#!/bin/bash

set -e
set -u

usage() {
    echo "Usage: $0 DEVICE IMAGE HOSTNAME"
    echo "Example: $0 /dev/mmcblkX ArchLinuxARM-rpi-2-latest.tar.gz myrpi"
    exit 1
}

[ $# -ne 3 ] && { usage; }

DEVICE="$1"
IMAGE="$2"
HOSTNAME="$3"

if [ ! -e "$DEVICE" ]; then
    echo "Device $DEVICE not found!"
    echo "Give a valid device (e.g. /dev/sdX)"
    exit 2
fi

echo "Flashing device $DEVICE and setting hostname to $HOSTNAME"

TMP_DIR=$(mktemp -d)
echo "Temp directory: $TMP_DIR"
cd "$TMP_DIR"

cleanup() {
    echo "Cleaning up $TMP_DIR"
    rm -rf "$TMP_DIR"
}

trap cleanup 0

echo "Creating partitions"
echo "o
p
n
p
1

+100M
p
t
c
n
p
2


p
w
w
" | fdisk "$DEVICE"

echo "Creating boot filesystem"
mkfs.vfat "$DEVICE"p1
mkdir boot
mount "$DEVICE"p1 boot

echo "Creating root filesystem"
mkfs.ext4 "$DEVICE"p2
mkdir root
mount "$DEVICE"p2 root

echo "Copying base image"
tar -xf "$IMAGE" -C root
sync

echo "Copying boot files to boot partition"
mv root/boot/* boot

echo "Setting hostname to $HOSTNAME"
echo "$HOSTNAME" > root/etc/hostname

echo "Unmounting partitions"
sync
umount boot root