<?php
/**
*
* @package phpBB3
* @copyright (c) 2011 phpBB Group
* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
*
*/

/**
* @ignore
*/
if (!defined('IN_PHPBB'))
{
	exit;
}


/**
* Template locator. Maintains mapping from template handles to source paths.
*
* Template locator is aware of template inheritance, and can return actual
* filesystem paths (i.e., the "primary" template or the "parent" template)
* depending on what files exist.
*
* @package phpBB3
*/
class phpbb_template_locator
{
	/**
	* Paths to directories that templates are stored in.
	* @var array
	*/
	private $roots = array();

	/**
	* Index of the main template in the roots array
	* @var int
	*/
	private $main_root_id = 0;

	/**
	* Map from root index to handles to source template file paths.
	* Normally it only contains paths for handles that are used
	* (or are likely to be used) by the page being rendered and not
	* all templates that exist on the filesystem.
	* @var array
	*/
	private $files = array();

	/**
	* Map from handles to source template file names.
	* Covers the same data as $files property but maps to basenames
	* instead of paths.
	* @var array
	*/
	private $filenames = array();

	/**
	* Set main template location (must have been added through set_paths first).
	*
	* @param string $template_path Path to template directory
	* @return null
	*/
	public function set_main_template($template)
	{
		$this->main_root_id = array_search($template, $this->roots, true);
	}

	/**
	* Sets the list of template paths
	*
	* These paths will be searched for template files in the provided order.
	* Paths may be outside of phpBB, but templates loaded from these paths
	* will still be cached.
	*
	* @param array $template_paths An array of paths to template directories
	* @return null
	*/
	public function set_paths($template_paths)
	{
		$this->roots = array();
		$this->files = array();
		$this->filenames = array();
		$this->main_root_id = 0;

		foreach ($template_paths as $path)
		{
			// Make sure $path has no ending slash
			if (substr($path, -1) === '/')
			{
				$path = substr($path, 0, -1);
			}
			$this->roots[] = $path;
		}
	}

	/**
	* Sets the template filenames for handles. $filename_array
	* should be a hash of handle => filename pairs.
	*
	* @param array $filname_array Should be a hash of handle => filename pairs.
	*/
	public function set_filenames(array $filename_array)
	{
		foreach ($filename_array as $handle => $filename)
		{
			if (empty($filename))
			{
				trigger_error("template locator: set_filenames: Empty filename specified for $handle", E_USER_ERROR);
			}

			$this->filename[$handle] = $filename;

			foreach ($this->roots as $root_index => $root)
			{
				$this->files[$root_index][$handle] = $root . '/' . $filename;
			}
		}
	}

	/**
	* Determines the filename for a template handle.
	*
	* The filename comes from array used in a set_filenames call,
	* which should have been performed prior to invoking this function.
	* Return value is a file basename (without path).
	*
	* @param $handle string Template handle
	* @return string Filename corresponding to the template handle
	*/
	public function get_filename_for_handle($handle)
	{
		if (!isset($this->filename[$handle]))
		{
			trigger_error("template locator: get_filename_for_handle: No file specified for handle $handle", E_USER_ERROR);
		}
		return $this->filename[$handle];
	}

	/**
	* Determines the source file path for a template handle without
	* regard for template inheritance.
	*
	* This function returns the path in "primary" template directory
	* corresponding to the given template handle. That path may or
	* may not actually exist on the filesystem. Because this function
	* does not perform stat calls to determine whether the path it
	* returns actually exists, it is faster than get_source_file_for_handle.
	*
	* Use get_source_file_for_handle to obtain the actual path that is
	* guaranteed to exist (which might come from the parent/fallback
	* template directory if template inheritance is used).
	*
	* This function will trigger an error if the handle was never
	* associated with a template file via set_filenames.
	*
	* @param $handle string Template handle
	* @return string Path to source file path in primary template directory
	*/
	public function get_virtual_source_file_for_handle($handle)
	{
		// If we don't have a file assigned to this handle, die.
		if (!isset($this->files[$this->main_root_id][$handle]))
		{
			trigger_error("template locator: No file specified for handle $handle", E_USER_ERROR);
		}

		$source_file = $this->files[$this->main_root_id][$handle];
		return $source_file;
	}

	/**
	* Determines the source file path for a template handle, accounting
	* for template inheritance and verifying that the path exists.
	*
	* This function returns the actual path that may be compiled for
	* the specified template handle. It will trigger an error if
	* the template handle was never associated with a template path
	* via set_filenames or if the template file does not exist on the
	* filesystem.
	*
	* Use get_virtual_source_file_for_handle to just resolve a template
	* handle to a path without any filesystem or inheritance checks.
	*
	* @param string $handle Template handle (i.e. "friendly" template name)
	* @return string Source file path
	*/
	public function get_source_file_for_handle($handle)
	{
		// If we don't have a file assigned to this handle, die.
		if (!isset($this->files[$this->main_root_id][$handle]))
		{
			trigger_error("template locator: No file specified for handle $handle", E_USER_ERROR);
		}

		// locate a source file that exists
		$source_file = $this->files[0][$handle];
		$tried = $source_file;
		for ($i = 1, $n = count($this->roots); $i < $n && !file_exists($source_file); $i++)
		{
			$source_file = $this->files[$i][$handle];
			$tried .= ', ' . $source_file;
		}

		// search failed
		if (!file_exists($source_file))
		{
			trigger_error("template locator: File for handle $handle does not exist. Could not find: $tried", E_USER_ERROR);
		}

		return $source_file;
	}
}