'use strict';

const repeatString = require("repeat-string");
const assureArray = require("assure-array");

function debugPrintNode(node) {
	return `${node.type} | ${node.value || node.operator || node.identifier}`;
}

function prettyPrint(items, indentation) {
	if (indentation == null) {
		throw new Error(`Missing indentation parameter (node: ${debugPrintNode(node)})`);
	}

	return items.map((item) => {
		if (typeof item === "string") {
			return item.split("\n").map((line) => {
				return repeatString("\t", indentation) + line;
			}).join("\n");
		} else {
			return prettyPrint(item, indentation + 1);
		}
	}).join("\n");
}


function stringifyNode(node, indentation) {
	if (indentation == null) {
		throw new Error(`Missing indentation parameter (node: ${debugPrintNode(node)})`);
	}

	switch (node.type) {
		case "operatorExpression":
			return stringifyOperator(node, indentation);
		case "numberLiteral":
			return stringifyNumberLiteral(node, indentation);
		case "stringLiteral":
			return stringifyStringLiteral(node, indentation);
		case "identifier":
			return stringifyIdentifier(node, indentation);
		case "set":
			return stringifySet(node, indentation);
		case "letBlock":
			return stringifyLetBlock(node, indentation);
		case "list":
			return stringifyList(node, indentation);
		case "functionDefinition":
			return stringifyFunctionDefinition(node, indentation);
		case "group":
			return stringifyGroup(node, indentation);
		default:
			throw new Error(`Unexpected node type '${node.type}'`);
	}
}

function stringifyOperator(node, indentation) {
	let result;

	switch (node.operator) {
		case "+":
		case "-":
		case "/":
		case "*":
		case "++":
		case "//":
		case "&&":
		case "||":
		case "==":
		case "!=":
		case "<":
		case "<=":
		case ">":
		case ">=":
			result = `${stringifyNode(node.left, indentation)} ${node.operator} ${stringifyNode(node.right, indentation)}`;
			break;
		case "call":
			result = `${stringifyNode(node.left, indentation)} ${stringifyNode(node.right, indentation)}`;
			break;
		case "numericalNegate":
			result = `-${stringifyNode(node.right, indentation)}`;
			break;
		case "booleanNegate":
			result = `!${stringifyNode(node.right, indentation)}`;
			break;
	}

	return `(${result})`;
}

function stringifyStringLiteral(node, indentation) {
	return `"${node.value.replace(/\\/g, "\\\\").replace(/"/g, '\\"')}"`;
}

function stringifyNumberLiteral(node, indentation) {
	return `${node.value}`;
}

function stringifyIdentifier(node, indentation) {
	return `${node.identifier}`;
}

function stringifyBinding(node, indentation) {
	return `${stringifyNode(node.identifier, indentation)} = ${stringifyNode(node.expression, indentation)};`
}

function stringifyGroup(node, indentation) {
	return `(${stringifyNode(node.expression, indentation)})`
}

function stringifySet(node, indentation) {
	return prettyPrint([
		"{",
			node.assignments.map((binding) => {
				return stringifyBinding(binding, indentation);
			}),
		"}"
	], indentation);
}

function stringifyLetBlock(node, indentation) {
	return prettyPrint([
		"let",
			node.bindings.map((binding) => {
				return stringifyBinding(binding, indentation);
			}),
		"in",
			[stringifyNode(node.expression, indentation)]
	], indentation);
}

function stringifyList(node, indentation) {
	return `[ ${node.items.map(item => stringifyNode(item, indentation)).join(" ")} ]`;
}

function stringifyFunctionDefinition(node, indentation) {
	return prettyPrint([
		`${stringifyNode(node.argument, indentation)}:`,
			[stringifyNode(node.body, indentation)]
	], indentation);
}

module.exports = function stringifyTree(tree) {
	return assureArray(tree).map((subTree) => {
		return stringifyNode(subTree, 0);
	}).join("\n");
};