var planets = [];
var asteroids = [];
var canvas;
var ctx;

function spaceship(){
    this.location = new vector(500, 500);
    this.velocity = new vector(0, 0);
    this.power = 0.1;
    this.draw = function(){
        ctx.rect(this.location.x-10,this.location.y-10,20,20);
        ctx.stroke();
    }
    this.up = function(){
        this.velocity = this.velocity.add(new vector(0, -this.power));
    }
    this.down = function(){
        this.velocity = this.velocity.add(new vector(0, this.power));
    }
    this.left = function(){
        this.velocity = this.velocity.add(new vector(-this.power, 0));
    }
    this.right = function(){
        this.velocity = this.velocity.add(new vector(this.power, 0));
    }
}

var ss = new spaceship();

function vector(x, y) {
    //konstruuje wektor
    this.x = x;
    this.y = y;
    this.add = function(v){
        return new vector(this.x+v.x, this.y+v.y);
    }
    this.sub = function(v){
        return new vector(this.x-v.x, this.y-v.y);
    }
    this.div = function(n){
        return
    }
    this.dist = function(v){
        dx = this.x - v.x;
        dy = this.y - v.y;

        return Math.sqrt(dx*dx+dy*dy);
    }
}


function planet(location, size){
    //konstruuje planetę
    this.location = location;
    this.size = size;
    this.mass = size;

    this.dist = function(v){
        return this.location.dist(v);
    }
    this.gravity = function(point){
        var tmp = this.location.sub(point);
        tmp.x = (this.mass/(tmp.x))/10000;
        tmp.y = (this.mass/(tmp.y))/10000;
        return tmp;
    }
    this.draw = function(){
    centerX = this.location.x;
    centerY = this.location.y;
    radius = this.size;
    ctx.beginPath();
    ctx.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);
    ctx.fillStyle = 'green';
    ctx.fill();
    ctx.lineWidth = 5;
    ctx.strokeStyle = '#003300';
    ctx.stroke();
    }
}

function asteroid(location, velocity){
    //konstruuje planetę
    this.location = location;
    this.velocity = velocity;
    this.draw = function(){
    centerX = this.location.x;
    centerY = this.location.y;
    radius = 5;
    ctx.beginPath();
    ctx.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);
    ctx.fillStyle = 'red';
    ctx.fill();
    ctx.lineWidth = 5;
    ctx.strokeStyle = '#003300';
    ctx.stroke();
    }
}





function tick(){
//wykonuje sie co klatkę
for (var i = asteroids.length - 1; i >= 0; i--) {
    asteroids[i].location = asteroids[i].location.add(asteroids[i].velocity);
    ss.location = ss.location.add(ss.velocity);
    for (var j = planets.length - 1; j >= 0; j--) {
        asteroids[i].velocity = asteroids[i].velocity.add(planets[j].gravity(asteroids[i].location));
        //ss.velocity = ss.velocity.add(planets[j].gravity(ss.location));
        ctx.moveTo(500,500);
        var tmp = planets[j].gravity(ss.location);
        ctx.lineTo(500+tmp.x*10000000,500+tmp.y*10000000);
        ctx.stroke();
    };
};

//zmień prędkość statku


}


function draw(){
//zaktualizuj canvas
ctx.clearRect(0,0, window.innerWidth, window.innerHeight);
ss.draw();
for (var i = planets.length - 1; i >= 0; i--) {
    planets[i].draw();
};

for (var i = asteroids.length - 1; i >= 0; i--) {
    asteroids[i].draw();
};
}

$(function() {
//po załadowaniu
$("body").keydown(function(e){
//alert(e.keyCode);
var k = e.keyCode;
if(k == 38)
    ss.up();
if(k == 40)
    ss.down();
if(k == 37)
    ss.left();
if(k == 39)
    ss.right();
});
canvas = document.getElementById("board");
ctx = canvas.getContext("2d");
ctx.canvas.width  = window.innerWidth-20;
ctx.canvas.height = window.innerHeight-20;

//planets.push(new planet(new vector(50, 50), 10));
planets.push(new planet(new vector(750, 500), 1));
// planets.push(new planet(new vector(300, 100), 10));
// planets.push(new planet(new vector(100, 355), 10));
// planets.push(new planet(new vector(70, 70), 10));

for(var i=0; i<10; i++){
    var location = new vector(Math.random()*1000, Math.random()*1000);
    var velocity = new vector((Math.random()-0.5)*1, (Math.random()-0.5)*1);
    asteroids.push(new asteroid(location, velocity));
}




var timer = setInterval(function () {
tick();
draw();
}, 1000 / 60); // 60FPS


});