Guess a random number

<?php

/*
 * This code is just one of many possible solutions to the Weekly Challenge posed by Alex in his email
 * dated 13/Mar/2023. The Challenge was to create an interactive script that generates a random number
 * and asks the user to guess that number.
 *
 * If you are interested in improving your PHP skills, sign up for Alex's newsletter at
 * https://alexwebdevelop.com and join Alex PHP café at https://www.facebook.com/groups/289777711557686
 */

declare(strict_types=1);

/*
 * Check environment
 */
PHP_SAPI === 'cli'
or throw new RuntimeException('Must be run from the command line');

extension_loaded('readline')
or throw new RuntimeException("PHP 'readline' extension not loaded");


/*
 * Validate the command line arguments
 */
if ($argc == 3) {
    $max_random = validate_int($argv[1], 2, 65536);
    $max_attempts = validate_int($argv[2], 1, 32);
}

if (
    $argc != 3
    || $max_random === false
    || $max_attempts === false
) {
    /* arguments are not defined or invalid - display usage information */
    $script_name = basename(__FILE__);
    echo <<<USAGE

          Usage: $script_name max_random max_attempts

          Generates a random number and asks the user to guess that number.

          max_random:
            the maximum random value that can be generated, an integer between 2 and 65536
          max_attempts:
            the maximum number of attempts the user can make, an integer between 1 and 32

        USAGE;

    exit(254);  // indicate usage displayed
}


$eot = 1;  // default end of task code to indicate failure


/*
 * Generate a random number
 */
$random = random_int(1, $max_random);

print_line(PHP_EOL . "I've thought of a number between %d and %d" . PHP_EOL, 1, $max_random);


/*
 * Loop prompting the user to enter a guess
 */
$attempts = 0;
while (true) {
    if (
        ($input = readline('Enter guess: ')) === false
        || trim($input) === ''
    ) {
        break;  // no input - terminate loop
    }

    /* validate user input */
    if (($guess = validate_int($input, 1, $max_random)) !== false) {
        switch ($guess <=> $random) {  // use the spaceship operator to compare
            case 0:
                print_line('Congratulations!');
                $eot = 0;  // set end of task code to indicate success
                break 2;  // exit switch and while

            case -1:
                $msg = 'Too low';
                break;

            case 1:
                $msg = 'Too high';
                break;
        }

        /* only count valid attempts */
        if (++$attempts >= $max_attempts) {
            print_line('Too many attempts, the number was %d.', $random);
            break;
        }
    } else {
        $msg = sprintf('Enter an integer between 1 and %d', $max_random);
    }

    print_line('%s, try again.', $msg);
}

exit($eot);  // indicate whether successful or not


/*
 * Output a formatted string appending the correct end of line
 *
 * Example of a variable-length argument list using the variadic ('splat') operator
 */
function print_line(string $format, mixed ...$values): int
{
    return printf($format . PHP_EOL, ...$values);
}


/*
 * Validate a string as an integer within a range
 */
function validate_int(string $value, int $min, int $max): int|false
{
    return filter_var($value, FILTER_VALIDATE_INT,
                      ['options' => ['min_range' => $min, 'max_range' => $max]]);
}