<?php declare(strict_types=1);

namespace VeruA\DomainObjects\Validation;

use VeruA\Log;
use VeruA\DomainObjects\DomainObject;
use VeruA\DomainObjects\ValueObjects\Value;
use VeruA\DomainObjects\Validation\ResultCollection;

/**
 * Validator is a singleton base class for classes validating DomainObjects.
 */
abstract class AbstractValidator implements Validator
{
	use Log;

	/**
	 * Needs to be declared in every childclass
	 * @var callable[] A list of tests used to validate domainObjects dataTypes, indexed by fieldname
	 */
	protected $validators = [];

	/**
	 * Stores the single instance of Validator.
	 * @var Validator
	 * @abstract Needs to be redeclared in every child class
	 */
	protected static AbstractValidator $instance;

	private bool $validatorsLoaded = false;
	
	/**
	 * Implement constructor in childclasses and assign the validator functions to using setValidators() 
	 * All sub-classes should have protected constructors.
	 */
	protected abstract function __construct();

	// getValidators() {{{
	/**
	 * Returns the validator functions.
	 */
	public function getValidators()
	{
		return $this->validators;
		} // }}}

	// setValidators() {{{
	/**
	 * Sets the validator functions.
	 */
	protected function setValidators($tests)
	{
		$parentClass = get_parent_class($this);
		$parentTests = [];
		
		if ($parentClass !== false && $parentClass !== AbstractValidator::class)
		{
			$parentTests = $parentClass::getInstance()->getValidators();
		}
		$this->validators = array_merge($parentTests, $tests);
	} // }}}

	// addValidator() {{{
	/**
	 * Dynamically add a validator function
	 * @param string $field The DomainObject Field to validate
	 * @param callable $validator The Validator function to use
	 * @param string $validatorIndex The internal index used to store the validator function. Use this to 
	 *   remove or overwrite the validator
	 */
	public function addValidator(string $field, callable $validator, ?string $validatorIndex=null)
	{
		if (!isset($this->validators[$field])) $this->validators[$field] = [];
		$this->validators[$field][$validatorIndex] = $validator;
	} // }}}
	
	// removeValidator() {{{
	/**
	 * Dynamiocally remove a validator function
	 */
	public function removeValidator(string $field, $validatorIndex=null)
	{
		if (isset($validatorIndex))
		{
			unset($this->validators[$field][$validatorIndex]);
		} else
		{
			unset($this->validators[$field]);
		}
	} // }}}
	
	// getInstance() {{{
	/**
	 * Returnst the instances of the validator, instantiates a new one if there isn't one already.
	 * @return Validator
	 */
	public static function getInstance(): Validator
	{
		if (!isset(static::$instance)) {
			static::$instance = new static();
		}
		
		assert(
			array_column(
				(new \ReflectionClass(static::$instance))
					->getProperties(\ReflectionProperty::IS_STATIC | \ReflectionProperty::IS_PROTECTED),
				'class', 'name'
			)['instance'] === get_class(static::$instance),
			new \Exception('$instance has to be redeclared in '.get_class(static::$instance))
		);
		
		return static::$instance;
	} // }}}

	// validate() {{{
	/**
	 * Validates a DomainObject.
	 * @param DomainObject $domainObject
	 * @return ResultCollection|bool returns true if validations passed a ResultCollection otherwise 
	 */
	public function validate(Validatable $domainObject)
	{
		$this->loadDefaultValidators($domainObject);
		
		$rc = new ResultCollection((new \ReflectionClass($domainObject))->getShortName());
		$passed = true;
	   
		// Validate properties
		foreach ($this->validators as $col => $validators)
		{
			if (!isset($domainObject->$col)) {
				$this->log()->notice('DomainObject '.get_class($domainObject)." has no field '$col'");
				continue;
			}
			try {
				$valueObject = $domainObject->getValueObjectOf($col);
				foreach ($validators as $test)
				{
					if (true !== ($result = $test($valueObject))) {
						$rc->$col = $result;
						$passed = false;
					}
				}
			}
			catch (\OutOfRangeException $e) {
				self::log()->notice('Field not set', ['name' => $col]);
			}
		}

		return $passed ?: $rc;
	} // }}}
	
	// loadDefaultValidators() {{{
	/**
	 * load vaildators defined in ValueObjects.
	 * Defined as Default and as such meaning always used. An example is the EAN13 ValueObject
	 * which always validates checksum and length
	 */
	private function loadDefaultValidators(DomainObject $domainObject)
	{
		if (! $this->validatorsLoaded)
		{
			foreach ($domainObject->dataTypes() as $col => $dt)
			{
				if (is_subclass_of($dt, Value::class) && !empty($validators = ($dt)::defaultValidators()))
				{
					if (!isset($this->validators[$col])) $this->validators[$col] = [];
				
					$this->validators[$col] = array_merge($this->validators[$col], $validators);
				}
			}
			self::log()->debug('Registered Validators', $this->validators);

			$this->validatorsLoaded = true;
		}
	} // }}}
}

/* jEdit buffer local properties {{{
 * :folding=explicit:collapseFolds=1:
 }}}*/