#!/bin/bash -eu

function check_variable () {
  local var_name="$1"
  if [ -z "${!var_name+x}" ]
  then
    setup_progress "STOP: Define the variable $var_name like this: export $var_name=value"
    exit 1
  fi
}

function check_supported_hardware () {
  if grep -q 'Raspberry Pi Zero W' /sys/firmware/devicetree/base/model
  then
    return
  fi
  if grep -q 'Raspberry Pi 4' /sys/firmware/devicetree/base/model
  then
    return
  fi
  setup_progress "STOP: unsupported hardware: '$(cat /sys/firmware/devicetree/base/model)'"
  setup_progress "(only Pi Zero W and Pi 4 have the necessary hardware to run teslausb)"
  exit 1
}

function check_available_space () {
    if [ -z "$USB_DRIVE" ]
    then
      setup_progress "USB_DRIVE is not set. SD card will be used."
      check_available_space_sd
    else
      if grep -q 'Pi 4' /sys/firmware/devicetree/base/model
      then
        setup_progress "USB_DRIVE is set to $USB_DRIVE. This will be used for /mutable and backingfiles."
        check_available_space_usb
      else
        setup_progress "STOP: USB_DRIVE is supported only on a Pi 4. Set USB_DRIVE to blank or comment it to continue"
        exit 1
      fi
    fi
}

function check_available_space_sd () {
  setup_progress "Verifying that there is sufficient space available on the MicroSD card..."

  # The following assumes that the root and boot partitions are adjacent at the start
  # of the disk, and that all the free space is at the end.

  local totalsize
  local part1size
  local part2size
  local available_space

  totalsize=$(blockdev --getsize64 "${BOOT_DEVICE}")
  part1size=$(blockdev --getsize64 "${BOOT_DEVICE_PART}1")
  part2size=$(blockdev --getsize64 "${BOOT_DEVICE_PART}2")
  available_space=$((totalsize - part1size - part2size))

  # Require at least 12 GB of available space.
  if [ "$available_space" -lt  $(( (1<<30) * 12)) ]
  then
    setup_progress "STOP: The MicroSD card is too small: $available_space bytes available."
    setup_progress "$(parted "${BOOT_DEVICE}" print)"
    exit 1
  fi

  setup_progress "There is sufficient space available."
}

function check_available_space_usb () {
  setup_progress "Verifying that there is sufficient space available on the USB drive ..."

  # Verify that the disk has been provided and not a partition
  local drive_type
  drive_type=$(lsblk -pno TYPE "$USB_DRIVE" | head -n 1)

  if [ "$drive_type" != "disk" ]
  then
    setup_progress "STOP: The provided drive seems to be a partition. Please specify path to the disk."
    exit 1
  fi

  # This verifies only the total size of the USB Drive.
  # All existing partitions on the drive will be erased if backingfiles are to be created or changed.
  # EXISTING DATA ON THE USB_DRIVE WILL BE REMOVED.

  local drive_size
  drive_size=$(blockdev --getsize64 "$USB_DRIVE")

  # Require at least 16GB drive size.
  if [ "$drive_size" -lt  $(( (1<<30) * 16)) ]
  then
    setup_progress "STOP: The USB drive is too small: $(( drive_size / 1024 / 1024 / 1024 ))GB available. Expected at least 16GB"
    setup_progress "$(parted "$USB_DRIVE" print)"
    exit 1
  fi

  setup_progress "There is sufficient space available."
}

function check_setup_teslausb () {
  if [ ! -e /root/bin/setup-teslausb ]
  then
    setup_progress "STOP: setup-teslausb is not in /root/bin"
    exit 1
  fi
  if ! grep selfupdate /root/bin/setup-teslausb > /dev/null
  then
    setup_progress "setup-teslausb is outdated, attempting update"
    if curl --fail -s -o /root/bin/setup-teslausb.new https://raw.githubusercontent.com/marcone/teslausb/main-dev/setup/pi/setup-teslausb
    then
      if /root/bin/remountfs_rw > /dev/null && mv /root/bin/setup-teslausb.new /root/bin/setup-teslausb && chmod +x /root/bin/setup-teslausb
      then
        setup_progress "updated setup-teslausb"
        setup_progress "restarting updated setup-teslausb"
        /root/bin/setup-teslausb
        exit 0
      fi
    fi
    setup_progress "STOP: failed to update setup-teslausb"
    exit 1
  fi
}

check_supported_hardware

check_setup_teslausb

check_variable "CAM_SIZE"

check_available_space