<?php

$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
$input = str_split($input[0]);

$bin = '';
foreach ($input as $char) {
    $bin .= str_pad(base_convert($char, 16, 2), 4, '0', STR_PAD_LEFT);
}
print_r(decodeString($bin));
//decodeString($bin);


function decodeString($binaryString, $offset = 0)
{
    $data = [];
    $data['maxoffset'] = $offset;
    echo str_repeat(' ', $offset) . $binaryString . "\n";
    echo str_repeat(' ', $offset) . substr($binaryString, 0, 3) . "\n";
    echo str_repeat(' ', $offset + 3) . substr($binaryString, 3, 3) . "\n";
    $data['version'] = bindec(substr($binaryString, 0, 3));
    $data['type'] = bindec(substr($binaryString, 3, 3));
    if ($data['type'] == 4) {
        $isLast = 0;
        $bitNumber = 0;
        $literalValue = '';
        $position = 6;
        while (!$isLast) {
            $position = 6 + $bitNumber * 5;
            echo str_repeat(' ', $offset + $position) . substr($binaryString, $position, 5) . "\n";
            $data['maxoffset'] = $offset + $position + 5;
            $binaryBit = substr($binaryString, $position, 5);
            $literalValue .= substr($binaryBit, 1, 4);
            $isLast = !$binaryBit[0];
            $bitNumber++;
        }

        $data['literalValue'] = bindec($literalValue);
        $position += 5;
//        if ($nesting > 2) {
////            print_r($binaryString);
////            echo 1;
////            die(print_r($data, 1));
//        }
        if (strlen($binaryString) - $position > 10) {
            $data['subpacket'] = [];

            $decoded = decodeString(substr($binaryString, $position), $offset + $position);
            if ($data['maxoffset'] < $decoded['maxoffset']) {
                $data['maxoffset'] = $decoded['maxoffset'];
            }
            $data['subpacket'][] = $decoded;

        }
    } else {
        $data['lengthTypeId'] = bindec(substr($binaryString, 6, 1));
        echo str_repeat(' ', $offset + 6) . substr($binaryString, 6, 1) . "\n";
        if ($data['lengthTypeId']) {
            $data['numberOfPackets'] = bindec(substr($binaryString, 7, 11));
            echo str_repeat(' ', $offset + 7) . substr($binaryString, 7, 11) . "\n";
            $bin = substr($binaryString, 18);
            $data['subpacket'] = [];
//            if ($nesting > 2) {
////                print_r($binaryString);
////                echo 2;
////                die(print_r($data, 1));
//            }
            for ($i = 0; $i < $data['numberOfPackets']; $i++) {
                $decoded = decodeString($bin, $offset + 18);
                if ($data['maxoffset'] < $decoded['maxoffset']) {
                    $data['maxoffset'] = $decoded['maxoffset'];
                    $offset = $data['maxoffset']-18;
                }
                $data['subpacket'][] = $decoded;
                $bin = substr($bin, $data['maxoffset']);
            }
//            $data['subpacket'][] = decodeString($bin, $offset + 18);
        } else {
            $data['totalLengthOfPackets'] = bindec(substr($binaryString, 7, 15));
            $bin = substr($binaryString, 22, $data['totalLengthOfPackets']);
            echo str_repeat(' ', $offset + 7) . substr($binaryString, 7, 15) . "\n";
            $data['subpacket'] = [];
//            if ($nesting > 2) {
////                echo 3;
////                die(print_r($data, 1));
//            }
            $decoded = decodeString($bin, $offset + 22);
            if ($data['maxoffset'] < $decoded['maxoffset']) {
                $data['maxoffset'] = $decoded['maxoffset'];
            }
            $data['subpacket'][] = $decoded;
        }
    }
    return $data;
}
//echo chr(bindec('01010000001'));
//8A004A801A8002F478 represents an operator packet
// (version 4) which contains an operator packet
// (version 1) which contains an operator packet
// (version 5) which contains a literal value
// (version 6); this packet has a version sum of 16.