#!/usr/bin/env gjs -m
// SPDX-License-Identifier: GPL-3.0-or-later
// SPDX-FileCopyrightText: 2008 Robert Carr <carrr@rpi.edu>
// Based on https://gitlab.gnome.org/GNOME/gjs/-/blob/master/examples/calc.js

import Gtk from 'gi://Gtk?version=3.0';

Gtk.init(null);

var calcVal: string | number = '';

function updateDisplay() {
    label.set_markup(`<span size='30000'>${calcVal}</span>`);

    if (calcVal === '')
        label.set_markup("<span size='30000'>0</span>");
}

function clear() {
    calcVal = '';
    updateDisplay();
}

function backspace() {
    calcVal = calcVal.toString();
    calcVal = calcVal.substring(0, calcVal.length - 1);
    updateDisplay();
}

function pressedEquals() {
    calcVal = calcVal.toString();
    calcVal = calcVal.replace('sin', 'Math.sin');
    calcVal = calcVal.replace('cos', 'Math.cos');
    calcVal = calcVal.replace('tan', 'Math.tan');
    calcVal = eval(calcVal as string) as number;
    // Avoid ridiculous amounts of precision from toString.
    if (Number(calcVal) === Math.floor(Number(calcVal)))
        calcVal = Math.floor(calcVal);
    else // bizarrely gjs loses str.toFixed() somehow?!
        calcVal = Math.floor(calcVal * 10000) / 10000;
    label.set_markup(`<span size='30000'>${calcVal}</span>`);
}

function pressedOperator(button: Gtk.Button) {
    calcVal += button.label || '';
    updateDisplay();
}

function pressedNumber(button: Gtk.Button) {
    calcVal = (calcVal === 0 ? '' : calcVal) + (button.label || '');
    updateDisplay();
}

function swapSign() {
    calcVal = calcVal.toString();
    calcVal = calcVal[0] === '-' ? calcVal.toString().substring(1) : `-${calcVal}`;
    updateDisplay();
}

function randomNum() {
    calcVal = `${Math.floor(Math.random() * 1000)}`;
    updateDisplay();
}

function packButtons(buttons: Gtk.Button[], vbox: Gtk.VBox) {
    var hbox = new Gtk.HBox();

    hbox.homogeneous = true;

    vbox.pack_start(hbox, true, true, 2);

    for (let i = 0; i <= 4; i++)
        hbox.pack_start(buttons[i], true, true, 1);
}

function createButton(str: string, func: ((button: Gtk.Button) => void)) {
    var btn = new Gtk.Button({label: str});
    btn.connect('clicked', func);
    return btn;
}

function createButtons() {
    var vbox = new Gtk.VBox({homogeneous: true});

    packButtons([
        createButton('(', pressedNumber),
        createButton('←', backspace),
        createButton('↻', randomNum),
        createButton('Clr', clear),
        createButton('±', swapSign),
    ], vbox);

    packButtons([
        createButton(')', pressedNumber),
        createButton('7', pressedNumber),
        createButton('8', pressedNumber),
        createButton('9', pressedNumber),
        createButton('/', pressedOperator),
    ], vbox);

    packButtons([
        createButton('sin(', pressedNumber),
        createButton('4', pressedNumber),
        createButton('5', pressedNumber),
        createButton('6', pressedNumber),
        createButton('*', pressedOperator),
    ], vbox);

    packButtons([
        createButton('cos(', pressedNumber),
        createButton('1', pressedNumber),
        createButton('2', pressedNumber),
        createButton('3', pressedNumber),
        createButton('-', pressedOperator),
    ], vbox);

    packButtons([
        createButton('tan(', pressedNumber),
        createButton('0', pressedNumber),
        createButton('.', pressedNumber),
        createButton('=', pressedEquals),
        createButton('+', pressedOperator),
    ], vbox);

    return vbox;
}

var win = new Gtk.Window({
    title: 'Calculator',
    resizable: false,
    opacity: 0.6,
});

win.resize(250, 250);
win.connect('destroy', () => Gtk.main_quit());

var label = new Gtk.Label({label: ''});
label.set_alignment(1, 0);
updateDisplay();

var mainvbox = new Gtk.VBox();
mainvbox.pack_start(label, false, true, 1);
mainvbox.pack_start(new Gtk.HSeparator(), false, true, 5);
mainvbox.pack_start(createButtons(), true, true, 2);

win.add(mainvbox);
win.show_all();
Gtk.main();