// Copyright (c) 2025 Dominic Masters
// 
// This software is released under the MIT License.
// https://opensource.org/licenses/MIT

#include "Mesh.hpp"
#include "assert/Assert.hpp"

using namespace Dawn;

Mesh::Mesh(
  const int32_t vertexCount,
  const PrimitiveType primitiveType,
  const MeshVertex *vertices
) :
  vertexCount(vertexCount),
  primitiveType(primitiveType),
  vertices(vertices)
{

}

void Mesh::draw(
  int32_t vertexOffset,
  int32_t vertexCount
) const {
  const int32_t offset = vertexOffset == -1 ? 0 : vertexOffset;
  const int32_t count = vertexCount == -1 ? this->vertexCount : vertexCount;

  assertNotNull(this->vertices, "Mesh cannot be NULL");
  assertTrue(offset >= 0, "Vertex offset must be non-negative");
  assertTrue(count >= 0, "Vertex count must be non-negative");
  assertTrue(
    offset + count <= this->vertexCount, 
    "Vertex offset + count must not exceed vertex count"
  );

  #if DISPLAY_SDL2
    // PSP style pointer legacy OpenGL
    const GLsizei stride = sizeof(MeshVertex);

    glColorPointer(
      MESH_VERTEX_COLOR_SIZE,
      GL_UNSIGNED_BYTE,
      stride,
      (const GLvoid*)&this->vertices[offset].color[0]
    );

    glTexCoordPointer(
      MESH_VERTEX_UV_SIZE,
      GL_FLOAT,
      stride,
      (const GLvoid*)&this->vertices[offset].uv[0]
    );

    glVertexPointer(
      MESH_VERTEX_POS_SIZE,
      GL_FLOAT,
      stride,
      (const GLvoid*)&this->vertices[offset].pos[0]
    );
    
    glDrawArrays(
      this->primitiveType,
      0,
      count
    );
  #endif
}

Mesh::~Mesh() {

}