#!/bin/sh

prog=${0##*/}

cleanup() {
	if [ -n "$uninstalls" ]; then
		apk del -q syslinux
	fi
	if [ -n "$umounts" ]; then
		umount $umounts
	fi
}

die() {
	echo "$@" >&2
	cleanup
	exit 1
}

# get alpine dev from boot cmdline
get_alpine_dev() {

}

usage() {
	cat <<__EOF__
usage: $prog [-hu] SOURCE [DEST]

Copy the contents of SOURCE to DEST and make DEST bootable.

SOURCE can be a directory or a ISO image. DEST can be a mounted directory 
or a device. If DEST is ommitted it will be autodetected.

Options:
 -d  Delete existing files first. Unsafe.
 -f  Force overwriting of existing syslinux.cfg
 -h  Show this help
 -s  Run syslinux and install mbr.bin to make it bootable
 -v  Verbose mode. Display whats going on.

__EOF__
	exit 1
}

while getopts "ih" opt; do
	case "$opt" in
	-d) delete_first=1;;
	-f) force=1;;
	-h) usage;;
	-s) syslinux=1;;
	-v) verbose=1;;
	esac
done


src=${1:-/media/cdrom}
dest=${2:-/media/usb}

srcmnt=${MNT:-/mnt}

# Find the srcdir, mount loopback if needed
if [ -f "$src"/.alpine-release ]; then
	srcdir="$src"
	[ -n "$verbose" ] && echo "Using directory $src as source"
else
	mount -o loop -t iso9660 "$src" $srcmnt \
		|| die "Failed to mount loopback $src"
	[ -n "$verbose" ] && echo "Using image $src as source"
	umounts="$srcmnt"
	srcdir="$srcmnt"
	if ! [ -f "$srcdir"/.alpine-release ]; then
		echo "Warning! No .alpine-release found on image $src"
		[ -z "$force" ] && die "Aborting."
	fi
fi

# find target device
if [ -d "$dest" ]; then
	if ! awk '{print $2}' /proc/mounts | grep -q "^$dest\$"; then
		mount "$dest" || die "Failed to mount $dest"
		umounts="$umounts $dest"
	fi
	destdir="$dest"
	[ -n "$vserbose" ] && echo "Using $destdir as target"
elif [ -b "$dest" ]; then
	destdir="/media/${dest##*/}"
	mkdir -p "$destdir"
	mount "$dest" "$destdir" || die "Failed to mount $dest on $destdir"
	[ -n "$vserbose" ] && echo "Using $dest (mounted on $destdir) as target"
fi

# remove partial upgrades if any.
rm -rf "$destdir"/.new "$destdir"/.old

# check that we have the space we need
needed_space=$(cd "$srcdir" && du -s -c boot apks syslinux.cfg .alpine-release | awk '$2 == "total" {print $1}')
[ -n "$verbose" ] && echo "Needed space:    $needed_space kB"

available_space=$(df -k "$destdir" | tail -n 1 | awk '{print $4}')
[ -n "$verbose" ] && echo "Available space: $available_space kB"
[ $available_space -lt $needed_space ] && die "Not enough space on $destdir. Aborting."

# copy the files to .new
echo "Copying new files to $destdir/.new..."
mkdir -p "$destdir"/.new || die "Failed to create $destdir/.new"
for i in boot apks syslinux.cfg .alpine-release; do
	[ -n "$verbose" 
	cp -a "$srcdir"/$i "$destdir"/.new/
done

# make sure files are really there before we replace existing
sync

echo "Replacing existing files..."
mkdir -p "$destdir"/.old || die "Failed to create $destdir/.old"

# do we want keep existing syslinux.cfg?
tomove="boot apks .alpine-release"
if [ -n "$force" ] || ! [ -e "$destdir"/syslinux.cfg ]; then
	tomove="$tomove syslinux.cfg"
fi

# move current files to .old
for i in $tomove; do
	if [ -e "$destdir"/$i ]; then
		mv "$destdir"/$i "$destdir"/.old/ || die "Failed to move $destdir/$i to $destdir/.old/"
	fi
done

# move .new to current
for i in $tomove; do
	mv "$destdir"/.new/$i "$destdir"/ || die "Failed to move $destdir/.new/ to $destdir"
done

# cleanup
[ -z "$keep_old" ] && rm -rf "$destdir"/.old "$destdir"/.new
sync


# If we only copy then we are done.
if [ -z "$syslinux" ]; then
	cleanup
	echo "Done."
	exit 0
fi

echo "Making usb bootable..."
dev=$(awk "\$2 == \"$dest\" {print \$1}" /proc/mounts)
parent=$(basename $(dirname /sys/block/*/$(basename $dev)))
if ! apk info -q -e syslinux; then
	apk add -q syslinux || die "Failed to install syslinux"
	uninstalls="syslinux"
fi

syslinux $dev

if [ -b /dev/$parent ]; then
	dd if=/usr/share/syslinux/mbr.bin of=/dev/$parent
else
	echo "Warning: Could not find the parent device for $dev"
fi

cleanup
echo "Done."