<?php

namespace Automad\System;

use Automad\Core\Cache;
use Automad\Core\Debug;
use Automad\Core\FileSystem;
use Automad\Core\Str;
use Composer\Console\Application;
use Symfony\Component\Console\Input\StringInput;
use Symfony\Component\Console\Output\BufferedOutput;
use Symfony\Component\Process\PhpExecutableFinder;

/**
 * The Composer class is a wrapper for setting up Composer and executing commands.
 *
 * @author Marc Anton Dahmen
 * @copyright Copyright (c) 2019-2023 by Marc Anton Dahmen - https://marcdahmen.de
 * @license MIT license - https://automad.org/license
 */
class Composer
{
	/** Composer autoloader within the temporary extraction directory. */
	private string $autoloader = '/vendor/autoload.php';

	/** The path to the composer.json file. */
	private string $composerFile = AM_BASE_DIR . '/composer.json';

	/** The Composer version to be used. */
	private string $composerVersion = '2.5.1';

	/** Composer extraction directory within temporary directory. */
	private string $extractionDir = '/extracted';
	private string $installBaseDir;

	/** A chached file including the temporary Composer install directory. */
	private string $installDirCacheFile;

	/** The download URL for the composer.phar file. */
	private string $pharUrl;

	/**
	 * A variable to reserve memory for running a shutdown function
	 * when Composer reaches the allowd memory limit.
	 */
	private mixed $reservedShutdownMemory = null;


	/**
	 * The constructor runs the setup.
	 */
	public function __construct()
	{
		$this->pharUrl = 'https://getcomposer.org/download/' . $this->composerVersion . '/composer.phar';
		$this->installBaseDir = AM_DIR_TMP . '/composer/' . $this->composerVersion;
		$this->installDirCacheFile = $this->installBaseDir . '/path';
		$this->setUp();
	}


	/**
	 * Set up Composer by downloading and extracting the composer.phar to a temporary directory
	 * outside the document root, defining some environment variables, registering a shutdown
	 * function and including the autoloader.
	 */
	private function setUp(): void
	{
		$installDir = $this->getInstallDir();
		$updatePackageInstaller = false;

		$srcDir = $installDir . $this->extractionDir;

		if (!file_exists($srcDir)) {
			$file = $this->downloadPhar($installDir);

			if (is_null($file) || !is_readable($file)) {
				Debug::log($file, 'Download of composer.phar failed');

				return;
			}

			$phar = new \Phar($file);
			$phar->extractTo($srcDir);

			$updatePackageInstaller = true;
		}

		$autoloader = $installDir . $this->extractionDir . $this->autoloader;

		if (!is_readable($autoloader)) {
			Debug::log($autoloader, 'Composer autoloader not found');

			return;
		}

		putenv('COMPOSER_HOME=' . $installDir . '/home');

		Debug::log($autoloader, 'Require Composer autoloader');
		require_once($autoloader);

		$decoded = json_decode(file_get_contents($this->composerFile), true);
		$decoded['config'] = array('allow-plugins' => array('automad/package-installer' => true));
		FileSystem::write($this->composerFile, json_encode($decoded, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));

		if ($updatePackageInstaller) {
			$this->run('require automad/package-installer');
			$this->run('update automad/package-installer');
		}
	}


	/**
	 * Run a given Composer command.
	 *
	 * @param string $command
	 * @param bool $getBuffer
	 * @return string The command output on false or in case $getBuffer is true
	 */
	public function run(string $command, bool $getBuffer = false): string
	{
		$this->shutdownOnError();

		chdir(AM_BASE_DIR);

		set_time_limit(0);
		ini_set('memory_limit', '-1');

		$input = new StringInput($command);
		$output = new BufferedOutput();
		$application = new Application();

		$application->setAutoExit(false);
		$application->setCatchExceptions(false);

		Debug::log($command, 'Command');

		$buffer = '';

		try {
			$application->run($input, $output);
			$buffer = $output->fetch();
			Debug::log($buffer, 'Buffer');
		} catch (\Exception $e) {
			// Try to fall back to running composer.phar using exec() in case
			// there was any execption raised using the Composer API.
			// That could be for example the case on Windows machines.
			if (!function_exists('exec')) {
				return 'The exec() function is disabled in your php.ini file!';
			}

			$binFinder = new PhpExecutableFinder();
			$php = $binFinder->find();
			$phar = $this->getInstallDir() . '/composer.phar';
			$exitCode = null;

			@exec("$php $phar $command 2>&1", $output, $exitCode);
			$buffer = implode("\n", $output);

			Debug::log("$php $phar $command", 'Use exec() function as fallback');
			Debug::log($exitCode, 'exec() exit code');
			Debug::log($buffer, 'exec() buffer');

			if ($exitCode !== 0) {
				return $e->getMessage();
			}
		}

		$bufferJsonOnly = preg_replace('/^[^\{]*(\{.*\})[^\}]*$/is', '$1', $buffer);
		$bufferJsonOnly = preg_replace('/\s+/is', ' ', $bufferJsonOnly);

		Debug::log(round(memory_get_peak_usage() / 1024 / 1024) . ' mb', 'Memory used');
		Debug::log($bufferJsonOnly, 'Buffer JSON only');

		if ($getBuffer) {
			return $bufferJsonOnly;
		}

		return '';
	}


	/**
	 * Download the composer.phar file to a given directory.
	 *
	 * @param string $dir
	 * @return string|null The full path to the downloaded composer.phar file
	 */
	private function downloadPhar(string $dir): ?string
	{
		$phar = null;

		if (is_writable($dir)) {
			$phar = $dir . '/composer.phar';

			if (is_writable($phar)) {
				unlink($phar);
			}

			Fetch::download($this->pharUrl, $phar);
			Debug::log($phar, 'Downloaded Composer PHAR');
		}

		return $phar;
	}


	/**
	 * Read the Composer install directory from cache to reuse the installation
	 * in case Composer was already used before. In case Composer hasn't been used before,
	 * a new path will be generated and save to the cache.
	 *
	 * @return string The path to the installation directory
	 */
	private function getInstallDir(): string
	{
		if (is_readable($this->installDirCacheFile)) {
			$installDir = file_get_contents($this->installDirCacheFile);
			Debug::log($installDir, 'Getting Composer installation directory from cache');

			// To verify that the directory actually contains Composer, simply test for existance of the autoloader.
			if (!is_readable($installDir . $this->extractionDir . $this->autoloader)) {
				Debug::log($installDir . $this->extractionDir . $this->autoloader, 'Autoloader not found');

				return $this->newInstallDir();
			}

			return $installDir;
		}

		return $this->newInstallDir();
	}


	/**
	 * Generate a fresh installation directory for Composer.
	 *
	 * @return string The path to the directory
	 */
	private function newInstallDir(): string
	{
		$installDir = $this->installBaseDir . '/' . bin2hex(random_bytes(32));
		Debug::log($installDir, 'Generating new Composer installation path');
		FileSystem::write($this->installDirCacheFile, $installDir);
		FileSystem::makeDir($installDir);

		return $installDir;
	}


	/**
	 * A shutdown function to handle memory limit erros.
	 */
	private function shutdownOnError(): void
	{
		ini_set('display_errors', 'Off');
		error_reporting(E_ALL);

		// This memory is cleared on error (case of allowed memory exhausted)
		// to use that memory to run the shutdown function.
		$this->reservedShutdownMemory = str_repeat('*', 1024 * 1024);

		register_shutdown_function(function () {
			// Reuse the reserved memory.
			$this->reservedShutdownMemory = null;
			$error = error_get_last();

			if (is_array($error) && !empty($error['type']) && $error['type'] === 1) {
				exit('{"error": "' . $error['message'] . '", "trigger": "composerDone"}');
			}
		});
	}
}
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