// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <glad/glad.h>

#include "common/common_types.h"
#include "video_core/engines/maxwell_3d.h"
#include "video_core/renderer_opengl/gl_shader_manager.h"

namespace OpenGL::GLShader {

ProgramManager::ProgramManager() = default;

ProgramManager::~ProgramManager() = default;

void ProgramManager::Create() {
    graphics_pipeline.Create();
    glBindProgramPipeline(graphics_pipeline.handle);
}

void ProgramManager::BindGraphicsPipeline() {
    if (!is_graphics_bound) {
        is_graphics_bound = true;
        glUseProgram(0);
    }

    // Avoid updating the pipeline when values have no changed
    if (old_state == current_state) {
        return;
    }

    // Workaround for AMD bug
    static constexpr GLenum all_used_stages{GL_VERTEX_SHADER_BIT | GL_GEOMETRY_SHADER_BIT |
                                            GL_FRAGMENT_SHADER_BIT};
    const GLuint handle = graphics_pipeline.handle;
    glUseProgramStages(handle, all_used_stages, 0);
    glUseProgramStages(handle, GL_VERTEX_SHADER_BIT, current_state.vertex_shader);
    glUseProgramStages(handle, GL_GEOMETRY_SHADER_BIT, current_state.geometry_shader);
    glUseProgramStages(handle, GL_FRAGMENT_SHADER_BIT, current_state.fragment_shader);

    old_state = current_state;
}

void ProgramManager::BindComputeShader(GLuint program) {
    is_graphics_bound = false;
    glUseProgram(program);
}

void MaxwellUniformData::SetFromRegs(const Tegra::Engines::Maxwell3D& maxwell) {
    const auto& regs = maxwell.regs;

    // Y_NEGATE controls what value S2R returns for the Y_DIRECTION system value.
    y_direction = regs.screen_y_control.y_negate == 0 ? 1.0f : -1.0f;
}

} // namespace OpenGL::GLShader