#!/bin/bash

# load config
source installer.cfg || { exit 1; }

# load functions
source helper.sh || { exit 1; }


function check_network() {
  echo "Sending ping to wikipedia.de ..."
  ping -c 1 wikipedia.de || {
    echo "Pleas set up network access."
    return 1
  }
}

function increase_cow_space() {
  # May be useful when running 'pacman -Syu' on the live medium.
  # Usually not necessary!

  # make sure that we are on a live medium:
  findmnt /run/archiso/cowspace || {
    echo "Not on live medium, did not increase cowspace!"
    return 1
  }

  echo "Increasing cowspace partition of live medium ..."
  mount -o remount,size=2G /run/archiso/cowspace || return $?
}

function get_text_input {
  # If variable with name $1 is zero, then ask user for input.
  # Only one line user input is allowed.
  # User input must not be empty.
  #
  # $1: name of variable to store user input
  # $2: text to display (e.g. "Enter hostname:")
  if [ "$#" -ne 2 ]; then
    echo "get_text_input requires two args!";
    return 1
  fi
  for i in "$@"; do
    if [ -z "$i" ]; then
      echo "get_text_input: all given args must not be empty";
      return 1;
    fi
  done

  local -n ptr=$1
  if [ -z "$ptr" ]; then
    # if ptr has no value yet, ask user for input!
    echo "$2"
    read -r ptr || return $?
  fi

  # check string length to be greater than zero!
  if [ "${#ptr}" -lt 1 ]; then
    echo "get_text_input must not be empty!";
    return 1;
  fi
}

function get_single_choice {
  # If variable with name $1 is zero, then ask user to select one option.
  #
  # $1: name of variable to store the selected option
  # $2: text to display
  # $3: name of variable with space-separated menu options to display (each menu option consists of an item and a description)
  if [ "$#" -ne 3 ]; then
    echo "get_single_choice requires three args!";
    return 1
  fi
  for i in "$@"; do
    if [ -z "$i" ]; then
      echo "get_single_choice: all given args must not be empty";
      return 1;
    fi
  done


  local -n ptr=$1
  if [ -z "$ptr" ]; then
    # if ptr has no value yet, ask user for input!

    local -n MENU_OPTIONS=$3
    ptr=$(dialog --stdout --menu "$2" 0 0 0 ${MENU_OPTIONS}) || {
      echo "Error during menu selection!"
      exit 1
    }
    clear
  fi
}

function get_multi_choice {
  # If variable with name $1 is zero, then ask user to select one ore more options.
  #
  # $1: name of variable to store array of selected options
  # $2: text to display
  # $3: name of variable with space-separated menu options to display (each menu option consists of an item, a description and on/off if preselected or not)
    if [ "$#" -ne 3 ]; then
    echo "get_multi_choice requires three args!";
    return 1
  fi
  for i in "$@"; do
    if [ -z "$i" ]; then
      echo "get_multi_choice: all given args must not be empty";
      return 1;
    fi
  done


  local -n ptr=$1
  if [ -z "$ptr" ]; then
    # if ptr has no value yet, ask user for input!

    local -n MENU_OPTIONS=$3
    TMP1=$(dialog --stdout --checklist "$2" 0 0 0 ${MENU_OPTIONS}) || {
      echo "Error during menu selection!"
      exit 1
    }
    clear

    # Result of dialog is space separated list
    # Store this as an array
    # Without newline at last array element: https://unix.stackexchange.com/a/519917/315162
    # readarray -d " " -t ptr < <(printf '%s' "$TMP1")
    #
    space_separated_to_array TMP1 "$1"
  fi
}

function get_user_input() {
  # return: the following variables:
  #   BIOS_TYPE (uefi or bios)
  #   KERNEL    (linux or linux-lts)
  #   FS        (BTRFS, EXT4, F2FS)
  #   HOSTNAME
  #   USERNAME, USER_PWD
  #   LUKS_PWD

  get_block_devices_with_size || return $?
  get_single_choice  TARGET_BLOCK_DEVICE "Select target device for installation" BLOCK_DEVICE_SIZES || return $?

  TMP1="uefi Newer-mainboards bios Legacy-BIOS-on-older-mainboards"
  get_single_choice  BIOS_TYPE "Select your bios type" TMP1 || return $?

  TMP1="linux-lts Long-Time-Stable-Linux-kernel linux Latest-Linux-kernel"
  get_single_choice  KERNEL "Select kernel version" TMP1 || return $?

  TMP1="BTRFS allows-snapshots-and-dynamic-extension-of-the-fs EXT4 default-fs-of-many-distributions F2FS Flash-Friendly-fs-for-SSD-or-NVMe"
  get_single_choice  FS "Select filesystem to use" TMP1 || return $?

  get_text_input HOSTNAME "Enter hostname:" || return $?
  get_text_input USERNAME "Enter username:" || return $?

  if [ -z "${USER_PWD}" ]; then
    get_text_input USER_PWD "Enter a user password:" || return $?
    get_text_input USER_PWD2 "Please enter the password again:" || return $?
    [[ "${USER_PWD}" == "${USER_PWD2}" ]] || {
      echo "Passwords did not match";
      exit 1;
    }
  fi
  if [ -z "${LUKS_PWD}" ]; then
    get_text_input LUKS_PWD "Enter a disk encryption password:" || return $?
    get_text_input LUKS_PWD2 "Please enter the password again:" || return $?
    [[ "${LUKS_PWD}" == "${LUKS_PWD2}" ]] || {
      echo "Passwords did not match";
      exit 1;
    }
  fi
}

function get_cpu_vendor() {
  # return: the following variables:
  #   CPU_VENDOR ("amd", "intel", "none")

  if [ -z "${CPU_VENDOR}" ]; then
    # if CPU_VENDOR has no value yet, ask user for input!

    local vendor_id
    vendor_id=$(cat /proc/cpuinfo | grep vendor_id | head -1 | sed 's|vendor_id\s*:\s*||')

    if [ "$vendor_id" = "AuthenticAMD" ]; then
      CPU_VENDOR="amd"
    elif [ "$vendor_id" = "GenuineIntel" ]; then
      CPU_VENDOR="intel"
    else
      echo "Unknown CPU vendor: $vendor_id"
      return 1
    fi
  fi
}

function get_default_mount_options() {
  # return: the following variables:
  #   FS_DEFAULT_MOUNT_OPTIONS (array)

  FS_DEFAULT_MOUNT_OPTIONS=()

  case "${FS}" in
	BTRFS)
	  # compress=lzo: archwiki -> Btrfs#Compression
	  # "Enable compression (better performance, longer flash lifespan)"
		FS_DEFAULT_MOUNT_OPTIONS+=('compress=lzo')
		;;
	EXT4)
	  # https://wiki.archlinux.org/index.php/Ext4#Enabling_metadata_checksums
	  # If the CPU supports SSE 4.2, make sure the crc32c_intel kernel module is loaded (TODO)
		FS_DEFAULT_MOUNT_OPTIONS+=('metadata_csum')
		;;
  F2FS)
    # When mounting the filesystem, specify compress_algorithm=(lzo|lz4|zstd|lzo-rle).
    # Using compress_extension=txt will cause all txt files to be compressed by default.
    FS_DEFAULT_MOUNT_OPTIONS+=('compress_algorithm=lz4')
    ;;
	*)
		echo "Filesystem $FS not yet supported!"
		return 1
		;;
  esac
}

function choose_mount_options() {
  # return: the following variables:
  #   FS_MOUNT_OPTIONS (array)

  case "${FS}" in
	BTRFS)
	  # noatime, nodiratime:
	  # - The atime options do impact drive performance;
	  # - noatime implies nodiratime, one does not need to specify both;
	  # - The noatime option fully disables writing file access times to the drive every time you read a file.
	  #   This works well for almost all applications, except for those that need to know if a file has been
	  #   read since the last time it was modified.
	  TMP1="noatime Don't-write-file/folder-access-times off ssd Only-enable-when-on-ssd-or-nvme off"
		;;
	EXT4)
	  TMP1="noatime Don't-write-file/folder-access-times off"
		;;
  F2FS)
    TMP1="noatime Don't-write-file/folder-access-times off"
    ;;
	*)
		echo "Filesystem $FS not yet supported!"
		return 1
		;;
  esac

  get_multi_choice  FS_MOUNT_OPTIONS "Select mount options" TMP1 || return $?
}

function main() {
  check_network             || return $?
  get_user_input            || return $?
  get_cpu_vendor            || return $?

  get_default_mount_options || return $?
  choose_mount_options      || return $?

  # TODO: use FS_DEFAULT_MOUNT_OPTIONS and FS_MOUNT_OPTIONS in combination
}

main "$@"