<?php

/**
 * Usage:
 * $nextPost = $this->Post->find('next', array(
 * 	'id' => 1,
 * 	...
 * ));
 */
class FindNextBehavior extends ModelBehavior {

	public $defaultSettings = array(
		'findType' => 'next',
	);

	public function setup($Model, $config = array()) {
		$this->settings[$Model->alias] = Set::merge($this->defaultSettings, $config);
		$this->mapMethods = array(
			sprintf('/^_find%s$/', ucfirst($this->settings[$Model->alias]['findType'])) => '__findNext',
		);
		$Model->_findMethods[$this->settings[$Model->alias]['findType']] = true;
	}

	public function __findNext($Model, $method, $state, $query, $results = array()) {
		if ($state == 'before') {
			if (!array_key_exists('value', $query)) {
				throw new Exception(__d('findNext', 'query must contain value for findNext: ', true) . var_export($query, true));
			}
			$field = isset($query['field']) ? $field : $Model->alias . '.' . $Model->primaryKey;
			unset($query['field']);

			$greaterQuery = Set::merge($query, array(
				'conditions' => array(
					"$field >" => $query['value'],
				),
			));
			$greaterExists = $Model->find('count', $greaterQuery);
			if (!$greaterExists) {
				$littlerQuery = Set::merge($query, array(
					'conditions' => array(
						"$field <" => $query['value'],
					),
				));
				$query = $littlerQuery;
			} else {
				$query = $greaterQuery;
			}
			unset($query['value']);

			$query['order'] = array(
				$field => 'ASC',
			);

			return $Model->_findFirst($state, $query, $results);
		} elseif ($state == 'after') {
			return $Model->_findFirst($state, $query, $results);
		}
	}

}