namespace formgen.input
{
	
	/**
	 */
	export function from_raw(
		raw : any
	) : interface_input<unknown>
	{
		switch (raw.type)
		{
			case "checkbox":
			{
				return (
					new class_input_checkbox(
						{
							"label": formgen.helpers.map.read<(null | string)>(raw, "label", null),
						}
					)
				);
				break;
			}
			case "number":
			{
				return (
					new class_input_number(
						{
							"label": formgen.helpers.map.read<(null | string)>(raw, "label", null),
						}
					)
				);
				break;
			}
			case "text":
			{
				return (
					new class_input_text(
						{
							"label": formgen.helpers.map.read<(null | string)>(raw, "label", null),
						}
					)
				);
				break;
			}
			case "color":
			{
				return (
					new class_input_color(
						{
							"label": formgen.helpers.map.read<(null | string)>(raw, "label", null),
						}
					)
				);
				break;
			}
			case "select":
			{
				return (
					new class_input_select(
						(
							raw.options
							.map(
								(option_raw : Record<string, any>) => ({
									"value": option_raw["value"],
									"label": (formgen.helpers.map.read<(null | string)>(option_raw, "label", null) ?? String(option_raw["value"])),
								})
							)
						),
						{
							"label": formgen.helpers.map.read<(null | string)>(raw, "label", null),
						}
					)
				);
			}
			case "list":
			{
				return (
					new class_input_list(
						() => from_raw(raw.element),
						{
							"label": formgen.helpers.map.read<(null | string)>(raw, "label", null),
						}
					)
				);
				break;
			}
			case "group":
			{
				return (
					new class_input_group(
						formgen.helpers.list.transform(
							formgen.helpers.map.to_pairs(raw.members),
							(pair) => ({
								"name": pair.key,
								"input": from_raw(pair.value),
								"marked": (pair.value["required"] ?? false),
							})
						),
						{
							"label": formgen.helpers.map.read<(null | string)>(raw, "label", null),
						}
					)
				);
				break;
			}
			default:
			{
				throw (new Error("unhandled type: " + raw.type));
				break;
			}
		}
	}
	
	
	/**
	 * @todo description
	 * @todo if-then-else
	 */
	function from_json_schema_inner(
		defs : Map<string, formgen.helpers.json_schema.type_schema>,
		root : formgen.helpers.json_schema.type_schema,
		json_schema : formgen.helpers.json_schema.type_schema,
		{
			"fallback_label": fallback_label = null,
			"map_unhandled_refs_to_empty": map_unhandled_refs_to_empty = false,
		}
		:
		{
			fallback_label ?: (null | string);
			map_unhandled_refs_to_empty ?: boolean;
		}
		=
		{
		}
	) : interface_input<unknown>
	{
		const schema_adjusted : formgen.helpers.json_schema.type_schema = (() => {
			if (! ("$ref" in json_schema))
			{
				return json_schema;
			}
			else
			{
				const cases = [
					{
						"regexp": new RegExp('^#$'),
						"handling": (match) => {
							return root;
						},
					},
					{
						"regexp": new RegExp('^#/\\$defs/(.*)$'),
						"handling": (match) => {
							const key : string = match[1];
							return defs.get(key);
						},
					},
				];
				for (const case_ of cases)
				{
					const match = json_schema.$ref.match(case_.regexp);
					if (match === null)
					{
						// do nothing
					}
					else
					{
						return case_.handling(match);
					}
				}
				if (map_unhandled_refs_to_empty)
				{
					/**
					 * @todo warning
					 */
					return {
						"type": "null"
					};
				}
				else
				{
					throw (new Error("unhandled ref: " + json_schema.$ref));
				}
			}
		}) ();
		if ("enum" in schema_adjusted)
		{
			return (
				new class_input_select<any>(
					schema_adjusted.enum.map(
						(value, index) => (
							{
								"value": value,
								// "label": ("Option " + (index+1).toFixed(0)),
								"label": JSON.stringify(value),
							}
						)
					),
					{
						"label": (schema_adjusted.title ?? fallback_label ?? null),
					}
				)
			);
		}
		else if ("type" in schema_adjusted)
		{
			switch (schema_adjusted.type)
			{
				case "null":
				{
					return (
						new class_input_empty(
						)
					);
					break;
				}
				case "boolean":
				{
					return (
						new class_input_checkbox(
							{
								"label": (schema_adjusted.title ?? fallback_label ?? null),
								"hint": (schema_adjusted.description ?? null),
							}
						)
					);
					break;
				}
				/**
				 * @todo minimum
				 * @todo exclusiveMinimum
				 * @todo maximum
				 * @todo exclusiveMaximum
				 * @todo multipleOf
				 */
				case "integer":
				{
					return (
						new class_input_number(
							{
								"label": (schema_adjusted.title ?? fallback_label ?? null),
								"hint": (schema_adjusted.description ?? null),
							}
						)
					);
					break;
				}
				/**
				 * @todo minimum
				 * @todo exclusiveMinimum
				 * @todo maximum
				 * @todo exclusiveMaximum
				 * @todo multipleOf
				 */
				case "number":
				{
					return (
						new class_input_number(
							{
								"label": (schema_adjusted.title ?? fallback_label ?? null),
								"hint": (schema_adjusted.description ?? null),
							}
						)
					);
					break;
				}
				/**
				 * @todo pattern
				 * @todo minLength
				 * @todo maxLength
				 * @todo more format values
				 */
				case "string":
				{
					if ("format" in schema_adjusted)
					{
						switch (schema_adjusted.format)
						{
							case "date":
							{
								return (
									new class_input_date(
										{
											"label": (schema_adjusted.title ?? fallback_label ?? null),
											"hint": (schema_adjusted.description ?? null),
										}
									)
								);
								break;
							}
							case "time":
							{
								return (
									new class_input_time(
										{
											"label": (schema_adjusted.title ?? fallback_label ?? null),
											"hint": (schema_adjusted.description ?? null),
										}
									)
								);
								break;
							}
							default:
							{
								/**
								 * @todo warning
								 */
								return (
									new class_input_text(
										{
											"label": (schema_adjusted.title ?? fallback_label ?? null),
											"hint": (schema_adjusted.description ?? null),
										}
									)
								);
								break;
							}
						}
					}
					else
					{
						return (
							new class_input_text(
								{
									"label": (schema_adjusted.title ?? fallback_label ?? null),
									"hint": (schema_adjusted.description ?? null),
								}
							)
						);
					}
					break;
				}
				case "array":
				{
					if (! ("items" in schema_adjusted))
					{
						throw (new Error("can not generate array input without 'items' definition"));
					}
					else
					{
						return (
							new class_input_list(
								() => from_json_schema_inner(
									defs,
									root,
									(schema_adjusted.items as formgen.helpers.json_schema.type_schema),
									{
										"map_unhandled_refs_to_empty": map_unhandled_refs_to_empty,
									}
								),
								{
									"label": (schema_adjusted.title ?? fallback_label ?? null),
								}
							)
						);
					}
					break;
				}
				/**
				 * @todo required
				 * @todo additionalProperties
				 * @todo required
				 */
				case "object":
				{
					if ("properties" in schema_adjusted)
					{
						return (
							new class_input_group(
								formgen.helpers.list.transform(
									formgen.helpers.map.to_pairs<
										formgen.helpers.json_schema.type_schema
									>(schema_adjusted.properties as Record<string, formgen.helpers.json_schema.type_schema>),
									(pair : {key : string, value : formgen.helpers.json_schema.type_schema;}) => ({
										"name": pair.key,
										"input": from_json_schema_inner(
											defs,
											root,
											pair.value,
											{
												"fallback_label": pair.key,
												"map_unhandled_refs_to_empty": map_unhandled_refs_to_empty,
											}
										),
										"marked": (schema_adjusted.required ?? []).includes(pair.key),
									})
								),
								{
									"label": (schema_adjusted.title ?? fallback_label ?? null),
								}
							)
						);
					}
					else
					{
						throw (new Error("unhandled object situation"));
					}
					break;
				}
				default:
				{
					throw (new Error("unhandled json schema type: " + JSON.stringify(schema_adjusted)));
					break;
				}
			}
		}
		else if ("not" in schema_adjusted)
		{
			throw (new Error("not implemented"));
		}
		else if ("oneOf" in schema_adjusted)
		{
			return (
				new class_input_sum(
					formgen.helpers.list.transform<int, {input : interface_input<any>;}>(
						formgen.helpers.list.sequence(schema_adjusted.oneOf.length),
						(index) => {
							const sub_schema : formgen.helpers.json_schema.type_schema = schema_adjusted.oneOf[index];
							return {
								"input": from_json_schema_inner(
									defs,
									root,
									sub_schema,
									{
										"map_unhandled_refs_to_empty": map_unhandled_refs_to_empty,
									}
								),
								"label": (sub_schema.title ?? fallback_label ?? ("Art " + (index + 1).toFixed(0))),
							};
						}
					),
					{
						"label": (schema_adjusted.title ?? fallback_label ?? null),
					}
				)
			);
		}
		else if ("anyOf" in schema_adjusted)
		{
			return (
				new class_input_sum(
					formgen.helpers.list.transform<int, {input : interface_input<any>;}>(
						formgen.helpers.list.sequence(schema_adjusted.anyOf.length),
						(index) => {
							const sub_schema : formgen.helpers.json_schema.type_schema = schema_adjusted.anyOf[index];
							return {
								"input": from_json_schema_inner(
									defs,
									root,
									sub_schema,
									{
										"map_unhandled_refs_to_empty": map_unhandled_refs_to_empty,
									}
								),
								"label": (sub_schema.title ?? fallback_label ?? ("Art " + (index + 1).toFixed(0))),
							};
						}
					),
					{
						"label": (schema_adjusted.title ?? fallback_label ?? null),
					}
				)
			);
		}
		else if ("allOf" in schema_adjusted)
		{
			throw (new Error("not implemented"));
		}
		else
		{
			throw (new Error("unhandled schema: " + JSON.stringify(schema_adjusted)));
		}
	}

	
	/**
	 */
	export function from_json_schema(
		root : formgen.helpers.json_schema.type_root,
		{
			"map_unhandled_refs_to_empty": map_unhandled_refs_to_empty = false,
		}
		:
		{
			map_unhandled_refs_to_empty ?: boolean;
		}
		=
		{
		}
	) : interface_input<unknown>
	{
		let defs : Map<string, formgen.helpers.json_schema.type_schema> = new Map<string, formgen.helpers.json_schema.type_schema>();
		if ("$defs" in root)
		{
			for (const [name, value] of Object.entries(root.$defs))
			{
				defs.set(name, value);
			}
		}
		return from_json_schema_inner(
			defs,
			root,
			root,
			{
				"map_unhandled_refs_to_empty": map_unhandled_refs_to_empty,
			}
		);
	}
	
}