#define GLFW_INCLUDE_NONE
#include "XCEngine/RHI/OpenGL/OpenGLPipelineState.h"
#include <glad/glad.h>
#include <GLFW/glfw3.h>

namespace XCEngine {
namespace RHI {

OpenGLPipelineState::OpenGLPipelineState() {
    m_clearColor[0] = 0.1f;
    m_clearColor[1] = 0.1f;
    m_clearColor[2] = 0.1f;
    m_clearColor[3] = 1.0f;
}

OpenGLPipelineState::~OpenGLPipelineState() {
}

void OpenGLPipelineState::SetDepthStencilState(const DepthStencilState& state) {
    m_depthStencilState = state;
}

void OpenGLPipelineState::SetBlendState(const BlendState& state) {
    m_blendState = state;
}

void OpenGLPipelineState::SetRasterizerState(const RasterizerState& state) {
    m_rasterizerState = state;
}

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

static unsigned int ToGLComparisonFunc(ComparisonFunc func) {
    switch (func) {
        case ComparisonFunc::Never: return GL_NEVER;
        case ComparisonFunc::Less: return GL_LESS;
        case ComparisonFunc::Equal: return GL_EQUAL;
        case ComparisonFunc::LessEqual: return GL_LEQUAL;
        case ComparisonFunc::Greater: return GL_GREATER;
        case ComparisonFunc::NotEqual: return GL_NOTEQUAL;
        case ComparisonFunc::GreaterEqual: return GL_GEQUAL;
        case ComparisonFunc::Always: return GL_ALWAYS;
        default: return GL_LESS;
    }
}

static unsigned int ToGLBlendFactor(BlendFactor factor) {
    switch (factor) {
        case BlendFactor::Zero: return GL_ZERO;
        case BlendFactor::One: return GL_ONE;
        case BlendFactor::SrcColor: return GL_SRC_COLOR;
        case BlendFactor::OneMinusSrcColor: return GL_ONE_MINUS_SRC_COLOR;
        case BlendFactor::DstColor: return GL_DST_COLOR;
        case BlendFactor::OneMinusDstColor: return GL_ONE_MINUS_DST_COLOR;
        case BlendFactor::SrcAlpha: return GL_SRC_ALPHA;
        case BlendFactor::OneMinusSrcAlpha: return GL_ONE_MINUS_SRC_ALPHA;
        case BlendFactor::DstAlpha: return GL_DST_ALPHA;
        case BlendFactor::OneMinusDstAlpha: return GL_ONE_MINUS_DST_ALPHA;
        case BlendFactor::ConstantColor: return GL_CONSTANT_COLOR;
        case BlendFactor::OneMinusConstantColor: return GL_ONE_MINUS_CONSTANT_COLOR;
        case BlendFactor::ConstantAlpha: return GL_CONSTANT_ALPHA;
        case BlendFactor::OneMinusConstantAlpha: return GL_ONE_MINUS_CONSTANT_ALPHA;
        default: return GL_ONE;
    }
}

static unsigned int ToGLCullFace(CullFace face) {
    switch (face) {
        case CullFace::Front: return GL_FRONT;
        case CullFace::Back: return GL_BACK;
        case CullFace::FrontAndBack: return GL_FRONT_AND_BACK;
        default: return GL_BACK;
    }
}

static unsigned int ToGLFrontFace(FrontFace face) {
    switch (face) {
        case FrontFace::Clockwise: return GL_CW;
        case FrontFace::CounterClockwise: return GL_CCW;
        default: return GL_CCW;
    }
}

void OpenGLPipelineState::Apply() {
    if (m_depthStencilState.depthTestEnable) {
        glEnable(GL_DEPTH_TEST);
        glDepthFunc(ToGLComparisonFunc(m_depthStencilState.depthFunc));
        glDepthMask(m_depthStencilState.depthWriteEnable ? GL_TRUE : GL_FALSE);
    } else {
        glDisable(GL_DEPTH_TEST);
    }

    if (m_blendState.blendEnable) {
        glEnable(GL_BLEND);
        glBlendFunc(
            ToGLBlendFactor(m_blendState.srcBlend),
            ToGLBlendFactor(m_blendState.dstBlend)
        );
        glBlendFuncSeparate(
            ToGLBlendFactor(m_blendState.srcBlend),
            ToGLBlendFactor(m_blendState.dstBlend),
            ToGLBlendFactor(m_blendState.srcBlendAlpha),
            ToGLBlendFactor(m_blendState.dstBlendAlpha)
        );
    } else {
        glDisable(GL_BLEND);
    }

    if (m_rasterizerState.cullFaceEnable) {
        glEnable(GL_CULL_FACE);
        glCullFace(ToGLCullFace(m_rasterizerState.cullFace));
        glFrontFace(ToGLFrontFace(m_rasterizerState.frontFace));
    } else {
        glDisable(GL_CULL_FACE);
    }

    glViewport(
        m_viewportState.x,
        m_viewportState.y,
        m_viewportState.width,
        m_viewportState.height
    );
    glDepthRange(m_viewportState.minDepth, m_viewportState.maxDepth);
}

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 & 0x1) glBuffers |= GL_COLOR_BUFFER_BIT;
    if (buffers & 0x2) glBuffers |= GL_DEPTH_BUFFER_BIT;
    if (buffers & 0x4) glBuffers |= GL_STENCIL_BUFFER_BIT;
    glClear(glBuffers);
}

} // namespace RHI
} // namespace XCEngine