<?php

declare(strict_types=1);

namespace App;

/**
 * Calculate the layout of a collection of screens.
 *
 * @author Adam Pippin <hello@adampippin.ca>
 */
class Layout
{
	/**
	 * List of screens this layout uses.
	 * @var array<string,array>
	 */
	protected $_screens;

	/**
	 * Relations between the screens.
	 * @var array[]
	 */
	protected $_links;

	/**
	 * Initialize a new layout.
	 *
	 * @param array[] $screens
	 * @param array[] $links
	 */
	public function __construct(array $screens, array $links)
	{
		$this->_screens = $screens;
		$this->_links = $links;
	}

	/**
	 * Fetch the names of the screens this layout depends on.
	 *
	 * @return string[]
	 */
	public function getScreenNames(): array
	{
		return array_keys($this->_screens);
	}

	/**
	 * Execute this layout.
	 *
	 * @param  Configuration $config
	 * @param  ILayoutDriver $driver
	 * @return void
	 */
	public function execute(Configuration $config, ILayoutDriver $driver): void
	{
		$primary_name = $config->getPrimaryScreenName();
		$primary = $config->getPrimaryScreen();

		$layout_stack = [$primary_name];
		$did_layout = false;
		$layout = [$primary_name => ['x' => 0, 'y' => 0]];

		foreach ($this->_screens as $screen_name => $screen_data)
		{
			if (isset($screen_data['width']) && isset($screen_data['height']))
			{
				$config->getScreen($screen_name)->setDimensions($screen_data['width'], $screen_data['height']);
			}
		}

		while (sizeof($layout_stack))
		{
			$did_layout = false;
			$match_screen = array_pop($layout_stack);
			foreach ($this->_links as $link)
			{
				$target_name = $link['display'];
				$source_name = $link['above'] ?? $link['below'] ?? $link['right_of'] ?? $link['left_of'];
				if ($source_name == $match_screen)
				{
					$did_layout = true;

					$calculate_layout = null;
					if (isset($link['above']))
					{
						/**
						 * @return int[]
						 */
						$calculate_layout = static function(int $s_x, int $s_y, int $s_w, int $s_h, int $d_x, int $d_y, int $d_w, int $d_h): array {
							$center = $s_x + ($s_w / 2);
							$x = $center - ($d_w / 2);
							$y = $s_y - $d_h;

							return [$x, $y];
						};
					}
					elseif (isset($link['below']))
					{
						/**
						 * @return int[]
						 */
						$calculate_layout = static function(int $s_x, int $s_y, int $s_w, int $s_h, int $d_x, int $d_y, int $d_w, int $d_h): array {
							$center = $s_x + ($s_w / 2);
							$x = $center - ($d_w / 2);
							$y = $s_y + $s_h;

							return [$x, $y];
						};
					}
					elseif (isset($link['left_of']))
					{
						/**
						 * @return int[]
						 */
						$calculate_layout = static function(int $s_x, int $s_y, int $s_w, int $s_h, int $d_x, int $d_y, int $d_w, int $d_h): array {
							return [$s_x - $d_w, $s_y];
						};
					}
					elseif (isset($link['right_of']))
					{
						/**
						 * @return int[]
						 */
						$calculate_layout = static function(int $s_x, int $s_y, int $s_w, int $s_h, int $d_x, int $d_y, int $d_w, int $d_h): array {
							return [$s_x + $s_w, $s_y];
						};
					}

					$source = $config->getScreen($source_name);
					$target = $config->getScreen($target_name);

					if (isset($layout[$source_name]))
					{
						$s_x = $layout[$source_name]['x'];
						$s_y = $layout[$source_name]['y'];
					}
					else
					{
						[$s_x, $s_y] = $source->getOffset();
					}
					[$s_w, $s_h] = $source->getDimensions();

					if (isset($layout[$target_name]))
					{
						$d_x = $layout[$target_name]['x'];
						$d_y = $layout[$target_name]['y'];
					}
					else
					{
						[$d_x, $d_y] = $target->getOffset();
					}
					[$d_w, $d_h] = $target->getDimensions();

					[$x, $y] = $calculate_layout($s_x, $s_y, $s_w, $s_h, $d_x, $d_y, $d_w, $d_h);

					$layout[$target_name] = ['x' => $x, 'y' => $y];
					$layout_stack[] = $target_name;
				}
			}
		}

		$min_x = PHP_INT_MAX;
		$min_y = PHP_INT_MAX;

		foreach ($layout as $screen_name => $screen_offset)
		{
			$min_x = min($screen_offset['x'], $min_x);
			$min_y = min($screen_offset['y'], $min_y);
		}

		foreach ($layout as $screen_name => $screen_offset)
		{
			[$current_x, $current_y] = $config->getScreen($screen_name)->getOffset();
			if ($current_x != $screen_offset['x'] - $min_x || $current_y != $screen_offset['y'] - $min_y)
			{
				$config->getScreen($screen_name)->setOffset($screen_offset['x'] - $min_x, $screen_offset['y'] - $min_y);
			}
		}
	}
}