<?php
/**
 * PHP Hooks Class
 *
 * The PHP Hooks Class is a fork of the WordPress filters hook system rolled in to a class to be ported
 * into any php based system
 *
 * This class is heavily based on the WordPress plugin API and most (if not all) of the code comes from there.
 *
 *
 * @version 0.1.3
 * @copyright 2012 - 2014
 * @author Ohad Raz (email: admin@bainternet.info)
 * @link http://en.bainternet.info
 *
 * @license GNU General Public LIcense v3.0 - license.txt
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package PHP Hooks
 */

class Hooks
{
    /**
     * $filters holds list of hooks
     * @access public
     * @since 0.1
     * @var array
     */
    var $filters = array();
    /**
     * $merged_filters
     * @var array
     */
    var $merged_filters = array();
    /**
     * $actions
     * @var array
     */
    var $actions = array();
    /**
     * $current_filter  holds the name of the current filter
     * @access public
     * @since 0.1
     * @var array
     */
    var $current_filter = array();

    /**
     * __construct class constructor
     * @access public
     * @since 0.1
     */
    public function __construct($args = null)
    {
        $this->filters = array();
        $this->merged_filters = array();
        $this->actions = array();
        $this->current_filter = array();
    }

    /**
     * FILTERS
     */

    /**
     * add_filter Hooks a function or method to a specific filter action.
     * @access public
     * @since 0.1
     * @param string $tag The name of the filter to hook the $function_to_add to.
     * @param callback $function_to_add The name of the function to be called when the filter is applied.
     * @param int $priority optional. Used to specify the order in which the functions associated with a particular action are executed (default: 10). Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.
     * @param int $accepted_args optional. The number of arguments the function accept (default 1).
     * @param int $forced_args optional. Forced arguments that function will accept.
     * @return boolean true
     */
    public function add_filter($tag, $function_to_add, $priority = 10, $accepted_args = 1, $forced_args = array())
    {
        $idx = $this->_filter_build_unique_id($tag, $function_to_add, $priority);
        $this->filters[$tag][$priority][$idx] = array('function' => $function_to_add, 'accepted_args' => $accepted_args, 'forced_args' => $forced_args);
        unset($this->merged_filters[$tag]);
        return true;
    }

    /**
     * remove_filter Removes a function from a specified filter hook.
     * @access public
     * @since 0.1
     * @param string $tag The filter hook to which the function to be removed is hooked.
     * @param callback $function_to_remove The name of the function which should be removed.
     * @param int $priority optional. The priority of the function (default: 10).
     * @param int $accepted_args optional. The number of arguments the function accepts (default: 1).
     * @return boolean Whether the function existed before it was removed.
     */
    public function remove_filter($tag, $function_to_remove, $priority = 10)
    {
        $function_to_remove = $this->_filter_build_unique_id($tag, $function_to_remove, $priority);

        $r = isset($this->filters[$tag][$priority][$function_to_remove]);

        if (true === $r) {
            unset($this->filters[$tag][$priority][$function_to_remove]);
            if (empty($this->filters[$tag][$priority]))
                unset($this->filters[$tag][$priority]);
            unset($this->merged_filters[$tag]);
        }
        return $r;
    }

    /**
     * remove_all_filters Remove all of the hooks from a filter.
     * @access public
     * @since 0.1
     * @param string $tag The filter to remove hooks from.
     * @param int $priority The priority number to remove.
     * @return bool True when finished.
     */
    public function remove_all_filters($tag, $priority = false)
    {
        if (isset($this->filters[$tag])) {
            if (false !== $priority && isset($this->filters[$tag][$priority]))
                unset($this->filters[$tag][$priority]);
            else
                unset($this->filters[$tag]);
        }

        if (isset($this->merged_filters[$tag]))
            unset($this->merged_filters[$tag]);

        return true;
    }

    /**
     * has_filter  Check if any filter has been registered for a hook.
     * @access public
     * @since 0.1
     * @param string $tag The name of the filter hook.
     * @param callback $function_to_check optional.
     * @return mixed If $function_to_check is omitted, returns boolean for whether the hook has anything registered.
     *   When checking a specific function, the priority of that hook is returned, or false if the function is not attached.
     *   When using the $function_to_check argument, this function may return a non-boolean value that evaluates to false
     *   (e.g.) 0, so use the === operator for testing the return value.
     */
    public function has_filter($tag, $function_to_check = false)
    {
        $has = !empty($this->filters[$tag]);
        if (false === $function_to_check || false == $has)
            return $has;

        if (!$idx = $this->_filter_build_unique_id($tag, $function_to_check, false))
            return false;

        foreach ((array) array_keys($this->filters[$tag]) as $priority) {
            if (isset($this->filters[$tag][$priority][$idx]))
                return $priority;
        }
        return false;
    }

    /**
     * apply_filters Call the functions added to a filter hook.
     * @access public
     * @since 0.1
     * @param string $tag The name of the filter hook.
     * @param mixed $value The value on which the filters hooked to <tt>$tag</tt> are applied on.
     * @param mixed $var,... Additional variables passed to the functions hooked to <tt>$tag</tt>.
     * @return mixed The filtered value after all hooked functions are applied to it.
     */
    public function apply_filters($tag, $value)
    {
        $args = array();
        // Do 'all' actions first
        if (isset($this->filters['all'])) {
            $this->current_filter[] = $tag;
            $args = func_get_args();
            $this->_call_all_hook($args);
        }

        if (!isset($this->filters[$tag])) {
            if (isset($this->filters['all']))
                array_pop($this->current_filter);
            return $value;
        }

        if (!isset($this->filters['all']))
            $this->current_filter[] = $tag;

        // Sort
        if (!isset($this->merged_filters[$tag])) {
            ksort($this->filters[$tag]);
            $this->merged_filters[$tag] = true;
        }

        reset($this->filters[$tag]);

        if (empty($args))
            $args = func_get_args();

        do {
            foreach ((array) current($this->filters[$tag]) as $the_)
                if (!is_null($the_['function'])) {
                    $args[1] = $value;
                    $value = call_user_func_array($the_['function'], array_merge(array_slice($args, 1, (int)$the_['accepted_args']), $the_['forced_args']));
                }

        } while ( next($this->filters[$tag]) !== false );

        array_pop($this->current_filter);
        return $value;
    }

    /**
     * apply_filters_ref_array Execute functions hooked on a specific filter hook, specifying arguments in an array.
     * @access public
     * @since 0.1
     * @param string $tag The name of the filter hook.
     * @param array $args The arguments supplied to the functions hooked to <tt>$tag</tt>
     * @return mixed The filtered value after all hooked functions are applied to it.
     */
    public function apply_filters_ref_array($tag, $args)
    {
        // Do 'all' actions first
        if (isset($this->filters['all'])) {
            $this->current_filter[] = $tag;
            $all_args = func_get_args();
            $this->_call_all_hook($all_args);
        }

        if (!isset($this->filters[$tag])) {
            if (isset($this->filters['all']))
                array_pop($this->current_filter);
            return $args[0];
        }

        if (!isset($this->filters['all']))
            $this->current_filter[] = $tag;

        // Sort
        if (!isset($this->merged_filters[$tag])) {
            ksort($this->filters[$tag]);
            $this->merged_filters[$tag] = true;
        }

        reset($this->filters[$tag]);

        do {
            foreach ((array) current($this->filters[$tag]) as $the_)
                if (!is_null($the_['function']))
                    $args[0] = call_user_func_array($the_['function'], array_slice($args, 0, (int)$the_['accepted_args']));

        } while ( next($this->filters[$tag]) !== false );

        array_pop($this->current_filter);

        return $args[0];
    }

    /**
     * ACTIONS
     */

    /**
     * add_action Hooks a function on to a specific action.
     * @access public
     * @since 0.1
     * @param string $tag The name of the action to which the $function_to_add is hooked.
     * @param callback $function_to_add The name of the function you wish to be called.
     * @param int $priority optional. Used to specify the order in which the functions associated with a particular action are executed (default: 10). Lower numbers correspond with earlier execution, and functions with the same priority are executed in the order in which they were added to the action.
     * @param int $accepted_args optional. The number of arguments the function accept (default 1).
     * @param int $forced_args optional. Forced arguments that function will accept.
     */
    public function add_action($tag, $function_to_add, $priority = 10, $accepted_args = 1, $forced_args = array())
    {
        return $this->add_filter($tag, $function_to_add, $priority, $accepted_args, $forced_args);
    }

    /**
     * has_action Check if any action has been registered for a hook.
     * @access public
     * @since 0.1
     * @param string $tag The name of the action hook.
     * @param callback $function_to_check optional.
     * @return mixed If $function_to_check is omitted, returns boolean for whether the hook has anything registered.
     *   When checking a specific function, the priority of that hook is returned, or false if the function is not attached.
     *   When using the $function_to_check argument, this function may return a non-boolean value that evaluates to false
     *   (e.g.) 0, so use the === operator for testing the return value.
     */
    public function has_action($tag, $function_to_check = false)
    {
        return $this->has_filter($tag, $function_to_check);
    }

    /**
     * remove_action Removes a function from a specified action hook.
     * @access public
     * @since 0.1
     * @param string $tag The action hook to which the function to be removed is hooked.
     * @param callback $function_to_remove The name of the function which should be removed.
     * @param int $priority optional The priority of the function (default: 10).
     * @return boolean Whether the function is removed.
     */
    public function remove_action($tag, $function_to_remove, $priority = 10)
    {
        return $this->remove_filter($tag, $function_to_remove, $priority);
    }

    /**
     * remove_all_actions Remove all of the hooks from an action.
     * @access public
     * @since 0.1
     * @param string $tag The action to remove hooks from.
     * @param int $priority The priority number to remove them from.
     * @return bool True when finished.
     */
    public function remove_all_actions($tag, $priority = false)
    {
        return $this->remove_all_filters($tag, $priority);
    }

    /**
     * do_action Execute functions hooked on a specific action hook.
     * @access public
     * @since 0.1
     * @param string $tag The name of the action to be executed.
     * @param mixed $arg,... Optional additional arguments which are passed on to the functions hooked to the action.
     * @return null Will return null if $tag does not exist in $filter array
     */
    public function do_action($tag, $arg = '')
    {

        if (!isset($this->actions))
            $this->actions = array();

        if (!isset($this->actions[$tag]))
            $this->actions[$tag] = 1;
        else
            ++$this->actions[$tag];

        // Do 'all' actions first
        if (isset($this->filters['all'])) {
            $this->current_filter[] = $tag;
            $all_args = func_get_args();
            $this->_call_all_hook($all_args);
        }

        if (!isset($this->filters[$tag])) {
            if (isset($this->filters['all']))
                array_pop($this->current_filter);
            return;
        }

        if (!isset($this->filters['all']))
            $this->current_filter[] = $tag;

        $args = array();
        if (is_array($arg) && 1 == count($arg) && isset($arg[0]) && is_object($arg[0]))// array(&$this)
            $args[] = &$arg[0];
        else
            $args[] = $arg;
        for ($a = 2; $a < func_num_args(); $a++)
            $args[] = func_get_arg($a);

        // Sort
        if (!isset($this->merged_filters[$tag])) {
            ksort($this->filters[$tag]);
            $this->merged_filters[$tag] = true;
        }

        reset($this->filters[$tag]);

        do {
            foreach ((array) current($this->filters[$tag]) as $the_)
                if (!is_null($the_['function'])) {
                    call_user_func_array($the_['function'], array_merge(array_slice($args, 0, (int)$the_['accepted_args']), $the_['forced_args']));
                }

        } while ( next($this->filters[$tag]) !== false );

        array_pop($this->current_filter);
    }

    /**
     * do_action_ref_array Execute functions hooked on a specific action hook, specifying arguments in an array.
     * @access public
     * @since 0.1
     * @param string $tag The name of the action to be executed.
     * @param array $args The arguments supplied to the functions hooked to <tt>$tag</tt>
     * @return null Will return null if $tag does not exist in $filter array
     */
    public function do_action_ref_array($tag, $args)
    {

        if (!isset($this->actions))
            $this->actions = array();

        if (!isset($this->actions[$tag]))
            $this->actions[$tag] = 1;
        else
            ++$this->actions[$tag];

        // Do 'all' actions first
        if (isset($this->filters['all'])) {
            $this->current_filter[] = $tag;
            $all_args = func_get_args();
            $this->_call_all_hook($all_args);
        }

        if (!isset($this->filters[$tag])) {
            if (isset($this->filters['all']))
                array_pop($this->current_filter);
            return;
        }

        if (!isset($this->filters['all']))
            $this->current_filter[] = $tag;

        // Sort
        if (!isset($merged_filters[$tag])) {
            ksort($this->filters[$tag]);
            $merged_filters[$tag] = true;
        }

        reset($this->filters[$tag]);

        do {
            foreach ((array) current($this->filters[$tag]) as $the_)
                if (!is_null($the_['function']))
                    call_user_func_array($the_['function'], array_slice($args, 0, (int)$the_['accepted_args']));

        } while ( next($this->filters[$tag]) !== false );

        array_pop($this->current_filter);
    }

    /**
     * did_action Retrieve the number of times an action is fired.
     * @access public
     * @since 0.1
     * @param string $tag The name of the action hook.
     * @return int The number of times action hook <tt>$tag</tt> is fired
     */
    public function did_action($tag)
    {

        if (!isset($this->actions) || !isset($this->actions[$tag]))
            return 0;

        return $this->actions[$tag];
    }

    /**
     * HELPERS
     */

    /**
     * current_filter Retrieve the name of the current filter or action.
     * @access public
     * @since 0.1
     * @return string Hook name of the current filter or action.
     */
    public function current_filter()
    {
        return end($this->current_filter);
    }

    /**
     * Retrieve the name of the current action.
     *
     * @since 0.1.2
     *
     * @uses current_filter()
     *
     * @return string Hook name of the current action.
     */
    function current_action()
    {
        return $this->current_filter();
    }

    /**
     * Retrieve the name of a filter currently being processed.
     *
     * The function current_filter() only returns the most recent filter or action
     * being executed. did_action() returns true once the action is initially
     * processed. This function allows detection for any filter currently being
     * executed (despite not being the most recent filter to fire, in the case of
     * hooks called from hook callbacks) to be verified.
     *
     * @since 0.1.2
     *
     * @see current_filter()
     * @see did_action()
     * @global array $wp_current_filter Current filter.
     *
     * @param null|string $filter Optional. Filter to check. Defaults to null, which
     *                            checks if any filter is currently being run.
     * @return bool Whether the filter is currently in the stack
     */
    function doing_filter($filter = null)
    {
        if (null === $filter) {
            return !empty($this->current_filter);
        }
        return in_array($filter, $this->current_filter);
    }

    /**
     * Retrieve the name of an action currently being processed.
     *
     * @since 0.1.2
     *
     * @uses doing_filter()
     *
     * @param string|null $action Optional. Action to check. Defaults to null, which checks
     *                            if any action is currently being run.
     * @return bool Whether the action is currently in the stack.
     */
    function doing_action($action = null)
    {
        return $this->doing_filter($action);
    }

    /**
     * _filter_build_unique_id Build Unique ID for storage and retrieval.
     * @param string $tag Used in counting how many hooks were applied
     * @param callback $function Used for creating unique id
     * @param int|bool $priority Used in counting how many hooks were applied. If === false and $function is an object reference, we return the unique id only if it already has one, false otherwise.
     * @return string|bool Unique ID for usage as array key or false if $priority === false and $function is an object reference, and it does not already have a unique id.
     */
    private function _filter_build_unique_id($tag, $function, $priority)
    {
        static $filter_id_count = 0;

        if (is_string($function))
            return $function;

        if (is_object($function)) {
            // Closures are currently implemented as objects
            $function = array($function, '');
        } else {
            $function = (array)$function;
        }

        if (is_object($function[0])) {
            // Object Class Calling
            if (function_exists('spl_object_hash')) {
                return spl_object_hash($function[0]) . $function[1];
            } else {
                $obj_idx = get_class($function[0]) . $function[1];
                if (!isset($function[0]->filter_id)) {
                    if (false === $priority)
                        return false;
                    $obj_idx .= isset($this->filters[$tag][$priority]) ? count((array)$this->filters[$tag][$priority]) : $filter_id_count;
                    $function[0]->filter_id = $filter_id_count;
                    ++$filter_id_count;
                } else {
                    $obj_idx .= $function[0]->filter_id;
                }

                return $obj_idx;
            }
        } else if (is_string($function[0])) {
            // Static Calling
            return $function[0] . $function[1];
        }
    }

    /**
     * __call_all_hook
     * @access public
     * @since 0.1
     * @param  (array) $args [description]
     */
    public function __call_all_hook($args)
    {
        reset($this->filters['all']);
        do {
            foreach ((array) current($this->filters['all']) as $the_)
                if (!is_null($the_['function']))
                    call_user_func_array($the_['function'], $args);

        } while ( next($this->filters['all']) !== false );
    }

}
