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

_DEVTOOLS_LIBRARY_DIR=${_DEVTOOLS_LIBRARY_DIR:-@pkgdatadir@}
# shellcheck source=src/lib/common.sh
source "${_DEVTOOLS_LIBRARY_DIR}"/lib/common.sh


usage() {
	local -r COMMAND=${_DEVTOOLS_COMMAND:-${BASH_SOURCE[0]##*/}}
	cat <<- _EOF_
		Usage: ${COMMAND} [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 '${COMMAND}' will proceed as though this filename was
		initially specified.

		OPTIONS
		    -M, --makepkg-config Set an alternate makepkg configuration file
		    -P, --pool=DIR       Search diff target in pool dir (default '/srv/ftp/pool')
		    -v, --verbose        Provide more detailed/unfiltered output
		    -h, --help           Show this help text

		OUTPUT OPTIONS
		    --color[=WHEN]       Color output; WHEN is 'never', 'always', or 'auto';
		                         Plain --color means --color='auto'
		    -u, -U, --unified    Output 3 lines of unified context
		    -y, --side-by-side   Output in two columns
		    -W, --width=NUM      Output at most NUM (default 'auto') print columns
		                         NUM can be 'auto', 'columns' or a number

		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
POOLDIR=/srv/ftp/pool

VERBOSE=0
TARLIST=0
DIFFOSCOPE=0
PKGINFO=0
BUILDINFO=0

DIFFMODE=--side-by-side
DIFFCOLOR=--color=auto
DIFFWIDTH=--width=auto
DIFFOPTIONS=(--expand-tabs)

# option checking
while (( $# )); do
	case $1 in
		-h|--help)
			usage
			exit 0
			;;
		-M|--makepkg-config)
			(( $# <= 1 )) && die "missing argument for %s" "$1"
			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
			;;
		-u|-U|--unified)
			DIFFMODE=--unified
			shift
			;;
		-y|--side-by-side)
			DIFFMODE=--side-by-side
			shift
			;;
		--color|--color=*)
			if [[ $2 == never || $2 == always || $2 == auto ]]; then
				DIFFCOLOR="--color=$2"
				shift 2
				continue
			fi
			if [[ $1 == --color ]]; then
				DIFFCOLOR="--color=auto"
			else
				DIFFCOLOR="$1"
			fi
			shift
			;;
		-W|--width)
			(( $# <= 1 )) && die "missing argument for %s" "$1"
			DIFFWIDTH="--width=$2"
			shift 2
			;;
		--width=*)
			DIFFWIDTH="$1"
			shift
			;;
		-P|--pool)
			(( $# <= 1 )) && die "missing argument for %s" "$1"
			POOLDIR="$2"
			shift 2
			;;
		--pool=*)
			POOLDIR="${1#*=}"
			shift
			;;
		--)
			shift
			break
			;;
		-*|--*)
			die "invalid argument: %s" "$1"
			;;
		*)
			break
			;;
	esac
done

# Set options based on flags or magic values
if (( VERBOSE )); then
	if [[ $DIFFMODE == --unified ]]; then
		DIFFMODE="--unified=99999"
	fi
else
	DIFFOPTIONS+=(--suppress-common-lines)
fi
if [[ $DIFFWIDTH == --width=columns ]]; then
	DIFFWIDTH="--width=${COLUMNS:-130}"
fi
if [[ $DIFFWIDTH != --width=auto ]]; then
	DIFFOPTIONS+=("${DIFFWIDTH}")
fi
DIFFOPTIONS+=("${DIFFMODE}" "${DIFFCOLOR}")

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

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

file_line_length() {
	path="$1"
	wc -L "${path}" | tail -n1 | sed -E 's/^ +//g' | cut -d' ' -f1
}

file_diff_columns() {
	file1="$1"
	file2="$2"
	file1_length=$(file_line_length "$file1")
	file2_length=$(file_line_length "$file2")
	echo $(( file1_length + file2_length + 3 ))
}

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}"

	local -a diffoptions
	diffoptions=("${DIFFOPTIONS[@]}" --label "${oldpkg}" --label "${newpkg}")

	if (( TARLIST )); then
		tar_list "$oldpkg" > "$TMPDIR/old"
		tar_list "$newpkg" > "$TMPDIR/new"
	fi

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

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

	if (( TARLIST || PKGINFO || BUILDINFO )); then
		# Resolve dynamic auto width one we know the content to diff
		if [[ $DIFFWIDTH == --width=auto ]]; then
			AUTOLENGTH=$(file_diff_columns "$TMPDIR/old" "$TMPDIR/new")
			diffoptions+=("--width=${AUTOLENGTH}")
		fi

		# Print a header for side-by-side view as it lacks labels
		if [[ $DIFFMODE == --side-by-side ]]; then
			printf -- "--- %s\n+++ %s\n" "${oldpkg}" "${newpkg}"
		fi

		diff "${diffoptions[@]}" "$TMPDIR/old" "$TMPDIR/new"
	fi

	if (( DIFFOSCOPE )); then
		diffoscope "${DIFFCOLOR/--color/--text-color}" "$oldpkg" "$newpkg"
	fi
}

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

	if [[ -z ${pkgurl} ]]; then
		# Try to find latest package in pool dir
		if [[ -d ${POOLDIR} ]]; then
			shopt -s extglob nullglob
			pkgurl=$(printf "%s\n" "${POOLDIR}"/*/"${_pkgname}"-!(*-*)-!(*-*)-!(*-*).pkg.tar!(*.sig)|sort -Vr|head -1)
			shopt -u extglob nullglob
		fi
		# Search via pacman database if no pool file exists
		if [[ ! -f ${pkgurl} ]]; then
			pkgurl=$(pacman -Spdd --print-format '%l' --noconfirm "$pkg") ||
				die "Couldn't download previous package for %s." "$pkg"
		fi
	fi

	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"
}
shopt -u extglob

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

	# shellcheck source=contrib/makepkg/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