/*
 * Copyright (c) 2017 Samsung Electronics Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#include <dali/dali.h>
#include <dali-toolkit/dali-toolkit.h>

#include "look-camera.h"

using namespace Dali;
using namespace Toolkit;

namespace
{

/*
 * Vertex shader for a textured cube
 */
const char* VERTEX_SHADER_CUBE = DALI_COMPOSE_SHADER(
attribute mediump vec3 aPosition;\n // DALi shader builtin
attribute mediump vec2 aTexCoord;\n // DALi shader builtin
uniform   mediump mat4 uMvpMatrix;\n // DALi shader builtin
uniform   mediump vec3 uSize;\n // DALi shader builtin
\n
varying mediump vec2 vTexCoord;\n
void main()\n
{\n
  mediump vec4 vertexPosition = vec4(aPosition, 1.0);\n
  vertexPosition.xyz *= uSize;\n
  vTexCoord = aTexCoord;\n
  gl_Position = uMvpMatrix * vertexPosition;\n
}\n
);

/*
 * Fragment shader for a textured cube
 */
const char* FRAGMENT_SHADER_CUBE = DALI_COMPOSE_SHADER(
uniform sampler2D uTexture;\n
\n
varying mediump vec2 vTexCoord;\n
void main()\n
{\n
  mediump vec4 texColor = texture2D( uTexture, vTexCoord );\n
  gl_FragColor = texColor;\n
}\n
);

/*
 * Vertex shader for a skybox
 */
const char* VERTEX_SHADER_SKYBOX = DALI_COMPOSE_SHADER(
attribute mediump vec3 aPosition;\n // DALi shader builtin
uniform   mediump mat4 uMvpMatrix;\n // DALi shader builtin
\n
varying mediump vec3 vTexCoord;\n
void main()\n
{\n
  vTexCoord.x =  aPosition.x;\n
  vTexCoord.y = -aPosition.y;\n // convert to GL coords
  vTexCoord.z =  aPosition.z;\n

  mediump vec4 vertexPosition = vec4(aPosition, 1.0);\n
  vec4 clipSpacePosition = uMvpMatrix * vertexPosition;\n
  gl_Position = clipSpacePosition.xyww;\n // Writes 1.0, the maximum depth value, into the depth buffer.
                                          // This is an optimization to avoid running the fragment shader
                                          // for the pixels hidden by the scene's objects.
}\n
);

/*
 * Fragment shader for a skybox
 */
const char* FRAGMENT_SHADER_SKYBOX = DALI_COMPOSE_SHADER(
uniform samplerCube uSkyBoxTexture;\n
\n
varying mediump vec3 vTexCoord;\n
void main()\n
{\n
  mediump vec4 texColor = textureCube( uSkyBoxTexture, vTexCoord );\n
  gl_FragColor = texColor;\n
}\n
);

const float CAMERA_DEFAULT_FOV(    60.0f );
const float CAMERA_DEFAULT_NEAR(    0.1f );
const float CAMERA_DEFAULT_FAR(  1000.0f );
const Vector3 CAMERA_DEFAULT_POSITION( 0.0f, 0.0f, 100.0f );

const char* TEXTURE_URL = DEMO_IMAGE_DIR "wood.png";

const unsigned int SKYBOX_FACE_COUNT = 6;
const unsigned int SKYBOX_FACE_WIDTH  = 2048;
const unsigned int SKYBOX_FACE_HEIGHT = 2048;

/*
 * Credit to Joey do Vries for the following cubemap images
 * Take from git://github.com/JoeyDeVries/LearnOpenGL.git
 * The images are licensed under the terms of the CC BY 4.0 license:
 * https://creativecommons.org/licenses/by/4.0/
 */
const char* SKYBOX_FACES[ SKYBOX_FACE_COUNT ] =
{
  DEMO_IMAGE_DIR "lake_right.jpg",
  DEMO_IMAGE_DIR "lake_left.jpg",
  DEMO_IMAGE_DIR "lake_top.jpg",
  DEMO_IMAGE_DIR "lake_bottom.jpg",
  DEMO_IMAGE_DIR "lake_back.jpg",
  DEMO_IMAGE_DIR "lake_front.jpg"
};

}

// This example shows how to create a skybox
//
// Recommended screen size on desktop: 1280x720
//
class TexturedCubeController : public ConnectionTracker
{
public:

  TexturedCubeController( Application& application )
  : mApplication( application )
  {
    // Connect to the Application's Init signal
    mApplication.InitSignal().Connect( this, &TexturedCubeController::Create );
  }

  ~TexturedCubeController()
  {
    // Nothing to do here;
  }

  // The Init signal is received once (only) during the Application lifetime
  void Create( Application& application )
  {
    // Disable indicator.
    // It avoids reposition the camera to fit with the indicator height.
    Dali::Window winHandle = application.GetWindow();
    winHandle.ShowIndicator( Dali::Window::INVISIBLE );

    // Get a handle to the stage
    Stage stage = Stage::GetCurrent();
    stage.SetBackgroundColor( Color::WHITE );

    // Step 1. Setup camera
    SetupCamera();

    // Step 2. Create shaders
    CreateShaders();

    // Step 3. Create geometry
    CreateCubeGeometry();
    CreateSkyboxGeometry();

    // Step 4. Display first a cube at the world origin.
    //         The write on the depth buffer is enabled.
    DisplayCube();

    // Step 5. Display last the skybox surrounding the camera.
    //         The depth test is enabled, the shader sets 1.0, which is the maximum depth and
    //         the depth function is set to LESS or EQUAL so the fragment shader will run only
    //         in those pixels that any other object has written on them.
    DisplaySkybox();

    // Step 6. Play animation to rotate the cube
    PlayAnimation();

    // Respond to key events
    stage.KeyEventSignal().Connect( this, &TexturedCubeController::OnKeyEvent );
  }

  /**
   * @brief Called when any key event is received
   *
   * Will use this to quit the application if Back or the Escape key is received
   * @param[in] event The key event information
   */
  void OnKeyEvent( const KeyEvent& event )
  {
    if( event.state == KeyEvent::Down )
    {
      if ( IsKey( event, Dali::DALI_KEY_ESCAPE ) || IsKey( event, Dali::DALI_KEY_BACK ) )
      {
        mApplication.Quit();
      }
    }
  }

  /**
   * @brief Setup a perspective camera pointing in the negative Z direction
   */
  void SetupCamera()
  {
    Stage stage = Stage::GetCurrent();

    RenderTask renderTask = stage.GetRenderTaskList().GetTask( 0 );
    renderTask.SetCullMode( false ); // avoid frustum culling affecting the skybox

    mCamera.Initialise( CAMERA_DEFAULT_POSITION, CAMERA_DEFAULT_FOV, CAMERA_DEFAULT_NEAR, CAMERA_DEFAULT_FAR );
  }

  /**
   * Creates a shader using inlined variable VERTEX_SHADER and FRAGMENT_SHADER
   *
   * Shaders are very basic and all they do is transforming vertices and sampling
   * a texture.
   */
  void CreateShaders()
  {
    mShaderCube   = Shader::New( VERTEX_SHADER_CUBE, FRAGMENT_SHADER_CUBE );
    mShaderSkybox = Shader::New( VERTEX_SHADER_SKYBOX, FRAGMENT_SHADER_SKYBOX );
  }

  /**
   * @brief CreateCubeGeometry
   * This function creates a cube geometry including texture coordinates.
   * Also it demonstrates using the indexed draw feature by setting an index array.
   */
  void CreateCubeGeometry()
  {
    struct Vertex
    {
      Vector3 aPosition;
      Vector2 aTexCoord;
    };

    Vertex vertices[] = {
      { Vector3(  1.0f,-1.0f,-1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f, 1.0f,-1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f, 1.0f,-1.0f ), Vector2( 0.0, 1.0 ) },
      { Vector3( -1.0f, 1.0f, 1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3(  1.0f,-1.0f, 1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f, 1.0f, 1.0f ), Vector2( 0.0, 1.0 ) },
      { Vector3(  1.0f, 1.0f, 1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3(  1.0f,-1.0f,-1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f, 1.0f,-1.0f ), Vector2( 0.0, 1.0 ) },
      { Vector3(  1.0f,-1.0f, 1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f,-1.0f,-1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f,-1.0f,-1.0f ), Vector2( 0.0, 1.0 ) },
      { Vector3( -1.0f,-1.0f,-1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f, 1.0f, 1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3( -1.0f, 1.0f,-1.0f ), Vector2( 0.0, 1.0 ) },
      { Vector3(  1.0f, 1.0f,-1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f, 1.0f, 1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f, 1.0f, 1.0f ), Vector2( 0.0, 1.0 ) },
      { Vector3(  1.0f,-1.0f,-1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f,-1.0f,-1.0f ), Vector2( 1.0, 0.0 ) },
      { Vector3( -1.0f, 1.0f,-1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3( -1.0f, 1.0f, 1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f,-1.0f, 1.0f ), Vector2( 1.0, 0.0 ) },
      { Vector3(  1.0f,-1.0f, 1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f, 1.0f, 1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3(  1.0f,-1.0f, 1.0f ), Vector2( 1.0, 0.0 ) },
      { Vector3(  1.0f,-1.0f,-1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f,-1.0f, 1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f,-1.0f, 1.0f ), Vector2( 1.0, 0.0 ) },
      { Vector3( -1.0f,-1.0f,-1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3( -1.0f,-1.0f,-1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f,-1.0f, 1.0f ), Vector2( 1.0, 0.0 ) },
      { Vector3( -1.0f, 1.0f, 1.0f ), Vector2( 0.0, 0.0 ) },
      { Vector3(  1.0f, 1.0f,-1.0f ), Vector2( 1.0, 1.0 ) },
      { Vector3( -1.0f, 1.0f,-1.0f ), Vector2( 1.0, 0.0 ) },
      { Vector3( -1.0f, 1.0f, 1.0f ), Vector2( 0.0, 0.0 ) },
    };

    PropertyBuffer vertexBuffer = PropertyBuffer::New( Property::Map()
                                                       .Add( "aPosition", Property::VECTOR3 )
                                                       .Add( "aTexCoord", Property::VECTOR2 ) );
    vertexBuffer.SetData( vertices, sizeof(vertices) / sizeof(Vertex) );

    // create indices
    const unsigned short INDEX_CUBE[] = {
      2, 1, 0,
      5, 4, 3,
      8, 7, 6,
      11, 10, 9,
      14, 13, 12,
      17, 16, 15,
      20, 19, 18,
      23, 22, 21,
      26, 25, 24,
      29, 28, 27,
      32, 31, 30,
      35, 34, 33
    };

    mGeometry = Geometry::New();
    mGeometry.AddVertexBuffer( vertexBuffer );
    mGeometry.SetIndexBuffer( INDEX_CUBE,
                              sizeof(INDEX_CUBE)/sizeof(INDEX_CUBE[0]) );
    mGeometry.SetType( Geometry::TRIANGLES );
  }

  /**
   * @brief CreateCubeGeometry
   * This function creates a cube geometry including texture coordinates.
   * Also it demonstrates using the indexed draw feature by setting an index array.
   */
  void CreateSkyboxGeometry()
  {
    struct Vertex
    {
      Vector3 aPosition;
    };

    Vertex skyboxVertices[] = {
        // back
        { Vector3(  -1.0f,  1.0f, -1.0f ) },
        { Vector3(  -1.0f, -1.0f, -1.0f ) },
        { Vector3(   1.0f, -1.0f, -1.0f ) },
        { Vector3(   1.0f, -1.0f, -1.0f ) },
        { Vector3(   1.0f,  1.0f, -1.0f ) },
        { Vector3(  -1.0f,  1.0f, -1.0f ) },

        // left
        { Vector3(  -1.0f, -1.0f,  1.0f ) },
        { Vector3(  -1.0f, -1.0f, -1.0f ) },
        { Vector3(  -1.0f,  1.0f, -1.0f ) },
        { Vector3(  -1.0f,  1.0f, -1.0f ) },
        { Vector3(  -1.0f,  1.0f,  1.0f ) },
        { Vector3(  -1.0f, -1.0f,  1.0f ) },

        // right
        { Vector3(   1.0f, -1.0f, -1.0f ) },
        { Vector3(   1.0f, -1.0f,  1.0f ) },
        { Vector3(   1.0f,  1.0f,  1.0f ) },
        { Vector3(   1.0f,  1.0f,  1.0f ) },
        { Vector3(   1.0f,  1.0f, -1.0f ) },
        { Vector3(   1.0f, -1.0f, -1.0f ) },

        // front
        { Vector3(  -1.0f, -1.0f,  1.0f ) },
        { Vector3(  -1.0f,  1.0f,  1.0f ) },
        { Vector3(   1.0f,  1.0f,  1.0f ) },
        { Vector3(   1.0f,  1.0f,  1.0f ) },
        { Vector3(   1.0f, -1.0f,  1.0f ) },
        { Vector3(  -1.0f, -1.0f,  1.0f ) },

        // botton
        { Vector3(  -1.0f,  1.0f, -1.0f ) },
        { Vector3(   1.0f,  1.0f, -1.0f ) },
        { Vector3(   1.0f,  1.0f,  1.0f ) },
        { Vector3(   1.0f,  1.0f,  1.0f ) },
        { Vector3(  -1.0f,  1.0f,  1.0f ) },
        { Vector3(  -1.0f,  1.0f, -1.0f ) },

        // top
        { Vector3(  -1.0f, -1.0f, -1.0f ) },
        { Vector3(  -1.0f, -1.0f,  1.0f ) },
        { Vector3(   1.0f, -1.0f, -1.0f ) },
        { Vector3(   1.0f, -1.0f, -1.0f ) },
        { Vector3(  -1.0f, -1.0f,  1.0f ) },
        { Vector3(   1.0f, -1.0f,  1.0f ) }
    };

    PropertyBuffer vertexBuffer = PropertyBuffer::New( Property::Map()
                                                       .Add( "aPosition", Property::VECTOR3 ) );
    vertexBuffer.SetData( skyboxVertices, sizeof(skyboxVertices) / sizeof(Vertex) );

    mSkyboxGeometry = Geometry::New();
    mSkyboxGeometry.AddVertexBuffer( vertexBuffer );
    mSkyboxGeometry.SetType( Geometry::TRIANGLES );
  }

  /**
   * Display a cube at the world origin
   */
  void DisplayCube()
  {
    // Load image from file
    PixelData pixels = SyncImageLoader::Load( TEXTURE_URL );

    Texture texture = Texture::New( TextureType::TEXTURE_2D, pixels.GetPixelFormat(), pixels.GetWidth(), pixels.GetHeight() );
    texture.Upload( pixels, 0, 0, 0, 0, pixels.GetWidth(), pixels.GetHeight() );

    // create TextureSet
    mTextureSet = TextureSet::New();
    mTextureSet.SetTexture( 0, texture );

    mRenderer = Renderer::New( mGeometry, mShaderCube );
    mRenderer.SetTextures( mTextureSet );
    mRenderer.SetProperty( Renderer::Property::DEPTH_INDEX, 1.0f );

    // A further optimization would be to enable debug testing instead
    mRenderer.SetProperty( Renderer::Property::FACE_CULLING_MODE, FaceCullingMode::BACK );

    // Enables the write on the depth buffer.
    mRenderer.SetProperty( Renderer::Property::DEPTH_WRITE_MODE, DepthWriteMode::ON );

    mActor = Actor::New();
    mActor.SetName( "Cube" );
    mActor.SetAnchorPoint( AnchorPoint::CENTER );
    mActor.SetParentOrigin( ParentOrigin::CENTER );
    mActor.AddRenderer( mRenderer );

    mActor.SetSize( 10.f, 10.f, 10.f );

    Stage stage = Stage::GetCurrent();
    stage.Add( mActor );
  }

  /**
   * Display a skybox surrounding the camera
   */
  void DisplaySkybox()
  {
    // Load skybox faces from file
    Texture texture = Texture::New( TextureType::TEXTURE_CUBE, Pixel::RGBA8888, SKYBOX_FACE_WIDTH, SKYBOX_FACE_HEIGHT );
    for (unsigned int i = 0; i < SKYBOX_FACE_COUNT; i++)
    {
      PixelData pixels = SyncImageLoader::Load( SKYBOX_FACES[i] );
      texture.Upload( pixels, CubeMapLayer::POSITIVE_X + i, 0, 0, 0, SKYBOX_FACE_WIDTH, SKYBOX_FACE_HEIGHT );
    }

    // create TextureSet
    mSkyboxTextures = TextureSet::New();
    mSkyboxTextures.SetTexture( 0, texture );

    mSkyboxRenderer = Renderer::New( mSkyboxGeometry, mShaderSkybox );
    mSkyboxRenderer.SetTextures( mSkyboxTextures );
    mSkyboxRenderer.SetProperty( Renderer::Property::DEPTH_INDEX, 2.0f );

    // Enables the depth test.
    mSkyboxRenderer.SetProperty( Renderer::Property::DEPTH_TEST_MODE, DepthTestMode::ON );

    // The fragment shader will run only is those pixels that have the max depth value.
    mSkyboxRenderer.SetProperty( Renderer::Property::DEPTH_FUNCTION, DepthFunction::LESS_EQUAL );

    Stage stage = Stage::GetCurrent();

    mSkyboxActor = Actor::New();
    mSkyboxActor.SetName( "SkyBox" );
    mSkyboxActor.SetAnchorPoint( AnchorPoint::CENTER );
    mSkyboxActor.SetParentOrigin( ParentOrigin::CENTER );
    mSkyboxActor.SetPosition( CAMERA_DEFAULT_POSITION );
    mSkyboxActor.AddRenderer( mSkyboxRenderer );
    stage.Add( mSkyboxActor );
  }

  /**
   * Plays animation
   */
  void PlayAnimation()
  {
    mAnimation = Animation::New( 5.0f );
    mAnimation.SetLooping( true );
    mAnimation.AnimateBy( Property( mActor, Actor::Property::ORIENTATION ), Quaternion( Radian( Degree( 360 )), Vector3::ZAXIS ) );
    mAnimation.AnimateBy( Property( mActor, Actor::Property::ORIENTATION ), Quaternion( Radian( Degree( 360 )), Vector3::YAXIS ) );
    mAnimation.AnimateBy( Property( mActor, Actor::Property::ORIENTATION ), Quaternion( Radian( Degree( 360 )), Vector3::XAXIS ) );
    mAnimation.Play();
  }

private:
  Application&  mApplication;

  LookCamera mCamera;

  Shader mShaderCube;
  Shader mShaderSkybox;

  Geometry mGeometry;
  TextureSet mTextureSet;
  Renderer mRenderer;
  Actor mActor;
  Animation mAnimation;

  Geometry mSkyboxGeometry;
  TextureSet mSkyboxTextures;
  Renderer mSkyboxRenderer;
  Actor mSkyboxActor;
};

int DALI_EXPORT_API main( int argc, char **argv )
{
  Application application = Application::New( &argc, &argv );
  TexturedCubeController test( application );
  application.MainLoop();
  return 0;
}