// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/* global mat4, WGLUProgram */

/*
Like CubeSea, but designed around a users physical space. One central platform
that maps to the users play area and several floating cubes that sit just
those boundries (just to add visual interest)
*/
window.VRCubeIsland = (function () {
  "use strict";

  var cubeIslandVS = [
    "uniform mat4 projectionMat;",
    "uniform mat4 modelViewMat;",
    "attribute vec3 position;",
    "attribute vec2 texCoord;",
    "varying vec2 vTexCoord;",

    "void main() {",
    "  vTexCoord = texCoord;",
    "  gl_Position = projectionMat * modelViewMat * vec4( position, 1.0 );",
    "}",
  ].join("\n");

  var cubeIslandFS = [
    "precision mediump float;",
    "uniform sampler2D diffuse;",
    "varying vec2 vTexCoord;",

    "void main() {",
    "  gl_FragColor = texture2D(diffuse, vTexCoord);",
    "}",
  ].join("\n");

  var CubeIsland = function (gl, texture, width, depth) {
    this.gl = gl;

    this.statsMat = mat4.create();

    this.texture = texture;

    this.program = new WGLUProgram(gl);
    this.program.attachShaderSource(cubeIslandVS, gl.VERTEX_SHADER);
    this.program.attachShaderSource(cubeIslandFS, gl.FRAGMENT_SHADER);
    this.program.bindAttribLocation({
      position: 0,
      texCoord: 1
    });
    this.program.link();

    this.vertBuffer = gl.createBuffer();
    this.indexBuffer = gl.createBuffer();

    this.resize(width, depth);
  };

  CubeIsland.prototype.resize = function (width, depth) {
    var gl = this.gl;

    this.width = width;
    this.depth = depth;

    var cubeVerts = [];
    var cubeIndices = [];

    // Build a single box.
    function appendBox (left, bottom, back, right, top, front) {
      // Bottom
      var idx = cubeVerts.length / 5.0;
      cubeIndices.push(idx, idx + 1, idx + 2);
      cubeIndices.push(idx, idx + 2, idx + 3);

      cubeVerts.push(left, bottom, back, 0.0, 1.0);
      cubeVerts.push(right, bottom, back, 1.0, 1.0);
      cubeVerts.push(right, bottom, front, 1.0, 0.0);
      cubeVerts.push(left, bottom, front, 0.0, 0.0);

      // Top
      idx = cubeVerts.length / 5.0;
      cubeIndices.push(idx, idx + 2, idx + 1);
      cubeIndices.push(idx, idx + 3, idx + 2);

      cubeVerts.push(left, top, back, 0.0, 0.0);
      cubeVerts.push(right, top, back, 1.0, 0.0);
      cubeVerts.push(right, top, front, 1.0, 1.0);
      cubeVerts.push(left, top, front, 0.0, 1.0);

      // Left
      idx = cubeVerts.length / 5.0;
      cubeIndices.push(idx, idx + 2, idx + 1);
      cubeIndices.push(idx, idx + 3, idx + 2);

      cubeVerts.push(left, bottom, back, 0.0, 1.0);
      cubeVerts.push(left, top, back, 0.0, 0.0);
      cubeVerts.push(left, top, front, 1.0, 0.0);
      cubeVerts.push(left, bottom, front, 1.0, 1.0);

      // Right
      idx = cubeVerts.length / 5.0;
      cubeIndices.push(idx, idx + 1, idx + 2);
      cubeIndices.push(idx, idx + 2, idx + 3);

      cubeVerts.push(right, bottom, back, 1.0, 1.0);
      cubeVerts.push(right, top, back, 1.0, 0.0);
      cubeVerts.push(right, top, front, 0.0, 0.0);
      cubeVerts.push(right, bottom, front, 0.0, 1.0);

      // Back
      idx = cubeVerts.length / 5.0;
      cubeIndices.push(idx, idx + 2, idx + 1);
      cubeIndices.push(idx, idx + 3, idx + 2);

      cubeVerts.push(left, bottom, back, 1.0, 1.0);
      cubeVerts.push(right, bottom, back, 0.0, 1.0);
      cubeVerts.push(right, top, back, 0.0, 0.0);
      cubeVerts.push(left, top, back, 1.0, 0.0);

      // Front
      idx = cubeVerts.length / 5.0;
      cubeIndices.push(idx, idx + 1, idx + 2);
      cubeIndices.push(idx, idx + 2, idx + 3);

      cubeVerts.push(left, bottom, front, 0.0, 1.0);
      cubeVerts.push(right, bottom, front, 1.0, 1.0);
      cubeVerts.push(right, top, front, 1.0, 0.0);
      cubeVerts.push(left, top, front, 0.0, 0.0);
    }

    // Appends a cube with the given centerpoint and size.
    function appendCube (x, y, z, size) {
      var halfSize = size * 0.5;
      appendBox(x - halfSize, y - halfSize, z - halfSize,
                x + halfSize, y + halfSize, z + halfSize);
    }

    // Main "island", covers where the user can safely stand. Top of the cube
    // (the ground the user stands on) should be at Y=0 to align with users
    // floor. X=0 and Z=0 should be at the center of the users play space.
    appendBox(-width * 0.5, -width, -depth * 0.5, width * 0.5, 0, depth * 0.5);

    // A sprinkling of other cubes to make things more visually interesting.
    appendCube(1.1, 0.3, (-depth * 0.5) - 0.8, 0.5);
    appendCube(-0.5, 1.0, (-depth * 0.5) - 0.9, 0.75);
    appendCube(0.6, 1.5, (-depth * 0.5) - 0.6, 0.4);
    appendCube(-1.0, 0.5, (-depth * 0.5) - 0.5, 0.2);

    appendCube((-width * 0.5) - 0.8, 0.3, -1.1, 0.5);
    appendCube((-width * 0.5) - 0.9, 1.0, 0.5, 0.75);
    appendCube((-width * 0.5) - 0.6, 1.5, -0.6, 0.4);
    appendCube((-width * 0.5) - 0.5, 0.5, 1.0, 0.2);

    appendCube((width * 0.5) + 0.8, 0.3, 1.1, 0.5);
    appendCube((width * 0.5) + 0.9, 1.0, -0.5, 0.75);
    appendCube((width * 0.5) + 0.6, 1.5, 0.6, 0.4);
    appendCube((width * 0.5) + 0.5, 0.5, -1.0, 0.2);

    appendCube(1.1, 1.4, (depth * 0.5) + 0.8, 0.5);
    appendCube(-0.5, 1.0, (depth * 0.5) + 0.9, 0.75);
    appendCube(0.6, 0.4, (depth * 0.5) + 0.6, 0.4);


    gl.bindBuffer(gl.ARRAY_BUFFER, this.vertBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(cubeVerts), gl.STATIC_DRAW);

    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeIndices), gl.STATIC_DRAW);

    this.indexCount = cubeIndices.length;
  };

  CubeIsland.prototype.render = function (projectionMat, modelViewMat, stats) {
    var gl = this.gl;
    var program = this.program;

    program.use();

    gl.uniformMatrix4fv(program.uniform.projectionMat, false, projectionMat);
    gl.uniformMatrix4fv(program.uniform.modelViewMat, false, modelViewMat);

    gl.bindBuffer(gl.ARRAY_BUFFER, this.vertBuffer);
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.indexBuffer);

    gl.enableVertexAttribArray(program.attrib.position);
    gl.enableVertexAttribArray(program.attrib.texCoord);

    gl.vertexAttribPointer(program.attrib.position, 3, gl.FLOAT, false, 20, 0);
    gl.vertexAttribPointer(program.attrib.texCoord, 2, gl.FLOAT, false, 20, 12);

    gl.activeTexture(gl.TEXTURE0);
    gl.uniform1i(this.program.uniform.diffuse, 0);
    gl.bindTexture(gl.TEXTURE_2D, this.texture);

    gl.drawElements(gl.TRIANGLES, this.indexCount, gl.UNSIGNED_SHORT, 0);

    if (stats) {
      // To ensure that the FPS counter is visible in VR mode we have to
      // render it as part of the scene.
      mat4.fromTranslation(this.statsMat, [0, 1.5, -this.depth * 0.5]);
      mat4.scale(this.statsMat, this.statsMat, [0.5, 0.5, 0.5]);
      mat4.rotateX(this.statsMat, this.statsMat, -0.75);
      mat4.multiply(this.statsMat, modelViewMat, this.statsMat);
      stats.render(projectionMat, this.statsMat);
    }
  };

  return CubeIsland;
})();