#!/bin/bash
#
# Copy a img.gz image file to a Solid State Drive / Flash Card
#
# Copyright (C) 2016 Lonnie Abelbeck
# This is free software, licensed under the GNU General Public License
# version 3 as published by the Free Software Foundation; you can
# redistribute it and/or modify it under the terms of the GNU
# General Public License; and comes with ABSOLUTELY NO WARRANTY.
#
# Input Arg1: sda|sdb|sdc|sdd (usually 'sda')
# Input Arg2: img.gz or .img image file
#

exit_no_action()
{
  echo "Exiting, no action performed."
  exit 1
}

exit_with_usage()
{
  echo "Usage: chromeos-ssd-write sda|sdb|sdc|sdd image_file.img[.gz]"
  exit 1
}

if [ "$(id -u)" -ne 0 ]; then
  echo "Permission denied, run with 'sudo'"
  echo "Usage: sudo chromeos-ssd-write sda|sdb|sdc|sdd image_file.img[.gz]"
  echo ""
  exit_no_action
fi

if [ -z "$1" ]; then
  exit_with_usage
fi
DISK="${1#/dev/}"

if [ "${DISK%[a-d]}" != "sd" ]; then
  exit_with_usage
fi

if [ -z "$2" ]; then
  exit_with_usage
fi
IMAGEFILE="$2"

if [ ! -f "$IMAGEFILE" ]; then
  echo "File: $IMAGEFILE, can not be found."
  exit_no_action
fi

fdisk -l /dev/$DISK

printf "Is this the disk you want to OVERWRITE ? [y/N] "
read x

case $x in
  y|Y|yes)
      ;;
  *)  exit_no_action
      ;;
esac

if [ ! -e "/dev/$DISK" ]; then
  echo "Device not found: /dev/$DISK"
  exit_no_action
fi

#
# Inputs look good, off to work...
#

printf "\nOpen the 'Files' App and eject all partitions related to the '$DISK' disk.\n"
printf "Hit [enter] when complete or [q] to quit... "
read x

case $x in
  q|Q|quit)
      exit_no_action
      ;;
esac

sleep 1

for i in 1 2 3 4 5 6 7 8; do
  if [ -e "/dev/$DISK$i" ]; then
    umount "/dev/$DISK$i" 2>/dev/null
  fi
done

if [ ! -e "/dev/$DISK" ]; then
  echo "Device not found: /dev/$DISK"
  exit_no_action
fi

echo ""
echo "Erasing first 1 GB of /dev/$DISK..."
echo "This may take a long time..."

dd if=/dev/zero of=/dev/$DISK iflag=nocache oflag=direct bs=64k count=16000

echo ""
echo "Writing \"$IMAGEFILE\" to /dev/$DISK"
echo "This may take a long time..."

if [ "${IMAGEFILE}" != "${IMAGEFILE%.gz}" ]; then
  zcat "$IMAGEFILE" | dd of=/dev/$DISK iflag=fullblock oflag=direct bs=64k
else
  dd if="$IMAGEFILE" of=/dev/$DISK iflag=fullblock oflag=direct bs=64k
fi

sync

echo ""
echo "Ejecting /dev/$DISK"
eject /dev/$DISK

echo ""
echo "You can safely remove your '$DISK' disk."