DEFAULT: _target
.PHONY: _target _qemu _partition _format _mount _bootstrap _install _sparse _copy _config _syslinux _umount _partcopy _squash _mbr

ARCH := amd64
KEYRING := keys/debian-archive-stretch-stable.gpg
BOOTSTRAP := http://cdn.debian.net/debian

define SOURCES = 
deb	http://cdn.debian.net/debian stretch main
endef
PACKAGES := ${PACKAGES} apt btrfs-tools busybox-static bzip2 ca-certificates cron debian-archive-keyring deborphan firmware-linux-free gzip htop ifupdown init iputils-ping irqbalance isc-dhcp-client less make net-tools nmap ntpdate openssh-client psmisc rsync sshfs sudo systemd traceroute unzip vim wget wireless-tools wpasupplicant xz-utils zip

ifdef disk
VOLUME := ${disk}
PBOOT := ${disk}1
PROOT := ${disk}2
SYSROOT := hdd_mount/
CFGROOT := hdd_mount/

_target: _mbr _umount _config _install _partition

_partition:
_format: _partition
_mount: _format
_bootstrap: _mount
_install: _bootstrap _mount
_config: _install _mount
_syslinux: _mount
_umount: _mount _config _syslinux
_mbr: _umount _syslinux

else ifdef image
VOLUME := ${image}
PBOOT := part_boot.img
PROOT := part_root.img
SYSROOT := sys_root/
CFGROOT := img_mount/

_target: _mbr _umount _partcopy _config _install

_bootstrap:
_install: _bootstrap
_sparse:
_format: _sparse
_mount: _format
_copy: _install _mount
_config: _copy _mount
_syslinux: _mount
_umount: _mount _config _syslinux
_partition:
_partcopy: _partition _umount
_mbr: _partcopy _syslinux

else ifdef squash
SQUASH := ${squash}
SYSROOT := sys_root/
CFGROOT := cfg_root/

_target: _squash _install _config

_bootstrap:
_install: _bootstrap
_copy: _install
_config: _copy
_squash: _config

else ifdef raspi
VOLUME := ${image}
PBOOT := rpi_boot.img
PROOT := rpi_root.img
SYSROOT := rpi_root/
CFGROOT := img_mount/

ARCH := armhf
KEYRING := keys/raspbian-archive-keyring.gpg
BOOTSTRAP := http://raspbian.raspberrypi.org/raspbian

define SOURCES =
deb	http://raspbian.raspberrypi.org/raspbian stretch main non-free firmware rpi
deb	http://archive.raspberrypi.org/debian stretch main
endef
PACKAGES := ${PACKAGES} firmware-brcm8011 libraspberrypi-bin libraspberrypi0 pi-bluetooth raspberrypi-bootloader raspberrypi-kernel

_target: _umount _partcopy _config _install

_qemu:
_bootstrap: _qemu
_install: _bootstrap
_sparse:
_format: _sparse
_mount: _format
_copy: _install _mount
_config: _copy _mount
_umount: _mount _config
_partition:
_partcopy: _partition _umount

else
_target:
	false

endif

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

export SOURCES SYSROOT CFGROOT VOLUME PBOOT PROOT SQUASH ARCH KEYRING BOOTSTRAP

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

_bootstrap: ${SYSROOT}/bin/sh
${SYSROOT}/bin/sh: | ${SYSROOT}
	debootstrap --variant=minbase --arch="$${ARCH}" \
		--keyring="$${KEYRING}" \
		stretch "$${SYSROOT}" "$${BOOTSTRAP}"

.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: ${SYSROOT}
	mkdir -p "$(dir $@)"
	printf 'APT::Install-Recommends "false";\n' >"$@"
	chmod 644 "$@"

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

_install: ${SYSROOT} _aptkeys _norecommends
	printf %s "$${SOURCES}" >"$${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 "$${SYSROOT}" apt-get --yes install ${PACKAGES}
	chroot "$${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

_copy: ${SYSROOT}
	btrfs sub snap "$${SYSROOT}" "$${CFGROOT}" || \
		cp -a "$${SYSROOT}/." "$${CFGROOT}/"

.PHONY: _main_config
_config: _main_config
_main_config: ${CFGROOT} cfg_seed/
	cp -a cfg_seed/. "$${CFGROOT}"

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

_squash: ${SQUASH}

clean:
	[ "$${SYSROOT#/}" ] && [ "$${CFGROOT#/}" ] || false  # (abort receipe)
	-mount |grep -qwF "$${SYSROOT}/boot" && umount "$${SYSROOT}/boot"
	-mount |grep -qwF "$${SYSROOT}/proc" && umount "$${SYSROOT}/proc"
	-mount |grep -qwF "$${SYSROOT}/sys" && umount "$${SYSROOT}/sys"
	-mount |grep -qwF "$${SYSROOT}/dev" && umount "$${SYSROOT}/dev"
	-mount |grep -qwF "$${SYSROOT}" && umount "$${SYSROOT}"
	-mount |grep -qwF "$${CFGROOT}" && umount "$${CFGROOT}"
	if [ -d "$${SYSROOT}" ] && ! mount |grep -qwFe "$${SYSROOT}"; then \
		btrfs sub del "$${SYSROOT}" || echo rm -r "$${SYSROOT}"; \
	fi
	if [ -d "$${CFGROOT}" ] && ! mount |grep -qwFe "$${CFGROOT}"; then \
		btrfs sub del "$${CFGROOT}" || echo rm -r "$${CFGROOT}"; \
	fi
	-rm "$${SQUASH}"