/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2018                                                               *
 *                                                                                       *
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 * or substantial portions of the Software.                                              *
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 ****************************************************************************************/

#include <modules/space/rendering/renderableplanet.h>

#include <modules/space/spacemodule.h>
#include <modules/space/rendering/planetgeometry.h>
#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/engine/globals.h>
#include <openspace/rendering/renderengine.h>
#include <openspace/util/spicemanager.h>
#include <openspace/util/updatestructures.h>
#include <ghoul/filesystem/filesystem.h>
#include <ghoul/io/texture/texturereader.h>
#include <ghoul/logging/logmanager.h>
#include <ghoul/opengl/programobject.h>
#include <ghoul/opengl/texture.h>
#include <ghoul/opengl/textureunit.h>
#include <ghoul/opengl/textureunit.h>

namespace {
    constexpr const char* PlainProgramName = "PlanetProgram";
    constexpr const char* ShadowNightProgramName = "ShadowNightPlanetProgram";
    constexpr const char* NightProgramName = "NightPlanetProgram";
    constexpr const char* ShadowProgramName = "ShadowPlanetProgram";

    constexpr const char* KeyBody         = "Body";
    constexpr const char* KeyGeometry     = "Geometry";
    constexpr const char* KeyRadius       = "Radius";
    constexpr const char* _loggerCat      = "RenderablePlanet";

    constexpr const char* KeyShadowGroup  = "Shadow_Group";
    constexpr const char* KeyShadowSource = "Source";
    constexpr const char* KeyShadowCaster = "Caster";

    constexpr openspace::properties::Property::PropertyInfo ColorTextureInfo = {
        "ColorTexture",
        "Color Base Texture",
        "The path to the base color texture that is used on the planet prior to any "
        "image projection."
    };

    constexpr openspace::properties::Property::PropertyInfo HeightTextureInfo = {
        "HeightTexture",
        "Heightmap Texture",
        "The path to the height map texture that is used for the planet. If no height "
        "map is specified the planet does not use a height field."
    };

    constexpr openspace::properties::Property::PropertyInfo NightTextureInfo = {
        "NightTexture",
        "Night Texture",
        "The path to the night texture that is used for the part of the planet that is "
        "facing away from the Sun. If no night texture is loaded, the night side of the "
        "planet is rendered dark."
    };

    constexpr openspace::properties::Property::PropertyInfo HeightExaggerationInfo = {
         "HeightExaggeration",
         "Height Exaggeration",
         "This value determines the level of height exaggeration that is applied to a "
         "potential height field. A value of '0' inhibits the height field, whereas a "
         "value of '1' uses the measured height field."
    };

    constexpr openspace::properties::Property::PropertyInfo PerformShadingInfo = {
        "PerformShading",
        "Perform Shading",
        "If this value is enabled, the model will be shaded based on the relative "
        "location to the Sun. If this value is disabled, shading is disabled and the "
        "entire model is rendered brightly. If this value is 'false', any existing night "
        "texture will not be used."
    };
} // namespace

namespace openspace {

documentation::Documentation RenderablePlanet::Documentation() {
    using namespace documentation;
    return {
        "RenderablePlanet",
        "space_renderable_planet",
        {
            {
                KeyGeometry,
                new ReferencingVerifier("space_geometry_planet"),
                Optional::No,
                "Specifies the planet geometry that is used for this RenderablePlanet."
            },
            {
                KeyRadius,
                new DoubleVerifier,
                Optional::Yes,
                "Specifies the radius of the planet. If this value is not specified, it "
                "will try to query the SPICE library for radius values using the body "
                "key."
            },
            {
                KeyBody,
                new StringVerifier,
                Optional::Yes,
                "If that radius is not specified, this name is used to query the SPICE "
                "library for the radius values."
            },
            {
                ColorTextureInfo.identifier,
                new StringVerifier,
                Optional::Yes,
                ColorTextureInfo.description
            },
            {
                HeightTextureInfo.identifier,
                new StringVerifier,
                Optional::Yes,
                HeightTextureInfo.description
            },
            {
                NightTextureInfo.identifier,
                new StringVerifier,
                Optional::Yes,
                NightTextureInfo.description
            },
            {
                PerformShadingInfo.identifier,
                new BoolVerifier,
                Optional::Yes,
                PerformShadingInfo.description
            },
            {
                HeightExaggerationInfo.identifier,
                new DoubleVerifier,
                Optional::Yes,
                HeightExaggerationInfo.description
            },
            {
                PerformShadingInfo.identifier,
                new BoolVerifier,
                Optional::Yes,
                PerformShadingInfo.description
            }
        }
    };
}

RenderablePlanet::RenderablePlanet(const ghoul::Dictionary& dictionary)
    : Renderable(dictionary)
    , _colorTexturePath(ColorTextureInfo)
    , _nightTexturePath(NightTextureInfo)
    , _heightMapTexturePath(HeightTextureInfo)
    , _heightExaggeration(HeightExaggerationInfo, 1.f, 0.f, 10.f)
    , _performShading(PerformShadingInfo, true)
{
    documentation::testSpecificationAndThrow(
        Documentation(),
        dictionary,
        "RenderablePlanet"
    );

    ghoul::Dictionary geomDict = dictionary.value<ghoul::Dictionary>(KeyGeometry);

    if (dictionary.hasKeyAndValue<double>(KeyRadius)) {
        // If the user specified a radius, we want to use this
        _planetRadius = static_cast<float>(dictionary.value<double>(KeyRadius));
    }
    else {
        if (!dictionary.hasKey(KeyBody)) {
            documentation::TestResult res;
            res.success = false;
            documentation::TestResult::Offense offense = {
                fmt::format("{} or {}", KeyRadius, KeyBody),
                documentation::TestResult::Offense::Reason::MissingKey
            };
            res.offenses.push_back(std::move(offense));
            throw documentation::SpecificationError(
                std::move(res),
                std::move("RenderablePlanet")
            );
        }

        const std::string& body = dictionary.value<std::string>(KeyBody);

        // If the user didn't specfify a radius, but Spice has a radius, we can use this
        glm::dvec3 radius;
        SpiceManager::ref().getValue(body, "RADII", radius);
        radius *= 1000.0; // Spice gives radii in KM.
        std::swap(radius[1], radius[2]); // z is equivalent to y in our coordinate system
        geomDict.setValue(KeyRadius, radius);

        _planetRadius = static_cast<float>((radius.x + radius.y + radius.z) / 3.0);
    }

    _geometry = planetgeometry::PlanetGeometry::createFromDictionary(geomDict);

    if (dictionary.hasKeyAndValue<std::string>(ColorTextureInfo.identifier)) {
        _colorTexturePath = absPath(dictionary.value<std::string>(
            ColorTextureInfo.identifier
        ));
    }

    if (dictionary.hasKeyAndValue<std::string>(NightTextureInfo.identifier)) {
        _hasNightTexture = true;
        _nightTexturePath = absPath(dictionary.value<std::string>(
            NightTextureInfo.identifier
        ));
    }

    if (dictionary.hasKeyAndValue<std::string>(HeightTextureInfo.identifier)) {
        _hasHeightTexture = true;
        _heightMapTexturePath = absPath(dictionary.value<std::string>(
            HeightTextureInfo.identifier
        ));
    }

    if (dictionary.hasKeyAndValue<bool>(PerformShadingInfo.identifier)) {
        _performShading = dictionary.value<bool>(PerformShadingInfo.identifier);
    }
    addProperty(_performShading);

    addPropertySubOwner(_geometry.get());

    auto loadTextureCallback = [this]() { loadTexture(); };
    addProperty(_colorTexturePath);
    _colorTexturePath.onChange(loadTextureCallback);

    addProperty(_nightTexturePath);
    _nightTexturePath.onChange(loadTextureCallback);

    addProperty(_heightMapTexturePath);
    _heightMapTexturePath.onChange(loadTextureCallback);

    if (dictionary.hasKey(HeightExaggerationInfo.identifier)) {
        _heightExaggeration = static_cast<float>(
            dictionary.value<double>(HeightExaggerationInfo.identifier)
        );
    }
    addProperty(_heightExaggeration);

    //================================================================
    //======== Reads Shadow (Eclipses) Entries in mod file ===========
    //================================================================
    ghoul::Dictionary shadowDictionary;
    bool success = dictionary.getValue(KeyShadowGroup, shadowDictionary);
    bool disableShadows = false;
    if (success) {
        std::vector<std::pair<std::string, float>> sourceArray;
        unsigned int sourceCounter = 1;
        while (success) {
            std::string sourceName;
            success = shadowDictionary.getValue(
                KeyShadowSource + std::to_string(sourceCounter) + ".Name",
                sourceName
            );
            if (success) {
                float sourceRadius;
                success = shadowDictionary.getValue(
                    KeyShadowSource + std::to_string(sourceCounter) + ".Radius",
                    sourceRadius
                );
                if (success) {
                    sourceArray.emplace_back(sourceName, sourceRadius);
                }
                else {
                    LWARNING(fmt::format(
                        "No Radius value specified for Shadow Source Name '{}' from "
                        "'{}' planet. Disabling shadows for this planet",
                        sourceName, identifier()
                    ));
                    disableShadows = true;
                    break;
                }
            }
            sourceCounter++;
        }

        if (!disableShadows && !sourceArray.empty()) {
            success = true;
            std::vector<std::pair<std::string, float>> casterArray;
            unsigned int casterCounter = 1;
            while (success) {
                std::string casterName;
                success = shadowDictionary.getValue(
                    KeyShadowCaster + std::to_string(casterCounter) + ".Name",
                    casterName
                );
                if (success) {
                    float casterRadius;
                    success = shadowDictionary.getValue(
                        KeyShadowCaster + std::to_string(casterCounter) + ".Radius",
                        casterRadius
                    );
                    if (success) {
                        casterArray.emplace_back(casterName, casterRadius);
                    }
                    else {
                        LWARNING(fmt::format(
                            "No Radius value expecified for Shadow Caster Name '{}' from "
                            "'{}' planet. Disabling shadows for this planet.",
                            casterName, identifier()
                        ));
                        disableShadows = true;
                        break;
                    }
                }

                casterCounter++;
            }

            if (!disableShadows && (!sourceArray.empty() && !casterArray.empty())) {
                for (std::pair<std::string, float>& source : sourceArray) {
                    for (std::pair<std::string, float>& caster : casterArray) {
                        ShadowConfiguration sc;
                        sc.source = source;
                        sc.caster = caster;
                        _shadowConfArray.push_back({ source, caster });
                    }
                }
                _shadowEnabled = true;
            }
        }
    }
}

void RenderablePlanet::initializeGL() {
    // @FRAGILE: The shader deinitialization below relies on the name names for the
    //           request and the parameters to buildRenderProgram. That way, we can use
    //           the ProgramObject name in the releaseProgramObject method and release the
    //           correct one.

    if (!_programObject && _shadowEnabled && _hasNightTexture) {
        _programObject = SpaceModule::ProgramObjectManager.request(
            ShadowNightProgramName,
            []() -> std::unique_ptr<ghoul::opengl::ProgramObject> {
                return global::renderEngine.buildRenderProgram(
                    ShadowNightProgramName,
                    absPath("${MODULE_SPACE}/shaders/shadow_nighttexture_vs.glsl"),
                    absPath("${MODULE_SPACE}/shaders/shadow_nighttexture_fs.glsl")
                );
            }
        );
    }
    else if (!_programObject && _shadowEnabled) {
        _programObject = SpaceModule::ProgramObjectManager.request(
            ShadowProgramName,
            []() -> std::unique_ptr<ghoul::opengl::ProgramObject> {
                return global::renderEngine.buildRenderProgram(
                        ShadowProgramName,
                        absPath("${MODULE_SPACE}/shaders/shadow_vs.glsl"),
                        absPath("${MODULE_SPACE}/shaders/shadow_fs.glsl")
                );
            }
        );
    }
    else if (!_programObject && _hasNightTexture) {
        _programObject = SpaceModule::ProgramObjectManager.request(
            NightProgramName,
            []() -> std::unique_ptr<ghoul::opengl::ProgramObject> {
                return global::renderEngine.buildRenderProgram(
                    NightProgramName,
                    absPath("${MODULE_SPACE}/shaders/nighttexture_vs.glsl"),
                    absPath("${MODULE_SPACE}/shaders/nighttexture_fs.glsl")
                );
            }
        );
    }
    else if (!_programObject) {
        _programObject = SpaceModule::ProgramObjectManager.request(
            PlainProgramName,
            []() -> std::unique_ptr<ghoul::opengl::ProgramObject> {
                return global::renderEngine.buildRenderProgram(
                    PlainProgramName,
                    absPath("${MODULE_SPACE}/shaders/renderableplanet_vs.glsl"),
                    absPath("${MODULE_SPACE}/shaders/renderableplanet_fs.glsl")
                );
            }
        );
    }

    using IgnoreError = ghoul::opengl::ProgramObject::IgnoreError;
    _programObject->setIgnoreSubroutineUniformLocationError(IgnoreError::Yes);
    _programObject->setIgnoreUniformLocationError(IgnoreError::Yes);

    _geometry->initialize();
    setBoundingSphere(_geometry->boundingSphere());

    // Deactivate any previously activated shader program.
    _programObject->deactivate();

    loadTexture();
}

void RenderablePlanet::deinitializeGL() {
    if (_geometry) {
        _geometry->deinitialize();
        _geometry = nullptr;
    }

    SpaceModule::ProgramObjectManager.release(
        _programObject->name(),
        [](ghoul::opengl::ProgramObject* p) {
            global::renderEngine.removeRenderProgram(p);
        }
    );

    _texture = nullptr;
    _nightTexture = nullptr;
}

bool RenderablePlanet::isReady() const {
    return _programObject && _texture && _geometry;
}

glm::dmat4 RenderablePlanet::computeModelTransformMatrix(
                                            const openspace::TransformData& transformData)
{
    // scale the planet to appropriate size since the planet is a unit sphere
    glm::dmat4 modelTransform =
        glm::translate(glm::dmat4(1.0), transformData.translation) * // Translation
        glm::dmat4(transformData.rotation) *  // Spice rotation
        glm::scale(glm::dmat4(1.0), glm::dvec3(transformData.scale));

    // scale the planet to appropriate size since the planet is a unit sphere
    //glm::mat4 transform = glm::mat4(1);

    //earth needs to be rotated for that to work.
    glm::dmat4 rot = glm::rotate(
        glm::dmat4(1.0),
        glm::half_pi<double>(),
        glm::dvec3(1.0, 0.0, 0.0)
    );
    glm::dmat4 roty = glm::rotate(
        glm::dmat4(1.0),
        glm::half_pi<double>(),
        glm::dvec3(0.0, -1.0, 0.0)
    );

    return modelTransform = modelTransform * rot * roty /** rotProp*/;
}

void RenderablePlanet::render(const RenderData& data, RendererTasks&) {
    // activate shader
    _programObject->activate();

    glm::dmat4 modelTransform = computeModelTransformMatrix(data.modelTransform);
    glm::dmat4 modelViewTransform = data.camera.combinedViewMatrix() * modelTransform;

    _programObject->setUniform("transparency", _alpha);
    _programObject->setUniform("modelViewTransform", modelViewTransform);
    _programObject->setUniform(
        "modelViewProjectionTransform",
        data.camera.sgctInternal.projectionMatrix() * glm::mat4(modelViewTransform)
    );
    _programObject->setUniform("ModelTransform", glm::mat4(modelTransform));

    // Normal Transformation
    //glm::mat4 translateObjTrans = glm::translate(glm::mat4(1.0), data.position.vec3());
    //glm::mat4 translateCamTrans = glm::translate(
    //    glm::mat4(1.0),
    //    -data.camera.position().vec3()
    //);
    //float scaleFactor = data.camera.scaling().x * powf(10.0, data.camera.scaling().y);
    //glm::mat4 scaleCamTrans = glm::scale(glm::mat4(1.0), glm::vec3(scaleFactor));

//    glm::mat4 ModelViewTrans = data.camera.viewMatrix() * scaleCamTrans *
//        translateCamTrans * translateObjTrans * glm::mat4(modelTransform);

    setPscUniforms(*_programObject, data.camera, data.position);

    _programObject->setUniform("_performShading", _performShading);
    _programObject->setUniform("_hasHeightMap", _hasHeightTexture);
    _programObject->setUniform("_heightExaggeration", _heightExaggeration);

    // Bind texture
    ghoul::opengl::TextureUnit dayUnit;
    ghoul::opengl::TextureUnit nightUnit;
    ghoul::opengl::TextureUnit heightUnit;

    dayUnit.activate();
    _texture->bind();
    _programObject->setUniform("texture1", dayUnit);

    // Bind possible night texture
    if (_hasNightTexture && _nightTexture) {
        nightUnit.activate();
        _nightTexture->bind();
        _programObject->setUniform("nightTex", nightUnit);
    }

    if (_hasHeightTexture && _heightMapTexture) {
        heightUnit.activate();
        _heightMapTexture->bind();
        _programObject->setUniform("heightTex", heightUnit);
    }

    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);

    //=============================================================================
    //============= Eclipse Shadow Calculations and Uniforms Loading ==============
    //=============================================================================
    // TODO: Move Calculations to VIEW SPACE (let's avoid precision problems...)
    double lt;
    if (!_shadowConfArray.empty()) {
        std::vector<ShadowRenderingStruct> shadowDataArray;
        shadowDataArray.reserve(_shadowConfArray.size());

        for (const ShadowConfiguration& shadowConf : _shadowConfArray) {
            // TO REMEMBER: all distances and lengths in world coordinates are in meters!!
            // We need to move this to view space...
            // Getting source and caster:
            glm::dvec3 sourcePos = SpiceManager::ref().targetPosition(
                shadowConf.source.first,
                "SUN",
                "GALACTIC",
                {},
                _time,
                lt
            );
            sourcePos *= 1000.0; // converting to meters
            glm::dvec3 casterPos = SpiceManager::ref().targetPosition(
                shadowConf.caster.first,
                "SUN",
                "GALACTIC",
                {},
                _time,
                lt
            );
            casterPos *= 1000.0; // converting to meters
            psc caster_pos = PowerScaledCoordinate::CreatePowerScaledCoordinate(
                casterPos.x,
                casterPos.y,
                casterPos.z
            );

            // First we determine if the caster is shadowing the current planet (all
            // calculations in World Coordinates):
            const glm::vec3 planetCasterVec = (caster_pos - data.position).vec3();
            const glm::vec3 sourceCasterVec = glm::vec3(casterPos - sourcePos);
            const float sc_length = glm::length(sourceCasterVec);
            const glm::vec3 planetCaster_proj =
                (glm::dot(planetCasterVec, sourceCasterVec) / (sc_length*sc_length)) *
                sourceCasterVec;
            const float d_test = glm::length(planetCasterVec - planetCaster_proj);
            const float xp_test = shadowConf.caster.second * sc_length /
                                  (shadowConf.source.second + shadowConf.caster.second);
            const float rp_test = shadowConf.caster.second *
                                  (glm::length(planetCaster_proj) + xp_test) /
                                  xp_test;

            const double casterDistSun = glm::length(casterPos);
            const float planetDistSun = glm::length(data.position.vec3());

            ShadowRenderingStruct shadowData;
            shadowData.isShadowing = false;

            if (((d_test - rp_test) < _planetRadius) && (casterDistSun < planetDistSun)) {
                // The current caster is shadowing the current planet
                shadowData.isShadowing = true;
                shadowData.rs = shadowConf.source.second;
                shadowData.rc = shadowConf.caster.second;
                shadowData.sourceCasterVec = sourceCasterVec;
                shadowData.xp = xp_test;
                shadowData.xu = shadowData.rc * sc_length /
                                (shadowData.rs - shadowData.rc);
                shadowData.casterPositionVec = glm::vec3(casterPos);
            }
            shadowDataArray.push_back(shadowData);
        }

        constexpr const char* isShadowingTemplate = "shadowDataArray[{}].isShadowing";
        constexpr const char* xpTemplate = "shadowDataArray[{}].xp";
        constexpr const char* xuTemplate = "shadowDataArray[{}].xu";
        constexpr const char* rcTemplate = "shadowDataArray[{}].rc";
        constexpr const char* sourceTemplate = "shadowDataArray[{}].sourceCasterVec";
        constexpr const char* casterTemplate = "shadowDataArray[{}].casterPositionVec";

        const std::string uniformVarName("shadowDataArray[");
        unsigned int counter = 0;
        for (const ShadowRenderingStruct& sd : shadowDataArray) {
            _programObject->setUniform(
                fmt::format(isShadowingTemplate, counter),
                sd.isShadowing
            );

            if (sd.isShadowing) {
                _programObject->setUniform(fmt::format(xpTemplate, counter), sd.xp);
                _programObject->setUniform(fmt::format(xuTemplate, counter), sd.xu);
                _programObject->setUniform(fmt::format(rcTemplate, counter), sd.rc);
                _programObject->setUniform(
                    fmt::format(sourceTemplate, counter),
                    sd.sourceCasterVec
                );
                _programObject->setUniform(
                    fmt::format(casterTemplate, counter),
                    sd.casterPositionVec
                );
            }
            counter++;
        }
    }

    // render
    _geometry->render();

    // disable shader
    _programObject->deactivate();
}

void RenderablePlanet::update(const UpdateData& data) {
    // set spice-orientation in accordance to timestamp
    _stateMatrix = data.modelTransform.rotation;
    _time = data.time.j2000Seconds();

    if (_programObject && _programObject->isDirty()) {
        _programObject->rebuildFromFile();
    }
}

void RenderablePlanet::loadTexture() {
    _texture = nullptr;
    if (!_colorTexturePath.value().empty()) {
        using namespace ghoul::io;
        _texture = TextureReader::ref().loadTexture(absPath(_colorTexturePath));
        if (_texture) {
            if (_texture->numberOfChannels() == 1) {
                _texture->setSwizzleMask({ GL_RED, GL_RED, GL_RED, GL_RED });
            }

            LDEBUG(fmt::format("Loaded texture '{}'", _colorTexturePath.value()));
            _texture->uploadTexture();
            _texture->setFilter(ghoul::opengl::Texture::FilterMode::LinearMipMap);
        }
    }

    if (_hasNightTexture) {
        _nightTexture = nullptr;
        if (!_nightTexturePath.value().empty()) {
            using namespace ghoul::io;
            _nightTexture = TextureReader::ref().loadTexture(absPath(_nightTexturePath));
            if (_nightTexture) {
                LDEBUG(fmt::format("Loaded texture '{}'", _nightTexturePath.value()));
                _nightTexture->uploadTexture();
                _nightTexture->setFilter(
                    ghoul::opengl::Texture::FilterMode::LinearMipMap
                );
            }
        }
    }

    if (_hasHeightTexture) {
        _heightMapTexture = nullptr;
        if (!_heightMapTexturePath.value().empty()) {
            _heightMapTexture = ghoul::io::TextureReader::ref().loadTexture(
                absPath(_heightMapTexturePath)
            );
            if (_heightMapTexture) {
                LDEBUG(fmt::format(
                    "Loaded texture from '{}'",
                    _heightMapTexturePath.value()
                ));
                _heightMapTexture->uploadTexture();
                _heightMapTexture->setFilter(ghoul::opengl::Texture::FilterMode::Linear);
            }
        }
    }
}

} // namespace openspace