/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2025                                                               *
 *                                                                                       *
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 ****************************************************************************************/

#include <modules/base/rendering/renderablesphere.h>

#include <modules/base/basemodule.h>
#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/engine/globals.h>
#include <openspace/rendering/renderengine.h>
#include <openspace/util/sphere.h>
#include <openspace/util/updatestructures.h>
#include <ghoul/filesystem/filesystem.h>
#include <ghoul/glm.h>
#include <ghoul/logging/logmanager.h>
#include <ghoul/opengl/openglstatecache.h>
#include <ghoul/opengl/programobject.h>
#include <ghoul/opengl/textureunit.h>
#include <optional>

namespace {
    constexpr std::string_view _loggerCat = "RenderableSphere";
    constexpr int DefaultBlending = 0;
    constexpr int AdditiveBlending = 1;
    constexpr int PolygonBlending = 2;
    constexpr int ColorAddingBlending = 3;

    std::map<std::string, int> BlendingMapping = {
        { "Default", DefaultBlending },
        { "Additive", AdditiveBlending },
        { "Polygon", PolygonBlending },
        { "Color Adding", ColorAddingBlending }
    };

    constexpr openspace::properties::Property::PropertyInfo SizeInfo = {
        "Size",
        "Size (in meters)",
        "The radius of the sphere in meters.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo SegmentsInfo = {
        "Segments",
        "Number of Segments",
        "The number of segments that the sphere is split into.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    enum class Orientation : int {
        Outside = 0,
        Inside,
        Both
    };

    constexpr openspace::properties::Property::PropertyInfo OrientationInfo = {
        "Orientation",
        "Orientation",
        "Specifies whether the texture is applied to the inside of the sphere, the "
        "outside of the sphere, or both.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo MirrorTextureInfo = {
        "MirrorTexture",
        "Mirror Texture",
        "If true, mirror the texture along the x-axis.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo DisableFadeInOutInfo = {
        "DisableFadeInOut",
        "Disable Fade-In/Fade-Out effects",
        "Enables/Disables the fade in and out effects.",
        openspace::properties::Property::Visibility::User
    };

    constexpr openspace::properties::Property::PropertyInfo FadeInThresholdInfo = {
        "FadeInThreshold",
        "Fade-In Threshold",
        "The distance from the center of the Milky Way at which the sphere should start "
        "to fade in, given as a percentage of the size of the object. A value of zero "
        "means that no fading in will happen.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo FadeOutThresholdInfo = {
        "FadeOutThreshold",
        "Fade-Out Threshold",
        "A threshold for when the sphere should start fading out, given as a percentage "
        "of how much of the sphere that is visible before the fading should start. A "
        "value of zero means that no fading out will happen.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo UseColorMapInfo = {
        "UseColorMap",
        "Use Color Map",
        "Used to toggle color map on or off for the sphere. Mainly used to transform "
        "grayscale textures from data into color images.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo ColorMapInfo = {
        "ColorMap",
        "Transfer Function (Color Map) Path",
        "Color map / Transfer function to use if `UseColorMap` is enabled.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo BlendingOptionInfo = {
        "BlendingOption",
        "Blending Options",
        "Controls the blending function used to calculate the colors of the sphere with "
        "respect to the opacity.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    constexpr openspace::properties::Property::PropertyInfo DisableDepthInfo = {
        "DisableDepth",
        "Disable Depth",
        "If disabled, no depth values are taken into account for this sphere, meaning "
        "that depth values are neither written or tested against during the rendering. "
        "This can be useful for spheres that represent a background image.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    // This `Renderable` represents a simple sphere with an image. The image that is shown
    // should be in an equirectangular projection/spherical panoramic image or else
    // distortions will be introduced. The `Orientation` parameter determines whether the
    // provided image is shown on the inside, outside, or both sides of the sphere.
    struct [[codegen::Dictionary(RenderableSphere)]] Parameters {
        // [[codegen::verbatim(SizeInfo.description)]]
        std::optional<float> size [[codegen::greater(0.f)]];

        // [[codegen::verbatim(SegmentsInfo.description)]]
        std::optional<int> segments [[codegen::greaterequal(4)]];

        enum class [[codegen::map(Orientation)]] Orientation {
            Outside,
            Inside,
            Both
        };

        // [[codegen::verbatim(OrientationInfo.description)]]
        std::optional<Orientation> orientation;

        // [[codegen::verbatim(MirrorTextureInfo.description)]]
        std::optional<bool> mirrorTexture;

        // [[codegen::verbatim(DisableFadeInOutInfo.description)]]
        std::optional<bool> disableFadeInOut;

        // [[codegen::verbatim(FadeInThresholdInfo.description)]]
        std::optional<float> fadeInThreshold;

        // [[codegen::verbatim(FadeOutThresholdInfo.description)]]
        std::optional<float> fadeOutThreshold [[codegen::inrange(0.0, 1.0)]];

        // [[codegen::verbatim(ColorMapInfo.description)]]
        std::optional<std::filesystem::path> colorMap;

        // [[codegen::verbatim(UseColorMapInfo.description)]]
        std::optional<bool> useColorMap;

        // [[codegen::verbatim(BlendingOptionInfo.description)]]
        std::optional<std::string> blendingOption;

        // [[codegen::verbatim(DisableDepthInfo.description)]]
        std::optional<bool> disableDepth;
    };
#include "renderablesphere_codegen.cpp"
} // namespace

namespace openspace {

documentation::Documentation RenderableSphere::Documentation() {
    return codegen::doc<Parameters>("base_renderable_sphere");
}

RenderableSphere::RenderableSphere(const ghoul::Dictionary& dictionary)
    : Renderable(dictionary)
    , _size(SizeInfo, 1.f, 0.f, 1e25f)
    , _segments(SegmentsInfo, 16, 4, 1000)
    , _orientation(OrientationInfo)
    , _mirrorTexture(MirrorTextureInfo, false)
    , _disableFadeInDistance(DisableFadeInOutInfo, false)
    , _fadeInThreshold(FadeInThresholdInfo, 0.f, 0.f, 1.f, 0.001f)
    , _fadeOutThreshold(FadeOutThresholdInfo, 0.f, 0.f, 1.f, 0.001f)
    , _blendingFuncOption(BlendingOptionInfo)
    , _disableDepth(DisableDepthInfo, false)
    , _useColorMap(UseColorMapInfo, false)
    , _colorMap(ColorMapInfo)
{
    const Parameters p = codegen::bake<Parameters>(dictionary);

    addProperty(Fadeable::_opacity);

    _size = p.size.value_or(_size);
    _size.setExponent(15.f);
    _size.onChange([this]() {
        setBoundingSphere(_size);
        _sphereIsDirty = true;
    });
    addProperty(_size);

    _segments = p.segments.value_or(_segments);
    _segments.onChange([this]() {
        _sphereIsDirty = true;
    });
    addProperty(_segments);

    _orientation.addOptions({
        { static_cast<int>(Orientation::Outside), "Outside" },
        { static_cast<int>(Orientation::Inside), "Inside" },
        { static_cast<int>(Orientation::Both), "Both" }
    });
    _orientation = p.orientation.has_value() ?
        static_cast<int>(codegen::map<Orientation>(*p.orientation)):
        static_cast<int>(Orientation::Outside);
    addProperty(_orientation);

    _mirrorTexture = p.mirrorTexture.value_or(_mirrorTexture);
    addProperty(_mirrorTexture);

    _disableFadeInDistance = p.disableFadeInOut.value_or(_disableFadeInDistance);
    addProperty(_disableFadeInDistance);

    _fadeInThreshold = p.fadeInThreshold.value_or(_fadeInThreshold);
    addProperty(_fadeInThreshold);

    _fadeOutThreshold = p.fadeOutThreshold.value_or(_fadeOutThreshold);
    addProperty(_fadeOutThreshold);

    _blendingFuncOption.addOption(DefaultBlending, "Default");
    _blendingFuncOption.addOption(AdditiveBlending, "Additive");
    _blendingFuncOption.addOption(PolygonBlending, "Polygon");
    _blendingFuncOption.addOption(ColorAddingBlending, "Color Adding");

    addProperty(_blendingFuncOption);

    if (p.blendingOption.has_value()) {
        const std::string blendingOpt = *p.blendingOption;
        _blendingFuncOption = BlendingMapping[blendingOpt];
    }

    _disableDepth = p.disableDepth.value_or(_disableDepth);
    addProperty(_disableDepth);

    setBoundingSphere(_size);

    if (p.colorMap.has_value()) {
        _colorMap = p.colorMap->string();
        _useColorMap = true;
    }
    addProperty(_useColorMap);

    _colorMap.onChange([this]() {
        if (!std::filesystem::exists(_colorMap.value())) {
            LERROR(std::format(
                "Path {} to color map is invalid.",
                _colorMap.value()
            ));
            return;
        }
        _transferFunction = std::make_unique<TransferFunction>(_colorMap.value());
    });
    addProperty(_colorMap);

    // This check is after color map in case a color map is given
    // but using it on start-up is set to false.
    if (p.useColorMap.has_value()) {
        if (!p.colorMap.has_value()) {
            throw ghoul::RuntimeError("No color map path was provided");
        }
        _useColorMap = *p.useColorMap;
    }
}

bool RenderableSphere::isReady() const {
    return _shader != nullptr;
}

void RenderableSphere::initializeGL() {
    _sphere = std::make_unique<Sphere>(_size, _segments);
    _sphere->initialize();

    _shader = BaseModule::ProgramObjectManager.request(
        "Sphere",
        []() -> std::unique_ptr<ghoul::opengl::ProgramObject> {
            return global::renderEngine->buildRenderProgram(
                "Sphere",
                absPath("${MODULE_BASE}/shaders/sphere_vs.glsl"),
                absPath("${MODULE_BASE}/shaders/sphere_fs.glsl")
            );
        }
    );

    ghoul::opengl::updateUniformLocations(*_shader, _uniformCache);

    if (_useColorMap) {
        _transferFunction = std::make_unique<TransferFunction>(_colorMap.value());
    }
}

void RenderableSphere::deinitializeGL() {
    _sphere = nullptr;

    BaseModule::ProgramObjectManager.release(
        "Sphere",
        [](ghoul::opengl::ProgramObject* p) {
            global::renderEngine->removeRenderProgram(p);
        }
    );
    _shader = nullptr;
    _transferFunction = nullptr;
}

void RenderableSphere::render(const RenderData& data, RendererTasks&) {
    const Orientation orientation = static_cast<Orientation>(_orientation.value());

    // Activate shader
    using IgnoreError = ghoul::opengl::ProgramObject::IgnoreError;
    _shader->activate();
    _shader->setIgnoreUniformLocationError(IgnoreError::Yes);

    auto [modelTransform, modelViewTransform, modelViewProjectionTransform] =
        calcAllTransforms(data);
    const glm::dmat3 modelRotation = glm::dmat3(data.modelTransform.rotation);

    _shader->setUniform(_uniformCache.modelViewTransform, glm::mat4(modelViewTransform));
    _shader->setUniform(
        _uniformCache.modelViewProjection,
        glm::mat4(modelViewProjectionTransform)
    );

    const glm::mat3 modelViewRotation = glm::mat3(
        glm::dmat3(data.camera.viewRotationMatrix()) * modelRotation
    );
    _shader->setUniform(_uniformCache.modelViewRotation, modelViewRotation);

    float adjustedOpacity = opacity();

    if (!_disableFadeInDistance) {
        if (_fadeInThreshold > 0.f) {
            const double d = glm::distance(
                data.camera.positionVec3(),
                data.modelTransform.translation
            );
            const float logDist =
                d > 0.0 ?
                std::log(static_cast<float>(d)) :
                -std::numeric_limits<float>::max();

            const float startLogFadeDistance = glm::log(_size * _fadeInThreshold);
            const float stopLogFadeDistance = startLogFadeDistance + 1.f;

            if (logDist > startLogFadeDistance && logDist < stopLogFadeDistance) {
                const float fadeFactor = glm::clamp(
                    (logDist - startLogFadeDistance) /
                    (stopLogFadeDistance - startLogFadeDistance),
                    0.f,
                    1.f
                );
                adjustedOpacity *= fadeFactor;
            }
            else if (logDist <= startLogFadeDistance) {
                adjustedOpacity = 0.f;
            }
        }

        if (_fadeOutThreshold > 0.f) {
            const double d = glm::distance(
                data.camera.positionVec3(),
                data.modelTransform.translation
            );
            const float logDist =
                d > 0.0 ?
                std::log(static_cast<float>(d)) :
                -std::numeric_limits<float>::max();
            const float startLogFadeDistance = glm::log(_size * _fadeOutThreshold);
            const float stopLogFadeDistance = startLogFadeDistance + 1.f;

            if (logDist > startLogFadeDistance && logDist < stopLogFadeDistance) {
                const float fadeFactor = glm::clamp(
                    (logDist - startLogFadeDistance) /
                        (stopLogFadeDistance - startLogFadeDistance),
                    0.f,
                    1.f
                );
                adjustedOpacity *= (1.f - fadeFactor);
            }
            else if (logDist >= stopLogFadeDistance) {
                adjustedOpacity = 0.f;
            }
        }
    }
    // Performance wise
    if (adjustedOpacity < 0.01f) {
        return;
    }

    // TextureUnit cannot be declared in if statement below
    ghoul::opengl::TextureUnit transferFunctionUnit;
    _shader->setUniform("usingTransferFunction", _useColorMap);
    _shader->setUniform("transferFunction", transferFunctionUnit);
    _shader->setUniform("dataMinMaxValues", _dataMinMaxValues);
    if (_useColorMap) {
        transferFunctionUnit.activate();
        _transferFunction->bind();
    }

    _shader->setUniform(_uniformCache.opacity, adjustedOpacity);
    _shader->setUniform(_uniformCache.mirrorTexture, _mirrorTexture.value());

    ghoul::opengl::TextureUnit unit;
    unit.activate();
    bindTexture();
    defer{ unbindTexture(); };
    _shader->setUniform(_uniformCache.colorTexture, unit);

    // Setting these states should not be necessary,
    // since they are the default state in OpenSpace.
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);

    if (orientation == Orientation::Inside) {
        glCullFace(GL_FRONT);
    }
    else if (orientation == Orientation::Both) {
        glDisable(GL_CULL_FACE);
    }

    // Configure blending
    glEnablei(GL_BLEND, 0);
    switch (_blendingFuncOption) {
        case DefaultBlending:
            glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
            break;
        case AdditiveBlending:
            glBlendFunc(GL_SRC_ALPHA, GL_ONE);
            break;
        case PolygonBlending:
            glBlendFunc(GL_SRC_ALPHA_SATURATE, GL_ONE);
            break;
        case ColorAddingBlending:
            glBlendFunc(GL_SRC_COLOR, GL_DST_COLOR);
            break;
    };

    if (_disableDepth) {
        glDepthMask(GL_FALSE);
    }

    _sphere->render();

    _shader->setIgnoreUniformLocationError(IgnoreError::No);
    _shader->deactivate();

    // Reset
    global::renderEngine->openglStateCache().resetBlendState();
    global::renderEngine->openglStateCache().resetDepthState();
    global::renderEngine->openglStateCache().resetPolygonAndClippingState();
    unbindTexture();

    if (orientation == Orientation::Inside) {
        glCullFace(GL_BACK);
    }
    else if (orientation == Orientation::Both) {
        glEnable(GL_CULL_FACE);
    }
}

void RenderableSphere::update(const UpdateData&) {
    if (_shader->isDirty()) [[unlikely]] {
        _shader->rebuildFromFile();
        ghoul::opengl::updateUniformLocations(*_shader, _uniformCache);
    }
    if (!_transferFunction && std::filesystem::exists(_colorMap.value())) {
        _transferFunction = std::make_unique<TransferFunction>(_colorMap.value());
    }
    if (_sphereIsDirty) [[unlikely]] {
        _sphere = std::make_unique<Sphere>(_size, _segments);
        _sphere->initialize();
        _sphereIsDirty = false;
    }
}

void RenderableSphere::unbindTexture() {
    glBindTexture(GL_TEXTURE_2D, 0);
}

} // namespace openspace