#!/bin/bash
set -o pipefail


################################################
# Initialize script environment

# Find the directory this script is stored in. (from: http://stackoverflow.com/questions/59895)
function get_source_dir() {
	local source="${BASH_SOURCE[0]}"
	while [[ -h $source ]]
	do
		local tmp
		tmp="$(cd -P "$(dirname "${source}")" && pwd)"
		source="$(readlink "${source}")"
		[[ $source != /* ]] && source="${tmp}/${source}"
	done

	echo -n "$(realpath "$(dirname "${source}")")"
}

export GENTOO_INSTALL_REPO_DIR="$(get_source_dir)"
export GENTOO_INSTALL_REPO_SCRIPT_ACTIVE=true

source "$GENTOO_INSTALL_REPO_DIR/scripts/utils.sh"

# Remember actual config file path
CONFIG_FILE="$(realpath "${1-"gentoo.conf"}" 2>/dev/null)"
RELA_CONFIG_FILE="$(realpath --relative-to="$(pwd)" "$CONFIG_FILE" 2>/dev/null)"

# Check if help is requested
while [[ $# -gt 0 ]]; do
	case "$1" in
		""|"help"|"--help"|"-help"|"-h")
			echo "Usage: $0 [config]"
			echo "Starts the gentoo configurator. If no file is given, it defaults to 'gentoo.conf'."
			echo "If the file doesn't exist, the configurator loads default values, otherwise, the"
			echo "the configuration is loaded into the configurator."
			exit 0
			;;
	esac
	shift
done

# TODO check install dialog
echo "Please install dialog on your system to use the configurator"


################################################
# Configuration helper functions

function get_timezone() {
	local file
	if file="$(readlink /etc/localtime)"; then
		# /etc/localtime is a symlink as expected
		local timezone
		timezone=${file#*zoneinfo/}
		if [[ $timezone = "$file" || ! $timezone =~ ^[^/]+/[^/]+$ ]]; then
			# not pointing to expected location or not Region/City
			echo "Europe/London"
		fi
		echo "$timezone"
	else
		# compare files by contents
		# https://stackoverflow.com/questions/12521114/getting-the-canonical-time-zone-name-in-shell-script#comment88637393_12523283
		find /usr/share/zoneinfo -type f ! -regex ".*/Etc/.*" -exec \
			cmp -s {} /etc/localtime \; -print | sed -e 's@.*/zoneinfo/@@' | head -n1
	fi
}

function get_default_keymap() {
	local keymap
	keymap="$(grep KEYMAP /etc/vconsole.conf)"
	keymap="${keymap#KEYMAP=}"

	local map
	for map in "${ALL_KEYMAPS[@]}"; do
		if [[ $map == "$keymap" ]]; then
			echo -n "${keymap}"
			return
		fi
	done

	# Fallback to us
	echo -n "us"
}


################################################
# Configuration constants

function get_all_keymaps() {
	ALL_KEYMAPS=()
	local map
	for map in $(find /usr/share/keymaps/ /usr/share/kbd/keymaps/ -type f -iname '*.map.gz' -printf "%f\n" 2>/dev/null | sort -u); do
		ALL_KEYMAPS+=("${map%%.map.gz}")
	done
}; get_all_keymaps


INIT_SYSTEMS=("systemd" "OpenRC")
readarray -t SUPPORTED_LOCALES < /usr/share/i18n/SUPPORTED


################################################
# Load/Default configuration

function load_config() {
	# Load settings
	source "$1" || die "Could not load given configuration."

	if [[ "$SYSTEMD" == true ]]; then
		INIT_SYSTEM="systemd"
	else
		INIT_SYSTEM="OpenRC"
	fi

	if [[ "$KEYMAP" == "$KEYMAP_INITRAMFS" ]]; then
		KEYMAP_INITRAMFS_OTHER=false
	else
		KEYMAP_INITRAMFS_OTHER=true
	fi

	# After loading a config no unsaved changes exist.
	UNSAVED_CHANGES=false
}

function load_default_config() {
	HOSTNAME="gentoo"
	TIMEZONE="$(get_timezone)"
	KEYMAP="$(get_default_keymap)"
	KEYMAP_INITRAMFS=""
	LOCALES=""
	LOCALE="C.utf8"

	GENTOO_MIRROR="https://mirror.eu.oneandone.net/linux/distributions/gentoo/gentoo"
	GENTOO_ARCH="amd64"
	STAGE3_BASENAME="stage3-$GENTOO_ARCH-systemd"

	SELECT_MIRRORS=true
	SELECT_MIRRORS_LARGE_FILE=false

	ADDITIONAL_PACKAGES=("app-editors/neovim")
	INSTALL_SSHD=true
	ROOT_SSH_AUTHORIZED_KEYS=""

	INIT_SYSTEM="systemd"
	KEYMAP_INITRAMFS_OTHER=false

	# All settings are unsaved.
	UNSAVED_CHANGES=true
}

SAVE_AS_FILENAME="$RELA_CONFIG_FILE"
if [[ -e "$CONFIG_FILE" ]]; then
	load_config "$CONFIG_FILE"
else
	load_default_config
fi


################################################
# Menu helpers and constants

function clear_and_exit() {
	dialog --clear
	clear -x
	exit 0
}

function ellipsis() {
	if [[ "${#2}" -gt "$1" ]]; then
		echo "${2:0:$1}…"
	else
		echo "$2"
	fi
}

function on_off_toggle() {
	if [[ "${!1}" == true ]]; then
		declare -g "$1"=false
	else
		declare -g "$1"=true
	fi
}

function on_off_label() {
	if [[ "$1" == true ]]; then
		echo -n "[*]"
	else
		echo -n "[ ]"
	fi
}

function is_on() {
	[[ "$1" == true ]]
}

function is_off() {
	[[ "$1" != true ]]
}

SELECTED_MENU_ITEM=""
MENU_SIZE="20 76 12"
INPUTBOX_SIZE="8 76"
RADIOLIST_SIZE="20 76 8"
BUILDLIST_SIZE="20 76 8"
HELP_POPUP_SIZE="8 66"
CONFIRM_SIZE="8 66"


################################################
# Menu definition

MENU_ITEMS=(
	"HOSTNAME"
	"TIMEZONE"
	"KEYMAP"
	"KEYMAP_INITRAMFS_OTHER"
	"KEYMAP_INITRAMFS"
	"--------"
	"LOCALES"
	"LOCALE"
	"--------"
	"INIT_SYSTEM"
	"KEYFILE"
)

function --------_tag()   { echo "────────────────────────────"; }
function --------_label() { echo "────────────────────────────"; }
function --------_show()  { return 0; }
function --------_help()  { echo "Congratulations, you found a separator."; }
function --------_menu()  { true; }

function HOSTNAME_tag()   { echo "Hostname"; }
function HOSTNAME_label() { echo "($HOSTNAME)"; }
function HOSTNAME_show()  { return 0; }
function HOSTNAME_help()  { echo "Enter the desired system hostname here. Be aware that when creating mdadm raid arrays, this value will be recorded in metadata block. If you change it later, you should also update the metadata."; }
function HOSTNAME_menu()  {
	local sel
	# shellcheck disable=SC2086
	sel="$(dialog \
		--title "Select hostname" \
		--inputbox "Enter the hostname for your new system." \
		$INPUTBOX_SIZE "$HOSTNAME" 3>&2 2>&1 1>&3 3>&-)"
	UNSAVED_CHANGES=true
}

function TIMEZONE_tag()   { echo "Timezone"; }
function TIMEZONE_label() { echo "($TIMEZONE)"; }
function TIMEZONE_show()  { return 0; }
function TIMEZONE_help()  { echo "The timezone for the new system."; }
function TIMEZONE_menu()  {
	true
}

# $1: title
# $2: description
# $3: space separated index list of selected items (e.g. "0 1 5 6")
# $@: all items
function menu_splitlist()  {
	local title="$1"
	local description="$2"
	local selected_index_list="$3"
	shift 3

	# Build option array
	local items=()
	local item
	local i=0
	for item in "$@"; do
		items+=("$((i++))" "$item" "off")
	done

	# Show selection dialog
	local sel
	# shellcheck disable=SC2086
	sel="$(dialog \
		--title "$title" \
		--buildlist "$description\nUse ^ to focus the list of unselected items and $ to focus the list of selected items. Use <Space> to select/deselect an item and select <OK> by pressing <Enter> when finished." \
		$BUILDLIST_SIZE "${items[@]}" 3>&2 2>&1 1>&3 3>&-)"

	local diag_exit="$?"
	if [[ $diag_exit == 0 ]]; then
		# <OK>
		echo -n "$sel"
		return 0
	elif [[ $diag_exit == 1 ]]; then
		# <Cancel>
		return 1
	elif [[ $diag_exit == 2 ]]; then
		# <Select>
		local sel="${sel#HELP }"
		local sel_cur="${sel% *}"
		#local sel_radio="${sel#* }"
		echo -n "$sel_cur"
		return 0
	else
		# <ESC><ESC>
		return 1
	fi
}

# $1: title
# $2: description
# $3: default item
# $@: items
function menu_radiolist()  {
	local title="$1"
	local description="$2"
	local default_item="$3"
	shift 3

	# Build option array
	local items=()
	local item
	for item in "$@"; do
		if [[ $item == "$default_item" ]]; then
			items+=("$item" "on")
		else
			items+=("$item" "off")
		fi
	done

	# Show selection dialog
	local sel
	# shellcheck disable=SC2086
	sel="$(dialog \
		--no-items \
		--title "$title" \
		--help-button \
		--help-label "Select" \
		--help-status \
		--ok-label "OK" \
		--default-item "$default_item" \
		--default-button help \
		--radiolist "$description\nUse <Select> to select the option under the cursor, or <OK> to use the option which is selected with an asterisk." \
		$RADIOLIST_SIZE "${items[@]}" 3>&2 2>&1 1>&3 3>&-)"

	local diag_exit="$?"
	if [[ $diag_exit == 0 ]]; then
		# <OK>
		echo -n "$sel"
		return 0
	elif [[ $diag_exit == 1 ]]; then
		# <Cancel>
		return 1
	elif [[ $diag_exit == 2 ]]; then
		# <Select>
		local sel="${sel#HELP }"
		local sel_cur="${sel% *}"
		#local sel_radio="${sel#* }"
		echo -n "$sel_cur"
		return 0
	else
		# <ESC><ESC>
		return 1
	fi
}

function KEYMAP_tag()   { echo "Keymap"; }
function KEYMAP_label() { echo "($KEYMAP)"; }
function KEYMAP_show()  { return 0; }
function KEYMAP_help()  { echo "The default vconsole keymap for the system."; }
function KEYMAP_menu()  {
	local sel
	if sel="$(menu_radiolist \
		"Select initramfs keymap" \
		"Select which keymap to use in the vconsole." \
		"$KEYMAP" \
		"${ALL_KEYMAPS[@]}")"
	then
		# Save keymap
		KEYMAP="$sel"
	else
		# Return to menu
		true
	fi
}

function KEYMAP_INITRAMFS_OTHER_tag()   { echo "Other keymap in initramfs"; }
function KEYMAP_INITRAMFS_OTHER_label() { on_off_label "$KEYMAP_INITRAMFS_OTHER"; }
function KEYMAP_INITRAMFS_OTHER_show()  { return 0; }
function KEYMAP_INITRAMFS_OTHER_help()  { echo "Whether another keymap should be used for the initramfs. If enabled, you will be able to choose a separate keymap below."; }
function KEYMAP_INITRAMFS_OTHER_menu()  {
	on_off_toggle "KEYMAP_INITRAMFS_OTHER"
	[[ -z $KEYMAP_INITRAMFS ]] \
		&& KEYMAP_INITRAMFS="$KEYMAP"
}

function KEYMAP_INITRAMFS_tag()   { echo " └ Keymap (initramfs)"; }
function KEYMAP_INITRAMFS_label() { echo " └ ($KEYMAP_INITRAMFS)"; }
function KEYMAP_INITRAMFS_show()  { is_on "$KEYMAP_INITRAMFS_OTHER"; }
function KEYMAP_INITRAMFS_help()  { echo "The default vconsole keymap for the initrams. This is important if need to unlock an encrypted partition when booting."; }
function KEYMAP_INITRAMFS_menu()  {
	local sel
	if sel="$(menu_radiolist \
		"Select initramfs keymap" \
		"Select which keymap to use in the initramfs vconsole." \
		"$KEYMAP_INITRAMFS" \
		"${ALL_KEYMAPS[@]}")"
	then
		# Save keymap
		KEYMAP_INITRAMFS="$sel"
	else
		# Return to menu
		true
	fi
}

function LOCALES_tag()   { echo "Locales"; }
function LOCALES_label() { echo "($(ellipsis 20 "$LOCALES"))"; }
function LOCALES_show()  { return 0; }
function LOCALES_help()  { echo "The locales to generate for the new system. Be careful that the syntax for locales is a different from the resulting name of the genereated locales of locale-gen. For example the locale 'en_US.utf8' is enabled via 'en_US.UTF-8 UTF-8')."; }
function LOCALES_menu()  {
	menu_splitlist "Select locales" "Select which locales to generate." "${SUPPORTED_LOCALES[@]}"
}

function LOCALE_tag()   { echo "Locale"; }
function LOCALE_label() { echo "($LOCALE)"; }
function LOCALE_show()  { return 0; }
function LOCALE_help()  { echo "The locale to use for the new system. See \`locale -a\` for available options, and be sure to generate the locale by adding it to the list of locales above."; }
function LOCALE_menu()  {
	# TODO say enable before in locales
	true
}

function INIT_SYSTEM_tag()   { echo "Init system"; }
function INIT_SYSTEM_label() { echo "($INIT_SYSTEM)"; }
function INIT_SYSTEM_show()  { return 0; }
function INIT_SYSTEM_help()  { echo ""; }
function INIT_SYSTEM_menu()  {
	local sel
	if sel="$(menu_radiolist \
		"Select init system" \
		"Select the init system you want to use." \
		"$INIT_SYSTEM" \
		"${INIT_SYSTEMS[@]}")"
	then
		# Save keymap
		INIT_SYSTEM="$sel"
	else
		# Return to menu
		true
	fi
}

function KEYFILE_tag()   { echo "Key file"; }
function KEYFILE_label() { echo "($KEYFILE)"; }
function KEYFILE_show()  { return 0; }
function KEYFILE_help()  { echo ""; }
function KEYFILE_menu()  {
	true
}


################################################
# Menu functions

# $1: filename
function save() {
	echo save to "$1"
cat > "$1" <<EOF
# vim: set ft=sh ts=4 sw=4 sts=-1 noet:
# This file will be interpreted by /bin/bash.

################################################
# Disk configuration

create_btrfs_raid_layout swap=8GiB luks=true /dev/sdX
luks_getkeyfile() {
	case "\$1" in
		#'my_luks_partition') echo -n '/path/to/my_luks_partition_keyfile' ;;
		*) echo -n "/path/to/luks-keyfile" ;;
	esac
}


################################################
# System configuration

HOSTNAME=${HOSTNAME@Q}
TIMEZONE=${TIMEZONE@Q}
KEYMAP=${KEYMAP@Q}
KEYMAP_INITRAMFS=${KEYMAP_INITRAMFS@Q}

LOCALES=${LOCALES@Q}
LOCALE=${LOCALE@Q}


################################################
# Gentoo configuration

GENTOO_MIRROR="https://mirror.eu.oneandone.net/linux/distributions/gentoo/gentoo"
GENTOO_ARCH="amd64"
STAGE3_BASENAME="stage3-$GENTOO_ARCH-systemd"
SELECT_MIRRORS=true
SELECT_MIRRORS_LARGE_FILE=false
SYSTEMD=true


################################################
# Additional (optional) configuration

ADDITIONAL_PACKAGES=("app-editors/neovim")
INSTALL_SSHD=true
ROOT_SSH_AUTHORIZED_KEYS=""


################################################
# Prove that you have read the config

I_HAVE_READ_AND_EDITED_THE_CONFIG_PROPERLY=true
EOF
}

function msgbox_help() {
	# shellcheck disable=SC2086
	dialog \
		--msgbox "$1" \
		$HELP_POPUP_SIZE 3>&2 2>&1 1>&3 3>&-
}

function menu_exit() {
	if [[ $UNSAVED_CHANGES == "true" ]]; then
		local sel
		# shellcheck disable=SC2086
		sel="$(dialog \
			--help-button --help-label "Back" \
			--yes-label "Save" --no-label "Discard" \
			--yesno "Do you want to save your configuration?\n(Press <ESC><ESC>, or choose <Back> to continue gentoo configuration)." \
			$CONFIRM_SIZE 3>&2 2>&1 1>&3 3>&-)"

		local diag_exit="$?"
		if [[ $diag_exit == 0 ]]; then
			# <Save>
			save "$CONFIG_FILE"
			clear_and_exit 0
		elif [[ $diag_exit == 1 ]]; then
			# <Discard>
			clear_and_exit 0
		else
			# Back to menu (<ESC><ESC>, <Back>)
			true
		fi
	else
		# Nothing was changed. Exit immediately.
		clear_and_exit 0
	fi
}

function menu_save_as() {
	local sel
	# shellcheck disable=SC2086
	sel="$(dialog \
		--ok-label "Save" \
		--inputbox "Enter a filename to which this configuration should be saved.\n(Press <ESC><ESC>, or choose <Cancel> to abort)." \
		$INPUTBOX_SIZE "$SAVE_AS_FILENAME" 3>&2 2>&1 1>&3 3>&-)"

	local diag_exit="$?"
	if [[ $diag_exit == 0 ]]; then
		# <Save>
		SAVE_AS_FILENAME="$sel"
		save "$SAVE_AS_FILENAME"
		UNSAVED_CHANGES=false
	else
		# Back to menu (<ESC><ESC>, <Cancel>)
		true
	fi
}

function menu() {
	local item
	local item_tag
	local tag_item_list=()
	declare -A reverse_lookup

	# Create menu list
	for item in "${MENU_ITEMS[@]}"; do
		# Only if item is visible
		"${item}_show" || continue

		item_tag="$("${item}_tag")"
		tag_item_list+=("$item_tag" "$("${item}_label")")
		reverse_lookup["$item_tag"]="$item"
	done

	local sel
	# shellcheck disable=SC2086
	sel="$(dialog --colors \
		--title "Gentoo configuration ($RELA_CONFIG_FILE)" \
		--extra-button --extra-label "Exit" \
		--help-button \
		--default-item "$SELECTED_MENU_ITEM" \
		--ok-label "Select" --cancel-label "Save" \
		--menu "This is the gentoo configuration menu. Read and adjust all options below carefully. Save your desired configuration and run ./install afterwards. Use <Help> if you want further information on any option." \
		$MENU_SIZE "${tag_item_list[@]}" 3>&2 2>&1 1>&3 3>&-)"

	local diag_exit="$?"
	if [[ $diag_exit == 0 ]]; then
		# <Select>
		SELECTED_MENU_ITEM="$sel"
		"${reverse_lookup[$SELECTED_MENU_ITEM]}_menu"
	elif [[ $diag_exit == 1 ]]; then
		# <Save>
		SELECTED_MENU_ITEM="$sel"
		menu_save_as
	elif [[ $diag_exit == 2 ]]; then
		# <Help>
		SELECTED_MENU_ITEM="${sel#HELP }"
		msgbox_help "$("${reverse_lookup[$SELECTED_MENU_ITEM]}_help")"
	else
		# Exit (<ESC><ESC>, <Exit>)
		SELECTED_MENU_ITEM="${sel-$SELECTED_MENU_ITEM}"
		menu_exit
		true
	fi
}

# Begin menu loop. Exit will be called to end this loop where it is appropriate.
while true; do
	menu
done