#!/usr/bin/env bash

set -euo pipefail

IMMORTALWRT_VERSION="${IMMORTALWRT_VERSION:-v25.12.1}"
IMMORTALWRT_URL="${IMMORTALWRT_URL:-https://github.com/immortalwrt/immortalwrt.git}"
MIHOMO_FEED_URL="${MIHOMO_FEED_URL:-https://git.laysense.com/SerinaNya/mihomo-openwrt.git}"
JOBS="${JOBS:-$(nproc)}"

ROOT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
WORK_DIR="${WORK_DIR:-${ROOT_DIR}/.build}"
SOURCE_DIR="${WORK_DIR}/immortalwrt"
DIST_DIR="${ROOT_DIR}/dist"

APT_PACKAGES=(
	ack antlr3 asciidoc autoconf automake autopoint binutils bison
	build-essential bzip2 ccache clang cmake cpio curl device-tree-compiler
	ecj fastjar flex gawk gettext gcc-multilib g++-multilib git gnutls-dev
	gperf haveged help2man intltool lib32gcc-s1 libc6-dev-i386 libelf-dev
	libglib2.0-dev libgmp3-dev libltdl-dev libmpc-dev libmpfr-dev
	libncurses-dev libpython3-dev libreadline-dev libssl-dev libtool
	libyaml-dev libz-dev lld llvm lrzsz mkisofs msmtp nano ninja-build
	p7zip p7zip-full patch pkgconf python3 python3-pip python3-ply
	python3-docutils python3-pyelftools qemu-utils re2c rsync scons
	squashfs-tools subversion swig texinfo uglifyjs upx-ucl unzip vim wget
	xmlto xxd zlib1g-dev zstd
)

log() {
	printf '\n==> %s\n' "$*"
}

die() {
	printf 'Error: %s\n' "$*" >&2
	exit 1
}

check_host() {
	[[ "${EUID}" -ne 0 ]] || die "Run this script as an unprivileged user, not root."
	[[ "$(uname -m)" == "x86_64" ]] || die "This script supports x86_64 build hosts only."
	[[ "${ROOT_DIR}" != *" "* ]] || die "The repository path must not contain spaces."
	[[ "${WORK_DIR}" != *" "* ]] || die "WORK_DIR must not contain spaces."

	if LC_ALL=C grep -q '[^ -~]' <<<"${ROOT_DIR}${WORK_DIR}"; then
		die "Repository and work paths must contain ASCII characters only."
	fi

	mkdir -p "${WORK_DIR}"
	local probe
	probe="$(mktemp -d "${WORK_DIR}/.case-test.XXXXXX")"
	touch "${probe}/lowercase"
	if [[ -e "${probe}/LOWERCASE" ]]; then
		rm -rf "${probe}"
		die "The build filesystem must be case-sensitive."
	fi
	rm -rf "${probe}"
}

install_dependencies() {
	if [[ "${SKIP_DEPS:-0}" == "1" ]]; then
		log "Skipping APT dependency installation"
		return
	fi

	command -v apt-get >/dev/null 2>&1 || die "apt-get is required for automatic dependency installation."
	command -v sudo >/dev/null 2>&1 || die "sudo is required to install APT dependencies."

	log "Installing ImmortalWrt build dependencies"
	sudo apt-get update
	sudo env DEBIAN_FRONTEND=noninteractive apt-get install -y "${APT_PACKAGES[@]}"
}

prepare_source() {
	if [[ ! -d "${SOURCE_DIR}/.git" ]]; then
		log "Cloning ImmortalWrt ${IMMORTALWRT_VERSION}"
		git clone -b "${IMMORTALWRT_VERSION}" --single-branch --filter=blob:none \
			"${IMMORTALWRT_URL}" "${SOURCE_DIR}"
	else
		git -C "${SOURCE_DIR}" diff --quiet || die "ImmortalWrt checkout has modified tracked files."
		git -C "${SOURCE_DIR}" diff --cached --quiet || die "ImmortalWrt checkout has staged changes."

		log "Refreshing ImmortalWrt ${IMMORTALWRT_VERSION}"
		git -C "${SOURCE_DIR}" fetch --depth=1 origin \
			"refs/tags/${IMMORTALWRT_VERSION}:refs/tags/${IMMORTALWRT_VERSION}"
		git -C "${SOURCE_DIR}" checkout --detach "${IMMORTALWRT_VERSION}"
	fi
}

prepare_feeds() {
	log "Configuring feeds"
	if [[ ! -f "${SOURCE_DIR}/feeds.conf" ]]; then
		cp "${SOURCE_DIR}/feeds.conf.default" "${SOURCE_DIR}/feeds.conf"
	fi

	sed -i '/^src-git mihomo /d' "${SOURCE_DIR}/feeds.conf"
	printf 'src-git mihomo %s\n' "${MIHOMO_FEED_URL}" >>"${SOURCE_DIR}/feeds.conf"

	(
		cd "${SOURCE_DIR}"
		./scripts/feeds update packages mihomo
		./scripts/feeds install -p packages golang
		./scripts/feeds install -f -p mihomo mihomo
	)
}

configure_target() {
	log "Configuring the x86/64 target"
	cat >"${SOURCE_DIR}/.config" <<'EOF'
CONFIG_TARGET_x86=y
CONFIG_TARGET_x86_64=y
CONFIG_TARGET_x86_64_DEVICE_generic=y
CONFIG_PACKAGE_mihomo=m
EOF

	make -C "${SOURCE_DIR}" defconfig
	grep -q '^CONFIG_TARGET_x86_64=y$' "${SOURCE_DIR}/.config" || die "x86/64 target configuration failed."
	grep -q '^CONFIG_PACKAGE_mihomo=m$' "${SOURCE_DIR}/.config" || die "mihomo package selection failed."
}

build_package() {
	log "Building mihomo with ${JOBS} parallel jobs"
	make -C "${SOURCE_DIR}" package/feeds/mihomo/mihomo/download -j"${JOBS}" V=s
	make -C "${SOURCE_DIR}" package/feeds/mihomo/mihomo/clean

	if [[ -d "${SOURCE_DIR}/bin/packages" ]]; then
		find "${SOURCE_DIR}/bin/packages" -type f -name 'mihomo-*.apk' -delete
	fi

	make -C "${SOURCE_DIR}" package/feeds/mihomo/mihomo/compile -j"${JOBS}" V=s
}

collect_artifacts() {
	log "Collecting APK artifacts"
	mkdir -p "${DIST_DIR}"
	find "${DIST_DIR}" -maxdepth 1 -type f -name 'mihomo-*.apk' -delete

	local artifacts=()
	while IFS= read -r -d '' artifact; do
		artifacts+=("${artifact}")
	done < <(find "${SOURCE_DIR}/bin/packages" -type f -name 'mihomo-*.apk' -print0)

	((${#artifacts[@]} > 0)) || die "Build completed but no mihomo APK was found."
	cp -v "${artifacts[@]}" "${DIST_DIR}/"

	log "Build complete"
	printf 'APK output directory: %s\n' "${DIST_DIR}"
}

check_host
install_dependencies
prepare_source
prepare_feeds
configure_target
build_package
collect_artifacts