#include "XCEngine/RHI/OpenGL/OpenGLPipelineState.h"
#include <glad/glad.h>

namespace XCEngine {
namespace RHI {

OpenGLPipelineState::OpenGLPipelineState()
    : m_program(0), m_programAttached(false) {
}

OpenGLPipelineState::~OpenGLPipelineState() {
}

void OpenGLPipelineState::SetInputLayout(const InputLayoutDesc& layout) {
    m_inputLayoutDesc = layout;
}

void OpenGLPipelineState::SetRasterizerState(const RasterizerDesc& state) {
    m_rasterizerDesc = state;
}

void OpenGLPipelineState::SetBlendState(const BlendDesc& state) {
    m_blendDesc = state;
}

void OpenGLPipelineState::SetDepthStencilState(const DepthStencilStateDesc& state) {
    m_depthStencilDesc = state;
}

void OpenGLPipelineState::SetTopology(uint32_t topologyType) {
    m_topologyType = topologyType;
}

void OpenGLPipelineState::SetRenderTargetFormats(uint32_t count, const uint32_t* formats, uint32_t depthFormat) {
}

void OpenGLPipelineState::SetSampleCount(uint32_t count) {
}

PipelineStateHash OpenGLPipelineState::GetHash() const {
    PipelineStateHash hash = {};
    return hash;
}

void OpenGLPipelineState::Shutdown() {
    m_program = 0;
    m_programAttached = false;
}

void OpenGLPipelineState::Bind() {
    if (m_programAttached) {
        glUseProgram(m_program);
    }
    Apply();
}

void OpenGLPipelineState::Unbind() {
    glUseProgram(0);
}

void OpenGLPipelineState::Apply() {
    ApplyDepthStencil();
    ApplyBlend();
    ApplyRasterizer();
}

void OpenGLPipelineState::ApplyDepthStencil() {
    if (m_glDepthStencilState.depthTestEnable) {
        glEnable(GL_DEPTH_TEST);
    } else {
        glDisable(GL_DEPTH_TEST);
    }
    glDepthMask(m_glDepthStencilState.depthWriteEnable ? GL_TRUE : GL_FALSE);
    glDepthFunc(static_cast<GLenum>(m_glDepthStencilState.depthFunc));

    if (m_glDepthStencilState.stencilEnable) {
        glEnable(GL_STENCIL_TEST);
        glStencilMask(m_glDepthStencilState.stencilWriteMask);
        glStencilFunc(
            static_cast<GLenum>(m_glDepthStencilState.stencilFunc),
            m_glDepthStencilState.stencilRef,
            m_glDepthStencilState.stencilReadMask
        );
        glStencilOp(
            static_cast<GLenum>(m_glDepthStencilState.stencilFailOp),
            static_cast<GLenum>(m_glDepthStencilState.stencilDepthFailOp),
            static_cast<GLenum>(m_glDepthStencilState.stencilDepthPassOp)
        );
    } else {
        glDisable(GL_STENCIL_TEST);
    }
}

void OpenGLPipelineState::ApplyBlend() {
    if (m_glBlendState.blendEnable) {
        glEnable(GL_BLEND);
        glBlendFuncSeparate(
            static_cast<GLenum>(m_glBlendState.srcBlend),
            static_cast<GLenum>(m_glBlendState.dstBlend),
            static_cast<GLenum>(m_glBlendState.srcBlendAlpha),
            static_cast<GLenum>(m_glBlendState.dstBlendAlpha)
        );
        glBlendEquationSeparate(
            static_cast<GLenum>(m_glBlendState.blendOp),
            static_cast<GLenum>(m_glBlendState.blendOpAlpha)
        );
        glColorMask(
            (m_glBlendState.colorWriteMask & 1) != 0,
            (m_glBlendState.colorWriteMask & 2) != 0,
            (m_glBlendState.colorWriteMask & 4) != 0,
            (m_glBlendState.colorWriteMask & 8) != 0
        );
    } else {
        glDisable(GL_BLEND);
    }
}

void OpenGLPipelineState::ApplyRasterizer() {
    if (m_glRasterizerState.cullFaceEnable) {
        glEnable(GL_CULL_FACE);
        glCullFace(static_cast<GLenum>(m_glRasterizerState.cullFace));
        glFrontFace(static_cast<GLenum>(m_glRasterizerState.frontFace));
    } else {
        glDisable(GL_CULL_FACE);
    }

    glPolygonMode(GL_FRONT_AND_BACK, static_cast<GLenum>(m_glRasterizerState.polygonMode));

    if (m_glRasterizerState.multisampleEnable) {
        glEnable(GL_MULTISAMPLE);
    } else {
        glDisable(GL_MULTISAMPLE);
    }
}

void OpenGLPipelineState::ApplyViewport() {
    glViewport((GLint)m_viewportState.x, (GLint)m_viewportState.y,
               (GLsizei)m_viewportState.width, (GLsizei)m_viewportState.height);
    glDepthRange(m_viewportState.minDepth, m_viewportState.maxDepth);
}

void OpenGLPipelineState::ApplyScissor() {
    if (m_scissorState.enable) {
        glEnable(GL_SCISSOR_TEST);
        glScissor(m_scissorState.x, m_scissorState.y, m_scissorState.width, m_scissorState.height);
    } else {
        glDisable(GL_SCISSOR_TEST);
    }
}

void OpenGLPipelineState::SetProgram(unsigned int program) {
    m_program = program;
    m_programAttached = (program != 0);
}

void OpenGLPipelineState::SetDepthStencilState(const OpenGLDepthStencilState& state) {
    m_glDepthStencilState = state;
}

void OpenGLPipelineState::SetBlendState(const OpenGLBlendState& state) {
    m_glBlendState = state;
}

void OpenGLPipelineState::SetRasterizerState(const OpenGLRasterizerState& state) {
    m_glRasterizerState = state;
}

void OpenGLPipelineState::SetViewport(const ViewportState& state) {
    m_viewportState = state;
}

void OpenGLPipelineState::SetScissor(const ScissorState& state) {
    m_scissorState = state;
}

void OpenGLPipelineState::SetClearColor(float r, float g, float b, float a) {
    m_clearColor[0] = r;
    m_clearColor[1] = g;
    m_clearColor[2] = b;
    m_clearColor[3] = a;
    glClearColor(r, g, b, a);
}

void OpenGLPipelineState::Clear(unsigned int buffers) {
    unsigned int glBuffers = 0;
    if (buffers & 1) glBuffers |= GL_COLOR_BUFFER_BIT;
    if (buffers & 2) glBuffers |= GL_DEPTH_BUFFER_BIT;
    if (buffers & 4) glBuffers |= GL_STENCIL_BUFFER_BIT;
    glClear(glBuffers);
}

void OpenGLPipelineState::AttachShader(unsigned int program) {
    m_program = program;
    m_programAttached = true;
    glUseProgram(program);
}

void OpenGLPipelineState::DetachShader() {
    m_program = 0;
    m_programAttached = false;
    glUseProgram(0);
}

const OpenGLDepthStencilState& OpenGLPipelineState::GetOpenGLDepthStencilState() const {
    return m_glDepthStencilState;
}

const OpenGLBlendState& OpenGLPipelineState::GetOpenGLBlendState() const {
    return m_glBlendState;
}

const OpenGLRasterizerState& OpenGLPipelineState::GetOpenGLRasterizerState() const {
    return m_glRasterizerState;
}

} // namespace RHI
} // namespace XCEngine