"use strict";

// Simple data type to represent a query path and corresponding schema path tied together, because these are basically always used together, and it would bloat up the implementation code otherwise

function createInstance({ queryPath, schemaPath, queryObject, schemaObject }) {
	 return {
		queryPath: queryPath,
		schemaPath: schemaPath,
		query: queryObject,
		schema: schemaObject,
		child: function (queryKey, schemaKey, { queryOverride, schemaOverride } = {}) {
			return createInstance({
				queryPath: (queryKey != null)
					? queryPath.concat([ queryKey ])
					: queryPath,
				schemaPath: (schemaKey != null)
					? schemaPath.concat([ schemaKey ])
					: schemaPath,
				queryObject: queryOverride ?? queryObject[queryKey],
				schemaObject: schemaOverride ?? schemaObject[schemaKey]
			});
		},
		toPathString: function () {
			return queryPath
				.map((segment, i) => {
					if (segment === schemaPath[i]) {
						return segment;
					} else {
						// This is used for representing aliases, showing the original schema key in brackets
						return `${segment} [${schemaPath[i]}]`;
					}
				})
				.join(" -> ");
		}
	 };
}

module.exports = function createCursor({ query, schema }) {
	return createInstance({
		queryPath: [],
		schemaPath: [],
		queryObject: query,
		schemaObject: schema
	});
};