#!/bin/sh

# Copyright (C) 2012 Michael Gorven <http://michael.gorven.za.net/>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

set -ev

NAME="${1?Please specify output image name.}"
IMAGE_SIZE=1000
BOOT_SIZE=64
ALIGN_SECTORS=8192
ALIGN_FSBLOCKS="$(($ALIGN_SECTORS*512/4096))"
MIRROR="http://mirrordirector.raspbian.org/raspbian"
BASE_PACKAGES="openssh-server sudo ntp fake-hwclock raspi-copies-and-fills raspi-config"
XBMC_PACKAGES="nfs-client xbmc udisks avahi-daemon"
XBMC_USER="xbmc"
XBMC_HOSTNAME="xbmc"

export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8

check_host() {
	if [ $(id -u) != 0 ]; then
		echo "This script must be run as root."
		exit 2
	fi

	for BINARY in wget gpg qemu-debootstrap rsync kpartx sfdisk mkfs.ext4 mkfs.vfat tune2fs tar sha256sum; do
		if ! which $BINARY > /dev/null; then
			echo "Unable to find $BINARY binary, please install it"
			exit 1
		fi
	done
}

bootstrap() {
	if [ ! "$BUILDROOT" ]; then
		echo "BUILDROOT is empty, aborting."
		exit 1
	fi

	KEYRING="${TMPDIR:-/tmp}/raspbian.gpg"
	if [ ! -s "$KEYRING" ]; then
		wget -O- http://archive.raspbian.org/raspbian.public.key | gpg --no-default-keyring --keyring "$KEYRING" --import
	fi

	qemu-debootstrap --arch=armhf --keyring="$KEYRING" wheezy "$BUILDROOT" "$MIRROR"
}

configure_base() {
	if [ ! "$BUILDROOT" ]; then
		echo "BUILDROOT is empty, aborting."
		exit 1
	fi

	cat > "$BUILDROOT/usr/sbin/policy-rc.d" <<-EOF
	#!/bin/sh
	exit 101
	EOF
	chmod +x "$BUILDROOT/usr/sbin/policy-rc.d"

	cat > "$BUILDROOT/etc/apt/sources.list" <<-EOF
	deb $MIRROR wheezy main contrib non-free rpi
	EOF

	cat > "$BUILDROOT/etc/apt/sources.list.d/mene.list" <<-EOF
	deb http://archive.mene.za.net/raspbian wheezy contrib
	EOF

	cat > "$BUILDROOT/etc/apt/sources.list.d/raspi.list" <<-EOF
	deb http://archive.raspberrypi.org/debian/ wheezy main
	EOF

	if [ "$http_proxy" ]; then
		cat > "$BUILDROOT/etc/apt/apt.conf.d/30proxy" <<-EOF
		Acquire::http::proxy "$http_proxy";
		EOF
	fi

	wget -O- http://archive.raspberrypi.org/debian/raspberrypi.gpg.key | chroot "$BUILDROOT" apt-key add -
	wget -O- http://archive.mene.za.net/key.asc | chroot "$BUILDROOT" apt-key add -

	export DEBIAN_FRONTEND=noninteractive
	chroot "$BUILDROOT" apt-get --yes dist-upgrade
	chroot "$BUILDROOT" apt-get --yes update
	chroot "$BUILDROOT" apt-get --yes install raspberrypi-bootloader libraspberrypi-bin $BASE_PACKAGES

	cat > "$BUILDROOT/boot/config.txt" <<-EOF
	disable_overscan=1
	EOF

	cat > "$BUILDROOT/boot/cmdline.txt" <<-EOF
	dwc_otg.lpm_enable=0 dwc_otg.fiq_fix_enable=1 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=noop rootwait
	EOF

	chroot "$BUILDROOT" adduser --disabled-password --gecos 'Raspberry Pi User,,,,' pi
	echo 'pi:raspberry' | chroot "$BUILDROOT" chpasswd
	chroot "$BUILDROOT" adduser pi sudo

	cat >> "$BUILDROOT/etc/network/interfaces" <<-EOF
	auto eth0
	iface eth0 inet dhcp
	EOF

	echo "$XBMC_HOSTNAME" > "$BUILDROOT/etc/hostname"

	cat >> "$BUILDROOT/etc/hosts" <<-EOF
	127.0.0.2	$XBMC_HOSTNAME
	EOF

	cat > "$BUILDROOT/etc/fstab" <<-EOF
	LABEL=boot	/boot	vfat	defaults	0	2
	LABEL=root	/		ext4	errors=remount-ro,noatime,nodiratime	0	1
	EOF

	cat >> "$BUILDROOT/etc/modules" <<-EOF
	vchiq
	snd_bcm2835
	EOF

	cat > "$BUILDROOT/etc/sysctl.d/raspi.conf" <<-EOF
	vm.min_free_kbytes = 8192
	EOF

	cat > "$BUILDROOT/etc/init.d/regenerate_ssh_host_keys" <<-"EOF"
	#!/bin/sh
	### BEGIN INIT INFO
	# Provides:          regenerate_ssh_host_keys
	# Required-Start:
	# Required-Stop:
	# Default-Start: 2
	# Default-Stop:
	# Short-Description: Regenerate ssh host keys
	# Description:
	### END INIT INFO

	. /lib/lsb/init-functions

	set -e

	case "$1" in
	  start)
		log_daemon_msg "Regenerating ssh host keys (in background)"
		nohup sh -c "yes | ssh-keygen -q -N '' -t dsa -f /etc/ssh/ssh_host_dsa_key && \
		  yes | ssh-keygen -q -N '' -t rsa -f /etc/ssh/ssh_host_rsa_key && \
		  yes | ssh-keygen -q -N '' -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key && \
		  update-rc.d ssh enable && sync && \
		  rm /etc/init.d/regenerate_ssh_host_keys && \
		  update-rc.d regenerate_ssh_host_keys remove && \
		  printf '\nfinished\n' && invoke-rc.d ssh start" > /var/log/regen_ssh_keys.log 2>&1 &
		log_end_msg $?
		;;
	  *)
		echo "Usage: $0 start" >&2
		exit 3
		;;
	esac
	EOF

	chmod +x "$BUILDROOT/etc/init.d/regenerate_ssh_host_keys"
	chroot "$BUILDROOT" update-rc.d ssh disable
	chroot "$BUILDROOT" update-rc.d regenerate_ssh_host_keys defaults
}

configure_xbmc() {
	cp "$BUILDROOT/boot/arm128_start.elf" "$BUILDROOT/boot/start.elf"

	chroot "$BUILDROOT" apt-get --yes install $XBMC_PACKAGES

	chroot "$BUILDROOT" addgroup --system input
	chroot "$BUILDROOT" adduser --disabled-login --shell /bin/false --gecos 'XBMC Media Centre,,,' "$XBMC_USER"
	chroot "$BUILDROOT" adduser "$XBMC_USER" video
	chroot "$BUILDROOT" adduser "$XBMC_USER" audio
	chroot "$BUILDROOT" adduser "$XBMC_USER" plugdev
	chroot "$BUILDROOT" adduser "$XBMC_USER" input

	cat > "$BUILDROOT/etc/default/xbmc" <<-EOF
	ENABLED=1
	USER="$XBMC_USER"
	NICE=-5
	EOF

	cat > "$BUILDROOT/etc/udev/rules.d/99-input.rules" <<-EOF
	SUBSYSTEM=="input", GROUP="input", MODE="0660"
	EOF

	cat > "$BUILDROOT/var/lib/polkit-1/localauthority/50-local.d/50-xbmc.pkla" <<-EOF
	[Actions for $XBMC_USER user]
	Identity=unix-user:$XBMC_USER
	Action=Action=org.freedesktop.upower.*;org.freedesktop.consolekit.system.*;org.freedesktop.udisks.*
	ResultActive=yes
	ResultAny=yes
	ResultInactive=no
	EOF

	chown -R 1001:1001 "$BUILDROOT/home/$XBMC_USER"
}

cleanup() {
	chroot "$BUILDROOT" apt-get --yes clean
	find "$BUILDROOT/var/lib/apt/lists/" -type f -delete
	rm -f "$BUILDROOT/etc/apt/apt.conf.d/30proxy" "$BUILDROOT/usr/sbin/policy-rc.d"
}

mkimage() {
	IMAGE="$NAME.img"
	TAR="$NAME.tar.xz"

	dd if=/dev/zero of="$IMAGE" bs=1MB count=0 seek="$IMAGE_SIZE"
	BOOT_SECTORS="$(($BOOT_SIZE*2048/$ALIGN_SECTORS*$ALIGN_SECTORS))"
	cat | sfdisk --quiet --unit S --force "$IMAGE" <<-EOF
	$ALIGN_SECTORS,$(($BOOT_SECTORS)),c,*
	$(($ALIGN_SECTORS+$BOOT_SECTORS)),,L

	EOF

	LOOP="$(basename $(losetup -f))"
	kpartx -a "$IMAGE"
	BOOT="/dev/mapper/${LOOP}p1"
	ROOT="/dev/mapper/${LOOP}p2"

	mkfs.vfat -F 32 -n boot "$BOOT"
	mkfs.ext4 -b 4096 -E stride=$ALIGN_FSBLOCKS,stripe-width=$ALIGN_FSBLOCKS -m 1 -L root "$ROOT"
	tune2fs -i 0 -c 0 "$ROOT"

	MNT="$(mktemp -d --tmpdir raspbian.XXXXXX)"
	mount "$ROOT" "$MNT"
	mkdir "$MNT/boot"
	mount "$BOOT" "$MNT/boot"

	rsync --archive --devices --specials --hard-links --acls --xattrs --sparse --verbose "$BUILDROOT" "$MNT"

	umount "$MNT/boot"
	umount "$MNT"

	kpartx -d "$IMAGE"
	tar -cSJvf "$TAR" "$IMAGE"
	sha256sum "$TAR" > "$TAR.sha256"
}


BUILDROOT="$(mktemp -d $PWD/raspbian.XXXXXX)/root/"
check_host
bootstrap
configure_base
configure_xbmc
cleanup
mkimage