// SPDX-FileCopyrightText: In 2019, Chris Pressey, the original author of this work, placed it into the public domain.
// SPDX-License-Identifier: Unlicense
// For more information, please refer to <https://unlicense.org/>


/* --[ Constants ]---------------------------------------------------------------- */


const SCREEN_WIDTH = 640;
const SCREEN_HEIGHT = 400;


/* --[ Utility functions ]-------------------------------------------------------- */


function degreesToRadians(deg) {
    return (deg / 360) * Math.PI * 2;
}


function sign(n) {
    return n > 0 ? 1 : (n < 0 ? -1 : 0);
}


function cap(n, absMax) {
    return (Math.abs(n) > absMax) ? absMax * sign(n) : n;
}


function limitWithin(low, high, v) {
    if (v >= low && v < high) {
        return v
    } else if (v < 0) {
        return limitWithin(low, high, v + high);
    } else {
        return limitWithin(low, high, v - high)
    }
}


function updatePosition(obj) {
    return obj.set("x", limitWithin(0, SCREEN_WIDTH, obj.get("x") + obj.get("vx")))
              .set("y", limitWithin(0, SCREEN_HEIGHT, obj.get("y") + obj.get("vy")));
}


function decr(x) {
    return x - 1;
}


function incr(x) {
    return x + 1;
}


function countDown(obj, callback) {
    const obj2 = obj.update("timer", decr);
    return (obj2.get("timer") <= 0) ? callback(obj2) : obj2;
}


function countDownToMode(obj, toMode) {
    return countDown(obj, function(obj2) {
        return obj2.set("mode", toMode);
    });
}


function fireWentDown(action) {
    return (!action.prev.firePressed) && action.firePressed;
}


function fireWentUp(action) {
    return action.prev.firePressed && (!action.firePressed);
}

export {
    SCREEN_WIDTH, SCREEN_HEIGHT,
    degreesToRadians, sign, cap, limitWithin,
    updatePosition,
    decr, incr, countDown, countDownToMode, fireWentDown, fireWentUp
}