<?php
/**
 * @version   $Id: Context.php 53534 2012-06-06 18:21:34Z btowles $
 * @author    RocketTheme http://www.rockettheme.com
 * @copyright Copyright (C) 2007 - ${copyright_year} RocketTheme, LLC
 * @license   http://www.gnu.org/licenses/gpl-2.0.html GNU/GPLv2 only
 *
 * Original Copyright below
 */

defined('ROKCOMMON') or die;

/**
 *
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy
 * of the License at http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an
 * "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is State Machine Compiler (SMC).
 *
 * The Initial Developer of the Original Code is Charles W. Rapp.
 * Portions created by Charles W. Rapp are
 * Copyright (C) 2005. Charles W. Rapp.
 * All Rights Reserved.
 *
 * Port (from the Python port) to PHP5 by Toni Arnold
 *
 * Contributor(s):
 *
 * See: http://smc.sourceforge.net/
 *
 */

class RokCommon_State_Context
{
    protected $_state;
    protected $_previous_state;
    protected $_state_stack;
    protected $_transition;
    protected $_debug_flag;

    public function __construct($init_state)
    {
        $this->_state = $init_state;
        $this->_previous_state = NULL;
        $this->_state_stack = array();
        $this->_transition = NULL;
        $this->_debug_flag = FALSE;
        // using STDERR works only on cli, but explicitly opening
        // stderr writes to /var/log/apache2/error_log
        $this->_debug_stream = fopen("php://stderr", "w");
    }

    // Returns the debug flag's current setting.
    public function getDebugFlag()
    {
        return $this->_debug_flag;
    }

    // Sets the debug flag.
    // A true value means debugging is on and false means off.
    public function setDebugFlag($flag)
    {
        $this->_debug_flag = $flag;
    }

    // Returns the stream to which debug output is written.
    public function getDebugStream()
    {
        return $this->_debug_stream;
    }

    // Sets the debug output stream.
    public function setDebugStream($stream)
    {
        $this->_debug_stream = $stream;
    }

    // Is this state machine already inside a transition?
    // True if state is undefined.
    public function isInTransition()
    {
        if ($this->_state == NULL)
            return TRUE;
        else
            return FALSE;
    }

    // Returns the current transition's name.
    // Used only for debugging purposes.
    public function getTransition()
    {
        return $this->_transition;
    }

    // Clears the current state.
    public function clearState()
    {
        $this->_previous_state = $this->_state;
        $this->_state = NULL;
    }

    // Returns the state which a transition left.
    // May be Null
    public function getPreviousState()
    {
        return $this->_previous_state;
    }

    // Sets the current state to the specified state.
    public function setState($state)
    {
        if (!is_subclass_of($state,'RokCommon_State'))
            throw new Exception('$state should be of class State');
        $this->_state = $state;
        if ($this->_debug_flag)
            fwrite($this->_debug_stream, "NEW STATE    : {$this->_state->getName()}\n");
    }

    // Returns True if the state stack is empty and False otherwise.
    public function isStateStackEmpty()
    {
        return count($this->_state_stack) == 0;
    }

    // Returns the state stack's depth.
    public function getStateStackDepth()
    {
        return count($this->_state_stack);
    }

    // Push the current state on top of the state stack
    // and make the specified state the current state.
    public function pushState($state)
    {
        if (!is_subclass_of($state,'RokCommon_State'))
            throw new Exception('$state should be of class State');
        if ($this->_state != NULL)
            array_push($this->_state_stack, $this->_state);
        $this->_state = $state;
        if ($this->_debug_flag)
            fwrite($this->_debug_stream, "PUSH TO STATE: {$this->_state->getName()}\n");
    }

    // Make the state on top of the state stack the current state.
    public function popState()
    {
        if (count($this->_state_stack) == 0)
        {
            if ($this->_debug_flag)
                fwrite($this->_debug_stream, "POPPING ON EMPTY STATE STACK.\n");
            throw new Exception('empty state stack');
        } else
        {
            $this->_state = array_pop($this->_state_stack);
            if ($this->_debug_flag)
                fwrite($this->_debug_stream, "POP TO STATE : {$this->_state->getName()}\n");
        }
    }

    // Remove all states from the state stack.
    public function emptyStateStack()
    {
        $this->_state_stack = array();
    }
}