/**
 * @param sizeX Number
 * @param sizeY Number
 * @param matrix matrix 2D Array with height data (Column Major)
 * @param elementSize Number
 * @param heightScale Number
 * @constructor
 */
R3.D3.Heightmap = function Heightmap(
    sizeX,
    sizeY,
    matrix,
    elementSize,
    heightScale
) {
    if (typeof sizeX == 'undefined') {
        sizeX = 0;
    }
    this.sizeX = sizeX;

    if (typeof sizeY == 'undefined') {
        sizeY = 0;
    }
    this.sizeY = sizeY;

    if (typeof matrix == 'undefined') {
        matrix = [];
    }
    this.matrix = matrix;

    if (typeof elementSize == 'undefined') {
        elementSize = 10;
    }
    this.elementSize = elementSize;

    if (typeof heightScale == 'undefined') {
        heightScale = 15;
    }
    this.elementSize = heightScale;
};


R3.D3.Heightmap.prototype.toApiHeightMap = function() {
    //TODO - create API heightmap someday
    return {
        sizeX: this.sizeX,
		sizeY: this.sizeY,
		matrix: this.matrix,
		elementSize: this.elementSize,
		heightScale: this.heightScale
    }
};

/**
 * Creates a graphics instance mesh from the graphics, physics and physics shape
 * @param graphics R3.D3.Graphics
 * @param shape R3.D3.Shape
 * @param engine R3.D3.Engine
 * @returns {THREE.Mesh|this.meshes}
 */
R3.D3.Heightmap.GenerateInstanceMesh = function(
    graphics,
    shape,
    engine
) {
    graphics.isNotThreeThrow();
    engine.isNotCannonThrow();

    var geometry = new graphics.instance.Geometry();

    var v0 = new engine.instance.Vec3();
    var v1 = new engine.instance.Vec3();
    var v2 = new engine.instance.Vec3();

     for (var xi = 0; xi < shape.instance.data.length - 1; xi++) {
        for (var yi = 0; yi < shape.instance.data[xi].length - 1; yi++) {
            for (var k = 0; k < 2; k++) {
                shape.instance.getConvexTrianglePillar(xi, yi, k===0);
                v0.copy(shape.instance.pillarConvex.vertices[0]);
                v1.copy(shape.instance.pillarConvex.vertices[1]);
                v2.copy(shape.instance.pillarConvex.vertices[2]);
                v0.vadd(shape.instance.pillarOffset, v0);
                v1.vadd(shape.instance.pillarOffset, v1);
                v2.vadd(shape.instance.pillarOffset, v2);
                geometry.vertices.push(
                    new graphics.instance.Vector3(v0.x, v0.y, v0.z),
                    new graphics.instance.Vector3(v1.x, v1.y, v1.z),
                    new graphics.instance.Vector3(v2.x, v2.y, v2.z)
                );
                var i = geometry.vertices.length - 3;
                geometry.faces.push(new graphics.instance.Face3(i, i+1, i+2));
            }
        }
    }
    geometry.computeBoundingSphere();
    geometry.computeFaceNormals();

    return new graphics.instance.Mesh(
        geometry,
        new graphics.instance.MeshNormalMaterial(
            {
                wireframe: false,
                shading : graphics.instance.SmoothShading
            }
        )
    );
};

/**
 * Needs an RGBA
 * @param imagePath string
 * @param heightScale
 * @param callback
 * @constructor
 */
R3.D3.Heightmap.GenerateHeightmapDataFromImage = function (
    imagePath,
    heightScale,
    callback
) {
    var img = new Image();

    img.onload = function () {

        var canvas = document.createElement('canvas');
        canvas.width = img.width;
        canvas.height = img.height;

        var context = canvas.getContext('2d');
        context.drawImage(img, 0, 0);

        var imgd = context.getImageData(0, 0, img.width, img.height);
        var pixels = imgd.data;

        var heightList = [];
        for (var i = 0, n = pixels.length; i < n; i += (4)) {
            heightList.push(pixels[i]);
        }

        var matrix = [];
        var sizeX = img.width,
            sizeY = img.height;

        for (var x = 0; x < sizeX; x++) {
            matrix.push([]);
            for (var j = 0; j < sizeY; j++) {
                var height = (heightList[(sizeX - x) + j * sizeY] / 255) * heightScale;
                matrix[x].push(height);
            }
        }

        // todo: delete canvas here

        callback(
            new R3.D3.Heightmap(
                sizeX,
                sizeY,
                matrix,
                10,
                heightScale
            )
        );
    };

    img.src = imagePath;
};