namespace formgen.input
{
	
	/**
	 */
	type type_entry<type_element> = {
		id : string;
		input : interface_input<type_element>;
		element : Element;
	};
	
	
	/**
	 */
	export class class_input_list<type_element> implements interface_input<Array<type_element>>
	{

		/**
		 */
		private element_input_factory : (() => interface_input<type_element>);
		

		/**
		 */
		private label : (null | string);
		
		
		/**
		 */
		private element_entries : (null | Element);
		
		
		/**
		 */
		private entries : Array<type_entry<type_element>>;
		
		
		/**
		 */
		public constructor(
			element_input_factory : (() => interface_input<type_element>),
			{
				"label": label = null,
			}
			:
			{
				label ?: (null | string);
			}
			=
			{
			}
		)
		{
			this.element_input_factory = element_input_factory;
			this.label = label;
			this.element_entries = null;
			this.entries = [];
		}
		
		
		/**
		 */
		private remove(
			id : string
		) : void
		{
			const index : int = this.entries.findIndex(entry => (entry.id === id));
			this.entries[index].element.remove();
			this.entries.splice(index, 1);
		}
		
		
		/**
		 */
		private async add(
		) : Promise<void>
		{
			const id : string = formgen.helpers.string.generate();
			const input : interface_input<type_element> = this.element_input_factory();
			const element_entry : Element = document.createElement("div");
			element_entry.classList.add("formgen-input-list-element");
			element_entry.setAttribute("rel", id);
			// remover
			{
				const element_remover : Element = document.createElement("button");
				element_remover.classList.add("formgen-input-list-remover");
				element_remover.textContent = "-";
				element_remover.addEventListener(
					"click",
					(event) => {
						event.preventDefault();
						this.remove(id);
					}
				);
				element_entry.appendChild(element_remover);
			}
			// input
			{
				await input.setup(element_entry);
			}
			this.entries.push(
				{
					"id": id,
					"input": input,
					"element": element_entry,
				}
			);
			this.element_entries.appendChild(element_entry);
		}
		
		
		/**
		 * [implementation]
		 */
		public async setup(
			element_target : Element
		) : Promise<void>
		{
			const element_container : Element = document.createElement("div");
			{
				// label
				{
					if (this.label === null)
					{
						// do nothing
					}
					else
					{
						const element_label : Element = document.createElement("label");
						element_label.textContent = this.label;
						element_container.appendChild(element_label);
					}
				}
				// entries
				{
					const element_entries : Element = document.createElement("div");
					element_entries.classList.add("formgen-input-list-entries");
					element_container.appendChild(element_entries);
					this.element_entries = element_entries;
				}
				// adder
				{
					const element_adder : Element = document.createElement("div");
					element_adder.classList.add("formgen-input-list-adder");
					{
						const element_adder_button : Element = document.createElement("button");
						element_adder_button.textContent = "+";
						element_adder.appendChild(element_adder_button);
						element_adder.addEventListener(
							"click",
							(event) => {
								event.preventDefault();
								this.add();
							}
						);
					}
					element_container.appendChild(element_adder);
				}
			}
			element_target.appendChild(element_container);
		}
		
		
		/**
		 * [implementation]
		 */
		public async read(
		) : Promise<Array<type_element>>
		{
			let result : Array<type_element> = [];
			for (const entry of this.entries)
			{
				result.push(await entry.input.read());
			}
			return result;
		}
		
		
		/**
		 * [implementation]
		 */
		public write(
			value : Array<type_element>
		) : Promise<void>
		{
			return Promise.reject(new Error("not implemented"));
		}
		
	}
	
}