var Example = Example || {};

Example.car = function() {
    var Engine = Matter.Engine,
        Render = Matter.Render,
        Runner = Matter.Runner,
        Composites = Matter.Composites,
        MouseConstraint = Matter.MouseConstraint,
        Mouse = Matter.Mouse,
        Composite = Matter.Composite,
        Bodies = Matter.Bodies;

    // create engine
    var engine = Engine.create(),
        world = engine.world;

    // create renderer
    var render = Render.create({
        element: document.body,
        engine: engine,
        options: {
            width: 800,
            height: 600,
            showAngleIndicator: true,
            showCollisions: true
        }
    });

    Render.run(render);

    // create runner
    var runner = Runner.create();
    Runner.run(runner, engine);

    // add bodies
    Composite.add(world, [
        // walls
        Bodies.rectangle(400, 0, 800, 50, { isStatic: true }),
        Bodies.rectangle(400, 600, 800, 50, { isStatic: true }),
        Bodies.rectangle(800, 300, 50, 600, { isStatic: true }),
        Bodies.rectangle(0, 300, 50, 600, { isStatic: true })
    ]);

    // see car function defined later in this file
    var scale = 0.9;
    Composite.add(world, Example.car.car(150, 100, 150 * scale, 30 * scale, 30 * scale));
    
    scale = 0.8;
    Composite.add(world, Example.car.car(350, 300, 150 * scale, 30 * scale, 30 * scale));
    
    Composite.add(world, [
        Bodies.rectangle(200, 150, 400, 20, { isStatic: true, angle: Math.PI * 0.06, render: { fillStyle: '#060a19' }}),
        Bodies.rectangle(500, 350, 650, 20, { isStatic: true, angle: -Math.PI * 0.06, render: { fillStyle: '#060a19' }}),
        Bodies.rectangle(300, 560, 600, 20, { isStatic: true, angle: Math.PI * 0.04, render: { fillStyle: '#060a19' }})
    ]);

    // add mouse control
    var mouse = Mouse.create(render.canvas),
        mouseConstraint = MouseConstraint.create(engine, {
            mouse: mouse,
            constraint: {
                stiffness: 0.2,
                render: {
                    visible: false
                }
            }
        });

    Composite.add(world, mouseConstraint);

    // keep the mouse in sync with rendering
    render.mouse = mouse;

    // fit the render viewport to the scene
    Render.lookAt(render, {
        min: { x: 0, y: 0 },
        max: { x: 800, y: 600 }
    });

    // context for MatterTools.Demo
    return {
        engine: engine,
        runner: runner,
        render: render,
        canvas: render.canvas,
        stop: function() {
            Matter.Render.stop(render);
            Matter.Runner.stop(runner);
        }
    };
};

Example.car.title = 'Car';
Example.car.for = '>=0.14.2';

/**
* Creates a composite with simple car setup of bodies and constraints.
* @method car
* @param {number} xx
* @param {number} yy
* @param {number} width
* @param {number} height
* @param {number} wheelSize
* @return {composite} A new composite car body
*/
Example.car.car = function(xx, yy, width, height, wheelSize) {
    var Body = Matter.Body,
        Bodies = Matter.Bodies,
        Composite = Matter.Composite,
        Constraint = Matter.Constraint;

    var group = Body.nextGroup(true),
        wheelBase = 20,
        wheelAOffset = -width * 0.5 + wheelBase,
        wheelBOffset = width * 0.5 - wheelBase,
        wheelYOffset = 0;

    var car = Composite.create({ label: 'Car' }),
        body = Bodies.rectangle(xx, yy, width, height, { 
            collisionFilter: {
                group: group
            },
            chamfer: {
                radius: height * 0.5
            },
            density: 0.0002
        });

    var wheelA = Bodies.circle(xx + wheelAOffset, yy + wheelYOffset, wheelSize, { 
        collisionFilter: {
            group: group
        },
        friction: 0.8
    });
                
    var wheelB = Bodies.circle(xx + wheelBOffset, yy + wheelYOffset, wheelSize, { 
        collisionFilter: {
            group: group
        },
        friction: 0.8
    });
                
    var axelA = Constraint.create({
        bodyB: body,
        pointB: { x: wheelAOffset, y: wheelYOffset },
        bodyA: wheelA,
        stiffness: 1,
        length: 0
    });
                    
    var axelB = Constraint.create({
        bodyB: body,
        pointB: { x: wheelBOffset, y: wheelYOffset },
        bodyA: wheelB,
        stiffness: 1,
        length: 0
    });
    
    Composite.addBody(car, body);
    Composite.addBody(car, wheelA);
    Composite.addBody(car, wheelB);
    Composite.addConstraint(car, axelA);
    Composite.addConstraint(car, axelB);

    return car;
};

if (typeof module !== 'undefined') {
    module.exports = Example.car;
}