export const validatorStack = {};
export const inputStack     = new WeakMap();

export class Class{

	static get _validators(){ return validatorStack; }


	/* (1) Push a new Format
	*
	* @_format<String>					Format name
	* @_validator<Function>				Format callback
	* @_error<String>					Error message
	*
	* @return pushed<bool>				Whether the validator has been pushed
	*
	---------------------------------------------------------*/
	static pushFormat(_format=null, _validator=null, _error='error'){

		/* (1) Error: invalid _format */
		if( typeof _format !== 'string' )
			return false;

		/* (2) Error: invalid _validator */
		if( !(_validator instanceof Function) )
			return false;

		/* (3) Store validator */
		Class._validators[_format] = { error: _error, validator: _validator };

		return true;

	}

	/* (1) Pop an existing Format
	*
	* @_format<String>					Format name
	*
	* @return popped<bool>				Whether the validator has been popped
	*
	---------------------------------------------------------*/
	static popFormat(_format=null){

		/* (1) Error: invalid _format */
		if( typeof _format !== 'string' )
			return false;

		/* (2) Error: _validator not found */
		if( Class._validators[_format] == null )
			return false;

		/* (3) Remove validator */
		delete Class._validators[_format];

		return true;

	}



	/* (2) Builds an validat-able input
	*
	* @_format<String>					Existing validator name
	* @_default<mixed>					[OPT] Mutable input default value (default to NULL)
	*
	---------------------------------------------------------*/
	constructor(_format, _default=null){

		/* (1) Store fields (default value) */
		this.mutable = _default;

		/* (2) Store _format in STATIC inputStack */
		inputStack.set(this, { format: _format });

	}


	/* (3) Checks if the _mutable has a current valid value
	*
	* @return valid<bool>				Whether the _mutable is valid or not
	*
	---------------------------------------------------------*/
	is_valid(){

		// 1. Extract validator name
		let format = inputStack.get(this).format;

		// 2. Dispatch validation
		return validatorStack[format].validator( this.mutable );

	}


	/* (3) Get current error message
	*
	* @return NULL if is_valid()
	*
	---------------------------------------------------------*/
	get error(){

		// 1. NULL if valid
		if( this.is_valid() )
			return '';

		// 2. Extract validator name
		let format = inputStack.get(this).format;

		// 3. Dispatch validation
		return validatorStack[format].error;

	}




}