#!/bin/bash

set -e
if [ "$DEBUG" ]; then
  set -x
fi

create_loop() {
  local loop_device=$(losetup -f)
  losetup -P $loop_device "${1}"
  echo $loop_device
}

make_mountable() {
  sh lib/ssd_util.sh --no_resign_kernel --remove_rootfs_verification -i $1
  printf '\000' | dd of=$1 seek=$((0x464 + 3)) conv=notrunc count=1 bs=1 
}

partition_disk() {
  local image_path=$(realpath "${1}")
  local bootloader_size=${2}

  #create partition table with fdisk
  ( 
    echo g #new gpt disk label

    #create 1MB stateful
    echo n #new partition
    echo #accept default parition number
    echo #accept default first sector
    echo +1M #partition size is 1M

    #create 32MB kernel partition
    echo n
    echo #accept default parition number
    echo #accept default first sector
    echo +32M #partition size is 32M
    echo t #change partition type
    echo #accept default parition number
    echo FE3A2A5D-4F32-41A7-B725-ACCC3285A309 #chromeos kernel type

    #create bootloader partition
    echo n
    echo #accept default parition number
    echo #accept default first sector
    echo "+${bootloader_size}M" #set partition size
    echo t #change partition type
    echo #accept default parition number
    echo 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC #chromeos rootfs type

    #create rootfs partition
    echo n
    echo #accept default parition number
    echo #accept default first sector
    echo #accept default size to fill rest of image

    #write changes
    echo w
  ) | fdisk $image_path
}

safe_mount() {
  rm -rf $2
  mkdir -p $2
  mount $1 $2
}

create_partitions() {
  local image_loop=$(realpath "${1}")
  local kernel_path=$(realpath "${2}")

  #create stateful
  mkfs.ext4 "${image_loop}p1"
  #copy kernel
  dd if=$kernel_path of="${image_loop}p2" bs=1M oflag=sync
  #create bootloader partition
  mkfs.ext2 "${image_loop}p3"
  #create rootfs partition
  mkfs.ext4 "${image_loop}p4"
}

populate_partitions() {
  local image_loop=$(realpath "${1}")
  local bootloader_dir=$(realpath "${2}")
  local rootfs_dir=$(realpath "${3}")

  #mount and write empty file to stateful
  local stateful_mount=/tmp/shim_stateful
  safe_mount "${image_loop}p1" $stateful_mount
  mkdir -p $stateful_mount/dev_image/etc/
  touch $stateful_mount/dev_image/etc/lsb-factory
  umount $stateful_mount

  #mount and write to bootloader rootfs
  local bootloader_mount=/tmp/shim_bootloader
  safe_mount "${image_loop}p3" $bootloader_mount
  cp -r $bootloader_dir/* $bootloader_mount
  umount $bootloader_mount

  local rootfs_mount=/tmp/shim_rootfs
  safe_mount "${image_loop}p4" $rootfs_mount
  cp -r $rootfs_dir/* $rootfs_mount
  umount $rootfs_mount
}

create_image() {
  local image_path=$(realpath "${1}")
  local bootloader_size=${2}
  local rootfs_size=${3}
  
  #stateful + kernel + bootloader + rootfs
  local total_size=$((1 + 32 + $bootloader_size + $rootfs_size))
  dd if=/dev/zero of=$image_path bs=1M oflag=sync count=$total_size status=progress

  partition_disk $image_path $bootloader_size
}

if [ $0 == "./build_image.sh" ]; then
  create_image ./test.bin 20 200
  image_loop=$(create_loop ./test.bin)
  create_partitions $image_loop /tmp/shim_kernel/kernel.bin
  populate_partitions $image_loop ./tmp/shim_initramfs ./lib
  losetup -d $image_loop
fi