo '' >> "${commit_message}"
	cat "${pre_commit_report}" >> "${commit_message}"

	return 0
}

# Main execution sequence.
main() {
	init
	if [[ "$?" -ne 0 ]]; then
		on_error 1
	fi
	lint
	if [[ "$?" -ne 0 ]]; then
		on_error 1
	fi
	append_pre_commit_report
	if [[ "$?" -ne 0 ]]; then
		on_error 1
	fi
	cleanup
	exit 0
}

# Run main:
main