#!/usr/bin/env bash
# -----------------------------------------------------------------------------

# Copyright (C) 2025 Moko Consulting <hello@mokoconsulting.tech>
#
# This file is part of a Moko Consulting project.
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
# 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 3 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 (./LICENSE.md).
# -----------------------------------------------------------------------------
# FILE INFORMATION
# DEFGROUP: MokoStandards
# INGROUP: Generic.Script
# REPO: https://github.com/mokoconsulting-tech/MokoDefaults
# PATH: /scripts/update_changelog.sh
# VERSION: 03.06.00
# BRIEF: Insert a versioned CHANGELOG.md entry immediately after the main Changelog heading
# Purpose:
# - Apply the MokoWaaS-Brand CHANGELOG template entry for a given version.
# - Insert a new header at the top of CHANGELOG.md, immediately after "# Changelog".
# - Avoid duplicates if an entry for the version already exists.
# - Preserve the rest of the file verbatim.
#
# Usage:
#   ./scripts/update_changelog.sh <VERSION>
#
# Example:
#   ./scripts/update_changelog.sh 01.05.00
# =============================================================================

set -euo pipefail

CHANGELOG_FILE="CHANGELOG.md"

die() {
	echo "ERROR: $*" 1>&2
	exit 1
}

info() {
	echo "INFO: $*"
}

require_cmd() {
	command -v "$1" >/dev/null 2>&1 || die "Missing required command: $1"
}

validate_version() {
	local v="$1"
	[[ "$v" =~ ^[0-9]{2}\.[0-9]{2}\.[0-9]{2}$ ]] || die "Invalid version '$v'. Expected NN.NN.NN (example 03.01.00)."
}

main() {
	require_cmd awk
	require_cmd grep
	require_cmd mktemp
	require_cmd date

	[[ $# -eq 1 ]] || die "Usage: $0 <VERSION>"
	local version="$1"
	validate_version "$version"

	[[ -f "$CHANGELOG_FILE" ]] || die "Missing $CHANGELOG_FILE in repo root."

	if ! grep -qE '^# Changelog[[:space:]]*$' "$CHANGELOG_FILE"; then
		die "$CHANGELOG_FILE must contain a top level heading exactly: # Changelog"
	fi

	if grep -qE "^## \[$version\][[:space:]]" "$CHANGELOG_FILE"; then
		info "CHANGELOG.md already contains an entry for version $version. No action taken."
		exit 0
	fi

	local stamp
	stamp="$(date '+%Y-%m-%d')"

	local tmp
	tmp="$(mktemp)"
	trap 'rm -f "$tmp"' EXIT

	awk -v v="$version" -v d="$stamp" '
		BEGIN { inserted=0 }
		{
	print $0
	if (inserted==0 && $0 ~ /^# Changelog[[:space:]]*$/) {
		print ""
		print "## [" v "] " d
		print "- Version bump."
		print ""
		inserted=1
	}
		}
		END {
	if (inserted==0) {
		exit 3
	}
		}
	' "$CHANGELOG_FILE" > "$tmp" || {
		rc=$?
		if [[ $rc -eq 3 ]]; then
	die "Insertion point not found. Expected: # Changelog"
		fi
		die "Failed to update $CHANGELOG_FILE (awk exit code $rc)."
	}

	mv "$tmp" "$CHANGELOG_FILE"
	trap - EXIT

	info "Inserted CHANGELOG.md entry for version $version on $stamp."
}

main "$@"