CORES 		:= $(shell nproc)
PWD 		:= $(shell pwd)
LINUX_DIR 	:= $(PWD)/components/linux
MUSL_DIR 	:= $(PWD)/components/musl
BUSYBOX_DIR 	:= $(PWD)/components/busybox
LINUX_CFG 	:= $(LINUX_DIR)/.config
MUSL_CFG 	:= $(MUSL_DIR)/config.mak
BUSYBOX_CFG 	:= $(BUSYBOX_DIR)/.config
LINUX_OUT 	:= $(LINUX_DIR)/arch/x86/boot/bzImage
MUSL_OUT 	:= $(MUSL_DIR)/lib/libc.so
BUSYBOX_OUT 	:= $(BUSYBOX_DIR)/busybox
DOWNLOAD_SCRIPT := $(PWD)/scripts/download-components.sh
CONFIGS_DIR 	:= $(PWD)/configs

MUSL_GCC 	:= "${REALGCC:-gcc}" "$@" -specs "$(MUSL_DIR)/lib/musl-gcc.specs"

.PHONY: all deps linux busybox clean

all: dirs deps linux busybox

dirs:
	mkdir -p initramfs/{etc,proc,sys,usr/{bin,lib},dev,tmp,mnt,root}
	ln -sf usr/bin initramfs/bin
	ln -sf usr/bin initramfs/sbin
	ln -sf usr/lib initramfs/lib
	ln -sf usr/lib initramfs/lib64

deps:
	@echo "Downloading dependencies..."
	@$(DOWNLOAD_SCRIPT)

linux: $(LINUX_OUT)

$(LINUX_OUT): $(LINUX_CFG)
	@echo "Building Linux kernel..."
	@$(MAKE) -C $(LINUX_DIR) -j $(CORES)

$(LINUX_CFG):
	@echo "Copying Linux config..."
	@cp -r $(CONFIGS_DIR)/linux/. $(LINUX_DIR)/

musl: $(MUSL_OUT)

$(MUSL_SPECS): $(MUSL_OUT)
$(MUSL_OUT): $(MUSL_CFG)
	make -C components/musl -j $(CORES)

$(MUSL_CFG):
	@echo "Configuring musl..."
	cd components/musl && ./configure --prefix=/usr

busybox: musl $(BUSYBOX_OUT)

$(BUSYBOX_OUT): $(BUSYBOX_CFG)
	@echo "Building BusyBox..."
	@$(MAKE) -C $(BUSYBOX_DIR) -j $(CORES) CC="$(MUSL_GCC)"

$(BUSYBOX_CFG):
	@echo "Copying BusyBox config..."
	@cp -r $(CONFIGS_DIR)/busybox/. $(BUSYBOX_DIR)/

install: linux busybox
	@cp $(LINUX_OUT) cdroot/
	$(MAKE) -C $(BUSYBOX_DIR) install CONFIG_PREFIX=$(PWD)/initramfs -j $(CORES)

clean:
	@echo "Cleaning up build artifacts..."
	@$(MAKE) -C $(LINUX_DIR) clean
	@$(MAKE) -C $(BUSYBOX_DIR) clean