<?php
$input_file = '../inputs/day11.txt';
if (file_exists($input_file)) {
	$input = file_get_contents($input_file);
	if ($input != null) {
		$rows = array_map('trim', explode("\n", $input));
		print 'Part 1 answer: ' . solve($rows, false) . "\n";
		print 'Part 2 answer: ' . solve($rows, true) . "\n";
	}
}

function solve(array $rows, bool $moreTolerant): int
{
	$changed = true;
	$occupied = 0;
	$newState = $rows;

	while ($changed) {
		$simulation_result = simulate($newState, $moreTolerant);
		$changed = $simulation_result->changed;
		$occupied = $simulation_result->full;
		$newState = $simulation_result->state;
	}

	return $occupied;
}

function simulate(array $rows, bool $moreTolerant): day11_state
{
	$newState = $rows;
	$changed = false;
	$empty = 0;
	$floor = 0;
	$full = 0;
	for ($i = 0; $i < count($rows); $i++) {
		for ($j = 0; $j < strlen($rows[$i]); $j++) {
			$adjacent_occupied = get_adjacent_occupied($moreTolerant, $rows, $i, $j);
			if ($rows[$i][$j] === 'L' && $adjacent_occupied === 0) {
				$changed = true;
				$full += 1;
				$newState[$i][$j] = '#';
			} elseif ($rows[$i][$j] === '#' && $adjacent_occupied >= ($moreTolerant ? 5 : 4)) {
				$changed = true;
				$empty += 1;
				$newState[$i][$j] = 'L';
			} else {
				if ($rows[$i][$j] === 'L')
					$empty += 1;
				elseif ($rows[$i][$j] === '#')
					$full += 1;
				else
					$floor += 1;
			}
		}
	}

	return new day11_state($newState, $changed, $empty, $floor, $full);
}

function get_adjacent_occupied(bool $moreTolerant, array $state, int $y, int $x): int
{
	$occupied = 0;

	if ($moreTolerant === false) {
		for ($i = $y - 1; $i < $y + 2; $i++) {
			if ($i >= 0 && $i < count($state)) {
				for ($j = $x - 1; $j < $x + 2; $j++) {
					if ($j >= 0 && $j < strlen($state[$i]) && !($i === $y && $j === $x)) {
						$occupied += $state[$i][$j] === '#' ? 1 : 0;
					}
				}
			}
		}
	} else {
		$x_dir = -1;
		$y_dir = -1;
		while (true) {
			$x_pos = $x;
			$y_pos = $y;

			while (true) {
				if ($x_dir === 0 && $y_dir === 0)
					break;

				$x_pos += $x_dir;
				$y_pos += $y_dir;
				if ($y_pos < 0 || $y_pos >= count($state) || $x_pos < 0 || $x_pos >= strlen($state[$y_pos]))
					break;
				elseif ($state[$y_pos][$x_pos] === '.')
					continue;
				else {
					$occupied += $state[$y_pos][$x_pos] === '#';
					break;
				}
			}

			$y_dir += 1;
			if ($y_dir == 2) {
				$y_dir = -1;
				$x_dir += 1;
			}
			if ($x_dir == 2)
				break;
		}
	}

	return $occupied;
}

class day11_state
{
	public array $state;
	public bool $changed;
	public int $empty;
	public int $floor;
	public int $full;

	function __construct(array $state, bool $changed, int $empty, int $floor, int $full)
	{
		$this->state = $state;
		$this->changed = $changed;
		$this->empty = $empty;
		$this->floor = $floor;
		$this->full = $full;
	}
}