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

#include "mesh.h"
#include "util/memory.h"
#include "assert/assert.h"

#include "console/console.h"

void meshInit(
  mesh_t *mesh,
  const GLenum primitiveType,
  const int32_t vertexCount,
  const meshvertex_t *vertices
) {
  assertNotNull(mesh, "Mesh cannot be NULL");
  assertNotNull(vertices, "Vertices cannot be NULL");
  assertTrue(vertexCount > 0, "Vertex count must be greater than 0");

  memoryZero(mesh, sizeof(mesh_t));
  
  mesh->primitiveType = primitiveType;
  mesh->vertexCount = vertexCount;
  mesh->vertices = vertices;
}

void meshDraw(
  const mesh_t *mesh,
  const int32_t vertexOffset,
  const int32_t vertexCount
) {
  const int32_t offset = vertexOffset == -1 ? 0 : vertexOffset;
  const int32_t count = vertexCount == -1 ? mesh->vertexCount : vertexCount;

  assertNotNull(mesh, "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 <= mesh->vertexCount, 
    "Vertex offset + count must not exceed vertex count"
  );

  #if 1
    // PSP style pointer legacy OpenGL
    const GLsizei stride = sizeof(meshvertex_t);

    glColorPointer(
      MESH_VERTEX_COLOR_SIZE,
      GL_UNSIGNED_BYTE,
      stride,
      (const GLvoid*)&mesh->vertices[offset].color[0]
    );
    glTexCoordPointer(
      MESH_VERTEX_UV_SIZE,
      GL_FLOAT,
      stride,
      (const GLvoid*)&mesh->vertices[offset].uv[0]
    );
    glVertexPointer(
      MESH_VERTEX_POS_SIZE,
      GL_FLOAT,
      stride,
      (const GLvoid*)&mesh->vertices[offset].pos[0]
    );
    
    glDrawArrays(
      mesh->primitiveType,
      0,
      count
    );
  #else
    #error "Need to support modern OpenGL with VAOs and VBOs"
  #endif
}

void meshDispose(mesh_t *mesh) {
  assertNotNull(mesh, "Mesh cannot be NULL");
  memoryZero(mesh, sizeof(mesh_t));
}