IMG_FILE := bootable.img
IMG_SIZE_MB := 100
EFI_FILE := bootx64.efi
MNT_DIR := esp_mnt
USB_DEV ?= /dev/sdX

.PHONY: all clean flash

# The default target, which is to build the image file.
all: $(EFI_FILE)
	@echo "--- Creating blank disk image: $(IMG_FILE) ($(IMG_SIZE_MB)MB)..."
	dd if=/dev/zero of=$(IMG_FILE) bs=1M count=$(IMG_SIZE_MB) status=none

	sudo -v

	@echo "--- Creating GPT and EFI System Partition..."
	# Use sgdisk for non-interactive partitioning.
	# --new=1:0:0 creates partition 1, starting at the first available sector and filling the disk.
	# --typecode=1:ef00 sets the partition type to 'EFI System'.
	sudo sgdisk --new=1:0:0 --typecode=1:ef00 $(IMG_FILE)

	@# This block handles setting up, using, and cleaning up a loop device and mount point.
	@# 'set -e' ensures the script will exit immediately if a command fails.
	@# The trap command guarantees that we unmount the partition and detach the loop device on exit,
	@# even if an error occurs.
	set -e; \
	LOOP_DEV=$$(sudo losetup --partscan --show --find $(IMG_FILE)); \
	trap 'echo "--- Cleaning up mount point and loop device..."; sudo umount $(MNT_DIR) 2>/dev/null || true; sudo losetup -d $$LOOP_DEV 2>/dev/null || true; rm -rf $(MNT_DIR);' EXIT; \
	\
	echo "--- Using loop device: $$LOOP_DEV"; \
	echo "--- Formatting EFI partition (FAT32)..."; \
	sudo mkfs.vfat -F32 $${LOOP_DEV}p1; \
	\
	echo "--- Mounting partition..."; \
	mkdir -p $(MNT_DIR); \
	sudo mount $${LOOP_DEV}p1 $(MNT_DIR); \
	\
	echo "--- Copying EFI executable to EFI/BOOT/BOOTX64.EFI..."; \
	sudo mkdir -p $(MNT_DIR)/EFI/BOOT; \
	sudo cp $(EFI_FILE) $(MNT_DIR)/EFI/BOOT/BOOTX64.EFI; \
	\
	echo "--- Syncing filesystem..."; \
	sync;

	@echo "\nSuccess! Bootable image created: $(IMG_FILE)"

$(EFI_FILE):
	zig build-exe -OReleaseFast -target x86_64-uefi-msvc --name bootx64 main.zig

# Rule to flash the image to a USB device.
flash: $(IMG_FILE)
	@if [ "$(USB_DEV)" = "/dev/sdX" ]; then \
		echo "\nERROR: USB_DEV is not set."; \
		echo "Please specify the target device, e.g., 'make flash USB_DEV=/dev/sdb'"; \
		exit 1; \
	fi
	@echo "\n!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
	@echo "!! WARNING: This will ERASE ALL DATA on $(USB_DEV) !!"
	@echo "!! Verify that this is the correct device before proceeding.   !!"
	@echo "!! Press Ctrl+C to cancel, or Enter to continue.             !!"
	@echo "!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
	@read
	sudo dd if=$(IMG_FILE) of=$(USB_DEV) bs=4M status=progress conv=fsync

# Rule to clean up all generated files and temporary directories.
clean:
	@echo "--- Cleaning up..."
	@-sudo umount $(MNT_DIR) >/dev/null 2>&1 || true
	@-rm -rf $(MNT_DIR)
	@-if losetup -j $(IMG_FILE) > /dev/null 2>&1; then \
		LOOP_DEV=$$(losetup -j $(IMG_FILE) | cut -d: -f1); \
		echo "Detaching loop device $$LOOP_DEV..."; \
		sudo losetup -d $$LOOP_DEV; \
	fi
	@-rm -f $(IMG_FILE)
	@echo "Cleanup complete."