var Example = Example || {};

Example.softBody = 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: false
        }
    });

    Render.run(render);

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

    // add bodies
    var particleOptions = { 
        friction: 0.05,
        frictionStatic: 0.1,
        render: { visible: true } 
    };

    Composite.add(world, [
        // see softBody function defined later in this file
        Example.softBody.softBody(250, 100, 5, 5, 0, 0, true, 18, particleOptions),
        Example.softBody.softBody(400, 300, 8, 3, 0, 0, true, 15, particleOptions),
        Example.softBody.softBody(250, 400, 4, 4, 0, 0, true, 15, particleOptions),
        // 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 })
    ]);

    // add mouse control
    var mouse = Mouse.create(render.canvas),
        mouseConstraint = MouseConstraint.create(engine, {
            mouse: mouse,
            constraint: {
                stiffness: 0.9,
                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.softBody.title = 'Soft Body';
Example.softBody.for = '>=0.14.2';

/**
* Creates a simple soft body like object.
* @method softBody
* @param {number} xx
* @param {number} yy
* @param {number} columns
* @param {number} rows
* @param {number} columnGap
* @param {number} rowGap
* @param {boolean} crossBrace
* @param {number} particleRadius
* @param {} particleOptions
* @param {} constraintOptions
* @return {composite} A new composite softBody
*/
Example.softBody.softBody = function(xx, yy, columns, rows, columnGap, rowGap, crossBrace, particleRadius, particleOptions, constraintOptions) {
    var Common = Matter.Common,
        Composites = Matter.Composites,
        Bodies = Matter.Bodies;

    particleOptions = Common.extend({ inertia: Infinity }, particleOptions);
    constraintOptions = Common.extend({ stiffness: 0.2, render: { type: 'line', anchors: false } }, constraintOptions);

    var softBody = Composites.stack(xx, yy, columns, rows, columnGap, rowGap, function(x, y) {
        return Bodies.circle(x, y, particleRadius, particleOptions);
    });

    Composites.mesh(softBody, columns, rows, crossBrace, constraintOptions);

    softBody.label = 'Soft Body';

    return softBody;
};

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