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

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

		this._fields = new Map();

		for(let f of fields){
			this.addField(f);
		}
	}

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

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

		if(isArray){
			fieldName = fieldName.replace(/^\[(\d*)\]/, '');
			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]){
						if(k == ""){
							json[key] = f[key].serialize()
							continue;
						}
						json[k][key] = f[key].serialize()
					}
				}
			} else {
				if(k == ""){
					json = f.serialize()
					continue;
				}
				json[k] = f.serialize()
			}	
		}
		return json;
	}
}