// Copyright 2017 Google Inc. All Rights Reserved.
//
// 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 "cobalt/renderer/rasterizer/egl/textured_mesh_renderer.h"

#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>

#include <string>
#include <vector>

#include "base/stringprintf.h"
#include "cobalt/math/size.h"
#include "cobalt/renderer/backend/egl/utils.h"
#include "third_party/glm/glm/gtc/type_ptr.hpp"

namespace cobalt {
namespace renderer {
namespace rasterizer {
namespace egl {

TexturedMeshRenderer::TexturedMeshRenderer(
    backend::GraphicsContextEGL* graphics_context)
    : graphics_context_(graphics_context) {}

TexturedMeshRenderer::~TexturedMeshRenderer() {
  graphics_context_->MakeCurrent();
  if (quad_vbo_) {
    GL_CALL(glDeleteBuffers(1, &quad_vbo_.value()));
  }
  for (ProgramCache::iterator iter = blit_program_cache_.begin();
       iter != blit_program_cache_.end(); ++iter) {
    GL_CALL(glDeleteProgram(iter->second.gl_program_id));
  }
}

namespace {
void ConvertContentRegionToScaleTranslateVector(
    const math::Rect* content_region, const math::Size& texture_size,
    float* out_vec4) {
  if (!content_region) {
    // If no content region is provided, use the identity matrix.
    out_vec4[0] = 1.0f;
    out_vec4[1] = 1.0f;
    out_vec4[2] = 0.0f;
    out_vec4[3] = 0.0f;
    return;
  }

  float scale_x =
      content_region->width() / static_cast<float>(texture_size.width());
  float scale_y =
      content_region->height() / static_cast<float>(texture_size.height());
  float translate_x =
      content_region->x() / static_cast<float>(texture_size.width());
  float translate_y = (texture_size.height() - content_region->bottom()) /
                      static_cast<float>(texture_size.height());
  out_vec4[0] = scale_x;
  out_vec4[1] = scale_y;
  out_vec4[2] = translate_x;
  out_vec4[3] = translate_y;
}

// Used for RGB images.
const float kIdentityColorMatrix[16] = {1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f,
                                        0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f,
                                        0.0f, 0.0f, 0.0f, 1.0f};

// Used for YUV images.
const float kBT709ColorMatrix[16] = {
    1.164f, 0.0f,   1.793f, -0.96925f, 1.164f, -0.213f, -0.533f, 0.30025f,
    1.164f, 2.112f, 0.0f,   -1.12875f, 0.0f,   0.0f,    0.0f,    1.0};

const float* GetColorMatrixForImageType(
    TexturedMeshRenderer::Image::Type type) {
  switch (type) {
    case TexturedMeshRenderer::Image::RGBA: {
      return kIdentityColorMatrix;
    } break;
    case TexturedMeshRenderer::Image::YUV_2PLANE_BT709:
    case TexturedMeshRenderer::Image::YUV_3PLANE_BT709:
    case TexturedMeshRenderer::Image::YUV_UYVY_422_BT709: {
      return kBT709ColorMatrix;
    } break;
    default: { NOTREACHED(); }
  }
  return NULL;
}

}  // namespace

void TexturedMeshRenderer::RenderVBO(uint32 vbo, int num_vertices, uint32 mode,
                                     const Image& image,
                                     const glm::mat4& mvp_transform) {
  ProgramInfo blit_program = GetBlitProgram(image);

  GL_CALL(glUseProgram(blit_program.gl_program_id));

  GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, vbo));
  GL_CALL(glVertexAttribPointer(kBlitPositionAttribute, 3, GL_FLOAT, GL_FALSE,
                                sizeof(float) * 5, 0));
  GL_CALL(glVertexAttribPointer(kBlitTexcoordAttribute, 2, GL_FLOAT, GL_FALSE,
                                sizeof(float) * 5,
                                reinterpret_cast<GLvoid*>(sizeof(float) * 3)));
  GL_CALL(glEnableVertexAttribArray(kBlitPositionAttribute));
  GL_CALL(glEnableVertexAttribArray(kBlitTexcoordAttribute));

  GL_CALL(glUniformMatrix4fv(blit_program.mvp_transform_uniform, 1, GL_FALSE,
                             glm::value_ptr(mvp_transform)));

  for (int i = 0; i < image.num_textures(); ++i) {
    DCHECK_EQ(image.textures[0].texture->GetTarget(),
              image.textures[i].texture->GetTarget());

    GL_CALL(glActiveTexture(GL_TEXTURE0 + i));
    GL_CALL(glBindTexture(image.textures[i].texture->GetTarget(),
                          image.textures[i].texture->gl_handle()));
    if (image.type == Image::YUV_UYVY_422_BT709) {
      // For UYVY, wrap mode is handled within the fragment shader, ensure here
      // that it is always set to GL_REPEAT.
      GL_CALL(glTexParameteri(
          image.textures[0].texture->GetTarget(), GL_TEXTURE_WRAP_S,
          GL_REPEAT));
    }

    GL_CALL(glUniform1i(blit_program.texture_uniforms[i], i));

    if (blit_program.texture_size_uniforms[i] != -1) {
      math::Size texture_size = image.textures[i].texture->GetSize();
      int texture_sizes[2] = {texture_size.width(), texture_size.height()};
      GL_CALL(glUniform2iv(blit_program.texture_size_uniforms[i], 1,
                           texture_sizes));
    }

    math::Size content_size = image.textures[i].texture->GetSize();

    float scale_translate_vector[4];
    ConvertContentRegionToScaleTranslateVector(
        &image.textures[i].content_region, content_size,
        scale_translate_vector);
    GL_CALL(glUniform4fv(blit_program.texcoord_scale_translate_uniforms[i], 1,
                         scale_translate_vector));
  }

  GL_CALL(glDrawArrays(mode, 0, num_vertices));

  for (int i = 0; i < image.num_textures(); ++i) {
    GL_CALL(glActiveTexture(GL_TEXTURE0 + i));
    GL_CALL(glBindTexture(image.textures[i].texture->GetTarget(), 0));
  }

  GL_CALL(glDisableVertexAttribArray(kBlitTexcoordAttribute));
  GL_CALL(glDisableVertexAttribArray(kBlitPositionAttribute));
  GL_CALL(glUseProgram(0));
}

void TexturedMeshRenderer::RenderQuad(const Image& image,
                                      const glm::mat4& mvp_transform) {
  RenderVBO(GetQuadVBO(), 4, GL_TRIANGLE_STRIP, image, mvp_transform);
}

uint32 TexturedMeshRenderer::GetQuadVBO() {
  if (!quad_vbo_) {
    // Setup a vertex buffer that can blit a quad with a full texture, to be
    // used by Frame::BlitToRenderTarget().
    struct QuadVertex {
      float position_x;
      float position_y;
      float position_z;
      float tex_coord_u;
      float tex_coord_v;
    };
    const QuadVertex kBlitQuadVerts[4] = {
        {-1.0f, -1.0f, 0.0f, 0.0f, 0.0f},
        {1.0f, -1.0f, 0.0f, 1.0f, 0.0f},
        {-1.0f, 1.0f, 0.0f, 0.0f, 1.0f},
        {1.0f, 1.0, 0.0f, 1.0f, 1.0f},
    };

    quad_vbo_ = 0;
    GL_CALL(glGenBuffers(1, &quad_vbo_.value()));
    GL_CALL(glBindBuffer(GL_ARRAY_BUFFER, *quad_vbo_));
    GL_CALL(glBufferData(GL_ARRAY_BUFFER, sizeof(kBlitQuadVerts),
                         kBlitQuadVerts, GL_STATIC_DRAW));
  }

  return *quad_vbo_;
}

// static
uint32 TexturedMeshRenderer::CreateVertexShader(
    const std::vector<TextureInfo>& textures) {
  uint32 blit_vertex_shader = glCreateShader(GL_VERTEX_SHADER);
  std::string blit_vertex_shader_source =
      "attribute vec3 a_position;"
      "attribute vec2 a_tex_coord;";
  for (unsigned int i = 0; i < textures.size(); ++i) {
    blit_vertex_shader_source +=
        StringPrintf("varying vec2 v_tex_coord_%s;", textures[i].name.c_str());
  }
  for (unsigned int i = 0; i < textures.size(); ++i) {
    blit_vertex_shader_source += StringPrintf(
        "uniform vec4 scale_translate_%s;", textures[i].name.c_str());
  }
  blit_vertex_shader_source +=
      "uniform mat4 model_view_projection_transform;"
      "void main() {"
      "  gl_Position = model_view_projection_transform * "
      "                    vec4(a_position.xyz, 1.0);";
  for (unsigned int i = 0; i < textures.size(); ++i) {
    const char* texture_name = textures[i].name.c_str();
    blit_vertex_shader_source += StringPrintf(
        "  v_tex_coord_%s = "
        "      a_tex_coord * scale_translate_%s.xy + scale_translate_%s.zw;",
        texture_name, texture_name, texture_name);
  }
  blit_vertex_shader_source += "}";

  int blit_vertex_shader_source_length = blit_vertex_shader_source.size();
  const char* blit_vertex_shader_source_c_str =
      blit_vertex_shader_source.c_str();
  GL_CALL(glShaderSource(blit_vertex_shader, 1,
                         &blit_vertex_shader_source_c_str,
                         &blit_vertex_shader_source_length));
  GL_CALL(glCompileShader(blit_vertex_shader));

  return blit_vertex_shader;
}

namespace {

uint32 CompileShader(const std::string& shader_source) {
  uint32 blit_fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);

  int shader_source_length = shader_source.size();
  const char* shader_source_c_str = shader_source.c_str();
  GL_CALL(glShaderSource(blit_fragment_shader, 1, &shader_source_c_str,
                         &shader_source_length));
  GL_CALL(glCompileShader(blit_fragment_shader));

  GLint is_compiled = GL_FALSE;
  GL_CALL(glGetShaderiv(blit_fragment_shader, GL_COMPILE_STATUS, &is_compiled));
  if (is_compiled != GL_TRUE) {
    const GLsizei kMaxLogLength = 2048;
    GLsizei log_length = 0;
    GLchar log[kMaxLogLength];
    glGetShaderInfoLog(blit_fragment_shader, kMaxLogLength, &log_length, log);
    DLOG(ERROR) << "shader error: " << log;
    DLOG(ERROR) << "shader source:\n" << shader_source;
  }
  CHECK_EQ(is_compiled, GL_TRUE);

  return blit_fragment_shader;
}

struct SamplerInfo {
  std::string type;
  std::string preamble;
};

SamplerInfo GetSamplerInfo(uint32 texture_target) {
  SamplerInfo sampler_info;
  sampler_info.type = "sampler2D";

  if (texture_target == GL_TEXTURE_EXTERNAL_OES) {
    sampler_info.type = "samplerExternalOES";
    sampler_info.preamble = "#extension GL_OES_EGL_image_external : require\n";
  }

  return sampler_info;
}
}  // namespace

// static
uint32 TexturedMeshRenderer::CreateFragmentShader(
    uint32 texture_target, const std::vector<TextureInfo>& textures) {
  SamplerInfo sampler_info = GetSamplerInfo(texture_target);

  std::string blit_fragment_shader_source = sampler_info.preamble;

  blit_fragment_shader_source += "precision mediump float;";
  for (unsigned int i = 0; i < textures.size(); ++i) {
    blit_fragment_shader_source +=
        StringPrintf("varying vec2 v_tex_coord_%s;", textures[i].name.c_str());
  }
  for (unsigned int i = 0; i < textures.size(); ++i) {
    blit_fragment_shader_source +=
        StringPrintf("uniform %s texture_%s;", sampler_info.type.c_str(),
                     textures[i].name.c_str());
  }
  blit_fragment_shader_source +=
      "uniform mat4 to_rgb_color_matrix;"
      "void main() {"
      "  vec4 untransformed_color = vec4(";
  int components_used = 0;
  for (unsigned int i = 0; i < textures.size(); ++i) {
    if (i > 0) {
      blit_fragment_shader_source += ", ";
    }
    blit_fragment_shader_source += StringPrintf(
        "texture2D(texture_%s, v_tex_coord_%s).%s", textures[i].name.c_str(),
        textures[i].name.c_str(), textures[i].components.c_str());
    components_used += textures[i].components.length();
  }
  if (components_used == 3) {
    // Add an alpha component of 1.
    blit_fragment_shader_source += ", 1.0";
  }
  blit_fragment_shader_source +=
      ");"
      "  gl_FragColor = untransformed_color * to_rgb_color_matrix;"
      "}";

  return CompileShader(blit_fragment_shader_source);
}

// static
uint32 TexturedMeshRenderer::CreateUYVYFragmentShader(uint32 texture_target,
                                                      int32 texture_wrap_s) {
  SamplerInfo sampler_info = GetSamplerInfo(texture_target);

  std::string blit_fragment_shader_source = sampler_info.preamble;

  blit_fragment_shader_source += "precision mediump float;";
  blit_fragment_shader_source += "varying vec2 v_tex_coord_uyvy;";
  blit_fragment_shader_source +=
      StringPrintf("uniform %s texture_uyvy;", sampler_info.type.c_str());

  // The fragment shader below manually performs horizontal linear interpolation
  // filtering of color values.  Specifically it needs to interpolate the UV
  // values differently than Y values because UV values occur at half the
  // frequency.
  blit_fragment_shader_source +=
      "uniform mat4 to_rgb_color_matrix;"
      "uniform ivec2 texture_size_uyvy;"
      "void main() {"
      // Convert from normalized [0,1] texture coordinates into [0, width]
      // texture space coordinates.
      "  float texture_space_x ="
      "      float(texture_size_uyvy.x) * v_tex_coord_uyvy.x;";
  if (texture_wrap_s == GL_CLAMP_TO_EDGE) {
    // We manually clamp our edges to 0.25 to ensure that the Y components are
    // clamped properly.  We let GL's standard texture wrapping flow take care
    // of the UV clamping (i.e. at [0.5, float(texture_size_uyvy.x) - 0.5]).
    blit_fragment_shader_source +=
        "  texture_space_x = clamp("
        "      texture_space_x, 0.25, float(texture_size_uyvy.x) - 0.25);";
  }
  blit_fragment_shader_source +=
      "  float texel_step_u = 1.0 / float(texture_size_uyvy.x);"
      // As our first (left-most) sample, we choose the pixel that will be on
      // the left side of the UV interpolation.  We add 0.5 to the result in
      // order to get a coordinate representing the center of the pixel.
      "  float sample_1_texture_space = floor(texture_space_x - 0.5) + 0.5;"
      "  float sample_1_normalized ="
      "      sample_1_texture_space * texel_step_u;"
      "  float sample_2_normalized = sample_1_normalized + texel_step_u;"
      "  vec4 sample_1 = texture2D("
      "      texture_uyvy, vec2(sample_1_normalized, v_tex_coord_uyvy.y));"
      "  vec4 sample_2 = texture2D("
      "      texture_uyvy, vec2(sample_2_normalized, v_tex_coord_uyvy.y));"
      // Our lerp progress is how far away |texture_space_x| is from
      // sample 1, or in other words how close it is to sample 2.
      "  float lerp_progress = texture_space_x - sample_1_texture_space;"
      "  vec2 uv_value = mix(sample_1.rb, sample_2.rb, lerp_progress);"
      // Since |lerp_progress| represents progress from the center of the
      // sample 1 pixel (uyvy group) to the center of the sample 2 pixel (uyvy)
      // group, we need to determine whether to interpolate between the two
      // y values within sample 1, the last y value of sample 1 and the first
      // y value of sample 2, or the two y values within sample 2.
      "  float y_value;"
      "  if (lerp_progress < 0.25) {"
      "    y_value = mix(sample_1.g, sample_1.a, lerp_progress * 2.0 + 0.5);"
      "  } else if (lerp_progress < 0.75) {"
      "    y_value = mix(sample_1.a, sample_2.g, lerp_progress * 2.0 - 0.5);"
      "  } else {"
      "    y_value = mix(sample_2.g, sample_2.a, lerp_progress * 2.0 - 1.5);"
      "  }"
      // Perform the YUV->RGB transform and output the color value.
      "  vec4 untransformed_color = vec4(y_value, uv_value.r, uv_value.g, 1.0);"
      "  gl_FragColor = untransformed_color * to_rgb_color_matrix;"
      "}";

  return CompileShader(blit_fragment_shader_source);
}

// static
TexturedMeshRenderer::ProgramInfo TexturedMeshRenderer::MakeBlitProgram(
    const float* color_matrix, const std::vector<TextureInfo>& textures,
    uint32 blit_fragment_shader) {
  int total_components = 0;
  for (unsigned int i = 0; i < textures.size(); ++i) {
    total_components += textures[i].components.length();
  }
  DCHECK(total_components == 3 || total_components == 4);

  ProgramInfo result;

  // Create the blit program.
  // Setup shaders used when blitting the current texture.
  result.gl_program_id = glCreateProgram();

  uint32 blit_vertex_shader = CreateVertexShader(textures);
  GL_CALL(glAttachShader(result.gl_program_id, blit_vertex_shader));

  GL_CALL(glAttachShader(result.gl_program_id, blit_fragment_shader));

  GL_CALL(glBindAttribLocation(result.gl_program_id, kBlitPositionAttribute,
                               "a_position"));
  GL_CALL(glBindAttribLocation(result.gl_program_id, kBlitTexcoordAttribute,
                               "a_tex_coord"));

  GL_CALL(glLinkProgram(result.gl_program_id));

  result.mvp_transform_uniform = glGetUniformLocation(
      result.gl_program_id, "model_view_projection_transform");
  for (unsigned int i = 0; i < textures.size(); ++i) {
    std::string scale_translate_uniform_name =
        StringPrintf("scale_translate_%s", textures[i].name.c_str());
    result.texcoord_scale_translate_uniforms[i] = glGetUniformLocation(
        result.gl_program_id, scale_translate_uniform_name.c_str());
    DCHECK_EQ(GL_NO_ERROR, glGetError());

    std::string texture_uniform_name =
        StringPrintf("texture_%s", textures[i].name.c_str());
    result.texture_uniforms[i] = glGetUniformLocation(
        result.gl_program_id, texture_uniform_name.c_str());
    DCHECK_EQ(GL_NO_ERROR, glGetError());

    std::string texture_size_name =
        StringPrintf("texture_size_%s", textures[i].name.c_str());
    result.texture_size_uniforms[i] =
        glGetUniformLocation(result.gl_program_id, texture_size_name.c_str());
    DCHECK_EQ(GL_NO_ERROR, glGetError());
  }

  // Upload the color matrix right away since it won't change from draw to draw.
  GL_CALL(glUseProgram(result.gl_program_id));
  uint32 to_rgb_color_matrix_uniform =
      glGetUniformLocation(result.gl_program_id, "to_rgb_color_matrix");
  GL_CALL(glUniformMatrix4fv(to_rgb_color_matrix_uniform, 1, GL_FALSE,
                             color_matrix));
  GL_CALL(glUseProgram(0));

  GL_CALL(glDeleteShader(blit_fragment_shader));
  GL_CALL(glDeleteShader(blit_vertex_shader));

  return result;
}

TexturedMeshRenderer::ProgramInfo TexturedMeshRenderer::GetBlitProgram(
    const Image& image) {
  Image::Type type = image.type;
  uint32 texture_target = image.textures[0].texture->GetTarget();
  base::optional<int32> texture_wrap_s;
  if (type == Image::YUV_UYVY_422_BT709) {
    texture_wrap_s.emplace();
    GL_CALL(glBindTexture(
        texture_target, image.textures[0].texture->gl_handle()));
    GL_CALL(glGetTexParameteriv(texture_target,
                                GL_TEXTURE_WRAP_S, &(*texture_wrap_s)));
    GL_CALL(glBindTexture(texture_target, 0));
  }

  CacheKey key(texture_target, type, texture_wrap_s);

  ProgramCache::iterator found = blit_program_cache_.find(key);
  if (found == blit_program_cache_.end()) {
    const float* color_matrix = GetColorMatrixForImageType(type);
    ProgramInfo result;
    switch (type) {
      case Image::RGBA: {
        std::vector<TextureInfo> texture_infos;
        texture_infos.push_back(TextureInfo("rgba", "rgba"));
        result = MakeBlitProgram(
            color_matrix, texture_infos,
            CreateFragmentShader(texture_target, texture_infos));
      } break;
      case Image::YUV_2PLANE_BT709: {
        std::vector<TextureInfo> texture_infos;
#if SB_API_VERSION >= 7
        switch (image.textures[0].texture->GetFormat()) {
          case GL_ALPHA:
            texture_infos.push_back(TextureInfo("y", "a"));
            break;
#if defined(GL_RED_EXT)
          case GL_RED_EXT:
            texture_infos.push_back(TextureInfo("y", "r"));
            break;
#endif
          default:
            NOTREACHED();
        }
        switch (image.textures[1].texture->GetFormat()) {
          case GL_LUMINANCE_ALPHA:
            texture_infos.push_back(TextureInfo("uv", "ba"));
            break;
#if defined(GL_RG_EXT)
          case GL_RG_EXT:
            texture_infos.push_back(TextureInfo("uv", "rg"));
            break;
#endif
          default:
            NOTREACHED();
        }
#else  // SB_API_VERSION >= 7
        texture_infos.push_back(TextureInfo("y", "a"));
        texture_infos.push_back(TextureInfo("uv", "ba"));
#endif  // SB_API_VERSION >= 7
        result = MakeBlitProgram(
            color_matrix, texture_infos,
            CreateFragmentShader(texture_target, texture_infos));
      } break;
      case Image::YUV_3PLANE_BT709: {
        std::vector<TextureInfo> texture_infos;
        texture_infos.push_back(TextureInfo("y", "a"));
        texture_infos.push_back(TextureInfo("u", "a"));
        texture_infos.push_back(TextureInfo("v", "a"));
        result = MakeBlitProgram(
            color_matrix, texture_infos,
            CreateFragmentShader(texture_target, texture_infos));
      } break;
      case Image::YUV_UYVY_422_BT709: {
        std::vector<TextureInfo> texture_infos;
        texture_infos.push_back(TextureInfo("uyvy", "rgba"));
        result = MakeBlitProgram(color_matrix, texture_infos,
                                 CreateUYVYFragmentShader(texture_target,
                                                          *texture_wrap_s));
      } break;
      default: { NOTREACHED(); }
    }

    // Save our shader into the cache.
    found = blit_program_cache_.insert(std::make_pair(key, result)).first;
  }

  return found->second;
}

}  // namespace egl
}  // namespace rasterizer
}  // namespace renderer
}  // namespace cobalt