<?php
/**
 * @package     FOF
 * @copyright   Copyright (c)2010-2019 Nicholas K. Dionysopoulos / Akeeba Ltd
 * @license     GNU GPL version 2 or later
 */

namespace FOF30\View\Engine;

use FOF30\Utils\Buffer;
use FOF30\View\Compiler\CompilerInterface;
use FOF30\View\Exception\PossiblySuhosin;

defined('_JEXEC') or die;

/**
 * View engine for compiling PHP template files.
 */
abstract class CompilingEngine extends AbstractEngine implements EngineInterface
{
	/** @var  CompilerInterface  The compiler used by this engine */
	protected $compiler = null;

	/**
	 * Get the 3ναlυa+3d contents of the view template. (I use leetspeak here because of bad quality hosts with broken scanners)
	 *
	 * @param   string  $path         The path to the view template
	 * @param   array   $forceParams  Any additional information to pass to the view template engine
	 *
	 * @return  array  Content evaluation information
	 */
	public function get($path, array $forceParams = array())
	{
		/**
		 * If the PHP Tokenizer extension is disabled or not present we try to fall back to precompiled templates.
		 *
		 * As we found out the hard way, there are still some hosts which disable / don't load the Tokenizer citing
		 * "security concerns". What they don't understand is that the tokenizer is basically a read-only extension. It
		 * can only read PHP code and break it into tokens, it cannot execute it. In fact, you can't easily convert
		 * tokenizer results back into executable PHP. In fact, you'd need https://github.com/nikic/PHP-Parser which is
		 * by no means trivial. Then again, it STILL cannot execute the PHP without either using 3v4l (sorry for the
		 * leetspeak, we have to deal with broken hosts killing our file due to this comment!) or writing to a PHP file
		 * and executing it. In short, the hosts which disable tokenizer don't know how PHP works, don't know the first
		 * thing about security and must NOT be trusted! If you are on such a host, run away fast, don't look back!
		 */
		if (!function_exists('token_get_all'))
		{
			$precompiledPath = $this->getPrecompiledPath($path);

			if (($precompiledPath !== false) && @file_exists($precompiledPath))
			{
				return array(
					'type'    => 'path',
					'content' => $precompiledPath,
				);
			}

			/**
			 * No precompiled templates and tokenized missing, i.e. I can't compile anything. Instead of throwing a
			 * fatal error I will throw a catchable runtime error explaining the error condition and how to solve it.
			 * If your extension does not trap the exception it will bubble up to Joomla's error handler which will
			 * display this message.
			 */
			throw new \RuntimeException("Your hosting provider has disabled the <code>token_get_all()</code> PHP function or they have not installed the Tokenizer extension for PHP. This is a safe and <em>secure</em> function of modern PHP, required to convert template files into HTML code your browser can display. Please ask them to enable it. This error occurred trying to render the template file <code>$path</code>", 500);
		}

		// If it's cached return the path to the cached file's path
		if ($this->isCached($path))
		{
			return array(
				'type'    => 'path',
				'content' => $this->getCachePath($path),
			);
		}

		// Compile it and cache it.
		$content = $this->compile($path, $forceParams);
		$cachePath = $this->putToCache($path, $content);

		// If we could cache it, return the cached file's path
		if ($cachePath !== false)
		{
			return array(
				'type'    => 'path',
				'content' => $cachePath,
			);
		}

		// We could not write to the cache. Hm, can I use a stream wrapper?
		$canUseStreams = Buffer::canRegisterWrapper();

		if ($canUseStreams)
		{
			$id = $this->getIdentifier($path);
			$streamPath = 'fof://' . $this->view->getContainer()->componentName . '/compiled_templates/' . $id . '.php';
			file_put_contents($streamPath, $content);

			return array(
				'type'    => 'path',
				'content' => $streamPath,
			);
		}

		// I couldn't use a stream wrapper. I have to give up.
		throw new PossiblySuhosin;
	}

	/**
	 * A method to compile the raw view template into valid PHP
	 *
	 * @param   string  $path         The path to the view template
	 * @param   array   $forceParams  Any additional information to pass to the view template compiler
	 *
	 * @return  string  The template compiled to executable PHP
	 */
	protected function compile($path, array $forceParams = array())
	{
		return $this->compiler->compile($path, $forceParams);
	}

	protected function getIdentifier($path)
	{
		if (function_exists('sha1'))
		{
			return sha1($path);
		}

		return md5($path);
	}

	protected function getCachePath($path)
	{
		$id = $this->getIdentifier($path);
		return JPATH_CACHE . '/' . $this->view->getContainer()->componentName . '/compiled_templates/' . $id . '.php';
	}

	protected function isCached($path)
	{
		if (!$this->compiler->isCacheable())
		{
			return false;
		}

		$cachePath = $this->getCachePath($path);

		if (!file_exists($cachePath))
		{
			return false;
		}

		$cacheTime = filemtime($cachePath);
		$fileTime = filemtime($path);

		return $fileTime <= $cacheTime;
	}

	protected function getCached($path)
	{
		$cachePath = $this->getCachePath($path);

		return file_get_contents($cachePath);
	}

	protected function putToCache($path, $content)
	{
		$cachePath = $this->getCachePath($path);

		if (@file_put_contents($cachePath, $content))
		{
			return $cachePath;
		}

		if (!class_exists('JFile'))
		{
			\JLoader::import('joomla.filesystem.file');
		}

		if (\JFile::write($cachePath, $content))
		{
			return $cachePath;
		}

		return false;
	}

	/**
	 * Returns the path where I can find a precompiled version of the uncompiled view template which lives in $path
	 *
	 * @param   string  $path  The path to the uncompiled view template
	 *
	 * @return  bool|string  False if the view template is outside the component's front- or backend.
	 *
	 * @since   3.3.1
	 */
	public function getPrecompiledPath($path)
	{
		// Normalize the path to the file
		$path = realpath($path);

		if ($path === false)
		{
			// The file doesn't exist
			return false;
		}

		// Is this path under the component's front- or backend?
		$frontendPath = realpath($this->view->getContainer()->frontEndPath);
		$backendPath  = realpath($this->view->getContainer()->backEndPath);

		$backPos = strpos($path, $backendPath);
		$frontPos = strpos($path, $frontendPath);

		if (($backPos !== 0) && ($frontPos !== 0))
		{
			// This is not a view template shipped with the component, i.e. it can't be precompiled
			return false;
		}

		// Eliminate the component path from $path to get the relative path to the file
		$componentPath = $frontendPath;

		if ($backPos === 0)
		{
			$componentPath = $backendPath;
		}

		$relativePath = ltrim(substr($path, strlen($componentPath)), '\\/');

		// Break down the relative path to its parts
		$relativePath = str_replace('\\', '/', $relativePath);
		$pathParts = explode('/', $relativePath);

		// Remove the prefix
		$prefix = array_shift($pathParts);

		// If it's a legacy view, View, Views, or views prefix remove the 'tmpl' part
		if ($prefix != 'ViewTemplates')
		{
			unset($pathParts[1]);
		}

		// Get the last part and process the extension
		$viewFile = array_pop($pathParts);
		$extensionWithoutDot = $this->compiler->getFileExtension();
		$pathParts[] = substr($viewFile, 0, -strlen($extensionWithoutDot)) . 'php';

		$precompiledRelativePath = implode(DIRECTORY_SEPARATOR, $pathParts);

		return $componentPath . DIRECTORY_SEPARATOR . 'PrecompiledTemplates' . DIRECTORY_SEPARATOR . $precompiledRelativePath;
	}
}
