<?php

/**
 * @todo Unit test
 */
class HTMLPurifier_ContentSets {
	
	/**
	 * List of content set strings (pipe separators) indexed by name.
	 * @type array
	 */
	public $info = array ();
	
	/**
	 * List of content set lookups (element => true) indexed by name.
	 * @type array
	 * @note This is in HTMLPurifier_HTMLDefinition->info_content_sets
	 */
	public $lookup = array ();
	
	/**
	 * Synchronized list of defined content sets (keys of info).
	 * @type array
	 */
	protected $keys = array ();
	/**
	 * Synchronized list of defined content values (values of info).
	 * @type array
	 */
	protected $values = array ();
	
	/**
	 * Merges in module's content sets, expands identifiers in the content
	 * sets and populates the keys, values and lookup member variables.
	 * 
	 * @param HTMLPurifier_HTMLModule[] $modules
	 *        	List of HTMLPurifier_HTMLModule
	 */
	public function __construct($modules) {
		if (! is_array ( $modules )) {
			$modules = array (
					$modules 
			);
		}
		// populate content_sets based on module hints
		// sorry, no way of overloading
		foreach ( $modules as $module ) {
			foreach ( $module->content_sets as $key => $value ) {
				$temp = $this->convertToLookup ( $value );
				if (isset ( $this->lookup [$key] )) {
					// add it into the existing content set
					$this->lookup [$key] = array_merge ( $this->lookup [$key], $temp );
				} else {
					$this->lookup [$key] = $temp;
				}
			}
		}
		$old_lookup = false;
		while ( $old_lookup !== $this->lookup ) {
			$old_lookup = $this->lookup;
			foreach ( $this->lookup as $i => $set ) {
				$add = array ();
				foreach ( $set as $element => $x ) {
					if (isset ( $this->lookup [$element] )) {
						$add += $this->lookup [$element];
						unset ( $this->lookup [$i] [$element] );
					}
				}
				$this->lookup [$i] += $add;
			}
		}
		
		foreach ( $this->lookup as $key => $lookup ) {
			$this->info [$key] = implode ( ' | ', array_keys ( $lookup ) );
		}
		$this->keys = array_keys ( $this->info );
		$this->values = array_values ( $this->info );
	}
	
	/**
	 * Accepts a definition; generates and assigns a ChildDef for it
	 * 
	 * @param HTMLPurifier_ElementDef $def
	 *        	HTMLPurifier_ElementDef reference
	 * @param HTMLPurifier_HTMLModule $module
	 *        	Module that defined the ElementDef
	 */
	public function generateChildDef(&$def, $module) {
		if (! empty ( $def->child )) { // already done!
			return;
		}
		$content_model = $def->content_model;
		if (is_string ( $content_model )) {
			// Assume that $this->keys is alphanumeric
			$def->content_model = preg_replace_callback ( '/\b(' . implode ( '|', $this->keys ) . ')\b/', array (
					$this,
					'generateChildDefCallback' 
			), $content_model );
			// $def->content_model = str_replace(
			// $this->keys, $this->values, $content_model);
		}
		$def->child = $this->getChildDef ( $def, $module );
	}
	public function generateChildDefCallback($matches) {
		return $this->info [$matches [0]];
	}
	
	/**
	 * Instantiates a ChildDef based on content_model and content_model_type
	 * member variables in HTMLPurifier_ElementDef
	 * @note This will also defer to modules for custom HTMLPurifier_ChildDef
	 * subclasses that need content set expansion
	 * 
	 * @param HTMLPurifier_ElementDef $def
	 *        	HTMLPurifier_ElementDef to have ChildDef extracted
	 * @param HTMLPurifier_HTMLModule $module
	 *        	Module that defined the ElementDef
	 * @return HTMLPurifier_ChildDef corresponding to ElementDef
	 */
	public function getChildDef($def, $module) {
		$value = $def->content_model;
		if (is_object ( $value )) {
			trigger_error ( 'Literal object child definitions should be stored in ' . 'ElementDef->child not ElementDef->content_model', E_USER_NOTICE );
			return $value;
		}
		switch ($def->content_model_type) {
			case 'required' :
				return new HTMLPurifier_ChildDef_Required ( $value );
			case 'optional' :
				return new HTMLPurifier_ChildDef_Optional ( $value );
			case 'empty' :
				return new HTMLPurifier_ChildDef_Empty ();
			case 'custom' :
				return new HTMLPurifier_ChildDef_Custom ( $value );
		}
		// defer to its module
		$return = false;
		if ($module->defines_child_def) { // save a func call
			$return = $module->getChildDef ( $def );
		}
		if ($return !== false) {
			return $return;
		}
		// error-out
		trigger_error ( 'Could not determine which ChildDef class to instantiate', E_USER_ERROR );
		return false;
	}
	
	/**
	 * Converts a string list of elements separated by pipes into
	 * a lookup array.
	 * 
	 * @param string $string
	 *        	List of elements
	 * @return array Lookup array of elements
	 */
	protected function convertToLookup($string) {
		$array = explode ( '|', str_replace ( ' ', '', $string ) );
		$ret = array ();
		foreach ( $array as $k ) {
			$ret [$k] = true;
		}
		return $ret;
	}
}

// vim: et sw=4 sts=4