'use strict';

const getNodes = require("../node/get-nodes");
const getNodeSequences = require("../node/get-node-sequences");

/* Simple node types are always simple, no matter what. */
let simpleNodeTypes = new Set([
	"Literal",
	"Identifier",
	"ThisExpression",
	"ContinueStatement",
	"MemberExpression", /* FIXME: This may be wrong if a computed property is involved? */
]);

/* "Semi-simple" node types are only considered simple if all of their children are also simple. */
let semiSimpleNodeTypes = new Set([
	"BinaryExpression",
	"UnaryExpression",
	"UpdateExpression",
	"LogicalExpression",
	"AssignmentPattern",
	"AssignmentExpression",
	"VariableDeclarator",
	"Property",
	"ReturnStatement",
	"IfStatement",
	"ConditionalExpression",
	"ExpressionStatement"
]);

/* TODO: CallExpression is only simple if nested one level deep at most. */

function checkChildNodes(node, predicate) {
	let nodeProperties = node.getNodeProperties();
	let nodeSequenceProperties = node.getNodeSequenceProperties();

	let checkFailed = false;

	for (let property of nodeProperties) {
		if (!predicate(node[property])) {
			checkFailed = true;
		}
	}

	for (let property of nodeSequenceProperties) {
		for (let item of node[property]) {
			if (!predicate(item)) {
				checkFailed = true;
			}
		}
	}

	return !checkFailed;
}

function _isSimple(node) {
	if (simpleNodeTypes.has(node.type)) {
		return true;
	} else if (semiSimpleNodeTypes.has(node.type)) {
		return checkChildNodes(node, (childNode) => childNode.isSimple());
	} else if (node.type === "CallExpression") {
		return checkChildNodes(node, (childNode) => childNode.type !== "CallExpression" && childNode.isSimple());
	} else if (node.type === "ObjectExpression") {
		return (node.properties.length === 0);
	} else if (node.type === "ArrayExpression") {
		return (node.elements.length === 0);
	} else {
		return false;
	}
}

function isSimple() {
	if (this._cacheIsSimple != null) {
		return this._cacheIsSimple;
	} else {
		let result = _isSimple(this);
		this._cacheIsSimple = result;
		return result;
	}
}

function getNodeProperties() {
	return getNodes(this);
}

function getNodeSequenceProperties() {
	return getNodeSequences(this);
}

module.exports = function createUtilityMethodsProcessor() {
	return {
		onEnter: function onEnter(node) {
			Object.assign(node, {
				isSimple: isSimple,
				getNodeProperties: getNodeProperties,
				getNodeSequenceProperties: getNodeSequenceProperties
			});
		}
	};
};