#!/bin/bash

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

# load functions
source lib/util.sh         || { exit 1; }
source lib/user-input.sh   || { exit 1; }
source lib/block-device.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_user_input() {
  # @post
  #   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() {
  # @post
  #   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() {
  # @pre
  #   FS
  # @post
  #   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() {
  # @pre
  #   FS
  # @post
  #   FS_CHOSEN_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" 'on' 'ssd' 'Enable if using SSD/NVMe' 'off')
		;;
	EXT4)
	  TMP1=('noatime'" Don't write file/folder access times" 'on')
		;;
  F2FS)
    TMP1=('noatime' "Don't write file/folder access times" 'on')
    ;;
	*)
		echo "Filesystem $FS not yet supported!"
		return 1
		;;
  esac

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

function run_pacstrap() {
  # @pre
  #   BIOS_TYPE
  #   KERNEL
  #   CPU_VENDOR

  PKGS=()

  case "${KERNEL}" in
  linux)
    PKGS+=("${KERNEL}" "${KERNEL}-headers")
    ;;
  linux-lts)
    PKGS+=("${KERNEL}" "${KERNEL}-headers")
    ;;
  *)
    echo "Not yet implemented!"
    return 1
    ;;
  esac

  case "${CPU_VENDOR}" in
  amd)
    PKGS+=("${CPU_VENDOR}-ucode")
    ;;
  intel)
    PKGS+=("${CPU_VENDOR}-ucode")
    ;;
  none)
    true
    ;;
  *)
    echo "Not yet implemented!"
    return 1
    ;;
  esac

  case "${BIOS_TYPE}" in
  uefi)
    PKGS+=('de-p1st-base-efi')
    ;;
  bios)
    echo "Not yet implemented"
    return 1
    ;;
  *)
    echo "Not yet implemented!"
    return 1
    ;;
  esac

  pacstrap /mnt "${PKGS[@]}" || return $?
}

function run_genfstab() {
  # @pre
  #   FS

  local fstab
  fstab="$(genfstab -U /mnt)"

  case "${FS}" in
	BTRFS)
	  # Remove "subvolid=..." mount option but leave "subvol=..." mount option
	  fstab=$(printf "%s" "${fstab}" | sed 's/,subvolid=[^,\s]\+//') || return $?
	  # Check if fstab does still contain subvolid mount option
    if printf "%s" "${fstab}" | grep -q 'subvolid='; then
	    echo "This should not happen!"
	    return 1
    fi
		;;
	EXT4)
	  true
		;;
  F2FS)
    true
    ;;
	*)
		echo "Filesystem $FS not yet supported!"
		return 1
		;;
  esac

  printf "%s" "${fstab}" > /mnt/etc/fstab || return $?
}

function config_hostname_and_hosts() {
  # @pre
  #   HOSTNAME
  #   FQDN (optional, e.g. sub.domain.de)
  #   STATIC_IP (optional, e.g. 93.133.433.133)
  #   IPV6_CAPABLE (optional, e.g. 1)

  echo "${HOSTNAME}" >/mnt/etc/hostname || return $?

  # If the system has a permanent IP address, it should be used instead of 127.0.1.1.
  # * https://wiki.archlinux.org/index.php/Installation_guide#Network_configuration

  # Desirable entries IPv4/IPv6:
  # * https://man.archlinux.org/man/hosts.5#EXAMPLES

  # If FQDN not given, use $HOSTNAME.localdomain instead
  FQDN="${FQDN:="${HOSTNAME}.localdomain"}"
  # If STATIC_IP not given, use 127.0.1.1 instead
  STATIC_IP="${STATIC_IP:='127.0.1.1'}"

  echo "# The following lines are desirable for IPv4 capable hosts
127.0.0.1     localhost
# 127.0.1.1 is often used for the FQDN of the machine
${STATIC_IP}  ${FQDN}  ${HOSTNAME}" > /mnt/etc/hosts || return $?

  if [ "${IPV6_CAPABLE}" = "1" ]; then
    echo "
# The following lines are desirable for IPv6 capable hosts
::1           localhost ip6-localhost ip6-loopback
ff02::1       ip6-allnodes
ff02::2       ip6-allrouters" >> /mnt/etc/hosts || return $?
  fi
}

function main() {
  # @pre
  #   bash libraries imported
  # @post
  #   installation finished

  check_network  || return $?
  # out: BIOS_TYPE, KERNEL, FS, HOSTNAME, USERNAME, USER_PWD, LUKS_PWD
  get_user_input || return $?
  # out: CPU_VENDOR
  get_cpu_vendor || return $?

  # in: FS
  # out: FS_DEFAULT_MOUNT_OPTIONS
  get_default_mount_options || return $?
  # in: FS
  # out: FS_CHOSEN_MOUNT_OPTIONS
  choose_mount_options      || return $?

  # in: TARGET_BLOCK_DEVICE, BIOS_TYPE
  # out: BOOT_PART, LUKS_PART
  partition || return $?
  # in: BIOS_TYPE, BOOT_PART, LUKS_PART, LUKS_PWD, FS
  # out: DATA_PART
  format    || return $?

  # Combine default and chosen mount options
  TMP1=("${FS_DEFAULT_MOUNT_OPTIONS[@]}" "${FS_CHOSEN_MOUNT_OPTIONS[@]}") || return $?
  # Join array elements by ","
  join_by "," TMP1 FS_MOUNT_OPTIONS || return $?

  echo "Mounting data partition with options: ${FS_MOUNT_OPTIONS}"
  mount -o "${FS_MOUNT_OPTIONS}" "$DATA_PART" /mnt || return $?

  echo "Mounting boot partition ..."
  mkdir /mnt/boot              || return $?
  mount "$BOOT_PART" /mnt/boot || return $?

  # in: BIOS_TYPE, KERNEL, CPU_VENDOR
  run_pacstrap || return $?
  # in: FS
  run_genfstab || return $?

  # in: HOSTNAME, FQDN (optional), STATIC_IP (optional), IPV6_CAPABLE (optional)
  config_hostname_and_hosts || return $?

}

main "$@"