#include "../../../include/RenderBackend/OpenGL/DeviceMemory.hpp"
#include "../../../include/RenderBackend/OpenGL/opengl.hpp"
#include <cassert>

namespace amalgine {
    u32 getOpenglStorageType(DeviceMemory::StorageType storageType) {
        switch(storageType) {
            case DeviceMemory::StorageType::STATIC:     return GL_STATIC_DRAW;
            case DeviceMemory::StorageType::DYNAMIC:    return GL_DYNAMIC_DRAW;
            case DeviceMemory::StorageType::STREAM:     return GL_STREAM_DRAW;
            default: assert(false); return -1;
        }
    }
    
    DeviceMemory::DeviceMemory(u32 vertex_array_object_id, i32 attrib_location) :
            vertex_array_object_id(vertex_array_object_id), vertex_buffer_object_id(-1), attrib_location(attrib_location),
            num_vertices(0), memory_type(DeviceMemoryType::NONE) {
        glGenBuffers(1, &vertex_buffer_object_id);
    }
    
    DeviceMemory::~DeviceMemory() {
        glDeleteBuffers(1, &vertex_buffer_object_id);
    }
    
    void DeviceMemory::use() {
        glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object_id);
    }

    void DeviceMemory::set(const DataView<vec2f> &texture_coords, StorageType storageType) {
        glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object_id);
        glBufferData(GL_ARRAY_BUFFER, texture_coords.getByteSize(), texture_coords.data, getOpenglStorageType(storageType));
        num_vertices = texture_coords.size * 2;
        memory_type = DeviceMemoryType::VEC2;

        glBindVertexArray(vertex_array_object_id); // Encapsulate DeviceMemory (vertex buffer object) inside the active vertex array object
        glVertexAttribPointer(attrib_location, 2, GL_FLOAT, GL_FALSE, 0, 0);
    }

    void DeviceMemory::set(const DataView<Triangle2D> &triangles, StorageType storageType) {
        glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object_id);
        glBufferData(GL_ARRAY_BUFFER, triangles.getByteSize(), triangles.data, getOpenglStorageType(storageType));
        num_vertices = triangles.size * 2;
        memory_type = DeviceMemoryType::VEC2;

        glBindVertexArray(vertex_array_object_id); // Encapsulate DeviceMemory (vertex buffer object) inside the active vertex array object
        glVertexAttribPointer(attrib_location, 2, GL_FLOAT, GL_FALSE, 0, 0);
    }

    void DeviceMemory::set(const DataView<Triangle3D> &triangles, StorageType storageType) {
        glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object_id);
        glBufferData(GL_ARRAY_BUFFER, triangles.getByteSize(), triangles.data, getOpenglStorageType(storageType));
        num_vertices = triangles.size * 3;
        memory_type = DeviceMemoryType::VEC3;

        glBindVertexArray(vertex_array_object_id); // Encapsulate DeviceMemory (vertex buffer object) inside the active vertex array object
        glVertexAttribPointer(attrib_location, 3, GL_FLOAT, GL_FALSE, 0, 0);
    }
}