<?php
/**
 * Revisions class with database interaction, data, and methods.
 *
 * @package CFF.
 * @since 1.0.232
 */

if(!class_exists('CPCFF_REVISIONS'))
{
	class CPCFF_REVISIONS
	{
		/**
		 * CPCFF_FORM instance
		 */
		private $_form_obj;

		/**
		 * List of revisions rows corresponding to the form
		 */
		private $_revisions;

		/**
		 * Instance of the $wpdb object
         */
		private $_db;

		/**
		 * Name of revisions table
		 */
		private $_table;

		/**
		 * The number of revisions per form
		 */
		private $_max = 20;

		/**
		 * Constructs a CPCFF_REVISIONS object.
		 *
		 * @param integer $form_obj instance of CPCFF_FORM
		 */
		public function __construct($form_obj)
		{
			global $wpdb;
			$this->_db = $wpdb;
			$this->_table = $wpdb->prefix.CP_CALCULATEDFIELDSF_FORMS_REVISIONS_TABLE;
			$this->_form_obj = $form_obj;
			$this->revisions_list();
		} // End construct

		/**
		 * Returns the list of revisions rows in the database as array
		 */
		public function revisions_list()
		{
			if(empty($this->_revisions))
			{
				$results = $this->_db->get_results(
					$this->_db->prepare(
						'SELECT * FROM '.$this->_table.' WHERE formid=%d ORDER BY time DESC',
						$this->_form_obj->get_id()
					),
					ARRAY_A
				);
				$this->_revisions = array();
				foreach($results as $revision)
				{
					$this->_revisions[$revision['id']] = $revision;
				}
			}
			return $this->_revisions;

		} // End revisions_list

		/**
		 * Creates a new entry in the revisions table, if there are more than _max revisions remove the older.
		 *
		 * @return int returns the revision's id or false if fails.
		 */
		public function create_revision()
		{
			$form_data = $this->_form_obj->get_raw_data();

			$data  = array(
				'formid' 	=> $this->_form_obj->get_id(),
				'time' 		=> current_time('mysql'),
				'revision' 	=> serialize($form_data)
			);

			if(
				$this->_db->insert(
					$this->_table,
					$data,
					array('%d','%s','%s')
				)
			)
			{
				$data['id'] = $this->_db->insert_id;
				$this->_revisions[$data['id']] = $data;
				krsort($this->_revisions);
				if($this->_max < count($this->_revisions))
				{
					array_splice($this->_revisions,$this->_max);
					$this->_delete_older();
				}
				return $data['id'];
			}
			return false;
		} // End create_revision

		/**
		 * returns the form data unserialized or an empty array
		 */
		public function data( $revision_id )
		{
			if(
				!empty($this->_revisions) &&
				isset($this->_revisions[$revision_id])
			)
			{
				return unserialize($this->_revisions[$revision_id]['revision']);
			}
			return array();
		} // End data

		/**
		 * Deletes the list of revisions belonging to the form
		 */
		public function delete_form()
		{
			$this->_db->delete(
				$this->_table,
				array('formid' => $this->_form_obj->get_id()),
				array('%d')
			);
			$this->_revisions = array();
		} // End delete_form


		/*********************************** PRIVATE METHODS  ********************************************/

		/**
         * Deletes the older revisions, leaving only the _max
		 */
		private function _delete_older()
		{
			$formid = $this->_form_obj->get_id();
			$this->_db->query(
				$this->_db->prepare(
					'DELETE FROM '.$this->_table.' WHERE formid=%d AND id IN (SELECT * FROM (SELECT id FROM '.$this->_table.' WHERE formid=%d ORDER BY time DESC LIMIT %d,18446744073709551615) AS tmp)',
					$formid,$formid,$this->_max
				)
			);
		} // End _delete_older
	} // End CPCFF_REVISIONS
}