<?php
$input_file = '../inputs/day2.txt';
if (file_exists($input_file)) {
	$input = file_get_contents($input_file);
	if ($input != null) {
		$passwords = explode("\n", $input);
		print 'Part 1 answer: ' . solve_part_one($passwords) . "\n";
		print 'Part 2 answer: ' . solve_part_two($passwords) . "\n";
	}
}

function solve_part_one(array $passwords): int
{
	function solve_1(int $min, int $max, string $key, string $pass): int
	{
		$letters = array_count_values(str_split($pass));
		if (array_key_exists($key, $letters) && $letters[$key] >= $min && $letters[$key] <= $max)
			return 1;
		return 0;
	}

	return parse_passwords_and_solve($passwords, 'solve_1');
}

function solve_part_two(array $passwords): int
{
	function solve_2(int $pos1, int $pos2, string $key, string $pass): int
	{
		if ($pass[$pos1 - 1] === $key xor $pass[$pos2 - 1] === $key)
			return 1;
		return 0;
	}

	return parse_passwords_and_solve($passwords, 'solve_2');
}

function parse_passwords_and_solve(array $passwords, callable $fun): int
{
	$ret = 0;
	foreach ($passwords as $policy) {
		preg_match('/^(\d+?)-(\d+?) ([a-z]): (.+?)$/', $policy, $matches);
		[$match, $min, $max, $key, $pass] = $matches;
		if ($match)
			$ret += $fun($min, $max, $key, $pass);
	}
	return $ret;
}