<?php
/**
 * Akeeba Engine
 * The modular PHP5 site backup engine
 * @copyright Copyright (c)2014-2018 Nicholas K. Dionysopoulos / Akeeba Ltd
 * @license GNU GPL version 3 or, at your option, any later version
 * @package akeebaengine
 *
 */

// Protection against direct access
defined('AKEEBAENGINE') or die();

/**
 * The superclass of all Akeeba Engine parts. The "parts" are intelligent stateful
 * classes which perform a single procedure and have preparation, running and
 * finalization phases. The transition between phases is handled automatically by
 * this superclass' tick() final public method, which should be the ONLY public API
 * exposed to the rest of the Akeeba Engine.
 */
abstract class AliceAbstractPart extends AliceAbstractObject
{
	/**
	 * Indicates whether this part has finished its initialisation cycle
	 * @var boolean
	 */
	protected $isPrepared = false;

	/**
	 * Indicates whether this part has more work to do (it's in running state)
	 * @var boolean
	 */
	protected $isRunning = false;

	/**
	 * Indicates whether this part has finished its finalization cycle
	 * @var boolean
	 */
	protected $isFinished = false;

	/**
	 * Indicates whether this part has finished its run cycle
	 * @var boolean
	 */
	protected $hasRan = false;

	/**
	 * The name of the engine part (a.k.a. Domain), used in return table
	 * generation.
	 * @var string
	 */
	protected $active_domain = "";

	/**
	 * The step this engine part is in. Used verbatim in return table and
	 * should be set by the code in the _run() method.
	 * @var string
	 */
	protected $active_step = "";

	/**
	 * A more detailed description of the step this engine part is in. Used
	 * verbatim in return table and should be set by the code in the _run()
	 * method.
	 * @var string
	 */
	protected $active_substep = "";

	/**
	 * Any configuration variables, in the form of an array.
	 * @var array
	 */
	protected $_parametersArray = array();

	/** @var string The database root key */
	protected $databaseRoot = array();

	/** @var int Last reported warnings's position in array */
	private $warnings_pointer = -1;

	/** @var bool Should we log the step nesting? */
	protected $nest_logging = false;

	/** @var object Embedded installer preferences */
	protected $installerSettings;

	/**
	 * Public constructor
	 */
	public function __construct()
	{
		parent::__construct();
	}

	/**
	 * Runs the preparation for this part. Should set _isPrepared
	 * to true
	 */
	abstract protected function _prepare();

	/**
	 * Runs the finalisation process for this part. Should set
	 * _isFinished to true.
	 */
	abstract protected function _finalize();

	/**
	 * Runs the main functionality loop for this part. Upon calling,
	 * should set the _isRunning to true. When it finished, should set
	 * the _hasRan to true. If an error is encountered, setError should
	 * be used.
	 */
	abstract protected function _run();

	/**
	 * Sets the BREAKFLAG, which instructs this engine part that the current step must break immediately,
	 * in fear of timing out.
	 */
	protected function setBreakFlag()
	{
		$registry = AliceFactory::getConfiguration();
		$registry->set('volatile.breakflag', true);
	}

	/**
	 * Sets the engine part's internal state, in an easy to use manner
	 *
	 * @param	string	$state			One of init, prepared, running, postrun, finished, error
	 * @param	string	$errorMessage	The reported error message, should the state be set to error
	 */
	protected function setState($state = 'init', $errorMessage='Invalid setState argument')
	{
		switch($state)
		{
			case 'init':
				$this->isPrepared = false;
				$this->isRunning  = false;
				$this->isFinished = false;
				$this->hasRun     = false;
				break;

			case 'prepared':
				$this->isPrepared = true;
				$this->isRunning  = false;
				$this->isFinished = false;
				$this->hasRun     = false;
				break;

			case 'running':
				$this->isPrepared = true;
				$this->isRunning  = true;
				$this->isFinished = false;
				$this->hasRun     = false;
				break;

			case 'postrun':
				$this->isPrepared = true;
				$this->isRunning  = false;
				$this->isFinished = false;
				$this->hasRun     = true;
				break;

			case 'finished':
				$this->isPrepared = true;
				$this->isRunning  = false;
				$this->isFinished = true;
				$this->hasRun     = false;
				break;

			case 'error':
			default:
				$this->setError($errorMessage);
				break;
		}
	}

	/**
	 * The public interface to an engine part. This method takes care for
	 * calling the correct method in order to perform the initialisation -
	 * run - finalisation cycle of operation and return a proper reponse array.
	 *
	 * @param   int     $nesting
	 *
	 * @return  array    A Reponse Array
	 */
	final public function tick($nesting = 0)
	{
		$configuration = AliceFactory::getConfiguration();
		$timer         = AliceFactory::getTimer();

		// Call the right action method, depending on engine part state
		switch( $this->getState() )
		{
			case "init":
				$this->_prepare();
				$breakFlag = $configuration->set('volatile.breakflag', false);
				break;
			case "prepared":
				$this->_run();
				break;
			case "running":
				$this->_run();
				break;
			case "postrun":
				$this->_finalize();
				$breakFlag = $configuration->set('volatile.breakflag', false);
				break;
		}

		// If there is still time, we are not finished and there is no break flag set, re-run the tick()
		// method.
		$breakFlag = $configuration->get('volatile.breakflag', false);

		if(
			!in_array( $this->getState(), array('finished','error') ) &&
			( $timer->getTimeLeft() > 0 ) &&
			!$breakFlag &&
			($nesting < 20) &&
			($this->nest_logging)
		)
		{
			// Nesting is only applied if $this->nest_logging == true (currently only Kettenrad has this)
			$nesting++;
			if($this->nest_logging) AliceUtilLogger::WriteLog(_AE_LOG_DEBUG, "*** Batching successive steps (nesting level $nesting)");
			$out = $this->tick($nesting);
		}
		else
		{
			// Return the output array
			$out = $this->_makeReturnTable();
			// Things to do for nest-logged parts (currently, only Kettenrad is)
			if($this->nest_logging) {
				if($breakFlag) AliceUtilLogger::WriteLog(_AE_LOG_DEBUG, "*** Engine steps batching: Break flag detected.");
				// Reset the break flag
				$configuration->set('volatile.breakflag', false);
				// Log that we're breaking the step
				AliceUtilLogger::WriteLog(_AE_LOG_DEBUG, "*** Batching of engine steps finished. I will now return control to the caller.");
				// Enforce minimum execution time
				$timer = AliceFactory::getTimer();
				$timer->enforce_min_exec_time(true);
			}
		}

		// Send a Return Table back to the caller
		return $out;
	}

	/**
	 * Returns a copy of the class's status array
	 * @return array
	 */
	public function getStatusArray()
	{
		return $this->_makeReturnTable();
	}

	/**
	 * Sends any kind of setup information to the engine part. Using this,
	 * we avoid passing parameters to the constructor of the class. These
	 * parameters should be passed as an indexed array and should be taken
	 * into account during the preparation process only. This function will
	 * set the error flag if it's called after the engine part is prepared.
	 *
	 * @param array $parametersArray The parameters to be passed to the
	 * engine part.
	 */
	final public function setup( $parametersArray )
	{
		if( $this->isPrepared )
		{
			$this->setState('error', "Can't modify configuration after the preparation of " . $this->active_domain);
		}
		else
		{
			$this->_parametersArray = $parametersArray;
			if(array_key_exists('root', $parametersArray))
			{
				$this->databaseRoot = $parametersArray['root'];
			}
		}
	}

	/**
	 * Returns the state of this engine part.
	 *
	 * @return string The state of this engine part. It can be one of
	 * error, init, prepared, running, postrun, finished.
	 */
	final public function getState()
	{
		if( $this->getError() )
		{
			return "error";
		}

		if( !($this->isPrepared) )
		{
			return "init";
		}

		if( !($this->isFinished) && !($this->isRunning) && !( $this->hasRun ) && ($this->isPrepared) )
		{
			return "prepared";
		}

		if ( !($this->isFinished) && $this->isRunning && !( $this->hasRun ) )
		{
			return "running";
		}

		if ( !($this->isFinished) && !($this->isRunning) && $this->hasRun )
		{
			return "postrun";
		}

		if ( $this->isFinished )
		{
			return "finished";
		}
	}

	/**
	 * Constructs a Response Array based on the engine part's state.
	 * @return array The Response Array for the current state
	 */
	final protected function _makeReturnTable()
	{
		// Get a list of warnings
		$warnings = $this->getWarnings();
		// Report only new warnings if there is no warnings queue size
		if( $this->_warnings_queue_size == 0 )
		{
			if( ($this->warnings_pointer > 0) && ($this->warnings_pointer < (count($warnings)) ) )
			{
				$warnings = array_slice($warnings, $this->warnings_pointer + 1);
				$this->warnings_pointer += count($warnings);
			}
			else
			{
				$this->warnings_pointer = count($warnings);
			}
		}

		$out =  array(
			'HasRun'	=> (!($this->isFinished)),
			'Domain'	=> $this->active_domain,
			'Step'		=> $this->active_step,
			'Substep'	=> $this->active_substep,
			'Error'		=> $this->getError(),
			'Warnings'	=> $warnings
		);

		return $out;
	}

	final protected function setDomain($new_domain)
	{
		$this->active_domain = $new_domain;
	}

	final public function getDomain()
	{
		return $this->active_domain;
	}

	final protected function setStep($new_step)
	{
		$this->active_step = $new_step;
	}

	final public function getStep()
	{
		return $this->active_step;
	}

	final protected function setSubstep($new_substep)
	{
		$this->active_substep = $new_substep;
	}

	final public function getSubstep()
	{
		return $this->active_substep;
	}

	/**
	 * Implement this if your Engine Part can return the percentage of its work already complete
	 * @return float A number from 0 (nothing done) to 1 (all done)
	 */
	public function getProgress()
	{
		return 0;
	}
}
