<?php
$input_file = '../inputs/day6.txt';
if (file_exists($input_file)) {
	$input = file_get_contents($input_file);
	if ($input != null) {
		$answer_groups = explode("\n", $input);
		print 'Part 1 answer: ' . solve_part_one($answer_groups) . "\n";
		print 'Part 2 answer: ' . solve_part_two($answer_groups) . "\n";
	}
}

function solve_part_one(array $answer_groups): int
{
	$solve_1 = fn ($form) => strlen(implode('', array_unique(str_split(implode('', $form)))));

	return parse_declaration_forms_and_solve($answer_groups, $solve_1);
}

function solve_part_two(array $answer_groups): int
{
	$solve_2 = fn ($form) => count(call_user_func_array('array_intersect', array_map(fn ($str) => str_split($str), $form)));

	return parse_declaration_forms_and_solve($answer_groups, $solve_2);
}

function parse_declaration_forms_and_solve(array $answer_groups, callable $fn): int
{
	$current_answers = [];
	$ret = 0;

	for ($i = 0; $i < count($answer_groups); $i++) {
		$answer = trim($answer_groups[$i]);
		if ($answer == '') {
			$ret += $fn(array_map(fn ($val) => trim($val), $current_answers));
			$current_answers = [];
		} else
			$current_answers[] = $answer;
	}

	if (count($current_answers) != 0)
		$ret += $fn(array_map(fn ($val) => trim($val), $current_answers));

	return $ret;
}