#!/usr/bin/env bash
# Installs the Satisfactory Sync mod into the Steam copy of Satisfactory on Linux (Proton).
#
#   curl -fsSL https://satisfactory-sync.jgabor.se | bash
#
# It finds the game in your Steam libraries, downloads the latest release, checks its SHA-256, and
# replaces FactoryGame/Mods/SatisfactorySync. Nothing else is changed.
# SATISFACTORY_DIR=<game folder> skips the Steam library search.
# The whole script is one function called on the last line, so a cut-off download runs nothing.

main() {
	set -euo pipefail
	local base="${SATISFACTORY_SYNC_URL:-https://satisfactory-sync.jgabor.se}"
	local game mods stage release file sha256 version actual

	fail() {
		echo "satisfactory-sync: $*" >&2
		exit 1
	}
	field() { # name, compact JSON
		sed -n "s/.*\"$1\": *\"\([^\"]*\)\".*/\1/p" <<<"$2"
	}
	find_game() {
		local root library dir
		for root in "$HOME/.local/share/Steam" "$HOME/.steam/steam" \
			"$HOME/.var/app/com.valvesoftware.Steam/.local/share/Steam"; do
			[[ -f "$root/steamapps/libraryfolders.vdf" ]] || continue
			while IFS= read -r library; do
				[[ -f "$library/steamapps/appmanifest_526870.acf" ]] || continue
				dir="$(sed -n 's/^[[:space:]]*"installdir"[[:space:]]*"\(.*\)"[[:space:]]*$/\1/p' \
					"$library/steamapps/appmanifest_526870.acf")"
				echo "$library/steamapps/common/${dir:-Satisfactory}"
				return 0
			done < <(
				echo "$root"
				sed -n 's/^[[:space:]]*"path"[[:space:]]*"\(.*\)"[[:space:]]*$/\1/p' "$root/steamapps/libraryfolders.vdf"
			)
		done
		return 1
	}

	command -v curl >/dev/null || fail "needs curl"
	command -v sha256sum >/dev/null || fail "needs sha256sum"
	command -v unzip >/dev/null || command -v bsdtar >/dev/null || fail "needs unzip or bsdtar"

	game="${SATISFACTORY_DIR:-}"
	if [[ -z "$game" ]]; then
		game="$(find_game)" || fail "Satisfactory not found in your Steam libraries; set SATISFACTORY_DIR to the game folder"
	fi
	[[ -d "$game/FactoryGame" ]] || fail "not a Satisfactory folder: $game"
	if pgrep -f 'FactoryGameSteam(-Win64-Shipping)?\.exe' >/dev/null; then
		fail "close Satisfactory first"
	fi
	mods="$game/FactoryGame/Mods"
	mkdir -p "$mods"

	local sml
	sml="$(sed -n 's/.*"VersionName": *"\([^"]*\)".*/\1/p' "$mods/SML/SML.uplugin" 2>/dev/null || true)"
	if [[ -z "$sml" ]]; then
		echo "satisfactory-sync: warning: SML is not installed; the mod needs SML 3.12 or newer" >&2
	elif [[ "$(printf '%s\n' 3.12.0 "$sml" | sort -V | head -1)" != 3.12.0 ]]; then
		echo "satisfactory-sync: warning: SML $sml is installed; the mod needs 3.12 or newer" >&2
	fi

	release="$(curl -fsSL "$base/latest.json" | tr -d '\n')" || fail "could not read $base/latest.json"
	file="$(field file "$release")"
	sha256="$(field sha256 "$release")"
	version="$(field version "$release")"
	[[ "$file" =~ ^SatisfactorySync-[A-Za-z0-9.+-]+\.zip$ && "$sha256" =~ ^[0-9a-f]{64}$ ]] ||
		fail "unexpected release data from $base/latest.json"

	# Stage next to Mods, not in it, so a stray copy is never loaded as a second plugin.
	stage="$(mktemp -d "$game/FactoryGame/.SatisfactorySync-install.XXXXXX")"
	# Expanded now: the trap runs after main returns, when its locals are gone.
	# shellcheck disable=SC2064
	trap "rm -rf -- $(printf '%q' "$stage")" EXIT
	echo "Downloading Satisfactory Sync $version"
	curl -fsSL "$base/download/$file" -o "$stage/package.zip" || fail "download failed"
	actual="$(sha256sum "$stage/package.zip" | cut -d' ' -f1)"
	[[ "$actual" == "$sha256" ]] || fail "SHA-256 mismatch: expected $sha256, got $actual"
	mkdir "$stage/unpacked"
	if command -v unzip >/dev/null; then
		unzip -q "$stage/package.zip" -d "$stage/unpacked"
	else
		bsdtar -xf "$stage/package.zip" -C "$stage/unpacked"
	fi
	[[ -f "$stage/unpacked/SatisfactorySync/SatisfactorySync.uplugin" ]] || fail "the package has an unexpected layout"

	if [[ -e "$mods/SatisfactorySync" ]]; then
		mv -- "$mods/SatisfactorySync" "$stage/previous"
	fi
	if ! mv -- "$stage/unpacked/SatisfactorySync" "$mods/SatisfactorySync"; then
		[[ -e "$stage/previous" ]] && mv -- "$stage/previous" "$mods/SatisfactorySync"
		fail "could not install into $mods"
	fi
	echo "Installed Satisfactory Sync $version in $mods/SatisfactorySync"
}

main "$@"