#!/bin/bash

URL="https://git.ipfire.org/?p=thirdparty/linux-firmware.git;a=snapshot;h=TAG;sf=tgz"

download() {
	local version="${1}"
	local install="${2}"
	local target

	local url="${URL/TAG/${version}}"

	echo "Downloading ${version}..."

	# Download and extract
	if ! curl --silent "${url}" | tar xz -C "${tmp}"; then
		echo "${0}: Could not download ${version}" >&2
		return 1
	fi

	echo "Installing ${version}..."

	# Install
	pushd "linux-firmware-${version}" &>/dev/null

	case "${version}" in
		2023*)
			target="install"
			;;
		*)
			target="install-nodedup"
			;;
	esac

	# Install to a new directory
	if ! make "${target}" DESTDIR="${install}"; then
		echo "${0}: Could not install ${version}" >&2
		popd &>/dev/null
		return 1
	fi

	popd &>/dev/null

	return 0
}

compare() {
	local removed_files=()
	local changed_files=()

	local line
	while read -r line; do
		# Find changed files
		if [[ ${line} =~ ^Files\ OLD/(.*)\ and ]]; then
			changed_files+=( "${BASH_REMATCH[1]}" )

		elif [[ ${line} =~ ^Only\ in\ NEW/(.*):\ (.*)$ ]]; then
			changed_files+=( "${BASH_REMATCH[1]}/${BASH_REMATCH[2]}" )

		elif [[ ${line} =~ ^Only\ in\ OLD/(.*):\ (.*)$ ]]; then
			removed_files+=( "${BASH_REMATCH[1]}/${BASH_REMATCH[2]}" )

		# Handle unknown lines
		else
			echo "Unknown line: ${line}" >&2
		fi
	done <<< "$(diff --recursive --brief OLD NEW)"

	local file

	# List all changed files
	if [ "${#changed_files[@]}" -gt 0 ]; then
		echo "# Changed files"
		for file in "${changed_files[@]}"; do
			echo "${file}"
		done

		echo # newline
	fi

	# List all removed files
	if [ "${#removed_files[@]}" -gt 0 ]; then
		echo "# Removed files"
		echo "rm -vrf \\"

		for file in "${removed_files[@]}"; do
			echo "	/${file} \\"
		done
	fi

	# Total size
	{
		pushd NEW &>/dev/null

		du -csh "${changed_files[@]}" | tail -n1

		popd &>/dev/null
	}

	return 0
}

run() {
	# Download the old and new versions
	download "${version_old}" "${tmp}/OLD" || return $?
	download "${version_new}" "${tmp}/NEW" || return $?

	compare || return $?
}

main() {
	local version_old="${1}"
	local version_new="${2}"

	local r=0

	# Check if we have enough arguments
	if [ -z "${version_old}" -o -z "${version_new}" ]; then
		echo "${0}: An old and a new version are required" >&2
		return 2
	fi

	# Create a temporary directory
	local tmp="$(mktemp -d)"

	# Change into the directory
	pushd "${tmp}" &>/dev/null

	# Run the operation...
	run || r="${?}"

	popd &>/dev/null

	# Remove the temporary directory
	rm -rf  "${tmp}"

	return "${r}"
}

main "$@" || exit $?