//
// Created by BZLZHH on 2025/5/1.
//

// TODO: Add more gl error check for vertex array state manager.

#include "VertexArrayState.h"

VertexArrayState::VertexArrayState() {
    vaos_[0];
}

GLenum VertexArrayState::Create(GLuint* array) {
    if (array == nullptr) return GL_INVALID_VALUE;

    GLuint id = freeId_.empty() ? lastId_++ : freeId_.back();
    if (!freeId_.empty()) {
        freeId_.pop_back();
    }

    *array = id;
    vaos_[id] = { .generated = false };
    return GL_NO_ERROR;
}

GLenum VertexArrayState::CreateN(GLsizei n, GLuint* arrays) {
    if (n <= 0 || arrays == nullptr) {
        return GL_INVALID_VALUE; 
    }

    for (GLsizei i = 0; i < n; ++i) {
        if (GLenum error = Create(&arrays[i]); error != GL_NO_ERROR) {
            return error;
        }
    }
    return GL_NO_ERROR;
}

GLenum VertexArrayState::Bind(GLuint array) {
    if (array != 0 && vaos_.find(array) == vaos_.end())
        return GL_INVALID_OPERATION;

    currentVao_ = array;
    GetCurrentVAO()->generated = true;
    return GL_NO_ERROR;
}

GLenum VertexArrayState::EnableAttrib(GLuint index) {
    if (currentVao_ == 0) return GL_INVALID_OPERATION;
    if (index >= GL_MAX_VERTEX_ATTRIBS) return GL_INVALID_VALUE;
    GetCurrentVAO()->attribs[index].enabled = true;
    MG_Util::Debug::LogD("Attrib vaos_[%u].attribs[%u].enabled = %d", currentVao_, index, vaos_[currentVao_].attribs[index].enabled);
    return GL_NO_ERROR;
}

GLenum VertexArrayState::DisableAttrib(GLuint index) {
    if (currentVao_ == 0) return GL_INVALID_OPERATION;
    if (index >= GL_MAX_VERTEX_ATTRIBS) return GL_INVALID_VALUE;
    GetCurrentVAO()->attribs[index].enabled = false;
    MG_Util::Debug::LogD("Attrib vaos_[%u].attribs[%u].enabled = %d", currentVao_, index, vaos_[currentVao_].attribs[index].enabled);
    return GL_NO_ERROR;
}

GLenum VertexArrayState::SetAttribPointer(GLuint index, GLint size, GLenum type,
                                          GLboolean normalized, GLsizei stride,
                                          const void* pointer, bool isInteger,
                                          GLuint currentArrayBuffer) {
    if (currentVao_ == 0) return GL_INVALID_OPERATION;
    if (index >= GL_MAX_VERTEX_ATTRIBS) return GL_INVALID_VALUE;

    VertexAttribState state;
    state.size = size;
    state.type = type;
    state.normalized = normalized;
    state.stride = stride;
    state.pointer = pointer;
    state.buffer = currentArrayBuffer;
    state.isInteger = isInteger;
    if (vaos_[currentVao_].attribs.count(index) && vaos_[currentVao_].attribs[index].enabled)
        state.enabled = true;

    vaos_[currentVao_].attribs[index] = state;
    return GL_NO_ERROR;
}

GLuint VertexArrayState::GetBoundElementBuffer() {
    auto it = vaos_.find(currentVao_);
    return (it != vaos_.end()) ? it->second.elementBuffer : 0;
}

VertexArrayObject* VertexArrayState::GetCurrentVAO() {
    auto it = vaos_.find(currentVao_);
    if (it != vaos_.end())
        return &it->second;
    else {
        MG_Util::Debug::LogD("%s: VAO not found, currentVao_ = %u !", __func__, currentVao_);
        return nullptr;
    }
}