// The following embedded xml is for the editor and describes how the behavior can be edited:
// Supported types are: int, float, string, bool, color, vect3d, scenenode, texture, action
/*
    <behavior jsname="behavior_WWoble" description="Weapon wobble demo">
        <property name="gunNode" type="scenenode" default="" />
    </behavior>
*/

// define constants
const KEY_W = 87;
const KEY_S = 83;
const KEY_A = 65;
const KEY_D = 68;

var behavior_WWoble = function () {
    this.lastTime = null;
    this.curWobbleDelta = 0;
    this.lerpIndex = 0.3;

    // WASD
    // TODO: do the same for arrow keys
    this.movementKeysStates = [false, false, false, false];
};

behavior_WWoble.prototype.onAnimate = function (node, timeMs) {
    if (!this.lastTime) {
        this.lastTime = timeMs;
        // get initial position on the first frame
        this.gunInitPos = ccbGetSceneNodeProperty(this.gunNode, 'Position');
        return false;
    }

    var delta = timeMs - this.lastTime;
    this.lastTime = timeMs;
    if (delta > 200) delta = 200;

    // increment curWobbleDelta every frame
    // reset it if it's greater than 2 * PI 
    // it's used to offset gun position relative to the initial position
    this.curWobbleDelta += delta * 0.01;
    if (this.curWobbleDelta > 2 * Math.PI) this.curWobbleDelta -= 2 * Math.PI;

    // get current gun position
    const gunPos = ccbGetSceneNodeProperty(this.gunNode, 'Position');
    // yOffset is current gun offset for this frame 
    let yOffset = 0;

    // check if any of moving keys are pressed
    if (this.movementKeysStates.some(function (key) { return key; })) {
        // if currently moving - calculate offset
        yOffset = Math.sin(this.curWobbleDelta) * 0.2;
    } else {
        // if not moving offset should be 0, i.e initial position
        // curWobbleDelta is reset to 0, since it's required to move from 0 position
        // in case player stops
        this.curWobbleDelta = 0;
    }

    // set gun position considering the calculated offset
    // lerp function (linear interpolation) with coefficient lerpIndex
    // is used in order to make it change smooth if value change by a big number
    // for example if player stops
    ccbSetSceneNodeProperty(
        this.gunNode,
        'Position',
        this.gunInitPos.x,
        lerp(gunPos.y, this.gunInitPos.y + yOffset, this.lerpIndex),
        this.gunInitPos.z);

    return true;
}

// update movement keys states based on user input
behavior_WWoble.prototype.onKeyEvent = function (key, pressed) {
    if (key === KEY_W) this.movementKeysStates[0] = pressed;
    if (key === KEY_A) this.movementKeysStates[1] = pressed;
    if (key === KEY_S) this.movementKeysStates[2] = pressed;
    if (key === KEY_D) this.movementKeysStates[3] = pressed;
}

function lerp(prev, next, delta) {
    return prev + delta * (next - prev);
}