/*
Copyright (C) 2025 filifa

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/
import { tokenize } from "./modules/lexer.js";
import { shunt } from "./modules/parser.js";

function evaluate() {
	const expr = document.querySelector("#expr");
	const modulus = document.querySelector("#modulus");
	const result = document.querySelector("#result");

	const m = BigInt(modulus.value);
	if (m <= 0n) {
		const e = Error("invalid modulus")
		result.value = e;
		console.log(e);
		return;
	}

	const tokens = tokenize(expr.value);
	console.log(tokens);
	let queue = [];
	try {
		queue = shunt(tokens);
	} catch(e) {
		result.value = e;
		console.log(e);
		return;
	}

	console.log(queue);

	worker.postMessage({command: "compute", queue, m});
	result.value = "calculating...";
}

const expr = document.querySelector("#expr");
let selectionStart = 0;
let selectionEnd = 0;

function setupExprInput() {
	selectionStart = expr.selectionStart;
	selectionEnd = expr.selectionEnd;
	switchButtons(true);
}

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

function keyPress(c) {
	expr.focus();
	const begin = expr.value.slice(0, selectionStart);
	const end = expr.value.slice(selectionEnd);
	expr.value = begin + c + end;
	expr.setSelectionRange(selectionStart+c.length, selectionStart+c.length);
}

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

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

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

	expr.value = begin + end;

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

function evalOnEnter(e) {
	if (e.key === "Enter") {
		evaluate();
	}
}

function switchButtons(enabled) {
	for (const btn of document.querySelectorAll("#main-buttons button")) {
		btn.disabled = !enabled;
	}

	for (const btn of document.querySelectorAll("#extra-buttons button")) {
		btn.disabled = !enabled;
	}
}

const worker = new Worker("./workers/compute.js");
worker.addEventListener("message", (message) => {
	document.querySelector("#result").value = message.data;
});

document.querySelector("#expr").addEventListener("focus", setupExprInput);
document.querySelector("#expr").addEventListener("keyup", (e) => evalOnEnter(e));

document.querySelector("#modulus").addEventListener("focus", () => switchButtons(false));
document.querySelector("#modulus").addEventListener("keyup", (e) => evalOnEnter(e));

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("#inv").addEventListener("click", () => keyPress("^-1"));
document.querySelector("#sqrt").addEventListener("click", () => keyPress("sqrt("));
document.querySelector("#ord").addEventListener("click", () => keyPress("ord("));

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

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