<?php

/**
 * This file is part of the Nette Framework (https://nette.org)
 * Copyright (c) 2004 David Grudl (https://davidgrudl.com)
 */

declare(strict_types=1);

namespace Nette\DI;

use Nette;


/**
 * DI container loader.
 */
class ContainerLoader
{
	use Nette\SmartObject;

	/** @var bool */
	private $autoRebuild = false;

	/** @var string */
	private $tempDirectory;


	public function __construct(string $tempDirectory, bool $autoRebuild = false)
	{
		$this->tempDirectory = $tempDirectory;
		$this->autoRebuild = $autoRebuild;
	}


	/**
	 * @param  callable  $generator  function (Nette\DI\Compiler $compiler): string|null
	 * @param  mixed  $key
	 */
	public function load(callable $generator, $key = null): string
	{
		$class = $this->getClassName($key);
		if (!class_exists($class, false)) {
			$this->loadFile($class, $generator);
		}

		return $class;
	}


	/**
	 * @param  mixed  $key
	 */
	public function getClassName($key): string
	{
		return 'Container_' . substr(md5(serialize($key)), 0, 10);
	}


	private function loadFile(string $class, callable $generator): void
	{
		$file = "$this->tempDirectory/$class.php";
		if (!$this->isExpired($file) && (@include $file) !== false) { // @ file may not exist
			return;
		}

		Nette\Utils\FileSystem::createDir($this->tempDirectory);

		$handle = @fopen("$file.lock", 'c+'); // @ is escalated to exception
		if (!$handle) {
			throw new Nette\IOException(sprintf("Unable to create file '%s.lock'. %s", $file, Nette\Utils\Helpers::getLastError()));
		} elseif (!@flock($handle, LOCK_EX)) { // @ is escalated to exception
			// the lock will automatically be freed when $handle goes out of scope
			throw new Nette\IOException(sprintf("Unable to acquire exclusive lock on '%s.lock'. %s", $file, Nette\Utils\Helpers::getLastError()));
		}

		if (!is_file($file) || $this->isExpired($file, $updatedMeta)) {
			if (isset($updatedMeta)) {
				$toWrite["$file.meta"] = $updatedMeta;
			} else {
				[$toWrite[$file], $toWrite["$file.meta"]] = $this->generate($class, $generator);
			}

			foreach ($toWrite as $name => $content) {
				if (file_put_contents("$name.tmp", $content) !== strlen($content) || !rename("$name.tmp", $name)) {
					@unlink("$name.tmp"); // @ - file may not exist
					throw new Nette\IOException(sprintf("Unable to create file '%s'.", $name));
				} elseif (function_exists('opcache_invalidate')) {
					@opcache_invalidate($name, true); // @ can be restricted
				}
			}
		}

		if ((@include $file) === false) { // @ - error escalated to exception
			throw new Nette\IOException(sprintf("Unable to include '%s'.", $file));
		}
	}


	private function isExpired(string $file, ?string &$updatedMeta = null): bool
	{
		if ($this->autoRebuild) {
			$meta = @unserialize((string) file_get_contents("$file.meta")); // @ - file may not exist
			$orig = $meta[2] ?? null;
			return empty($meta[0])
				|| DependencyChecker::isExpired(...$meta)
				|| ($orig !== $meta[2] && $updatedMeta = serialize($meta));
		}

		return false;
	}


	/** @return array of (code, file[]) */
	protected function generate(string $class, callable $generator): array
	{
		$compiler = new Compiler;
		$compiler->setClassName($class);
		$code = $generator(...[&$compiler]) ?: $compiler->compile();
		return [
			"<?php\n$code",
			serialize($compiler->exportDependencies()),
		];
	}
}
