#include <scwx/qt/gl/draw/placefile_icons.hpp>
#include <scwx/qt/util/maplibre.hpp>
#include <scwx/qt/util/texture_atlas.hpp>
#include <scwx/util/logger.hpp>

#include <QUrl>
#include <boost/unordered/unordered_flat_map.hpp>

namespace scwx
{
namespace qt
{
namespace gl
{
namespace draw
{

static const std::string logPrefix_ = "scwx::qt::gl::draw::placefile_icons";
static const auto        logger_    = scwx::util::Logger::Create(logPrefix_);

static constexpr std::size_t kNumRectangles        = 1;
static constexpr std::size_t kNumTriangles         = kNumRectangles * 2;
static constexpr std::size_t kVerticesPerTriangle  = 3;
static constexpr std::size_t kVerticesPerRectangle = kVerticesPerTriangle * 2;
static constexpr std::size_t kPointsPerVertex      = 11;
static constexpr std::size_t kBufferLength =
   kNumTriangles * kVerticesPerTriangle * kPointsPerVertex;

struct PlacefileIconInfo
{
   PlacefileIconInfo(
      const std::shared_ptr<const gr::Placefile::IconFile>& iconFile,
      const std::string&                                    baseUrlString) :
       iconFile_ {iconFile}
   {
      // Resolve using base URL
      auto baseUrl = QUrl::fromUserInput(QString::fromStdString(baseUrlString));
      auto relativeUrl = QUrl(QString::fromStdString(iconFile->filename_));
      resolvedUrl_     = baseUrl.resolved(relativeUrl).toString().toStdString();
   }

   void UpdateTextureInfo();

   std::string                                    resolvedUrl_;
   std::shared_ptr<const gr::Placefile::IconFile> iconFile_;
   util::TextureAttributes                        texture_ {};
   std::size_t                                    rows_ {};
   std::size_t                                    columns_ {};
   std::size_t                                    numIcons_ {};
   float                                          scaledWidth_ {};
   float                                          scaledHeight_ {};
};

class PlacefileIcons::Impl
{
public:
   explicit Impl(std::shared_ptr<GlContext> context) :
       context_ {context},
       shaderProgram_ {nullptr},
       uMVPMatrixLocation_(GL_INVALID_INDEX),
       uMapMatrixLocation_(GL_INVALID_INDEX),
       uMapScreenCoordLocation_(GL_INVALID_INDEX),
       uMapDistanceLocation_(GL_INVALID_INDEX),
       vao_ {GL_INVALID_INDEX},
       vbo_ {GL_INVALID_INDEX},
       numVertices_ {0}
   {
   }

   ~Impl() {}

   std::shared_ptr<GlContext> context_;

   bool dirty_ {false};
   bool thresholded_ {false};

   std::mutex iconMutex_;

   boost::unordered_flat_map<std::size_t, PlacefileIconInfo>
      currentIconFiles_ {};
   boost::unordered_flat_map<std::size_t, PlacefileIconInfo> newIconFiles_ {};

   std::vector<std::shared_ptr<const gr::Placefile::IconDrawItem>>
      currentIconList_ {};
   std::vector<std::shared_ptr<const gr::Placefile::IconDrawItem>>
      newIconList_ {};

   std::vector<float> iconBuffer_ {};
   std::vector<GLint> thresholdBuffer_ {};

   std::shared_ptr<ShaderProgram> shaderProgram_;
   GLint                          uMVPMatrixLocation_;
   GLint                          uMapMatrixLocation_;
   GLint                          uMapScreenCoordLocation_;
   GLint                          uMapDistanceLocation_;

   GLuint                vao_;
   std::array<GLuint, 2> vbo_;

   GLsizei numVertices_;

   void UpdateBuffers();
   void Update(bool textureAtlasChanged);
};

PlacefileIcons::PlacefileIcons(std::shared_ptr<GlContext> context) :
    DrawItem(context->gl()), p(std::make_unique<Impl>(context))
{
}
PlacefileIcons::~PlacefileIcons() = default;

PlacefileIcons::PlacefileIcons(PlacefileIcons&&) noexcept            = default;
PlacefileIcons& PlacefileIcons::operator=(PlacefileIcons&&) noexcept = default;

void PlacefileIcons::set_thresholded(bool thresholded)
{
   p->thresholded_ = thresholded;
}

void PlacefileIcons::Initialize()
{
   gl::OpenGLFunctions& gl = p->context_->gl();

   p->shaderProgram_ = p->context_->GetShaderProgram(
      {{GL_VERTEX_SHADER, ":/gl/geo_texture2d.vert"},
       {GL_GEOMETRY_SHADER, ":/gl/threshold.geom"},
       {GL_FRAGMENT_SHADER, ":/gl/texture2d.frag"}});

   p->uMVPMatrixLocation_ = p->shaderProgram_->GetUniformLocation("uMVPMatrix");
   p->uMapMatrixLocation_ = p->shaderProgram_->GetUniformLocation("uMapMatrix");
   p->uMapScreenCoordLocation_ =
      p->shaderProgram_->GetUniformLocation("uMapScreenCoord");
   p->uMapDistanceLocation_ =
      p->shaderProgram_->GetUniformLocation("uMapDistance");

   gl.glGenVertexArrays(1, &p->vao_);
   gl.glGenBuffers(2, p->vbo_.data());

   gl.glBindVertexArray(p->vao_);
   gl.glBindBuffer(GL_ARRAY_BUFFER, p->vbo_[0]);
   gl.glBufferData(GL_ARRAY_BUFFER, 0u, nullptr, GL_DYNAMIC_DRAW);

   // aLatLong
   gl.glVertexAttribPointer(0,
                            2,
                            GL_FLOAT,
                            GL_FALSE,
                            kPointsPerVertex * sizeof(float),
                            static_cast<void*>(0));
   gl.glEnableVertexAttribArray(0);

   // aXYOffset
   gl.glVertexAttribPointer(1,
                            2,
                            GL_FLOAT,
                            GL_FALSE,
                            kPointsPerVertex * sizeof(float),
                            reinterpret_cast<void*>(2 * sizeof(float)));
   gl.glEnableVertexAttribArray(1);

   // aTexCoord
   gl.glVertexAttribPointer(2,
                            2,
                            GL_FLOAT,
                            GL_FALSE,
                            kPointsPerVertex * sizeof(float),
                            reinterpret_cast<void*>(4 * sizeof(float)));
   gl.glEnableVertexAttribArray(2);

   // aModulate
   gl.glVertexAttribPointer(3,
                            4,
                            GL_FLOAT,
                            GL_FALSE,
                            kPointsPerVertex * sizeof(float),
                            reinterpret_cast<void*>(6 * sizeof(float)));
   gl.glEnableVertexAttribArray(3);

   // aAngle
   gl.glVertexAttribPointer(4,
                            1,
                            GL_FLOAT,
                            GL_FALSE,
                            kPointsPerVertex * sizeof(float),
                            reinterpret_cast<void*>(10 * sizeof(float)));
   gl.glEnableVertexAttribArray(4);

   gl.glBindBuffer(GL_ARRAY_BUFFER, p->vbo_[1]);
   gl.glBufferData(GL_ARRAY_BUFFER, 0u, nullptr, GL_DYNAMIC_DRAW);

   // aThreshold
   gl.glVertexAttribIPointer(5, //
                             1,
                             GL_INT,
                             0,
                             static_cast<void*>(0));
   gl.glEnableVertexAttribArray(5);

   p->dirty_ = true;
}

void PlacefileIcons::Render(
   const QMapLibreGL::CustomLayerRenderParameters& params,
   bool                                            textureAtlasChanged)
{
   std::unique_lock lock {p->iconMutex_};

   if (!p->currentIconList_.empty())
   {
      gl::OpenGLFunctions& gl = p->context_->gl();

      gl.glBindVertexArray(p->vao_);

      p->Update(textureAtlasChanged);
      p->shaderProgram_->Use();
      UseRotationProjection(params, p->uMVPMatrixLocation_);
      UseMapProjection(
         params, p->uMapMatrixLocation_, p->uMapScreenCoordLocation_);

      if (p->thresholded_)
      {
         // If thresholding is enabled, set the map distance
         units::length::nautical_miles<float> mapDistance =
            util::maplibre::GetMapDistance(params);
         gl.glUniform1f(p->uMapDistanceLocation_, mapDistance.value());
      }
      else
      {
         // If thresholding is disabled, set the map distance to 0
         gl.glUniform1f(p->uMapDistanceLocation_, 0.0f);
      }

      // Don't interpolate texture coordinates
      gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
      gl.glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

      // Draw icons
      gl.glDrawArrays(GL_TRIANGLES, 0, p->numVertices_);
   }
}

void PlacefileIcons::Deinitialize()
{
   gl::OpenGLFunctions& gl = p->context_->gl();

   gl.glDeleteVertexArrays(1, &p->vao_);
   gl.glDeleteBuffers(2, p->vbo_.data());

   std::unique_lock lock {p->iconMutex_};

   p->currentIconList_.clear();
   p->currentIconFiles_.clear();
   p->iconBuffer_.clear();
   p->thresholdBuffer_.clear();
}

void PlacefileIconInfo::UpdateTextureInfo()
{
   texture_ = util::TextureAtlas::Instance().GetTextureAttributes(resolvedUrl_);

   if (iconFile_->iconWidth_ > 0 && iconFile_->iconHeight_ > 0)
   {
      columns_ = texture_.size_.x / iconFile_->iconWidth_;
      rows_    = texture_.size_.y / iconFile_->iconHeight_;
   }
   else
   {
      columns_ = 0u;
      rows_    = 0u;
   }

   numIcons_ = columns_ * rows_;

   // Pixel size
   float xFactor = 0.0f;
   float yFactor = 0.0f;

   if (texture_.size_.x > 0 && texture_.size_.y > 0)
   {
      xFactor = (texture_.sRight_ - texture_.sLeft_) / texture_.size_.x;
      yFactor = (texture_.tBottom_ - texture_.tTop_) / texture_.size_.y;
   }

   scaledWidth_  = iconFile_->iconWidth_ * xFactor;
   scaledHeight_ = iconFile_->iconHeight_ * yFactor;
}

void PlacefileIcons::StartIcons()
{
   // Clear the new buffer
   p->newIconList_.clear();
   p->newIconFiles_.clear();
}

void PlacefileIcons::SetIconFiles(
   const std::vector<std::shared_ptr<const gr::Placefile::IconFile>>& iconFiles,
   const std::string&                                                 baseUrl)
{
   // Populate icon file map
   for (auto& file : iconFiles)
   {
      p->newIconFiles_.emplace(
         std::piecewise_construct,
         std::tuple {file->fileNumber_},
         std::forward_as_tuple(PlacefileIconInfo {file, baseUrl}));
   }
}

void PlacefileIcons::AddIcon(
   const std::shared_ptr<gr::Placefile::IconDrawItem>& di)
{
   if (di != nullptr)
   {
      p->newIconList_.emplace_back(di);
   }
}

void PlacefileIcons::FinishIcons()
{
   std::unique_lock lock {p->iconMutex_};

   // Swap buffers
   p->currentIconList_.swap(p->newIconList_);
   p->currentIconFiles_.swap(p->newIconFiles_);

   // Clear the new buffers
   p->newIconList_.clear();
   p->newIconFiles_.clear();

   // Mark the draw item dirty
   p->dirty_ = true;
}

void PlacefileIcons::Impl::UpdateBuffers()
{
   iconBuffer_.clear();
   iconBuffer_.reserve(currentIconList_.size() * kBufferLength);
   thresholdBuffer_.clear();
   thresholdBuffer_.reserve(currentIconList_.size() * kVerticesPerRectangle);
   numVertices_ = 0;

   for (auto& di : currentIconList_)
   {
      auto it = currentIconFiles_.find(di->fileNumber_);
      if (it == currentIconFiles_.cend())
      {
         // No file found
         logger_->trace("Could not find file number: {}", di->fileNumber_);
         continue;
      }

      auto& icon = it->second;

      // Validate icon
      if (di->iconNumber_ == 0 || di->iconNumber_ > icon.numIcons_)
      {
         // No icon found
         logger_->trace("Invalid icon number: {}", di->iconNumber_);
         continue;
      }

      // Threshold value
      units::length::nautical_miles<double> threshold = di->threshold_;
      GLint thresholdValue = static_cast<GLint>(std::round(threshold.value()));

      // Latitude and longitude coordinates in degrees
      const float lat = static_cast<float>(di->latitude_);
      const float lon = static_cast<float>(di->longitude_);

      // Base X/Y offsets in pixels
      const float x = static_cast<float>(di->x_);
      const float y = static_cast<float>(di->y_);

      // Icon size
      const float iw = static_cast<float>(icon.iconFile_->iconWidth_);
      const float ih = static_cast<float>(icon.iconFile_->iconHeight_);

      // Hot X/Y (zero-based icon center)
      const float hx = static_cast<float>(icon.iconFile_->hotX_);
      const float hy = static_cast<float>(icon.iconFile_->hotY_);

      // Final X/Y offsets in pixels
      const float lx = std::roundf(x - hx);
      const float rx = std::roundf(lx + iw);
      const float ty = std::roundf(y + hy);
      const float by = std::roundf(ty - ih);

      // Angle in degrees
      units::angle::degrees<float> angle = di->angle_;
      const float                  a     = angle.value();

      // Texture coordinates
      const std::size_t iconRow    = (di->iconNumber_ - 1) / icon.columns_;
      const std::size_t iconColumn = (di->iconNumber_ - 1) % icon.columns_;

      const float iconX = iconColumn * icon.scaledWidth_;
      const float iconY = iconRow * icon.scaledHeight_;

      const float ls = icon.texture_.sLeft_ + iconX;
      const float rs = ls + icon.scaledWidth_;
      const float tt = icon.texture_.tTop_ + iconY;
      const float bt = tt + icon.scaledHeight_;

      // Fixed modulate color
      const float mc0 = 1.0f;
      const float mc1 = 1.0f;
      const float mc2 = 1.0f;
      const float mc3 = 1.0f;

      iconBuffer_.insert(
         iconBuffer_.end(),
         {
            // Icon
            lat, lon, lx, by, ls, bt, mc0, mc1, mc2, mc3, a, // BL
            lat, lon, lx, ty, ls, tt, mc0, mc1, mc2, mc3, a, // TL
            lat, lon, rx, by, rs, bt, mc0, mc1, mc2, mc3, a, // BR
            lat, lon, rx, by, rs, bt, mc0, mc1, mc2, mc3, a, // BR
            lat, lon, rx, ty, rs, tt, mc0, mc1, mc2, mc3, a, // TR
            lat, lon, lx, ty, ls, tt, mc0, mc1, mc2, mc3, a  // TL
         });
      thresholdBuffer_.insert(thresholdBuffer_.end(),
                              {thresholdValue, //
                               thresholdValue,
                               thresholdValue,
                               thresholdValue,
                               thresholdValue,
                               thresholdValue});
   }

   dirty_ = true;
}

void PlacefileIcons::Impl::Update(bool textureAtlasChanged)
{
   // If the texture atlas has changed
   if (dirty_ || textureAtlasChanged)
   {
      // Update texture coordinates
      for (auto& iconFile : currentIconFiles_)
      {
         iconFile.second.UpdateTextureInfo();
      }

      // Update OpenGL buffer data
      UpdateBuffers();

      gl::OpenGLFunctions& gl = context_->gl();

      // Buffer vertex data
      gl.glBindBuffer(GL_ARRAY_BUFFER, vbo_[0]);
      gl.glBufferData(GL_ARRAY_BUFFER,
                      sizeof(float) * iconBuffer_.size(),
                      iconBuffer_.data(),
                      GL_DYNAMIC_DRAW);

      // Buffer threshold data
      gl.glBindBuffer(GL_ARRAY_BUFFER, vbo_[1]);
      gl.glBufferData(GL_ARRAY_BUFFER,
                      sizeof(GLint) * thresholdBuffer_.size(),
                      thresholdBuffer_.data(),
                      GL_DYNAMIC_DRAW);

      numVertices_ =
         static_cast<GLsizei>(iconBuffer_.size() / kVerticesPerRectangle);
   }

   dirty_ = false;
}

} // namespace draw
} // namespace gl
} // namespace qt
} // namespace scwx