'use strict';

class Vector{
    constructor(x, y){
        this.x = x;
        this.y = y;
    }

    scalarProduct(other){
        return this.x*other.x + this.y*other.y;
    }

    magnitude(){
        return Math.sqrt(this.x**2 + this.y**2);
    }

    //vector product would be useless because the resultant would be in the z-axis

    angle(other = new Vector(1, 0)){ //need some magnitude for origin vector to avoid division by 0
        //cosθ = a.b/|a||b| 
        return Math.acos(this.scalarProduct(other)/(this.magnitude()*other.magnitude()));
    }

    //figuring out coordinates from angle and distance
    positionFromAngle(angle, distance){
        return new Vector((this.x + distance) * Math.cos(angle), (this.y+distance)*Math.sin(angle));
    }
}

class Asteroid{

    //FIXME: Asteroid generation is very wonky
    constructor(size, position, edges=5){
        this.size = size;
        this.edges = edges;
        this.position = position;
        this.nodes = [this.position];

        for(let i=0; i<this.edges; i++){
            let pos = this.nodes[i].positionFromAngle( this.nodes[i].angle() + (Math.max(Math.PI/6, Math.random()*(Math.PI/3))), 5);
            this.nodes.push(pos);
        }
    }

    draw(ctx){
        ctx.beginPath();
        this.nodes.forEach((node, _) => {
            ctx.lineTo(node.x,node.y);
        })
        ctx.closePath();
        ctx.stroke();
    }
}

//initializing canvas
const canvas = document.getElementById("canvas");

canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

const ctx = canvas.getContext("2d");

const asteroid = new Asteroid(50, new Vector(300, 240));

function animate(){
    requestAnimationFrame(animate);
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    asteroid.draw(ctx);
}

animate();