import { tokenize } from "./modules/lexer.js";
import { shunt } from "./modules/parser.js";
import { compute } from "./modules/compute.js";

function evaluate() {
	// TODO: also have enter run this when expr/modulus is focused
	const expr = document.querySelector("#expr");
	const modulus = document.querySelector("#modulus");
	const m = BigInt(modulus.value);

	const tokens = tokenize(expr.value);
	console.log(tokens);

	const result = document.querySelector("#result");
	let queue = [];
	try {
		queue = shunt(tokens);
	} catch(e) {
		result.value = e;
		console.log(e);
		return;
	}

	console.log(queue);

	try {
		result.value = compute(queue, m);
	} catch(e) {
		result.value = e;
		console.log(e);
		return;
	}
}

let currentInput = null;
let selectionStart = null;
let selectionEnd = null;

function setCurrentInput() {
	currentInput = this;
	selectionStart = this.selectionStart;
	selectionEnd = this.selectionEnd;
}

function clear() {
	currentInput.value = "";
	currentInput.focus();
}

function keyPress(c) {
	// FIXME not working with modulus
	// errors in logs on each key press
	// wonder if it's an issue with it being a number type
	currentInput.focus();
	const begin = currentInput.value.slice(0, selectionStart);
	const end = currentInput.value.slice(selectionEnd);
	currentInput.value = begin + c + end;
	currentInput.setSelectionRange(selectionStart+1, selectionStart+1);
}

function backspace() {
	currentInput.focus();
	if (selectionEnd === 0) {
		return;
	}

	let begin = null;
	if (selectionStart === selectionEnd) {
		begin = currentInput.value.slice(0, selectionStart-1);
	} else {
		begin = currentInput.value.slice(0, selectionStart);
	}

	const end = currentInput.value.slice(selectionEnd);

	currentInput.value = begin + end;

	if (selectionStart === 0) {
		currentInput.setSelectionRange(0, 0);
	} else if (selectionStart === selectionEnd) {
		currentInput.setSelectionRange(selectionStart-1, selectionStart-1);
	} else {
		currentInput.setSelectionRange(selectionStart, selectionStart);
	}
}

document.querySelector("#expr").addEventListener("focus", setCurrentInput);
document.querySelector("#modulus").addEventListener("focus", setCurrentInput);

document.querySelector("#zero").addEventListener("click", () => keyPress("0"));
document.querySelector("#one").addEventListener("click", () => keyPress("1"));
document.querySelector("#two").addEventListener("click", () => keyPress("2"));
document.querySelector("#three").addEventListener("click", () => keyPress("3"));
document.querySelector("#four").addEventListener("click", () => keyPress("4"));
document.querySelector("#five").addEventListener("click", () => keyPress("5"));
document.querySelector("#six").addEventListener("click", () => keyPress("6"));
document.querySelector("#seven").addEventListener("click", () => keyPress("7"));
document.querySelector("#eight").addEventListener("click", () => keyPress("8"));
document.querySelector("#nine").addEventListener("click", () => keyPress("9"));

document.querySelector("#plus").addEventListener("click", () => keyPress("+"));
document.querySelector("#minus").addEventListener("click", () => keyPress("-"));
document.querySelector("#times").addEventListener("click", () => keyPress("*"));
document.querySelector("#divide").addEventListener("click", () => keyPress("/"));

document.querySelector("#lparen").addEventListener("click", () => keyPress("("));
document.querySelector("#rparen").addEventListener("click", () => keyPress(")"));

document.querySelector("#pow").addEventListener("click", () => keyPress("^"));

document.querySelector("#clear").addEventListener("click", clear);
document.querySelector("#enter").addEventListener("click", evaluate);

document.querySelector("#backspace").addEventListener("click", backspace);

// TODO implement square root and inverse keys