#!/bin/bash
#
# SPDX-License-Identifier: GPL-3.0-or-later

shopt -s extglob

m4_include(lib/common.sh)

usage() {
    cat <<- _EOF_
		Usage: ${BASH_SOURCE[0]##*/} [OPTIONS] [MODES]

		Searches for a locally built package corresponding to the PKGBUILD, and
		downloads the last version of that package from the Pacman repositories.
		It then compares them using different modes while using simple tar
		content list by default.

		OPTIONS
		    -M, --makepkg-config Set an alternate makepkg configuration file
		    -v, --verbose        Provide more detailed/unfiltered output
		    -h, --help           Show this help text

		MODES
		    -l, --list           Activate content list diff mode (default)
		    -d, --diffoscope     Activate diffoscope diff mode
		    -p, --pkginfo        Activate .PKGINFO diff mode
		    -b, --buildinfo      Activate .BUILDINFO diff mode
_EOF_
}

MAKEPKG_CONF=/etc/makepkg.conf
VERBOSE=0
TARLIST=0
DIFFOSCOPE=0
PKGINFO=0
BUILDINFO=0

# option checking
while (( $# )); do
	case $1 in
		-h|--help)
			usage
			exit 0
			;;
		-M|--makepkg-config)
			MAKEPKG_CONF="$2"
			shift 2
			;;
		-l|--list)
			TARLIST=1
			shift
			;;
		-d|--diffoscope)
			DIFFOSCOPE=1
			shift
			;;
		-p|--pkginfo)
			PKGINFO=1
			shift
			;;
		-b|--buildinfo)
			BUILDINFO=1
			shift
			;;
		-v|--verbose)
			VERBOSE=1
			shift
			;;
		--)
			shift
			break
			;;
		-*,--*)
			die "invalid argument: %s" "$1"
			;;
		*)
			break
			;;
	esac
done

if ! (( DIFFOSCOPE || TARLIST || PKGINFO || BUILDINFO )); then
	TARLIST=1
fi

# Source makepkg.conf; fail if it is not found
if [[ -r "${MAKEPKG_CONF}" ]]; then
	# shellcheck source=makepkg-x86_64.conf
	source "${MAKEPKG_CONF}"
else
	die "${MAKEPKG_CONF} not found!"
fi

# Source user-specific makepkg.conf overrides
if [[ -r "${XDG_CONFIG_HOME:-$HOME/.config}/pacman/makepkg.conf" ]]; then
	# shellcheck source=/dev/null
	source "${XDG_CONFIG_HOME:-$HOME/.config}/pacman/makepkg.conf"
elif [[ -r "$HOME/.makepkg.conf" ]]; then
	# shellcheck source=/dev/null
	source "$HOME/.makepkg.conf"
fi

if [[ ! -f PKGBUILD ]]; then
	die 'This must be run in the directory of a built package.'
fi

# shellcheck source=PKGBUILD.proto
. ./PKGBUILD
if [[ ${arch[0]} == 'any' ]]; then
	CARCH='any'
fi

STARTDIR=$(pwd)
trap 'rm -rf $TEMPDIR' EXIT INT TERM QUIT
TEMPDIR=$(mktemp -d --tmpdir diffpkg-script.XXXXXXXX)

tar_list() {
	bsdtar tf "$*" | if (( VERBOSE )); then
		cat
	else
		sed -E 's|^usr/lib/modules/[0-9][^/]+|usr/lib/modules/[…]|g'
	fi | sort
}

diff_pkgs() {
	local oldpkg=$1
	local newpkg=$2

	if (( TARLIST )); then
		tar_list "$oldpkg" > "$TEMPDIR/filelist-old"
		tar_list "$newpkg" > "$TEMPDIR/filelist"

		sdiff -s "$TEMPDIR/filelist-old" "$TEMPDIR/filelist"
	fi

	if (( PKGINFO )); then
		bsdtar xOqf "$oldpkg" .PKGINFO > "$TEMPDIR/pkginfo-old"
		bsdtar xOqf "$newpkg" .PKGINFO > "$TEMPDIR/pkginfo"

		sdiff -s "$TEMPDIR/pkginfo-old" "$TEMPDIR/pkginfo"
	fi

	if (( BUILDINFO )); then
		bsdtar xOqf "$oldpkg" .BUILDINFO > "$TEMPDIR/buildinfo-old"
		bsdtar xOqf "$newpkg" .BUILDINFO > "$TEMPDIR/buildinfo"

		sdiff -s "$TEMPDIR/buildinfo-old" "$TEMPDIR/buildinfo"
	fi

	if (( DIFFOSCOPE )); then
		diffoscope "$(readlink -e "$oldpkg")" "$(readlink -e "$newpkg")"
	fi
}

for _pkgname in "${pkgname[@]}"; do
	comparepkg=$_pkgname
	pkgurl=
	target_pkgver=$(get_full_version "$_pkgname")
	if ! pkgfile=$(find_cached_package "$_pkgname" "$target_pkgver" "$CARCH"); then
		die 'tarball not found for package: %s' "${_pkgname}-$target_pkgver"
	fi

	ln -s "$pkgfile" "$TEMPDIR"

	if (( $# )); then
		case $1 in
			*://*)
				pkgurl=$1 ;;
			/*|*/*)
				pkgurl=$(readlink -m "$1") ;;
			*.pkg.tar*)
				pkgurl=$1 ;;
			'')
				;;
			*)
				comparepkg=$1 ;;
		esac
		shift
	fi
	[[ -n $pkgurl ]] || pkgurl=$(pacman -Spdd --print-format '%l' --noconfirm "$comparepkg") ||
		die "Couldn't download previous package for %s." "$comparepkg"

	oldpkg=${pkgurl##*/}

	if [[ ${oldpkg} = "${pkgfile##*/}" ]]; then
		die "The built package (%s) is the one in the repo right now!" "$_pkgname"
	fi

	if [[ $pkgurl = file://* || ( $pkgurl = /* && -f $pkgurl ) ]]; then
		ln -s "${pkgurl#file://}" "$TEMPDIR/$oldpkg"
	elif [[ -f "$PKGDEST/$oldpkg" ]]; then
		ln -s "$PKGDEST/$oldpkg" "$TEMPDIR/$oldpkg"
	elif [[ -f "$STARTDIR/$oldpkg" ]]; then
		ln -s "$STARTDIR/$oldpkg" "$TEMPDIR/$oldpkg"
	else
		curl -fsLC - --retry 3 --retry-delay 3 -o "$TEMPDIR/$oldpkg" "$pkgurl"
	fi

	diff_pkgs "$TEMPDIR/$oldpkg" "$pkgfile"
done