#define TINYGLTF_IMPLEMENTATION
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
// STB_IMAGE_WRITE is NOT implemented by tinygltf automatically, we must define
// it.
#include "vendor/tiny_gltf.h"

#include <iostream>
#include <string>
#include <vector>

#include <SketchUpAPI/color.h>
#include <SketchUpAPI/common.h>
#include <SketchUpAPI/geometry.h>
#include <SketchUpAPI/initialize.h>
#include <SketchUpAPI/model/component_instance.h>
#include <SketchUpAPI/model/edge.h>
#include <SketchUpAPI/model/entities.h>
#include <SketchUpAPI/model/face.h>
#include <SketchUpAPI/model/geometry_input.h>
#include <SketchUpAPI/model/group.h>
#include <SketchUpAPI/model/material.h>
#include <SketchUpAPI/model/model.h>
#include <SketchUpAPI/model/texture.h>
#include <SketchUpAPI/model/vertex.h>

// constant for meters to inches conversion
const double kMetersToInches = 39.3701;

// Helper to get data from accessor
template <typename T>
std::vector<T> GetData(const tinygltf::Model &model,
                       const tinygltf::Accessor &accessor) {
  if (accessor.bufferView < 0) {
    std::cerr << "GetData: ERROR - accessor " << accessor.name
              << " has no bufferView (index=" << accessor.bufferView << ")"
              << std::endl;
    return std::vector<T>();
  }

  std::cout << "GetData: accessor=" << accessor.bufferView
            << " count=" << accessor.count << " stride="
            << accessor.ByteStride(model.bufferViews[accessor.bufferView])
            << std::endl;
  const tinygltf::BufferView &bufferView =
      model.bufferViews[accessor.bufferView];
  const tinygltf::Buffer &buffer = model.buffers[bufferView.buffer];

  // Check bounds
  if (bufferView.byteOffset + accessor.byteOffset + accessor.count * sizeof(T) >
      buffer.data.size()) {
    // Only strict if stride is tight, but rough check
    std::cerr << "WARNING: Accessor points outside buffer!" << std::endl;
  }

  const unsigned char *data =
      buffer.data.data() + bufferView.byteOffset + accessor.byteOffset;

  std::vector<T> output;
  output.resize(accessor.count);

  // Stride check
  int stride = accessor.ByteStride(bufferView);
  if (stride == sizeof(T)) {
    memcpy(output.data(), data, accessor.count * sizeof(T));
  } else {
    for (size_t i = 0; i < accessor.count; ++i) {
      memcpy(&output[i], data + i * stride, sizeof(T));
    }
  }
  return output;
}

// Simple struct for vec2 and vec3
struct Vec2 {
  float u, v;
};
struct Vec3 {
  float x, y, z;
};

// Global stats for debug output (declared before CreateMaterialFromGLTF)
int g_totalFaces = 0;
int g_texturedFaces = 0;
int g_totalVertices = 0;
size_t g_totalTextureBytes = 0;
int g_textureWidth = 0;
int g_textureHeight = 0;

// Helper to create SketchUp material from GLTF material
SUMaterialRef
CreateMaterialFromGLTF(const tinygltf::Model &model, int materialIndex,
                       SUModelRef su_model,
                       std::vector<SUMaterialRef> &created_materials) {
  if (materialIndex < 0 || materialIndex >= model.materials.size())
    return SU_INVALID;
  if (SUIsValid(created_materials[materialIndex]))
    return created_materials[materialIndex];

  const tinygltf::Material &gltf_mat = model.materials[materialIndex];
  SUMaterialRef mat = SU_INVALID;
  SUMaterialCreate(&mat);

  // Set Name
  std::string matName = gltf_mat.name;
  if (matName.empty()) {
    matName = "Material_" + std::to_string(materialIndex);
  }
  SUMaterialSetName(mat, matName.c_str());

  // Set Color
  if (gltf_mat.pbrMetallicRoughness.baseColorFactor.size() == 4) {
    SUColor color;
    color.red =
        (SUByte)(gltf_mat.pbrMetallicRoughness.baseColorFactor[0] * 255);
    color.green =
        (SUByte)(gltf_mat.pbrMetallicRoughness.baseColorFactor[1] * 255);
    color.blue =
        (SUByte)(gltf_mat.pbrMetallicRoughness.baseColorFactor[2] * 255);
    color.alpha =
        (SUByte)(gltf_mat.pbrMetallicRoughness.baseColorFactor[3] * 255);
    SUMaterialSetColor(mat, &color);
    if (color.alpha < 255) {
      SUMaterialSetUseOpacity(mat, true);
      SUMaterialSetOpacity(mat,
                           gltf_mat.pbrMetallicRoughness.baseColorFactor[3]);
    }
  }

  // Set Texture
  int texIndex = gltf_mat.pbrMetallicRoughness.baseColorTexture.index;
  if (texIndex >= 0 && texIndex < model.textures.size()) {
    int imgIndex = model.textures[texIndex].source;
    if (imgIndex >= 0 && imgIndex < model.images.size()) {
      const tinygltf::Image &image = model.images[imgIndex];

      // Check if image data is loaded
      if (image.width > 0 && image.height > 0 && !image.image.empty()) {
        // Track texture stats
        g_textureWidth = image.width;
        g_textureHeight = image.height;
        // g_totalTextureBytes calculated after writing file

        // Write to temp file
        std::string tempFileName;
        bool isJpeg =
            (image.mimeType == "image/jpeg" || image.mimeType == "image/jpg");

        if (isJpeg) {
          tempFileName = "temp_" + std::to_string(imgIndex) + ".jpg";

          // Convert RGBA to RGB if needed
          if (image.component == 4) {
            std::vector<unsigned char> rgb_data(image.width * image.height * 3);
            for (size_t i = 0; i < image.width * image.height; ++i) {
              rgb_data[i * 3 + 0] = image.image[i * 4 + 0];
              rgb_data[i * 3 + 1] = image.image[i * 4 + 1];
              rgb_data[i * 3 + 2] = image.image[i * 4 + 2];
            }
            stbi_write_jpg(tempFileName.c_str(), image.width, image.height, 3,
                           rgb_data.data(), 85);
          } else {
            stbi_write_jpg(tempFileName.c_str(), image.width, image.height,
                           image.component, image.image.data(), 85);
          }
        } else {
          tempFileName = "temp_" + std::to_string(imgIndex) + ".png";
          stbi_write_png(tempFileName.c_str(), image.width, image.height,
                         image.component, image.image.data(),
                         image.width * image.component);
        }

        // ACCURATE SIZE CALCULATION:
        // Read the size of the generated file (JPEG/PNG) instead of the raw
        // pixel buffer because SketchUp embeds the compressed file.
        std::ifstream in(tempFileName,
                         std::ifstream::ate | std::ifstream::binary);
        if (in.is_open()) {
          g_totalTextureBytes += in.tellg();
        }

        SUTextureRef texture = SU_INVALID;
        SUResult texRes =
            SUTextureCreateFromFile(&texture, tempFileName.c_str(), 1.0, 1.0);
        if (texRes == SU_ERROR_NONE) {
          SUMaterialSetTexture(mat, texture);
        } else {
          std::cerr << "Failed to create texture from file: " << tempFileName
                    << std::endl;
        }
      }
    }
  }

  // Add material to model
  SUModelAddMaterials(su_model, 1, &mat);
  created_materials[materialIndex] = mat;
  return mat;
}

void ProcessNode(const tinygltf::Model &model, const tinygltf::Node &node,
                 SUEntitiesRef entities, SUModelRef su_model,
                 std::vector<SUMaterialRef> &created_materials) {
  if (node.mesh >= 0) {
    if (node.mesh >= model.meshes.size()) {
      std::cerr << "Error: Mesh index out of bounds: " << node.mesh
                << std::endl;
      return;
    }
    const tinygltf::Mesh &mesh = model.meshes[node.mesh];
    std::cout << "Processing Mesh: " << mesh.name << std::endl;

    for (const auto &primitive : mesh.primitives) {
      SUGeometryInputRef input = SU_INVALID;
      SUGeometryInputCreate(&input);

      // Vertices
      std::vector<SUPoint3D> su_vertices;
      if (primitive.attributes.find("POSITION") != primitive.attributes.end()) {
        const tinygltf::Accessor &accessor =
            model.accessors[primitive.attributes.at("POSITION")];
        std::vector<Vec3> positions = GetData<Vec3>(model, accessor);

        if (positions.empty()) {
          std::cerr << "Error: No vertices retrieved for mesh " << mesh.name
                    << std::endl;
          SUGeometryInputRelease(&input);
          continue;
        }

        for (const auto &p : positions) {
          SUPoint3D pt;
          // GLB uses Y-up coordinate system
          // SketchUp uses Z-up coordinate system
          // Transformation: GLB(x,y,z) -> SKU(x, -z, y)
          // X stays X, GLB Y (up) becomes SKU Z (up), GLB Z (forward) becomes
          // SKU -Y (forward)
          pt.x = p.x * kMetersToInches;
          pt.y = -p.z * kMetersToInches; // GLB Z (forward) becomes SKU -Y
          pt.z =
              p.y * kMetersToInches; // GLB Y (up) becomes SKU Z (NO negation)
          su_vertices.push_back(pt);
        }
        g_totalVertices += su_vertices.size();
        SUGeometryInputSetVertices(input, su_vertices.size(),
                                   su_vertices.data());
      }

      // UVs
      std::vector<SUPoint2D> su_uvs;
      bool hasUVs = false;
      if (primitive.attributes.find("TEXCOORD_0") !=
          primitive.attributes.end()) {
        const tinygltf::Accessor &accessor =
            model.accessors[primitive.attributes.at("TEXCOORD_0")];
        std::vector<Vec2> uvs = GetData<Vec2>(model, accessor);
        for (const auto &uv : uvs) {
          SUPoint2D pt;
          pt.x = uv.u;
          pt.y = 1.0f - uv.v; // Flip V for SketchUp
          su_uvs.push_back(pt);
        }
        hasUVs = true;
      }

      std::cout << "  - Accessor: " << primitive.indices
                << " Mode: " << primitive.mode << std::endl;
      if (primitive.mode != TINYGLTF_MODE_TRIANGLES) {
        std::cerr
            << "WARNING: Primitive mode " << primitive.mode
            << " is not TRIANGLES (4). SketchUp converter expects TRIANGLES."
            << std::endl;
      }

      // Indices (Faces)
      std::vector<size_t> indices;
      if (primitive.indices >= 0) {
        const tinygltf::Accessor &indexAccessor =
            model.accessors[primitive.indices];

        if (indexAccessor.componentType ==
            TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT) {
          std::vector<unsigned short> raw =
              GetData<unsigned short>(model, indexAccessor);
          for (auto v : raw)
            indices.push_back(v);
        } else if (indexAccessor.componentType ==
                   TINYGLTF_COMPONENT_TYPE_UNSIGNED_INT) {
          std::vector<unsigned int> raw =
              GetData<unsigned int>(model, indexAccessor);
          for (auto v : raw)
            indices.push_back(v);
        } else if (indexAccessor.componentType ==
                   TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE) {
          std::vector<unsigned char> raw =
              GetData<unsigned char>(model, indexAccessor);
          for (auto v : raw)
            indices.push_back(v);
        }
      } else {
        // Handle non-indexed geometry (just vertices)
        // Generate sequential indices: 0, 1, 2, ... based on vertex count
        size_t vertexCount = su_vertices.size();
        for (size_t i = 0; i < vertexCount; i++) {
          indices.push_back(i);
        }
      }

      // Validate indices are within range
      size_t maxIndex = su_vertices.size();
      bool validIndices = true;
      for (size_t idx : indices) {
        if (idx >= maxIndex) {
          std::cerr << "Warning: Index " << idx << " out of range (max "
                    << maxIndex << ")" << std::endl;
          validIndices = false;
          break;
        }
      }

      if (!validIndices || indices.empty()) {
        std::cerr << "Skipping primitive due to invalid indices" << std::endl;
        SUGeometryInputRelease(&input);
        continue;
      }

      // Material
      SUMaterialRef material = SU_INVALID;
      if (primitive.material >= 0) {
        material = CreateMaterialFromGLTF(model, primitive.material, su_model,
                                          created_materials);
      }

      for (size_t i = 0; i + 2 < indices.size(); i += 3) {
        size_t i0 = indices[i];
        size_t i1 = indices[i + 1];
        size_t i2 = indices[i + 2];

        // Skip degenerate triangles (same vertex referenced multiple times)
        if (i0 == i1 || i1 == i2 || i0 == i2) {
          continue;
        }

        SULoopInputRef loop = SU_INVALID;
        SULoopInputCreate(&loop);

        // Add vertex indices for the triangle
        SULoopInputAddVertexIndex(loop, i0);
        SULoopInputAddVertexIndex(loop, i1);
        SULoopInputAddVertexIndex(loop, i2);

        // Set all edges as SOFT + SMOOTH so the model looks like smooth-shaded
        // GLB Edge indices are 0, 1, 2 for the three edges of the triangle This
        // makes the model render with smooth shading rather than faceted/boxy
        SULoopInputEdgeSetSoft(loop, 0, true);
        SULoopInputEdgeSetSmooth(loop, 0, true);
        SULoopInputEdgeSetSoft(loop, 1, true);
        SULoopInputEdgeSetSmooth(loop, 1, true);
        SULoopInputEdgeSetSoft(loop, 2, true);
        SULoopInputEdgeSetSmooth(loop, 2, true);

        size_t face_index;
        SUResult addResult = SUGeometryInputAddFace(input, &loop, &face_index);
        if (addResult != SU_ERROR_NONE) {
          // Face creation failed, skip
          continue;
        }
        g_totalFaces++;

        // Set Material and UVs
        if (SUIsValid(material)) {
          SUMaterialInput mat_input;
          mat_input.material = material;
          mat_input.num_uv_coords = 0;

          if (hasUVs && i0 < su_uvs.size() && i1 < su_uvs.size() &&
              i2 < su_uvs.size()) {
            mat_input.num_uv_coords = 3;
            mat_input.uv_coords[0] = su_uvs[i0];
            mat_input.uv_coords[1] = su_uvs[i1];
            mat_input.uv_coords[2] = su_uvs[i2];

            mat_input.vertex_indices[0] = i0;
            mat_input.vertex_indices[1] = i1;
            mat_input.vertex_indices[2] = i2;
          }

          SUGeometryInputFaceSetFrontMaterial(input, face_index, &mat_input);
          SUGeometryInputFaceSetBackMaterial(input, face_index, &mat_input);
          g_texturedFaces++;
        } else if (hasUVs) {
          // Even without a material, we might want to apply UVs?
          // SketchUp usually ties UVs to a material.
          // If no material, no texture to map. So skipping.
        }
      }

      // Fill entities (per primitive) - INSIDE the primitive loop
      SUEntitiesFill(entities, input, true);
      SUGeometryInputRelease(&input);
    }
  }

  // Children - INSIDE ProcessNode function
  for (int childIndex : node.children) {
    ProcessNode(model, model.nodes[childIndex], entities, su_model,
                created_materials);
  }
}

int main(int argc, char **argv) {
  if (argc < 3) {
    std::cerr << "Usage: " << argv[0] << " input.glb output.skp" << std::endl;
    return 1;
  }

  SUInitialize();

  std::string inputPath = argv[1];
  std::string outputPath = argv[2];

  tinygltf::Model model;
  tinygltf::TinyGLTF loader;

  // Set tolerent image loader
  loader.SetImageLoader(
      [](tinygltf::Image *image, const int image_idx, std::string *err,
         std::string *warn, int req_width, int req_height,
         const unsigned char *bytes, int size, void *user_data) {
        bool res =
            tinygltf::LoadImageData(image, image_idx, err, warn, req_width,
                                    req_height, bytes, size, user_data);
        if (!res) {
          // If default loader fails, consume the error and return true to
          // proceed without this image
          if (warn) {
            *warn += "Failed to load image: " + (err ? *err : "Unknown error") +
                     ". Skipping.\n";
          }
          if (err) {
            *err = ""; // Clear error
          }
          return true;
        }
        return true;
      },
      nullptr);

  std::string err;
  std::string warn;

  bool ret = loader.LoadBinaryFromFile(&model, &err, &warn, inputPath);

  if (!warn.empty()) {
    std::cerr << "Warn: " << warn << std::endl;
  }

  if (!err.empty()) {
    std::cerr << "Err: " << err << std::endl;
  }

  if (!ret) {
    std::cerr << "Failed to load GLTF" << std::endl;
    return 1;
  }

  SUModelRef su_model = SU_INVALID;
  SUResult res = SUModelCreate(&su_model);
  if (res != SU_ERROR_NONE)
    return 1;

  // Get model's root entities first (we need it to add the group)
  SUEntitiesRef model_entities = SU_INVALID;
  SUModelGetEntities(su_model, &model_entities);

  // Create a group to hold all geometry (makes it a single unit in SketchUp)
  SUGroupRef group = SU_INVALID;
  SUGroupCreate(&group);

  // Add the group to the model FIRST (required before filling its entities)
  SUEntitiesAddGroup(model_entities, group);

  // Now get the group's internal entities to add geometry
  SUEntitiesRef group_entities = SU_INVALID;
  SUGroupGetEntities(group, &group_entities);

  // Cache to store created SU materials to reuse them
  std::vector<SUMaterialRef> created_materials(model.materials.size(),
                                               SU_INVALID);

  // Iterate over scenes
  // Iterate over scenes
  int sceneindex = (model.defaultScene >= 0) ? model.defaultScene : 0;

  if (sceneindex >= 0 && sceneindex < model.scenes.size()) {
    const tinygltf::Scene &scene = model.scenes[sceneindex];
    for (size_t i = 0; i < scene.nodes.size(); i++) {
      ProcessNode(model, model.nodes[scene.nodes[i]], model_entities, su_model,
                  created_materials);
    }
  } else {
    // If no valid scene found, try processing all nodes (fallback for flat
    // GLBs)
    for (size_t i = 0; i < model.nodes.size(); i++) {
      ProcessNode(model, model.nodes[i], model_entities, su_model,
                  created_materials);
    }
  }
  // POST-PROCESSING: Soften ALL edges to make the model
  // appear smooth
  // This is crucial for imported meshes - it hides all triangle edges
  // and makes SketchUp render the model with smooth shading
  size_t edge_count = 0;
  SUEntitiesGetNumEdges(group_entities, false, &edge_count);

  if (edge_count > 0) {
    std::vector<SUEdgeRef> edges(edge_count);
    size_t actual_count = 0;
    SUEntitiesGetEdges(group_entities, false, edge_count, edges.data(),
                       &actual_count);

    // Soften and smooth ALL edges - this makes curved surfaces look smooth
    for (size_t i = 0; i < actual_count; i++) {
      SUEdgeSetSoft(edges[i], true);
      SUEdgeSetSmooth(edges[i], true);
    }
    std::cerr << "Softened " << actual_count << " edges for smooth appearance"
              << std::endl;
  }

  // Lock the group to prevent accidental exploding
  SUComponentInstanceRef group_instance = SUGroupToComponentInstance(group);
  if (group_instance.ptr !=
      0) { // Check if valid (though SUGroupRef is basically a subclass)
    SUComponentInstanceSetLocked(group_instance, true);
  }

  res = SUModelSaveToFile(su_model, outputPath.c_str());
  if (res != SU_ERROR_NONE) {
    std::cerr << "Failed to save SKP file" << std::endl;
  } else {
    std::cout << "Saved " << outputPath << std::endl;
  }

  // Cleanup images (optional, if we track temp files)

  SUModelRelease(&su_model);
  SUTerminate();

  // Calculate size breakdown estimates (in bytes)
  // Geometry: ~24 bytes per vertex (3x float position + 3x float normal + 2x
  // float UV) Face index: ~12 bytes per face (3x int32 indices)
  size_t estimatedGeometryBytes = (g_totalVertices * 24) + (g_totalFaces * 12);

  // Calculate SKP Overhead
  std::ifstream f(outputPath, std::ifstream::ate | std::ifstream::binary);
  size_t actualFileSize = f.tellg();
  f.close();

  long long overhead = (long long)actualFileSize -
                       (long long)estimatedGeometryBytes -
                       (long long)g_totalTextureBytes;
  if (overhead < 0)
    overhead = 0; // Should not happen unless estimates are way off

  // Output JSON stats for frontend to parse
  std::cout << "{" << std::endl;
  std::cout << "  \"status\": \"success\"," << std::endl;
  std::cout << "  \"vertices\": " << g_totalVertices << "," << std::endl;
  std::cout << "  \"faces\": " << g_totalFaces << "," << std::endl;
  std::cout << "  \"textured_faces\": " << g_texturedFaces << "," << std::endl;
  std::cout << "  \"materials\": " << model.materials.size() << ","
            << std::endl;
  std::cout << "  \"textures\": " << model.textures.size() << "," << std::endl;
  std::cout << "  \"texture_width\": " << g_textureWidth << "," << std::endl;
  std::cout << "  \"texture_height\": " << g_textureHeight << "," << std::endl;
  std::cout << "  \"texture_bytes\": " << g_totalTextureBytes << ","
            << std::endl;
  std::cout << "  \"estimated_geometry_bytes\": " << estimatedGeometryBytes
            << "," << std::endl;
  std::cout << "  \"skp_overhead_bytes\": " << overhead << std::endl;
  std::cout << "}" << std::endl;

  return 0;
}