DEFAULT: _target

nul_:=
comma_:= ,
space_:= ${nul_} ${nul_}

.PHONY: clean .FORCE _target
.PHONY: _qemu _bootstrap _install _copy _config 
.PHONY: _partition_gpt _partition_raspi _sparse _partcopy _mbr
.PHONY: _format _format_root _format_boot
.PHONY: _bootloader_raspi _bootloader_pc _bootloader_iso
.PHONY: _mount _mount_root _mount_boot _efi_mount
.PHONY: _umount _umount_root _umount_boot _efi_umount
.PHONY: _squash_modules _squash _isosquash _iso_image

ARCH := amd64
BOOTSTRAP := http://cdn.debian.net/debian
PACKAGES := ${PACKAGES} apt busybox-static debian-archive-keyring init systemd

# Partition Table (2M) + Boot Partition (126M)+ Root Partition + Slack Space (1M) = 2048M
BOOT_MB := 62
ROOT_MB := 959

config.mk:
	cp "config.example" "$@"

ifndef config
  include config.mk
else
  include ${config}
endif

ifdef release
  KEYRING := keys/debian-archive-${release}-stable.gpg
else
  release := stretch
  KEYRING := keys/debian-archive-stretch-stable.gpg
endif

ifndef SOURCES
define SOURCES := 
deb	http://cdn.debian.net/debian ${release} main
endef
endif

fstype := ext4

ifdef disk
  VOLUME := ${disk}
  PBOOT := ${disk}1
  PROOT := ${disk}2
  SYSROOT := hdd_mount/
  CFGROOT := hdd_mount/
  
  _target: _mbr _umount _config _install _partition_gpt
  
  _partition_gpt:
  _format: _partition_gpt
  _mount: _format
  _bootstrap: _mount
  _install: _bootstrap _mount
  _config: _install _mount
  _bootloader_pc: _mount
  _umount: _mount _config _bootloader_pc
  _mbr: _umount _bootloader_pc

else ifdef image
  VOLUME := ${image}
  PBOOT := part_boot.img
  PROOT := part_root.img
  SYSROOT := sys_root_${release}_${ARCH}/
  CFGROOT := img_mount/
  
  _target: _mbr _umount _config _install
  
  _bootstrap:
  _install: _bootstrap
  _sparse:
  _format: _sparse
  _partition_gpt: _sparse
  _partcopy: _partition_gpt _format
  _img_mount: _partcopy
  _copy: _install _img_mount
  _config: _copy _img_mount
  _bootloader_pc: _img_mount
  _umount: _img_mount _config _bootloader_pc
  _mbr: _partcopy _bootloader_pc

else ifdef subvol
  SYSROOT := sys_root_${release}_${ARCH}/
  CFGROOT := cfg_root/

  _target: _install _config ${subvol}
  
  _bootstrap:
  _install: _bootstrap
  _copy: _install
  _config: _copy

  ${subvol}: _config
	btrfs sub snap "${CFGROOT}" "$@"

else ifdef squash
  SQUASH := ${squash}
  SYSROOT := sys_root_${release}_${ARCH}/
  CFGROOT := cfg_root/

  PACKAGES += squashfs-tools nbd-client
  
  _target: _squash _install _config
  
  _bootstrap:
  _install: _bootstrap
  _copy: _install
  _config: _copy _squash_modules
  _squash: _config

else ifdef iso
  ISO := ${iso}
  ISOROOT := iso_root/
  SYSROOT := sys_root_${release}_${ARCH}/
  CFGROOT := cfg_root/
  BOOT_MB := 2
  PBOOT := ${ISOROOT}/efi.img

  PACKAGES += squashfs-tools
  
  _target: _iso_image _install _config
  
  _bootstrap:
  _install: _bootstrap
  _copy: _install
  _config: _copy _squash_modules
  _isosquash: _config
  _bootloader_iso: _config
  _iso_image: _bootloader_iso _isosquash # _efi_umount

else ifdef raspi
  ARCH := armhf

  VOLUME := ${raspi}
  PBOOT := rpi_boot.img
  PROOT := rpi_root.img
  SYSROOT := sys_root_${release}_${ARCH}/
  CFGROOT := img_mount/
  
  KEYRING := keys/raspbian-archive-keyring.gpg
  BOOTSTRAP := http://raspbian.raspberrypi.org/raspbian

  define SOURCES :=
  deb	http://raspbian.raspberrypi.org/raspbian ${release} main non-free firmware rpi
  deb	http://archive.raspberrypi.org/debian ${release} main
  endef

  PACKAGES += firmware-brcm80211 libraspberrypi-bin libraspberrypi0 pi-bluetooth raspberrypi-bootloader raspberrypi-kernel initramfs-tools btrfs-tools
  fstype := btrfs

  _target: _umount _config
  
  _qemu:
  _bootstrap: _qemu
  _install: _bootstrap
  _sparse:
  _format: _sparse
  _partition_raspi: _sparse
  _partcopy: _partition_raspi _format
  _img_mount: _partcopy
  _copy: _install _img_mount
  _config: _copy _img_mount
  _bootloader_raspi: _img_mount
  _umount: _copy _config _bootloader_raspi

else
  _target:
	false

endif

include modules/default.mk
ifdef modules
  include $(addsuffix .mk, $(addprefix modules/, $(subst ${comma_},${space_},${modules})))
endif

ifeq "${ARCH}" "amd64"
  PACKAGES += linux-image-amd64
else ifeq "${ARCH}" "i386"
  PACKAGES += linux-image-686
endif

export SOURCES SYSROOT CFGROOT VOLUME PBOOT PROOT SQUASH ARCH KEYRING BOOTSTRAP ISOROOT ISO

sys_root_${release}_${ARCH}/:
	btrfs subvol create "$@" || mkdir "$@"
	chmod 755 "$@"

cfg_root/: sys_root_${release}_${ARCH}/ _install
	-btrfs sub del "$@" || rm -r "$@"
	btrfs sub snap "$<" "$@" || mkdir "$@"
	chmod 755 "$@"

${ISOROOT}:
	-btrfs sub del "$@" || rm -r "$@"
	btrfs subvol create "$@" || mkdir "$@"
	mkdir "$@/live"
	chmod 755 "$@" "$@/live"

img_mount/:
	mkdir -p -m 755 "$@"
	chmod 755 "$@"

hdd_mount/:
	mkdir -p -m 755 "$@"

_qemu: ${SYSROOT}/usr/bin/qemu-arm-static
${SYSROOT}/usr/bin/qemu-arm-static: /usr/bin/qemu-arm-static ${SYSROOT}
	mkdir -p -m 755 "$${SYSROOT}"/usr/bin
	chmod 755 "$${SYSROOT}"/usr
	cp -p "$<" "$@"

_bootstrap: ${SYSROOT}/bin/sh
${SYSROOT}/bin/sh: | ${SYSROOT}
	debootstrap --variant=minbase --arch="$${ARCH}" \
		--keyring="$${KEYRING}" \
		"${release}" "$${SYSROOT}" "$${BOOTSTRAP}"
	printf 'APT::Default-Release "%s";' "${release}" >"$${SYSROOT}/etc/apt/apt.conf.d/10release"


.PHONY: _aptkeys _norecommends
_aptkeys: ${SYSROOT}/etc/apt/trusted.gpg.d/
_norecommends: ${SYSROOT}/etc/apt/apt.conf.d/10norecommends

${SYSROOT}/etc/apt/apt.conf.d/10norecommends: ${SYSROOT}
	mkdir -p -m 755 "$(dir $@)"
	printf 'APT::%s "false";\n' "Install-Recommends" "Keep-Recommends" "Install-Suggests" "Keep-Suggests" >"$@"
	chmod 644 "$@"

${SYSROOT}/etc/apt/trusted.gpg.d/: ${SYSROOT} _bootstrap
	mkdir -p -m 755 "$@"
	cp keys/*.gpg "$@"
	chmod 644 "$@"/*.gpg

_install: ${SYSROOT} _aptkeys _norecommends
	printf '%s\n' "$${SOURCES}" |sort -u >"$${SYSROOT}/etc/apt/sources.list"
	-cp /etc/resolv.conf "$${SYSROOT}/etc/"
	-chroot "$${SYSROOT}" sh -c 'apt-mark showmanual |xargs apt-mark auto'
	-chroot "$${SYSROOT}" apt-get update
	chroot "$${SYSROOT}" ln -sf /bin/true /usr/local/sbin/invoke-rc.d
	chroot "$${SYSROOT}" ln -sf /bin/true /usr/sbin/udevadm
	chroot "$${SYSROOT}" apt-get --yes install ${PACKAGES}
	mkdir -p -m 755 "$${SYSROOT}/var/lib/deborphan/"
	chroot "$${SYSROOT}" sh -c 'printf "%s\\n" ${PACKAGES} >/var/lib/deborphan/keep'
	-chroot "$${SYSROOT}" sh -c 'apt-get --yes purge $$(deborphan -an |sed "s;^.* ;;g")'
	chroot "$${SYSROOT}" apt-get --yes --auto-remove purge
	-chroot "$${SYSROOT}" apt-get --yes --auto-remove upgrade
	chroot "$${SYSROOT}" apt-get clean
	chroot "$${SYSROOT}" rm /usr/local/sbin/invoke-rc.d
	chroot "$${SYSROOT}" rm /usr/sbin/udevadm

_copy: ${SYSROOT} ${CFGROOT}
	sync
	cp -au "$${SYSROOT}/." "$${CFGROOT}/"

_config: ${CFGROOT}
	ln -sf /dev/null "$${CFGROOT}/etc/systemd/network/99-default.link"
	printf '\nsession	optional	pam_mkhomedir.so umask=0027\n' >>"$${CFGROOT}/etc/pam.d/common-session"
	printf 'LABEL=FSROOT / ${fstype} auto,nofail,rw 0 0\nLABEL=BOOT /boot vfat auto,nofail,ro 0 0\n' \
		>"$${CFGROOT}/etc/fstab"
	chroot "$${CFGROOT}" update-initramfs -u

${SQUASH}: ${CFGROOT}
	-rm "$${SQUASH}"
	mksquashfs "$${CFGROOT}" "$${SQUASH}" -comp xz

_squash_modules: ${CFGROOT}
	printf '%s\n' squashfs nbd >>"${CFGROOT}/etc/initramfs-tools/modules"

_squash: ${SQUASH} _squash_modules

_isosquash: ${ISOROOT}/live/live.squashfs
${ISOROOT}/live/live.squashfs: ${CFGROOT} ${ISOROOT} .FORCE
	-rm "$@"
	{ cd "$${CFGROOT}"; printf '%s\n' boot/*; } \
	| mksquashfs "$${CFGROOT}" "$@" -comp xz -ef /dev/stdin

${VOLUME}: .FORCE
	! printf '%s\n' "$${VOLUME}" |grep -q '^/dev/'  # abort if volume should be real device
	dd count=0 of="$${VOLUME}"  # truncate
	dd bs=1M count=0 seek=$$((3 + ${BOOT_MB} + ${ROOT_MB})) of="$${VOLUME}"
	chmod g+w "$${VOLUME}"

${PBOOT}: .FORCE
	! printf '%s\n' "$${PBOOT}" |grep -q '^/dev/'  # abort if volume should be real device
	dd count=0 of="$${PBOOT}"  # truncate
	dd bs=1M count=0 seek=${BOOT_MB} of="$${PBOOT}"

${PROOT}: .FORCE
	! printf '%s\n' "$${PROOT}" |grep -q '^/dev/'  # abort if volume should be real device
	dd count=0 of="$${PROOT}"  # truncate
	dd bs=1M count=0 seek=${ROOT_MB} of="$${PROOT}"

_partition_raspi: ${VOLUME}
	printf 'label: dos\n\n: start=2MiB, size=%iMiB, type=c\n: start=%iMiB, size=%iMiB, type=83\n' \
		${BOOT_MB} "$$((${BOOT_MB} + 2))" ${ROOT_MB} | sfdisk "$${VOLUME}"

_partition_gpt: ${VOLUME}
	printf 'label: gpt\n\n: start=2MiB, size=%iMiB, type=1, attrs="LegacyBIOSBootable"\n: size=%iMiB, type=20\n' \
		${BOOT_MB} ${ROOT_MB} | sfdisk "$${VOLUME}"

_sparse: ${PBOOT} ${PROOT}

ifdef raspi
_format_root: ${PROOT}
	-umount "$${CFGROOT}/boot" "$${CFGROOT}" "${PROOT}"
	mkfs.${fstype} -f -L FSROOT "$${PROOT}"
else
_format_root: ${PROOT}
	-umount "$${CFGROOT}/boot" "$${CFGROOT}" "${PROOT}"
	mkfs.ext4 -F -L FSROOT "$${PROOT}"
endif

_format_boot: ${PBOOT}
	-umount "$${CFGROOT}/boot" "${PBOOT}"
	mkfs.fat -F 32 -n BOOT "$${PBOOT}"

_format: _format_root _format_boot

_iso_image: ${ISOROOT}
	grub-mkrescue -o "$${ISO}" "$${ISOROOT}"

.PHONY: _syslinux_efi32 _syslinux_efi64 _syslinux_bios
.PHONY: _grub_efi32 _grub_efi64

_syslinux_efi32: ${CFGROOT}
	mkdir -p "$${CFGROOT}/boot/EFI/BOOT"
	cp /usr/lib/SYSLINUX.EFI/efi32/syslinux.efi "$${CFGROOT}/boot/EFI/BOOT/BOOTIA32.EFI"
	mkdir -p "$${CFGROOT}/boot/efi32"
	cp $(addprefix /usr/lib/syslinux/modules/efi32/, ldlinux.e32 menu.c32 libutil.c32) "$${CFGROOT}"/boot/efi32/
	cp /usr/lib/syslinux/modules/efi32/ldlinux.e32 "$${CFGROOT}/boot/EFI/BOOT/"  # workaround
	printf 'PATH /efi32\nINCLUDE /bootmenu.cfg\nMENU TITLE Syslinux EFI-32\n' >"$${CFGROOT}/boot/syslia32.cfg"

_syslinux_efi64: ${CFGROOT}
	mkdir -p "$${CFGROOT}/boot/EFI/BOOT"
	cp /usr/lib/SYSLINUX.EFI/efi64/syslinux.efi "$${CFGROOT}/boot/EFI/BOOT/BOOTX64.EFI"
	mkdir -p "$${CFGROOT}/boot/efi64"
	cp $(addprefix /usr/lib/syslinux/modules/efi64/, ldlinux.e64 menu.c32 libutil.c32) "$${CFGROOT}"/boot/efi64/
	cp /usr/lib/syslinux/modules/efi64/ldlinux.e64 "$${CFGROOT}/boot/EFI/BOOT/"  # workaround
	printf 'PATH /efi64\nINCLUDE /bootmenu.cfg\nMENU TITLE Syslinux EFI-64\n' >"$${CFGROOT}/boot/syslx64.cfg"

_syslinux_bios: ${CFGROOT}
	mkdir -p "$${CFGROOT}/boot/bios"
	cp $(addprefix /usr/lib/syslinux/modules/bios/,  menu.c32 libutil.c32) "$${CFGROOT}"/boot/bios/
	printf 'PATH bios\nINCLUDE bootmenu.cfg\nMENU TITLE Syslinux BIOS\n' >"$${CFGROOT}/boot/syslinux.cfg"

_grub_efi32: ${CFGROOT}
	mkdir -p "$${CFGROOT}/boot/EFI/BOOT"
	grub-mkimage -p / -O i386-efi   fat part_gpt normal linux all_video >"$${CFGROOT}/boot/EFI/BOOT/BOOTIA32.EFI"

_grub_efi64: ${CFGROOT}
	mkdir -p "$${CFGROOT}/boot/EFI/BOOT"
	grub-mkimage -p / -O x86_64-efi fat part_gpt normal linux all_video >"$${CFGROOT}/boot/EFI/BOOT/BOOTX64.EFI"

${CFGROOT}/boot/cmdline.txt: ${CFGROOT}
	printf 'root=/dev/mmcblk0p2 rootfstype=${fstype} fsck.repair=yes rootwait' >"$@"

_bootloader_raspi: ${CFGROOT} ${CFGROOT}/boot/cmdline.txt

_bootloader_pc: ${CFGROOT} _grub_efi32 _grub_efi64 _syslinux_bios #_syslinux_efi32 _syslinux_efi64
	printf 'UI menu.c32\nDEFAULT stretch\nTIMEOUT 30\n' >"$${CFGROOT}/boot/bootmenu.cfg"
	printf 'set timeout=3\ndefault=stretch\n\n' >"$${CFGROOT}/boot/grub.cfg"
	k="$$(printf ' %s' "$${CFGROOT}/boot/"vmlinuz-*)"; k="$${k##*/}"; \
	i="$$(printf ' %s' "$${CFGROOT}/boot/"initrd.img-*)";  i="$${i##*/}"; \
	printf '\nLABEL stretch\n MENU LABEL Debian Stretch\n KERNEL /%s\n INITRD /%s\n APPEND root=LABEL=FSROOT\n' \
		"$$k" "$$i" >>"$${CFGROOT}/boot/bootmenu.cfg"; \
	printf '\nLABEL rescue\n MENU LABEL Rescue\n KERNEL /%s\n INITRD /%s\n APPEND root=LABEL=FSROOT init=/bin/sh\n' \
		"$$k" "$$i" >>"$${CFGROOT}/boot/bootmenu.cfg"; \
	printf "menuentry 'Debian Stretch' --id 'stretch' {\n linux '/%s' root=LABEL=FSROOT\n initrd '/%s'\n}\n" \
		"$$k" "$$i" >>"$${CFGROOT}/boot/grub.cfg"; \
	printf "menuentry 'Rescue' --id 'rescue' {\n linux '/%s' root=LABEL=FSROOT init=/bin/sh\n initrd '/%s'\n}\n" \
		"$$k" "$$i" >>"$${CFGROOT}/boot/grub.cfg"

_bootloader_iso: ${CFGROOT} ${ISOROOT}
	mkdir -p "$${ISOROOT}/boot/grub/"
	cp -L "$${CFGROOT}/vmlinuz" "$${CFGROOT}/initrd.img" "$${ISOROOT}"
	printf '%s\n' "insmod all_video" "set gfxmode=auto" "load_video" "insmod gfxterm" \
		>"$${ISOROOT}/boot/grub/grub.cfg"
	printf '%s\n' "set timeout=10" "default=buster" \
		"menuentry 'Debian Buster' --id 'buster' {" \
		"linux '/vmlinuz' boot=live" "initrd '/initrd.img'" "}" \
		>>"$${ISOROOT}/boot/grub/grub.cfg"
	-[ -f "$${ISOROOT}/install/initrd.gz" -a -f "$${ISOROOT}/install/linux" ] && \
	printf '%s\n' "menuentry 'Install Debian' --id 'install' {" \
		"linux '/install/linux'" "initrd '/install/initrd.gz'" "}" \
		>>"$${ISOROOT}/boot/grub/grub.cfg"

_efi_mount: ${PBOOT}
	-umount "efi/"
	mkdir -p -m 755 "efi/"
	mount -t vfat -o loop "$${PBOOT}" "efi/"

_efi_umount: _efi_mount
	sync
	umount efi/ && rmdir efi/

.PHONY: _syslinux_mbr _grub_mbr

_syslinux_mbr: ${VOLUME}
	syslinux -t 2097152 -i "$${VOLUME}"
	dd conv=notrunc if=/usr/lib/syslinux/mbr/gptmbr.bin of="$${VOLUME}"

_grub_mbr: ${VOLUME}
	# grub-mkimage -p / -O i386-pc fat part_gpt normal linux all_video |dd conv=notrunc of="$${VOLUME}"

_mbr: _syslinux_mbr # _grub_mbr

_partcopy: ${VOLUME} ${PROOT} ${PBOOT}
	dd conv=notrunc,sparse bs=1M seek=2 if="$${PBOOT}" of="$${VOLUME}"
	dd conv=notrunc,sparse bs=1M seek=$$((2 + ${BOOT_MB})) if="$${PROOT}" of="$${VOLUME}"

_mount_root: ${PROOT} ${CFGROOT}
	mountpoint "$${CFGROOT}" \
	|| mount -t ${fstype} "$${PROOT}" "$${CFGROOT}"
	chmod 755 "$${CFGROOT}"

_mount_boot: ${PBOOT}
	mkdir -p -m 755 "$${CFGROOT}/boot"
	mountpoint "$${CFGROOT}/boot" \
	|| mount -t vfat "$${PBOOT}" "$${CFGROOT}/boot"

ifdef disk
  _mount_boot: _mount_root
endif

_mount: _mount_root _mount_boot

_img_mount: ${CFGROOT}
	mountpoint "$${CFGROOT}" \
	|| mount -o loop,offset="$$((${BOOT_MB} + 2))"M,sizelimit=${ROOT_MB}M \
		 -t ${fstype} "$${VOLUME}" "$${CFGROOT}"
	chmod 755 "$${CFGROOT}"
	mkdir -p -m 755 "$${CFGROOT}/boot"
	mountpoint "$${CFGROOT}/boot" \
	|| mount -o loop,offset=2M,sizelimit=${BOOT_MB}M \
		 -t vfat "$${VOLUME}" "$${CFGROOT}/boot"

_umount_boot: ${CFGROOT} _config
	sync
	-umount "$${CFGROOT}/boot"

_umount_root: _umount_boot _config
	sync
	umount "$${CFGROOT}" && rmdir "$${CFGROOT}"

_umount: _umount_boot _umount_root

clean:
	[ "$${SYSROOT#/}" ] && [ "$${CFGROOT#/}" ] || false  # (abort receipe)
	-umount img_mount/boot
	-umount img_mount
	-rmdir img_mount
	-umount hdd_mount/boot
	-umount hdd_mount
	-rmdir hdd_mount
	if [ -d "cfg_root/" ]; then btrfs sub del "cfg_root/" || rm -r "cfg_root/"; fi
	if [ -d "iso_root/" ]; then btrfs sub del "iso_root/" || rm -r "iso_root/"; fi
	if [ -d "sys_root_${release}_${ARCH}/" ]; then btrfs sub del "sys_root_${release}_${ARCH}/" || rm -r "sys_root_${release}_${ARCH}/"; fi
	-rm part_boot.img
	-rm part_root.img
	-rm rpi_boot.img
	-rm rpi_root.img
	-[ -f "$${SQUASH}" ] && rm "$${SQUASH}"
	-[ -f "$${VOLUME}" ] && rm "$${VOLUME}"
	-[ -f "$${ISO}" ] && rm "$${ISO}"