import * as three from "three-js";
import { actor } from "./actor.js";
import { factor } from "./factor.js";

class render_engine {
    #renderer;
    #scene;
    #camera;
    #canvas;
    #actors;
    #player;
    #looped;

    constructor(canvas, context, player) {
        if (!(canvas instanceof HTMLCanvasElement)) {
            throw new TypeError("Canvas must be an HTMLCanvasElement.");
        }

        if (!(context instanceof WebGL2RenderingContext)) {
            throw new TypeError("Context must be WebGL RenderingContext.");
        }

        if (!(player instanceof actor)) {
            throw new TypeError("Player must be an actor.");
        }

        this.#actors = new Array();
        this.#player = player;
        this.#canvas = canvas;
        this.#scene = new three.Scene();
        this.#camera = new three.PerspectiveCamera(75, 1, 0.1, 1000);

        this.#renderer = new three.WebGLRenderer({ 
            canvas: this.#canvas,
            context: context
        });

        this.#renderer.shadowMap.enable = true;
        this.#renderer.shadowMap.type = three.BasicShadowMap;
   
        this.#resize_canvas();
        this.#update_camera();

        window.addEventListener("resize", () => {
            this.#resize_canvas();
            this.#update_camera();
        });
    }

    get player() {
        return this.#player;
    }

    get canvas() {
        return this.#canvas;
    }

    set background(target) {
        if (typeof(target) !== "number") {
            throw new TypeError("Background must be an number.");
        }

        this.#scene.background = target;
    }

    get background() {
        return this.#scene.background;
    }

    #resize_canvas() {
        this.#canvas.width = window.innerWidth;
        this.#canvas.height = window.innerHeight;

        this.#renderer.setSize(this.#canvas.width, this.#canvas.height);
    }

    #update_camera() {
        this.#camera.aspect = this.#canvas.width / this.#canvas.height;
        this.#camera.updateProjectionMatrix();
    }

    run() {
        this.#looped = true;
        this.#loop();
    }

    stop() {
        this.#looped = false;
    }

    #loop() {
        if (!this.#looped) {
            return;
        }

        const start = performance.now();
        this.#render();
        const stop = performance.now();
        const tooked = stop - start;
        const new_frame = 1000 / 60 - tooked;

        if (new_frame <= 0) {
            setTimeout(() => { this.#loop(); }, 1);
            return;
        } 

        setTimeout(() => { this.#loop(); }, new_frame);
    }

    add_factor(target) {
        if (!(target instanceof factor)) {
            throw new TypeError("New factor must be in factor class.");
        }

        this.#actors.push(target);
        this.#scene.add(target.mesh);
    }

    #sync_camera() {
        this.#player.update();

        this.#camera.position.x = this.#player.x;
        this.#camera.position.z = this.#player.y;
        
        this.#camera.rotation.y 
        = three.MathUtils.degToRad(this.#player.rotate);
    }

    #render() {
        this.#sync_camera();

        this.#actors.forEach(actor => {
            actor.loop();
        });

        this.#renderer.render(this.#scene, this.#camera);
    }
}

export { render_engine };