#!/usr/bin/env bash

## SPDX-License-Identifier: GPL-2.0-only
## Copyright (C) 2020 - Dreemurrs Embedded Labs / DanctNIX

# Clear screen
clear

declare -A config
if [ ! -f /plr/config-plr.cfg ] ; then
	echo "Pineloader config not found! Please debug the issue via telnet"
	echo "$IP"
	loop_forever
else
	. /plr/config-plr.cfg
fi

# Renders a text based list of options that can be selected by the
# user using up, down and enter keys and returns the chosen option.
#
#   Arguments   : list of options, maximum of 256
#                 "opt1" "opt2" ...
#   Return value: selected index (0 for opt1, 1 for opt2 ...)
function select_option {

    # little helpers for terminal print control and key input
    ESC=$( printf "\033")
    cursor_blink_on()  { printf "$ESC[?25h"; }
    cursor_blink_off() { printf "$ESC[?25l"; }
    cursor_to()        { printf "$ESC[$1;${2:-1}H"; }
    print_option()     { printf "     $1 "; }
    print_selected()   { printf " -> $ESC[7m $1 $ESC[27m"; }
    get_cursor_row()   { IFS=';' read -sdR -p $'\E[6n' ROW COL; echo ${ROW#*[}; }
    key_input()        { read -s -n3 key 2>/dev/null >&2
                         if [[ $key = $ESC[A ]]; then echo up;    fi
                         if [[ $key = $ESC[B ]]; then echo down;    fi
                         if [[ $key = ""     ]]; then echo enter; fi; }

    # initially print empty new lines (scroll down if at bottom of screen)
    for opt; do printf "\n"; done

    # determine current screen position for overwriting the options
    local lastrow=`get_cursor_row`
    local startrow=$(($lastrow - $#))

    # ensure cursor and input echoing back on upon a ctrl+c during read -s
    trap "cursor_blink_on; stty echo; printf '\n'; exit" 2
    cursor_blink_off

    local selected=0
    while true; do
        # print options by overwriting the last lines
        local idx=0
        for opt; do
            cursor_to $(($startrow + $idx))
            if [ $idx -eq $selected ]; then
                print_selected "$opt"
            else
                print_option "$opt"
            fi
            ((idx++))
        done

        # user key control
        case `key_input` in
            enter) break;;
            up)    ((selected--));
                   if [ $selected -lt 0 ]; then selected=$(($# - 1)); fi;;
            down)  ((selected++));
                   if [ $selected -ge $# ]; then selected=0; fi;;
        esac
    done

    # cursor position back to normal
    cursor_to $lastrow
    printf "\n"
    cursor_blink_on

    return $selected
}

function select_opt {
    select_option "$@" 1>&2
    local result=$?
    echo $result
    return $result
}

echo "Welcome to PineLoader!"
echo "Copyright 2020 - Dreemurrs Embedded Labs / DanctNIX."
echo
echo "[VOLUME_UP/VOLUME_DOWN to select. POWER is OK.]"
echo

declare -a choices
for path in "${!config[@]}"; do
	choices+=( "$path" )
done

i=$(select_opt "${choices[@]}")
key="${choices[$i]}"
value="${config[$key]}"

if [ -z "$value" ]; then
	echo "ERROR: The selected boot variables are blank, please debug the issue by telnet to:"
	echo "$IP"
else
	mount -o ro $BOOTPART /mnt
	echo "Loading kernel and ramdisk to memory..."
	kexec -l --initrd="$INITRD" --command-line="$CMDLINE" $KERNEL
	echo "Starting kernel..."
	kexec -e
fi