#!/usr/bin/env bash

flash_sd () {
    img_file=$1
    sd_card=$2
    echo "Flashing $img_file to $sd_card ..."
    xzcat --stdout $img_file | dd of=$sd_card status=progress
}

enlarge_partition () {
    device=$1
    partnr=2
    echo "Resize main partition"
    sfdisk --backup $device -N $partnr << EOF
,+
print
EOF
    echo "Resize filesystem"
    e2fsck -f "$device"p$partnr
    resize2fs -p "$device"p$partnr
}

mount_temporary () {
    partnr=$1
    temp_mnt_point=$(mktemp -d)
    mount "$SD_CARD"p"$partnr" $temp_mnt_point
    echo $temp_mnt_point
}

unmount_temporary () {
    handle=$1
    umount $1
    rmdir $1
}

read -e -p "Compressed Image file: " IMG_FILE
read -e -p "SD Card: " SD_CARD

flash_sd "$IMG_FILE" "$SD_CARD"
enlarge_partition "$SD_CARD"
mnt_handle=$(mount_temporary "1")


unmount_temporary $mnt_handle