/*
 * Copyright (c) 2020 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.
 *
 */

// EXTERNAL INCLUDES
#include <dali-toolkit/dali-toolkit.h>
#include <dali/dali.h>
#include <dali/devel-api/adaptor-framework/file-loader.h>
#include <dali/integration-api/debug.h>

#include <cctype>
#include <limits>
#include <sstream>

// INTERNAL INCLUDES
#include "shared/utility.h"
#include "shared/view.h"
#include "generated/refraction-effect-flat-vert.h"
#include "generated/refraction-effect-flat-frag.h"
#include "generated/refraction-effect-refraction-vert.h"
#include "generated/refraction-effect-refraction-frag.h"

using namespace Dali;

namespace
{
const char* const APPLICATION_TITLE("Refraction Effect");
const char* const TOOLBAR_IMAGE(DEMO_IMAGE_DIR "top-bar.png");
const char* const CHANGE_TEXTURE_ICON(DEMO_IMAGE_DIR "icon-change.png");
const char* const CHANGE_TEXTURE_ICON_SELECTED(DEMO_IMAGE_DIR "icon-change-selected.png");
const char* const CHANGE_MESH_ICON(DEMO_IMAGE_DIR "icon-replace.png");
const char* const CHANGE_MESH_ICON_SELECTED(DEMO_IMAGE_DIR "icon-replace-selected.png");

const char* MESH_FILES[] =
  {
    DEMO_MODEL_DIR "surface_pattern_v01.obj",
    DEMO_MODEL_DIR "surface_pattern_v02.obj"};
const unsigned int NUM_MESH_FILES(sizeof(MESH_FILES) / sizeof(MESH_FILES[0]));

const char* TEXTURE_IMAGES[] =
  {
    DEMO_IMAGE_DIR "background-1.jpg",
    DEMO_IMAGE_DIR "background-2.jpg",
    DEMO_IMAGE_DIR "background-3.jpg",
    DEMO_IMAGE_DIR "background-4.jpg"};
const unsigned int NUM_TEXTURE_IMAGES(sizeof(TEXTURE_IMAGES) / sizeof(TEXTURE_IMAGES[0]));

struct LightOffsetConstraint
{
  LightOffsetConstraint(float radius)
  : mRadius(radius)
  {
  }

  void operator()(Vector2& current, const PropertyInputContainer& inputs)
  {
    float spinAngle = inputs[0]->GetFloat();
    current.x       = cos(spinAngle);
    current.y       = sin(spinAngle);

    current *= mRadius;
  }

  float mRadius;
};

/**
 * structure of the vertex in the mesh
 */
struct Vertex
{
  Vector3 position;
  Vector3 normal;
  Vector2 textureCoord;

  Vertex()
  {
  }

  Vertex(const Vector3& position, const Vector3& normal, const Vector2& textureCoord)
  : position(position),
    normal(normal),
    textureCoord(textureCoord)
  {
  }
};

} // namespace

/*************************************************/
/*Demo using RefractionEffect*****************/
/*************************************************/
class RefractionEffectExample : public ConnectionTracker
{
public:
  RefractionEffectExample(Application& application)
  : mApplication(application),
    mContent(),
    mTextureSet(),
    mGeometry(),
    mRenderer(),
    mMeshActor(),
    mShaderFlat(),
    mShaderRefraction(),
    mLightAnimation(),
    mStrenghAnimation(),
    mLightXYOffsetIndex(Property::INVALID_INDEX),
    mSpinAngleIndex(Property::INVALID_INDEX),
    mLightIntensityIndex(Property::INVALID_INDEX),
    mEffectStrengthIndex(Property::INVALID_INDEX),
    mChangeTextureButton(),
    mChangeMeshButton(),
    mCurrentTextureId(1),
    mCurrentMeshId(0)
  {
    // Connect to the Application's Init signal
    application.InitSignal().Connect(this, &RefractionEffectExample::Create);
  }

  ~RefractionEffectExample()
  {
  }

private:
  // The Init signal is received once (only) during the Application lifetime
  void Create(Application& application)
  {
    Window  window     = application.GetWindow();
    Vector2 windowSize = window.GetSize();

    window.KeyEventSignal().Connect(this, &RefractionEffectExample::OnKeyEvent);

    // Creates a default view with a default tool bar.
    // The view is added to the window.
    Toolkit::ToolBar toolBar;
    Toolkit::Control view;
    mContent = DemoHelper::CreateView(application,
                                      view,
                                      toolBar,
                                      "",
                                      TOOLBAR_IMAGE,
                                      APPLICATION_TITLE);

    // Add a button to change background. (right of toolbar)
    mChangeTextureButton = Toolkit::PushButton::New();
    mChangeTextureButton.SetProperty(Toolkit::Button::Property::UNSELECTED_BACKGROUND_VISUAL, CHANGE_TEXTURE_ICON);
    mChangeTextureButton.SetProperty(Toolkit::Button::Property::SELECTED_BACKGROUND_VISUAL, CHANGE_TEXTURE_ICON_SELECTED);
    mChangeTextureButton.ClickedSignal().Connect(this, &RefractionEffectExample::OnChangeTexture);
    toolBar.AddControl(mChangeTextureButton,
                       DemoHelper::DEFAULT_VIEW_STYLE.mToolBarButtonPercentage,
                       Toolkit::Alignment::HORIZONTAL_RIGHT,
                       DemoHelper::DEFAULT_MODE_SWITCH_PADDING);
    // Add a button to change mesh pattern. ( left of bar )
    mChangeMeshButton = Toolkit::PushButton::New();
    mChangeMeshButton.SetProperty(Toolkit::Button::Property::UNSELECTED_BACKGROUND_VISUAL, CHANGE_MESH_ICON);
    mChangeMeshButton.SetProperty(Toolkit::Button::Property::SELECTED_BACKGROUND_VISUAL, CHANGE_MESH_ICON_SELECTED);
    mChangeMeshButton.ClickedSignal().Connect(this, &RefractionEffectExample::OnChangeMesh);
    toolBar.AddControl(mChangeMeshButton,
                       DemoHelper::DEFAULT_VIEW_STYLE.mToolBarButtonPercentage,
                       Toolkit::Alignment::HORIZONTAL_LEFT,
                       DemoHelper::DEFAULT_MODE_SWITCH_PADDING);

    // shader used when the screen is not touched, render a flat surface
    mShaderFlat = Shader::New(SHADER_REFRACTION_EFFECT_FLAT_VERT, SHADER_REFRACTION_EFFECT_FLAT_FRAG);
    mGeometry   = CreateGeometry(MESH_FILES[mCurrentMeshId]);

    Texture texture = DemoHelper::LoadWindowFillingTexture(window.GetSize(), TEXTURE_IMAGES[mCurrentTextureId]);
    mTextureSet     = TextureSet::New();
    mTextureSet.SetTexture(0u, texture);

    mRenderer = Renderer::New(mGeometry, mShaderFlat);
    mRenderer.SetTextures(mTextureSet);

    mMeshActor = Actor::New();
    mMeshActor.AddRenderer(mRenderer);
    mMeshActor.SetProperty(Actor::Property::SIZE, windowSize);
    mMeshActor.SetProperty(Actor::Property::PARENT_ORIGIN, ParentOrigin::CENTER);
    mContent.Add(mMeshActor);

    // Connect the callback to the touch signal on the mesh actor
    mContent.TouchedSignal().Connect(this, &RefractionEffectExample::OnTouch);

    // shader used when the finger is touching the screen. render refraction effect
    mShaderRefraction = Shader::New(SHADER_REFRACTION_EFFECT_REFRACTION_VERT, SHADER_REFRACTION_EFFECT_REFRACTION_FRAG);

    // register uniforms
    mLightXYOffsetIndex = mMeshActor.RegisterProperty("uLightXYOffset", Vector2::ZERO);

    mLightIntensityIndex = mMeshActor.RegisterProperty("uLightIntensity", 2.5f);

    mEffectStrengthIndex = mMeshActor.RegisterProperty("uEffectStrength", 0.f);

    Vector3 lightPosition(-windowSize.x * 0.5f, -windowSize.y * 0.5f, windowSize.x * 0.5f); // top_left
    mMeshActor.RegisterProperty("uLightPosition", lightPosition);

    Property::Index lightSpinOffsetIndex = mMeshActor.RegisterProperty("uLightSpinOffset", Vector2::ZERO);

    mSpinAngleIndex       = mMeshActor.RegisterProperty("uSpinAngle", 0.f);
    Constraint constraint = Constraint::New<Vector2>(mMeshActor, lightSpinOffsetIndex, LightOffsetConstraint(windowSize.x * 0.1f));
    constraint.AddSource(LocalSource(mSpinAngleIndex));
    constraint.Apply();

    // the animation which spin the light around the finger touch position
    mLightAnimation = Animation::New(2.f);
    mLightAnimation.AnimateTo(Property(mMeshActor, mSpinAngleIndex), Math::PI * 2.f);
    mLightAnimation.SetLooping(true);
    mLightAnimation.Pause();
  }

  void SetLightXYOffset(const Vector2& offset)
  {
    mMeshActor.SetProperty(mLightXYOffsetIndex, offset);
  }

  /**
   * Create a mesh actor with different geometry to replace the current one
   */
  bool OnChangeMesh(Toolkit::Button button)
  {
    mCurrentMeshId = (mCurrentMeshId + 1) % NUM_MESH_FILES;
    mGeometry      = CreateGeometry(MESH_FILES[mCurrentMeshId]);
    mRenderer.SetGeometry(mGeometry);

    return true;
  }

  bool OnChangeTexture(Toolkit::Button button)
  {
    mCurrentTextureId = (mCurrentTextureId + 1) % NUM_TEXTURE_IMAGES;
    Texture texture   = DemoHelper::LoadWindowFillingTexture(mApplication.GetWindow().GetSize(), TEXTURE_IMAGES[mCurrentTextureId]);
    mTextureSet.SetTexture(0u, texture);
    return true;
  }

  bool OnTouch(Actor actor, const TouchEvent& event)
  {
    switch(event.GetState(0))
    {
      case PointState::DOWN:
      {
        mRenderer.SetShader(mShaderRefraction);

        SetLightXYOffset(event.GetScreenPosition(0));

        mLightAnimation.Play();

        if(mStrenghAnimation)
        {
          mStrenghAnimation.Clear();
        }

        mStrenghAnimation = Animation::New(0.5f);
        mStrenghAnimation.AnimateTo(Property(mMeshActor, mEffectStrengthIndex), 1.f);
        mStrenghAnimation.Play();

        break;
      }
      case PointState::MOTION:
      {
        // make the light position following the finger movement
        SetLightXYOffset(event.GetScreenPosition(0));
        break;
      }
      case PointState::UP:
      case PointState::LEAVE:
      case PointState::INTERRUPTED:
      {
        mLightAnimation.Pause();

        if(mStrenghAnimation)
        {
          mStrenghAnimation.Clear();
        }
        mStrenghAnimation = Animation::New(0.5f);
        mStrenghAnimation.AnimateTo(Property(mMeshActor, mEffectStrengthIndex), 0.f);
        mStrenghAnimation.FinishedSignal().Connect(this, &RefractionEffectExample::OnTouchFinished);
        mStrenghAnimation.Play();
        break;
      }
      case PointState::STATIONARY:
      {
        break;
      }
    }

    return true;
  }

  void OnTouchFinished(Animation& source)
  {
    mRenderer.SetShader(mShaderFlat);
    SetLightXYOffset(Vector2::ZERO);
  }

  Geometry CreateGeometry(const std::string& objFileName)
  {
    std::vector<Vector3> vertexPositions;
    Vector<unsigned int> faceIndices;
    Vector<float>        boundingBox;
    // read the vertice and faces from the .obj file, and record the bounding box
    ReadObjFile(objFileName, boundingBox, vertexPositions, faceIndices);

    std::vector<Vector2> textureCoordinates;
    // align the mesh, scale it to fit the screen size, and calculate the texture coordinate for each vertex
    ShapeResizeAndTexureCoordinateCalculation(boundingBox, vertexPositions, textureCoordinates);

    // re-organize the mesh, the vertices are duplicated, each vertex only belongs to one triangle.
    // Without sharing vertex between triangle, so we can manipulate the texture offset on each triangle conveniently.
    std::vector<Vertex> vertices;

    std::size_t size = faceIndices.Size();
    vertices.reserve(size);

    for(std::size_t i = 0; i < size; i = i + 3)
    {
      Vector3 edge1  = vertexPositions[faceIndices[i + 2]] - vertexPositions[faceIndices[i]];
      Vector3 edge2  = vertexPositions[faceIndices[i + 1]] - vertexPositions[faceIndices[i]];
      Vector3 normal = edge1.Cross(edge2);
      normal.Normalize();

      // make sure all the faces are front-facing
      if(normal.z > 0)
      {
        vertices.push_back(Vertex(vertexPositions[faceIndices[i]], normal, textureCoordinates[faceIndices[i]]));
        vertices.push_back(Vertex(vertexPositions[faceIndices[i + 1]], normal, textureCoordinates[faceIndices[i + 1]]));
        vertices.push_back(Vertex(vertexPositions[faceIndices[i + 2]], normal, textureCoordinates[faceIndices[i + 2]]));
      }
      else
      {
        normal *= -1.f;
        vertices.push_back(Vertex(vertexPositions[faceIndices[i]], normal, textureCoordinates[faceIndices[i]]));
        vertices.push_back(Vertex(vertexPositions[faceIndices[i + 2]], normal, textureCoordinates[faceIndices[i + 2]]));
        vertices.push_back(Vertex(vertexPositions[faceIndices[i + 1]], normal, textureCoordinates[faceIndices[i + 1]]));
      }
    }

    Property::Map vertexFormat;
    vertexFormat["aPosition"]    = Property::VECTOR3;
    vertexFormat["aNormal"]      = Property::VECTOR3;
    vertexFormat["aTexCoord"]    = Property::VECTOR2;
    VertexBuffer surfaceVertices = VertexBuffer::New(vertexFormat);
    surfaceVertices.SetData(&vertices[0], vertices.size());

    Geometry surface = Geometry::New();
    surface.AddVertexBuffer(surfaceVertices);

    return surface;
  }

  void ReadObjFile(const std::string&    objFileName,
                   Vector<float>&        boundingBox,
                   std::vector<Vector3>& vertexPositions,
                   Vector<unsigned int>& faceIndices)
  {
    std::streampos     bufferSize = 0;
    Dali::Vector<char> fileBuffer;
    if(!Dali::FileLoader::ReadFile(objFileName, bufferSize, fileBuffer, Dali::FileLoader::FileType::TEXT))
    {
      DALI_LOG_WARNING("file open failed for: \"%s\"", objFileName.c_str());
      return;
    }

    fileBuffer.PushBack('\0');

    std::stringstream iss(&fileBuffer[0], std::ios::in);

    boundingBox.Resize(6);
    boundingBox[0] = boundingBox[2] = boundingBox[4] = std::numeric_limits<float>::max();
    boundingBox[1] = boundingBox[3] = boundingBox[5] = -std::numeric_limits<float>::max();

    std::string line;
    while(std::getline(iss, line))
    {
      if(line[0] == 'v' && std::isspace(line[1])) // vertex
      {
        std::istringstream iss(line.substr(2), std::istringstream::in);
        unsigned int       i = 0;
        Vector3            vertex;
        while(iss >> vertex[i++] && i < 3)
          ;
        if(vertex.x < boundingBox[0]) boundingBox[0] = vertex.x;
        if(vertex.x > boundingBox[1]) boundingBox[1] = vertex.x;
        if(vertex.y < boundingBox[2]) boundingBox[2] = vertex.y;
        if(vertex.y > boundingBox[3]) boundingBox[3] = vertex.y;
        if(vertex.z < boundingBox[4]) boundingBox[4] = vertex.z;
        if(vertex.z > boundingBox[5]) boundingBox[5] = vertex.z;
        vertexPositions.push_back(vertex);
      }
      else if(line[0] == 'f') //face
      {
        unsigned int numOfInt = 3;
        while(true)
        {
          std::size_t found = line.find('/');
          if(found == std::string::npos)
          {
            break;
          }
          line[found] = ' ';
          numOfInt++;
        }

        std::istringstream         iss(line.substr(2), std::istringstream::in);
        Dali::Vector<unsigned int> indices;
        indices.Resize(numOfInt);
        unsigned int i = 0;
        while(iss >> indices[i++] && i < numOfInt)
          ;
        unsigned int step = (i + 1) / 3;
        faceIndices.PushBack(indices[0] - 1);
        faceIndices.PushBack(indices[step] - 1);
        faceIndices.PushBack(indices[2 * step] - 1);
      }
    }
  }

  void ShapeResizeAndTexureCoordinateCalculation(const Vector<float>&  boundingBox,
                                                 std::vector<Vector3>& vertexPositions,
                                                 std::vector<Vector2>& textureCoordinates)
  {
    Vector3 bBoxSize(boundingBox[1] - boundingBox[0], boundingBox[3] - boundingBox[2], boundingBox[5] - boundingBox[4]);
    Vector3 bBoxMinCorner(boundingBox[0], boundingBox[2], boundingBox[4]);

    Vector2 windowSize = mApplication.GetWindow().GetSize();
    Vector3 scale(windowSize.x / bBoxSize.x, windowSize.y / bBoxSize.y, 1.f);
    scale.z = (scale.x + scale.y) / 2.f;

    textureCoordinates.reserve(vertexPositions.size());

    for(std::vector<Vector3>::iterator iter = vertexPositions.begin(); iter != vertexPositions.end(); iter++)
    {
      Vector3 newPosition((*iter) - bBoxMinCorner);

      textureCoordinates.push_back(Vector2(newPosition.x / bBoxSize.x, newPosition.y / bBoxSize.y));

      newPosition -= bBoxSize * 0.5f;
      (*iter) = newPosition * scale;
    }
  }

  /**
   * Main key event handler
   */
  void OnKeyEvent(const KeyEvent& event)
  {
    if(event.GetState() == KeyEvent::DOWN)
    {
      if(IsKey(event, Dali::DALI_KEY_ESCAPE) || IsKey(event, Dali::DALI_KEY_BACK))
      {
        mApplication.Quit();
      }
    }
  }

private:
  Application& mApplication;
  Layer        mContent;
  TextureSet   mTextureSet;
  Geometry     mGeometry;
  Renderer     mRenderer;
  Actor        mMeshActor;

  Shader mShaderFlat;
  Shader mShaderRefraction;

  Animation mLightAnimation;
  Animation mStrenghAnimation;

  Property::Index mLightXYOffsetIndex;
  Property::Index mSpinAngleIndex;
  Property::Index mLightIntensityIndex;
  Property::Index mEffectStrengthIndex;

  Toolkit::PushButton mChangeTextureButton;
  Toolkit::PushButton mChangeMeshButton;
  unsigned int        mCurrentTextureId;
  unsigned int        mCurrentMeshId;
};

/*****************************************************************************/

int DALI_EXPORT_API main(int argc, char** argv)
{
  Application             app = Application::New(&argc, &argv, DEMO_THEME_PATH);
  RefractionEffectExample theApp(app);
  app.MainLoop();
  return 0;
}