<?php
/**
 * Model class file.
 *
 * @link http://www.yiiframework.com/
 * @copyright Copyright &copy; 2008-2012 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\base;

/**
 * Model is the base class for data models.
 *
 * Model implements the following commonly used features:
 *
 * - attribute declaration: by default, every public class member is considered as
 *   a model attribute
 * - attribute labels: each attribute may be associated with a label for display purpose
 * - massive attribute assignment
 * - scenario-based validation
 *
 * Model also provides a set of events for further customization:
 *
 * - [[onAfterConstruct]]: an event raised at the end of constructor
 * - [[onInit]]: an event raised when [[init]] is called
 * - [[onBeforeValidate]]: an event raised at the beginning of [[validate]]
 * - [[onAfterValidate]]: an event raised at the end of [[validate]]
 *
 * You may directly use Model to store model data, or extend it with customization.
 * You may also customize Model by attaching [[ModelBehavior|model behaviors]].
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class Model extends Component implements \IteratorAggregate, \ArrayAccess
{
	private static $_attributes = array(); // class name => array of attribute names
	private $_errors;                      // attribute name => array of errors
	private $_validators;                  // validators
	private $_scenario;                    // scenario

	/**
	 * Constructor.
	 * @param string $scenario name of the [[scenario]] that this model is used in.
	 */
	public function __construct($scenario='')
	{
		$this->_scenario = $scenario;
		$this->afterConstruct();
	}

	/**
	 * Returns the list of attribute names.
	 * By default, this method returns all public non-static properties of the class.
	 * You may override this method to change the default.
	 * @return array list of attribute names.
	 */
	public function attributeNames()
	{
		$className = get_class($this);
		if (isset(self::$_attributes[$className])) {
			return self::$_attributes[$className];
		}

		$class = new ReflectionClass($this);
		$names = array();
		foreach ($class->getProperties() as $property) {
			$name = $property->getName();
			if ($property->isPublic() && !$property->isStatic()) {
				$names[] = $name;
			}
		}
		return self::$_attributes[$className] = $names;
	}

	/**
	 * Returns the validation rules for attributes.
	 *
	 * Validation rules are used by [[validate]] to check if attribute values are valid.
	 * Child classes may override this method to declare different validation rules.
	 *
	 * Each rule is an array with the following structure:
	 *
	 * ~~~
	 * array(
	 *     'attribute list',
	 *     'validator type',
	 *     'on'=>'scenario name',
	 *     ...other parameters...
	 * )
	 * ~~~
	 *
	 * where
	 *
	 *  - attribute list: required, specifies the attributes (separated by commas) to be validated;
	 *  - validator type: required, specifies the validator to be used. It can be the name of a model
	 *    class method, the name of a built-in validator, or a validator class (or its path alias).
	 *  - on: optional, specifies the [[scenario|scenarios]] (separated by commas) when the validation
	 *    rule can be applied. If this option is not set, the rule will apply to any scenario.
	 *  - additional name-value pairs can be specified to initialize the corresponding validator properties.
	 *    Please refer to individual validator class API for possible properties.
	 *
	 * A validator can be either a model class method or an object.
	 * If the former, the method must have the following signature:
	 *
	 * ~~~
	 * // $params refers to validation parameters given in the rule
	 * function validatorName($attribute, $params)
	 * ~~~
	 *
	 * If the latter, the object must be extending from [[\yii\validators\Validator]].
	 * Yii provides a set of [[\yii\validators\Validator::builtInValidators|built-in validators]].
	 * They each have an alias name which can be used when specifying a validation rule.
	 *
	 * The following are some examples:
	 *
	 * ~~~
	 * array(
	 *     array('username', 'required'),
	 *     array('username', 'length', 'min'=>3, 'max'=>12),
	 *     array('password', 'compare', 'compareAttribute'=>'password2', 'on'=>'register'),
	 *     array('password', 'authenticate', 'on'=>'login'),
	 * );
	 * ~~~
	 *
	 * Note, in order to inherit rules defined in the parent class, a child class needs to
	 * merge the parent rules with child rules using functions such as `array_merge()`.
	 *
	 * @return array validation rules
	 */
	public function rules()
	{
		return array();
	}

	/**
	 * Returns the attribute labels.
	 *
	 * Attribute labels are mainly used for display purpose. For example, given an attribute
	 * `firstName`, we can declare a label `First Name` which is more user-friendly and can
	 * be displayed to end users.
	 *
	 * By default an attribute label is generated using [[generateAttributeLabel]].
	 * This method allows you to explicitly specify attribute labels.
	 *
	 * Note, in order to inherit labels defined in the parent class, a child class needs to
	 * merge the parent labels with child labels using functions such as `array_merge()`.
	 *
	 * @return array attribute labels (name=>label)
	 * @see generateAttributeLabel
	 */
	public function attributeLabels()
	{
		return array();
	}

	/**
	 * Initializes the model.
	 * The default implementation raises the [[onInit]] event.
	 * If you override this method, make sure you call the parent implementation.
	 */
	public function init()
	{
		parent::init();
		if ($this->hasEventHandlers('onInit')) {
			$this->onInit(new Event($this));
		}
	}

	/**
	 * Performs the data validation.
	 *
	 * This method executes the validation rules as declared in [[rules]].
	 * Only the rules applicable to the current [[scenario]] will be executed.
	 * A rule is considered applicable to a scenario if its `on` option is not set
	 * or contains the scenario.
	 *
	 * This method will call [[beforeValidate]] and [[afterValidate]] before and
	 * after actual validation, respectively. If [[beforeValidate]] returns false,
	 * the validation and [[afterValidate]] will be cancelled.
	 *
	 * Errors found during the validation can be retrieved via [[getErrors]].
	 *
	 * @param array $attributes list of attributes that should be validated.
	 * If this parameter is empty, it means any attribute listed in the applicable
	 * validation rules should be validated.
	 * @param boolean $clearErrors whether to call [[clearErrors]] before performing validation
	 * @return boolean whether the validation is successful without any error.
	 * @see beforeValidate
	 * @see afterValidate
	 */
	public function validate($attributes = null, $clearErrors = true)
	{
		if ($clearErrors) {
			$this->clearErrors();
		}
		if ($this->beforeValidate()) {
			foreach ($this->getActiveValidators() as $validator) {
				$validator->validate($this, $attributes);
			}
			$this->afterValidate();
			return !$this->hasErrors();
		}
		return false;
	}

	/**
	 * This method is invoked at the end of model constructor.
	 * The default implementation raises the [[onAfterConstruct]] event.
	 * You may override this method to do postprocessing after model creation.
	 * Make sure you call the parent implementation so that the event is raised properly.
	 */
	public function afterConstruct()
	{
		if ($this->hasEventHandlers('onAfterConstruct')) {
			$this->onAfterConstruct(new Event($this));
		}
	}

	/**
	 * This method is invoked before validation starts.
	 * The default implementation raises the [[onBeforeValidate]] event.
	 * You may override this method to do preliminary checks before validation.
	 * Make sure the parent implementation is invoked so that the event can be raised.
	 * @return boolean whether validation should be executed. Defaults to true.
	 * If false is returned, the validation will stop and the model is considered invalid.
	 */
	public function beforeValidate()
	{
		if ($this->hasEventHandlers('onBeforeValidate')) {
			$event = new ValidationEvent($this);
			$this->onBeforeValidate($event);
			return $event->isValid;
		}
		return true;
	}

	/**
	 * This method is invoked after validation ends.
	 * The default implementation raises the [[onAfterValidate]] event.
	 * You may override this method to do postprocessing after validation.
	 * Make sure the parent implementation is invoked so that the event can be raised.
	 */
	public function afterValidate()
	{
		if ($this->hasEventHandlers('onAfterValidate')) {
			$this->onAfterValidate(new Event($this));
		}
	}

	/**
	 * This event is raised by [[init]] when initializing the model.
	 * @param Event $event the event parameter
	 */
	public function onInit($event)
	{
		$this->raiseEvent(__METHOD__, $event);
	}

	/**
	 * This event is raised after the model instance is created by new operator.
	 * @param Event $event the event parameter
	 */
	public function onAfterConstruct($event)
	{
		$this->raiseEvent(__METHOD__, $event);
	}

	/**
	 * This event is raised before the validation is performed.
	 * @param ValidationEvent $event the event parameter
	 */
	public function onBeforeValidate($event)
	{
		$this->raiseEvent(__METHOD__, $event);
	}

	/**
	 * This event is raised after the validation is performed.
	 * @param Event $event the event parameter
	 */
	public function onAfterValidate($event)
	{
		$this->raiseEvent(__METHOD__, $event);
	}

	/**
	 * Returns all the validators declared in [[rules]].
	 *
	 * This method differs from [[getActiveValidators]] in that the latter
	 * only returns the validators applicable to the current [[scenario]].
	 *
	 * Because this method returns a [[Vector]] object, you may
	 * manipulate it by inserting or removing validators (useful in model behaviors).
	 * For example,
	 *
	 * ~~~
	 * $model->validators->add($newValidator);
	 * ~~~
	 *
	 * @return Vector all the validators declared in the model.
	 */
	public function getValidators()
	{
		if ($this->_validators === null) {
			$this->_validators = $this->createValidators();
		}
		return $this->_validators;
	}

	/**
	 * Returns the validators applicable to the current [[scenario]].
	 * @param string $attribute the name of the attribute whose applicable validators should be returned.
	 * If this is null, the validators for ALL attributes in the model will be returned.
	 * @return array the validators applicable to the current [[scenario]].
	 */
	public function getActiveValidators($attribute = null)
	{
		$validators = array();
		$scenario = $this->getScenario();
		foreach ($this->getValidators() as $validator) {
			if ($validator->applyTo($scenario)) {
				if ($attribute === null || in_array($attribute, $validator->attributes, true)) {
					$validators[] = $validator;
				}
			}
		}
		return $validators;
	}

	/**
	 * Creates validator objects based on the validation rules specified in [[rules]].
	 * Unlike [[getValidators]], calling this method each time, it will return a new list of validators.
	 * @return Vector validators
	 */
	public function createValidators()
	{
		$validators = new Vector;
		foreach ($this->rules() as $rule) {
			if (isset($rule[0], $rule[1])) {  // attributes, validator type
				$validator = \yii\validators\Validator::createValidator($rule[1], $this, $rule[0], array_slice($rule, 2));
				$validators->add($validator);
			}
			else {
				throw new Exception('Invalid validation rule: a rule must specify both attribute names and validator type.');
			}
		}
		return $validators;
	}

	/**
	 * Returns a value indicating whether the attribute is required.
	 * This is determined by checking if the attribute is associated with a
	 * [[\yii\validators\RequiredValidator|required]] validation rule in the
	 * current [[scenario]].
	 * @param string $attribute attribute name
	 * @return boolean whether the attribute is required
	 */
	public function isAttributeRequired($attribute)
	{
		foreach ($this->getActiveValidators($attribute) as $validator) {
			if ($validator instanceof \yii\validators\RequiredValidator) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Returns a value indicating whether the attribute is safe for massive assignments.
	 * @param string $attribute attribute name
	 * @return boolean whether the attribute is safe for massive assignments
	 */
	public function isAttributeSafe($attribute)
	{
		$validators = $this->getActiveValidators();
		foreach ($validators as $validator) {
			if (!$validator->safe) {
				return false;
			}
		}
		return $validators !== array();
	}

	/**
	 * Returns the text label for the specified attribute.
	 * @param string $attribute the attribute name
	 * @return string the attribute label
	 * @see generateAttributeLabel
	 * @see attributeLabels
	 */
	public function getAttributeLabel($attribute)
	{
		$labels = $this->attributeLabels();
		return isset($labels[$attribute]) ? $labels[$attribute] : $this->generateAttributeLabel($attribute)
	}

	/**
	 * Returns a value indicating whether there is any validation error.
	 * @param string $attribute attribute name. Use null to check all attributes.
	 * @return boolean whether there is any error.
	 */
	public function hasErrors($attribute = null)
	{
		return $attribute === null ? !empty($this->_errors) : isset($this->_errors[$attribute]);
	}

	/**
	 * Returns the errors for all attribute or a single attribute.
	 * @param string $attribute attribute name. Use null to retrieve errors for all attributes.
	 * @return array errors for all attributes or the specified attribute. Empty array is returned if no error.
	 * Note that when returning errors for all attributes, the result is a two-dimensional array, like the following:
	 *
	 * ~~~
	 * array(
	 *     'username' => array(
	 *         'Username is required.',
	 *         'Username must contain only word characters.',
	 *     ),
	 *     'email' => array(
	 *         'Email address is invalid.',
	 *     )
	 * )
	 * ~~~
	 *
	 * @see getError
	 */
	public function getErrors($attribute = null)
	{
		if ($attribute === null) {
			return $this->_errors === null ? array() : $this->_errors;
		}
		else {
			return isset($this->_errors[$attribute]) ? $this->_errors[$attribute] : array();
		}
	}

	/**
	 * Returns the first error of the specified attribute.
	 * @param string $attribute attribute name.
	 * @return string the error message. Null is returned if no error.
	 * @see getErrors
	 */
	public function getError($attribute)
	{
		return isset($this->_errors[$attribute]) ? reset($this->_errors[$attribute]) : null;
	}

	/**
	 * Adds a new error to the specified attribute.
	 * @param string $attribute attribute name
	 * @param string $error new error message
	 */
	public function addError($attribute, $error)
	{
		$this->_errors[$attribute][] = $error;
	}

	/**
	 * Adds a list of errors.
	 * @param array $errors a list of errors. The array keys must be attribute names.
	 * The array values should be error messages. If an attribute has multiple errors,
	 * these errors must be given in terms of an array.
	 */
	public function addErrors($errors)
	{
		foreach ($errors as $attribute => $error) {
			if (is_array($error)) {
				foreach ($error as $e) {
					$this->_errors[$attribute][] = $e;
				}
			}
			else {
				$this->_errors[$attribute][] = $error;
			}
		}
	}

	/**
	 * Removes errors for all attributes or a single attribute.
	 * @param string $attribute attribute name. Use null to remove errors for all attribute.
	 */
	public function clearErrors($attribute = null)
	{
		if ($attribute === null) {
			$this->_errors = array();
		}
		else {
			unset($this->_errors[$attribute]);
		}
	}

	/**
	 * Generates a user friendly attribute label based on the give attribute name.
	 * This is done by replacing underscores, dashes and dots with blanks and
	 * changing the first letter of each word to upper case.
	 * For example, 'department_name' or 'DepartmentName' will generate 'Department Name'.
	 * @param string $name the column name
	 * @return string the attribute label
	 */
	public function generateAttributeLabel($name)
	{
		return ucwords(trim(strtolower(str_replace(array('-', '_', '.'), ' ', preg_replace('/(?<![A-Z])[A-Z]/', ' \0', $name)))));
	}

	/**
	 * Returns attribute values.
	 * @param array $names list of attributes whose value needs to be returned.
	 * Defaults to null, meaning all attributes listed in [[attributeNames]] will be returned.
	 * If it is an array, only the attributes in the array will be returned.
	 * @return array attribute values (name=>value).
	 */
	public function getAttributes($names = null)
	{
		$values = array();

		if (is_array($names)) {
			foreach ($this->attributeNames() as $name) {
				if (in_array($name, $names, true)) {
					$values[$name] = $this->$name;
				}
			}
		}
		else {
			foreach ($this->attributeNames() as $name) {
				$values[$name] = $this->$name;
			}
		}

		return $values;
	}

	/**
	 * Sets the attribute values in a massive way.
	 * @param array $values attribute values (name=>value) to be assigned to the model.
	 * @param boolean $safeOnly whether the assignments should only be done to the safe attributes.
	 * A safe attribute is one that is associated with a validation rule in the current [[scenario]].
	 * @see getSafeAttributeNames
	 * @see attributeNames
	 */
	public function setAttributes($values, $safeOnly = true)
	{
		if (is_array($values)) {
			$attributes = array_flip($safeOnly ? $this->getSafeAttributeNames() : $this->attributeNames());
			foreach ($values as $name => $value) {
				if (isset($attributes[$name])) {
					$this->$name = $value;
				}
				elseif ($safeOnly) {
					$this->onUnsafeAttribute($name, $value);
				}
			}
		}
	}

	/**
	 * This method is invoked when an unsafe attribute is being massively assigned.
	 * The default implementation will log a warning message if YII_DEBUG is on.
	 * It does nothing otherwise.
	 * @param string $name the unsafe attribute name
	 * @param mixed $value the attribute value
	 */
	public function onUnsafeAttribute($name, $value)
	{
		if (YII_DEBUG) {
			\Yii::warning(sprintf('Failed to set unsafe attribute "%s" in "%s".', $name, get_class($this));
		}
	}

	/**
	 * Returns the scenario that this model is used in.
	 *
	 * Scenario affects how validation is performed and which attributes can
	 * be massively assigned.
	 *
	 * A validation rule will be performed when calling [[validate]]
	 * if its 'on' option is not set or contains the current scenario value.
	 *
	 * And an attribute can be massively assigned if it is associated with
	 * a validation rule for the current scenario. An exception is
	 * the [[\yii\validators\UnsafeValidator|unsafe]] validator which marks
	 * the associated attributes as unsafe and not allowed to be massively assigned.
	 *
	 * @return string the scenario that this model is in.
	 */
	public function getScenario()
	{
		return $this->_scenario;
	}

	/**
	 * Sets the scenario for the model.
	 * @param string $value the scenario that this model is in.
	 * @see getScenario
	 */
	public function setScenario($value)
	{
		$this->_scenario = $value;
	}

	/**
	 * Returns the attribute names that are safe to be massively assigned.
	 * A safe attribute is one that is associated with a validation rule in the current [[scenario]].
	 * @return array safe attribute names
	 */
	public function getSafeAttributeNames()
	{
		$attributes = array();
		$unsafe = array();
		foreach ($this->getActiveValidators() as $validator) {
			if (!$validator->safe) {
				foreach ($validator->attributes as $name) {
					$unsafe[] = $name;
				}
			}
			else {
				foreach ($validator->attributes as $name) {
					$attributes[$name] = true;
				}
			}
		}

		foreach ($unsafe as $name) {
			unset($attributes[$name]);
		}
		return array_keys($attributes);
	}

	/**
	 * Returns an iterator for traversing the attributes in the model.
	 * This method is required by the interface IteratorAggregate.
	 * @return CMapIterator an iterator for traversing the items in the list.
	 */
	public function getIterator()
	{
		$attributes = $this->getAttributes();
		return new DictionaryIterator($attributes);
	}

	/**
	 * Returns whether there is an element at the specified offset.
	 * This method is required by the SPL interface `ArrayAccess`.
	 * It is implicitly called when you use something like `isset($model[$offset])`.
	 * @param mixed $offset the offset to check on
	 * @return boolean
	 */
	public function offsetExists($offset)
	{
		return property_exists($this, $offset) && $this->$offset !== null;
	}

	/**
	 * Returns the element at the specified offset.
	 * This method is required by the SPL interface `ArrayAccess`.
	 * It is implicitly called when you use something like `$value = $model[$offset];`.
	 * @param mixed $offset the offset to retrieve element.
	 * @return mixed the element at the offset, null if no element is found at the offset
	 */
	public function offsetGet($offset)
	{
		return $this->$offset;
	}

	/**
	 * Sets the element at the specified offset.
	 * This method is required by the SPL interface `ArrayAccess`.
	 * It is implicitly called when you use something like `$model[$offset] = $item;`.
	 * @param integer $offset the offset to set element
	 * @param mixed $item the element value
	 */
	public function offsetSet($offset, $item)
	{
		$this->$offset = $item;
	}

	/**
	 * Unsets the element at the specified offset.
	 * This method is required by the SPL interface `ArrayAccess`.
	 * It is implicitly called when you use something like `unset($model[$offset])`.
	 * @param mixed $offset the offset to unset element
	 */
	public function offsetUnset($offset)
	{
		unset($this->$offset);
	}
}