"use strict";

const mapObj = require("map-obj");
const filterObj = require("filter-obj");

const typeRules = require("./type-rules");
const generateDescriptor = require("./generate-descriptor");
const getSchemaKeys = require("./util/get-schema-keys");
const nullMissingFields = require("./util/null-missing-fields");

/* TODO: Traits implementing traits */

module.exports = function createTrait(name, schema, options = {}) {
	let schemaDescriptors = mapObj(schema, (key, rule) => {
		return generateDescriptor(rule, key, true);
	});

	let schemaKeys = getSchemaKeys(schema);

	return typeRules._createTypeRule({
		_isTrait: true,
		_name: name,
		_schema: schema,
		applyImplementation: function (implementation) {
			/* FIXME: Verify that there are no extraneous keys or unspecified values */
			let validatedImplementation = Object.create({
				_data: {}
			}, schemaDescriptors);

			let implementationWithoutSlots = filterObj(implementation, (key, value) => {
				return (value == null || value._isSlotRule !== true);
			});

			let nullFields = nullMissingFields(implementation, schemaKeys);
			Object.assign(validatedImplementation, implementationWithoutSlots, nullFields);

			let implementationSchema = mapObj(implementation, (key, value) => {
				if (value != null && value._isSlotRule === true) {
					return [key, {
						isSlot: true,
						rule: schema[key]
					}];
				} else {
					return [key, {
						isSlot: false,
						rule: value
					}];
				}
			});

			let implementationDescriptors = mapObj(implementationSchema, (key, value) => {
				return generateDescriptor(value.rule, key, value.isSlot);
			});

			let slotSchemaKeys = Object.keys(filterObj(implementationSchema, (key, value) => {
				return value.isSlot;
			}));

			return {implementationSchema, implementationDescriptors, slotSchemaKeys};
		}
	});
};