#!/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] [FILE|PKGNAME...]

		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 the package archives using different modes while using
		simple tar content list by default.

		When given one package, use it to diff against the locally built one.
		When given two packages, diff both packages against each other.

		In either case, a package name will be converted to a filename from the
		cache, and diffpkg will proceed as though this filename was initially
		specified.

		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

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

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 newpkg
	oldpkg=$(readlink -m "$1")
	newpkg=$(readlink -m "$2")

	[[ -f $oldpkg ]] || die "No such file: %s" "${oldpkg}"
	[[ -f $newpkg ]] || die "No such file: %s" "${newpkg}"

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

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

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

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

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

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

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

fetch_pkg() {
	local pkg pkgdest pkgurl
	case $1 in
		*://*)
			pkgurl=$1 ;;
		/*|*/*)
			pkgurl=$(readlink -m "$1") ;;
		*.pkg.tar*)
			pkgurl=$1 ;;
		'')
			;;
		*)
			pkg=$1 ;;
	esac

	[[ -n $pkgurl ]] || pkgurl=$(pacman -Spdd --print-format '%l' --noconfirm "$pkg") ||
		die "Couldn't download previous package for %s." "$pkg"

	pkg=${pkgurl##*/}
	pkgdest=$(mktemp -t -d "${pkg}-XXXXXX")/${pkg}

	if [[ $pkgurl = file://* || ( $pkgurl = /* && -f $pkgurl ) ]]; then
		ln -sf "${pkgurl#file://}" "$pkgdest"
	elif [[ -f "$PKGDEST/$pkg" ]]; then
		ln -sf "$PKGDEST/$pkg" "$pkgdest"
	elif [[ -f "$STARTDIR/$pkg" ]]; then
		ln -sf "$STARTDIR/$pkg" "$pkgdest"
	elif [[ $pkgurl = *://* ]]; then
		curl -fsLC - --retry 3 --retry-delay 3 -o "$pkgdest" "$pkgurl" || \
			die "Couldn't download %s" "$pkgurl"
	else
		die "File not found: %s" "$pkgurl"
	fi

	echo "$pkgdest"
}

if (( $# < 2 )); then
	if [[ ! -f PKGBUILD ]]; then
		die "This must be run in the directory of a built package.\nTry '$(basename "$0") --help' for more information."
	fi

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

		if (( $# )); then
			comparepkg="$1"
		fi

		oldpkg=$(fetch_pkg "$comparepkg") || exit 1

		diff_pkgs "$oldpkg" "$pkgfile"
	done
else
	file1=$(fetch_pkg "$1") || exit 1
	file2=$(fetch_pkg "$2") || exit 1

	diff_pkgs "$file1" "$file2"
fi