HTMLElement.prototype.isChildOf = function(parent){
	var node = this.parentNode;
	while (node != null) {
		if (node == parent) {
			return true;
		}
		node = node.parentNode;
	}
	return false;
}

class SerializerField {
	/**
	 * constructor
	 *
	 * @param {HTMLElement} f Input field (input|select|textarea)
	 * @returns {SerializerField}
	 */
	constructor(f){
		this.name;
		this.parent;
		this.field = f;
		this.required = f.required
		this.type = this.field.getAttribute("type");
	}

	/**
	 * serialize
	 *
	 * @returns {(String|Number|Boolean|Date)}
	 */
	serialize(){
		if(this.type == "number" || this.type == "range"){
			return Number(this.field.value);
		} else if(this.type == "date" || this.type == "datetime-local" || this.type == "month" || this.type == "week") {
			return new Date(this.field.value);
		} else if(this.type == "checkbox") {
			let checked = this.field.checked;
			if(this.field.hasAttribute("string")){
				if(checked) {
					return this.field.value
				} else {
					return null;
				}
			}
			return checked;
		} else {
			return this.field.value;
		}	
	}
}

class Serializer {
	/**
	 * constructor
	 *
	 * @param {HTMLElement} element
	 * @returns {Serializer}
	 */
	constructor(element){
		let fields = element.querySelectorAll(`:scope input:not([type="submit"]), :scope select, :scope textarea, :scope group`);
		let groups = [].slice.call(element.querySelectorAll(`:scope group`));

		this.name = ":root";
		this.parent;
		this._fields = new Map();
		this.min = Number(element.getAttribute("min") || -1);

		this.required = element.getAttribute("required") !== null || this.min != -1;

		for(let f of fields){
			if(f.isChildOf(element) && groups.every(g => !f.isChildOf(g))){
				this.addField(f);
			}
		}
	}

	/**
	 * addField
	 *
	 * @param {HTMLElement} f
	 */
	addField(f){
		let fieldName = f.getAttribute("name");
		let isArray = fieldName.match(/^\[(\d*)\]/)

		fieldName = fieldName.replace(/^\[\d*\]/, '');

		let field;
		if(f.tagName == "GROUP"){
			field = new Serializer(f)
		} else {
			field = new SerializerField(f);
		}
		field.name = fieldName;
		field.parent = this;

		f.serializer = field

		if(isArray){
			if(!this._fields.has(fieldName)){
				this._fields.set(fieldName, [])
			}
			if(isArray[1] != ""){
				this._fields.get(fieldName)[isArray[1]] = field
			} else {
				this._fields.get(fieldName).push(field)
			}
		} else {
			this._fields.set(fieldName, field)
		}
	}

	/**
	 * serialize
	 *
	 * @returns {Object}
	 */
	serialize(){
		let json = {};
		for(let [k, f] of this._fields){
			if(Array.isArray(f)){
				if(k != ""){
					json[k] = [];
				} else {
					json = [];
				}
				for(let key in f){
					if(f[key]){
						let d = f[key].serialize();
						if(d !== null){
							if(k == ""){
								json[key] = d;
								continue;
							}
							json[k][key] = d;
						}
					}
				}
			} else {
				let d = f.serialize();
				if(f !== null){
					if(k == ""){
						json = d
						continue;
					}
					json[k] = d
				}
			}	
		}
		return json;
	}
}

class Validator {
	/**
	 * validateRequired
	 *
	 * @static
	 * @param {(erializer|SerializerField)} field
	 * @returns {Object}
	 */
	static validateRequired(field){
		let e = {
			valid: true,
			errors: {},
		}
		let v;
		if(field instanceof Serializer){
			v = Validator.validateRequiredSerializer(field);
		} else {
			v = Validator.validateRequiredSerialzerField(field)
		}
		if(!v.valid){
			e.valid = false;
			e.errors = v.errors;
		}
		return e;
	}

	/**
	 * validateRequiredSerializer
	 *
	 * @static
	 * @param {Serializer} field
	 * @returns {Object}
	 */
	static validateRequiredSerializer(field){
		let e = {
			valid: true,
			errors: {},
		}
		
		let min = field.min;
		let validFieldsCount = 0;
		for(let [k, f] of field._fields){
			if(Array.isArray(f)){
				e.errors = {
					message: null,
				};
				let validCount = 0;
				for(let sf of f){
					if(!(sf.name in e.errors)){
						e.errors[sf.name] = [];
					}

					let v = Validator.validateRequired(sf)
					if(!v.valid){
						console.log(e.errors)
						e.errors[sf.name].push(v.errors);		
						continue;
					}
					validCount++
				}
				
				e.valid = min <= validCount
				if(e.valid){
					e.errors = {}
				} else {
					e.errors.message = `Should contain atleast ${min} value(s)`
				}
			} else {
				let v = Validator.validateRequired(f);
				if(!v.valid){
					e.valid = false;
					e.errors[f.name] = v.errors;
				}
			}
		}

		return e;
	}

	/**
	 * validateRequiredSerialzerField
	 *
	 * @static
	 * @param {SerializerField} field
	 * @returns {Object}
	 */
	static validateRequiredSerialzerField(field){
		let e = {
			valid: true,
			errors: {},
		}

		if(field.required || (field.parent && field.parent.required)){
			if(field.type != "checkbox"){
				e.valid = field.field.validity.valueMissing !== true
				e.errors = "Is required"
			} else {
				e.valid = field.field.checked
				e.errors = "Not checked"
			}
		}
		return e;
	}
}