/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2019                                                               *
 *                                                                                       *
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#include <modules/globebrowsing/src/ringscomponent.h>

#include <modules/globebrowsing/globebrowsingmodule.h>
#include <modules/globebrowsing/src/renderableglobe.h>
#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/engine/globals.h>
#include <openspace/engine/moduleengine.h>
#include <openspace/engine/openspaceengine.h>
#include <openspace/rendering/renderengine.h>
#include <openspace/scene/scene.h>
#include <openspace/util/updatestructures.h>
#include <ghoul/filesystem/cachemanager.h>
#include <ghoul/filesystem/filesystem.h>
#include <ghoul/font/fontmanager.h>
#include <ghoul/font/fontrenderer.h>
#include <ghoul/logging/logmanager.h>
#include <ghoul/misc/dictionary.h>
#include <ghoul/opengl/programobject.h>
#include <ghoul/opengl/texture.h>
#include <ghoul/opengl/textureunit.h>
#include <ghoul/io/texture/texturereader.h>
#include <fstream>
#include <cstdlib>
#include <locale>

namespace {
    constexpr const char* _loggerCat = "RingsComponent";

    constexpr const std::array<const char*, 9> UniformNames = {
        "modelViewProjectionMatrix", "textureOffset", "transparency", "_nightFactor", 
        "sunPosition", "ringTexture", "shadowMatrix", "shadowMapTexture",
        "zFightingPercentage"
    };

    constexpr const std::array<const char*, 3> GeomUniformNames = {
        "modelViewProjectionMatrix", "textureOffset", "ringTexture"
    };

    constexpr openspace::properties::Property::PropertyInfo TextureInfo = {
        "Texture",
        "Texture",
        "This value is the path to a texture on disk that contains a one-dimensional "
        "texture which is used for these rings."
    };

    constexpr openspace::properties::Property::PropertyInfo SizeInfo = {
        "Size",
        "Size",
        "This value specifies the radius of the rings in meter."
    };

    constexpr openspace::properties::Property::PropertyInfo OffsetInfo = {
        "Offset",
        "Offset",
        "This value is used to limit the width of the rings.Each of the two values is a "
        "value between 0 and 1, where 0 is the center of the ring and 1 is the maximum "
        "extent at the radius. If this value is, for example {0.5, 1.0}, the ring is "
        "only shown between radius/2 and radius. It defaults to {0.0, 1.0}."
    };

    constexpr openspace::properties::Property::PropertyInfo NightFactorInfo = {
        "NightFactor",
        "Night Factor",
        "This value is a multiplicative factor that is applied to the side of the rings "
        "that is facing away from the Sun. If this value is equal to '1', no darkening "
        "of the night side occurs."
    };

    constexpr openspace::properties::Property::PropertyInfo TransparencyInfo = {
        "Transparency",
        "Transparency",
        "This value determines the transparency of part of the rings depending on the "
        "color values. For this value v, the transparency is equal to length(color) / v."
    };

    constexpr openspace::properties::Property::PropertyInfo ZFightingPercentageInfo = {
        "ZFightingPercentage",
        "Z-Fighting Percentage",
        "The percentage of the correct distance to the surface being shadowed. "
        "Possible values: [0.0, 1.0]"
    };

    constexpr openspace::properties::Property::PropertyInfo NumberShadowSamplesInfo = {
        "NumberShadowSamples",
        "Number of Shadow Samples",
        "The number of samples used during shadow mapping calculation "
        "(Percentage Closer Filtering)."
    };
} // namespace

namespace openspace {

documentation::Documentation RingsComponent::Documentation() {
    using namespace documentation;
    return {
        "Rings Component",
        "globebrowsing_rings_component",
        {
            {
                TextureInfo.identifier,
                new StringVerifier,
                Optional::Yes,
                TextureInfo.description
            },
            {
                SizeInfo.identifier,
                new DoubleVerifier,
                Optional::Yes,
                SizeInfo.description
            },
            {
                OffsetInfo.identifier,
                new DoubleVector2Verifier,
                Optional::Yes,
                OffsetInfo.description
            },
            {
                NightFactorInfo.identifier,
                new DoubleVerifier,
                Optional::Yes,
                NightFactorInfo.description
            },
            {
                TransparencyInfo.identifier,
                new DoubleVerifier,
                Optional::Yes,
                TransparencyInfo.description
            },
            {
                ZFightingPercentageInfo.identifier,
                new DoubleVerifier,
                Optional::Yes,
                ZFightingPercentageInfo.description
            },
            {
                NumberShadowSamplesInfo.identifier,
                new IntVerifier,
                Optional::Yes,
                NumberShadowSamplesInfo.description
            }
        }
    };
}

RingsComponent::RingsComponent(const ghoul::Dictionary& dictionary)
    : properties::PropertyOwner({ "Rings" })
    , _texturePath(TextureInfo)
    , _size(SizeInfo, 1.f, 0.f, 1e25f)
    , _offset(OffsetInfo, glm::vec2(0.f, 1.f), glm::vec2(0.f), glm::vec2(1.f))
    , _nightFactor(NightFactorInfo, 0.33f, 0.f, 1.f)
    , _transparency(TransparencyInfo, 0.15f, 0.f, 1.f)
    , _enabled({ "Enabled", "Enabled", "Enable/Disable Rings" }, true)
    , _zFightingPercentage(ZFightingPercentageInfo, 0.995f, 0.000001f, 1.f)
    , _nShadowSamples(NumberShadowSamplesInfo, 2, 1, 7)
    , _ringsDictionary(dictionary)
{
    using ghoul::filesystem::File;
        
    if (dictionary.hasKey("Rings")) {
        // @TODO (abock, 2019-12-16) It would be better to not store the dictionary long
        // term and rather extract the values directly here.  This would require a bit of
        // a rewrite in the RenderableGlobe class to not create the RingsComponent in the
        // class-initializer list though
        dictionary.getValue("Rings", _ringsDictionary);
    }
        
    documentation::testSpecificationAndThrow(
        Documentation(),
        _ringsDictionary,
        "RingsComponent"
    );
}

void RingsComponent::initialize() {
    using ghoul::filesystem::File;

    addProperty(_enabled);

    _size = static_cast<float>(_ringsDictionary.value<double>(SizeInfo.identifier));
    //setBoundingSphere(_size);
    _size.onChange([&]() { _planeIsDirty = true; });
    addProperty(_size);

    _texturePath = absPath(
        _ringsDictionary.value<std::string>(TextureInfo.identifier)
    );
    _textureFile = std::make_unique<File>(_texturePath);

    if (_ringsDictionary.hasKeyAndValue<glm::vec2>(OffsetInfo.identifier)) {
        _offset = _ringsDictionary.value<glm::vec2>(OffsetInfo.identifier);
    }
    addProperty(_offset);

    _texturePath.onChange([&]() { loadTexture(); });
    addProperty(_texturePath);

    _textureFile->setCallback([&](const File&) { _textureIsDirty = true; });

    if (_ringsDictionary.hasKeyAndValue<double>(NightFactorInfo.identifier)) {
        _nightFactor = static_cast<float>(
            _ringsDictionary.value<double>(NightFactorInfo.identifier)
        );
    }
    addProperty(_nightFactor);

    if (_ringsDictionary.hasKeyAndValue<double>(TransparencyInfo.identifier)) {
        _transparency = static_cast<float>(
            _ringsDictionary.value<double>(TransparencyInfo.identifier)
        );
    }

    // Shadow Mapping Quality Controls
    if (_ringsDictionary.hasKey(ZFightingPercentageInfo.identifier)) {
        _zFightingPercentage = _ringsDictionary.value<float>(
            ZFightingPercentageInfo.identifier
        );
    }
    addProperty(_zFightingPercentage);

    if (_ringsDictionary.hasKey(NumberShadowSamplesInfo.identifier)) {
        _nShadowSamples = _ringsDictionary.value<int>(NumberShadowSamplesInfo.identifier);
    }
    _nShadowSamples.onChange([this]() { compileShadowShader(); });
    addProperty(_nShadowSamples);

    addProperty(_transparency);
}

bool RingsComponent::isReady() const {
    return (_shader || _geometryOnlyShader) && _texture;
}

void RingsComponent::initializeGL() {
    compileShadowShader();

    _geometryOnlyShader = global::renderEngine.buildRenderProgram(
        "RingsGeomOnlyProgram",
        absPath("${MODULE_GLOBEBROWSING}/shaders/rings_geom_vs.glsl"),
        absPath("${MODULE_GLOBEBROWSING}/shaders/rings_geom_fs.glsl")
    );

    ghoul::opengl::updateUniformLocations(*_shader, _uniformCache, UniformNames);
    ghoul::opengl::updateUniformLocations(
        *_geometryOnlyShader, 
        _geomUniformCache, 
        GeomUniformNames
    );

    glGenVertexArrays(1, &_quad);
    glGenBuffers(1, &_vertexPositionBuffer);

    createPlane();
    loadTexture();
}

void RingsComponent::deinitializeGL() {
    glDeleteVertexArrays(1, &_quad);
    _quad = 0;

    glDeleteBuffers(1, &_vertexPositionBuffer);
    _vertexPositionBuffer = 0;

    _textureFile = nullptr;
    _texture = nullptr;

    global::renderEngine.removeRenderProgram(_shader.get());
    _shader = nullptr;

    global::renderEngine.removeRenderProgram(_geometryOnlyShader.get());
    _geometryOnlyShader = nullptr;
}

void RingsComponent::draw(const RenderData& data,
                          const RingsComponent::RenderPass renderPass,
                          const ShadowComponent::ShadowMapData& shadowData)
{
    if (renderPass == GeometryAndShading) {
        _shader->activate();
    }
    else if (renderPass == GeometryOnly) {
        _geometryOnlyShader->activate();
    }
                
    const glm::dmat4 modelTransform =
        glm::translate(glm::dmat4(1.0), data.modelTransform.translation) *
        glm::dmat4(data.modelTransform.rotation) *
        glm::scale(glm::dmat4(1.0), glm::dvec3(data.modelTransform.scale));

    const glm::dmat4 modelViewProjectionTransform = 
        glm::dmat4(data.camera.projectionMatrix()) * data.camera.combinedViewMatrix() 
        * modelTransform;

    ghoul::opengl::TextureUnit ringTextureUnit;
    if (renderPass == GeometryAndShading) {
        _shader->setUniform(
            _uniformCache.modelViewProjectionMatrix, 
            modelViewProjectionTransform
        );
        _shader->setUniform(_uniformCache.textureOffset, _offset);
        _shader->setUniform(_uniformCache.transparency, _transparency);
        _shader->setUniform(_uniformCache.nightFactor, _nightFactor);
        _shader->setUniform(_uniformCache.sunPosition, _sunPosition);
        _shader->setUniform(_uniformCache.zFightingPercentage, _zFightingPercentage);

        ringTextureUnit.activate();
        _texture->bind();
        _shader->setUniform(_uniformCache.ringTexture, ringTextureUnit);

        // Adding the model transformation to the final shadow matrix so we have a 
        // complete transformation from the model coordinates to the clip space of 
        // the light position.
        _shader->setUniform(
            _uniformCache.shadowMatrix, 
            shadowData.shadowMatrix * modelTransform
        );

        ghoul::opengl::TextureUnit shadowMapUnit;
        shadowMapUnit.activate();
        glBindTexture(GL_TEXTURE_2D, shadowData.shadowDepthTexture);
        
        _shader->setUniform(_uniformCache.shadowMapTexture, shadowMapUnit);
    }
    else if (renderPass == GeometryOnly) {
        _geometryOnlyShader->setUniform(
            _geomUniformCache.modelViewProjectionMatrix,
            modelViewProjectionTransform
        );
        _geometryOnlyShader->setUniform(_geomUniformCache.textureOffset, _offset);

        ringTextureUnit.activate();
        _texture->bind();
        _shader->setUniform(_geomUniformCache.ringTexture, ringTextureUnit);
    }

    glEnable(GL_DEPTH_TEST);
    glDisable(GL_CULL_FACE);

    glBindVertexArray(_quad);
    glDrawArrays(GL_TRIANGLES, 0, 6);

    glEnable(GL_CULL_FACE);

    if (renderPass == GeometryAndShading) {
        _shader->deactivate();
    }
    else if (renderPass == GeometryOnly) {
        _geometryOnlyShader->deactivate();
    }
}

void RingsComponent::update(const UpdateData& data) {
    if (_shader->isDirty()) {
        compileShadowShader();
    }

    if (_geometryOnlyShader->isDirty()) {
        _geometryOnlyShader->rebuildFromFile();
        ghoul::opengl::updateUniformLocations(
            *_geometryOnlyShader, 
            _geomUniformCache, 
            GeomUniformNames
        );
    }

    if (_planeIsDirty) {
        createPlane();
        _planeIsDirty = false;
    }

    if (_textureIsDirty) {
        loadTexture();
        _textureIsDirty = false;
    }

    _sunPosition = glm::normalize(
        global::renderEngine.scene()->sceneGraphNode("Sun")->worldPosition() -
        data.modelTransform.translation
    );
}

void RingsComponent::loadTexture() {
    if (!_texturePath.value().empty()) {
        using namespace ghoul::io;
        using namespace ghoul::opengl;
        std::unique_ptr<Texture> texture = TextureReader::ref().loadTexture(
            absPath(_texturePath)
        );

        if (texture) {
            LDEBUGC(
                "RingsComponent",
                fmt::format("Loaded texture from '{}'", absPath(_texturePath))
            );
            _texture = std::move(texture);

            _texture->uploadTexture();
            _texture->setFilter(ghoul::opengl::Texture::FilterMode::AnisotropicMipMap);

            _textureFile = std::make_unique<ghoul::filesystem::File>(_texturePath);
            _textureFile->setCallback(
                [&](const ghoul::filesystem::File&) { _textureIsDirty = true; }
            );
        }
    }
}

void RingsComponent::createPlane() {
    const GLfloat size = _size;

    struct VertexData {
        GLfloat x;
        GLfloat y;
        GLfloat s;
        GLfloat t;
    };

    VertexData data[] = {
        { -size, -size, 0.f, 0.f },
        {  size,  size, 1.f, 1.f },
        { -size,  size, 0.f, 1.f },
        { -size, -size, 0.f, 0.f },
        {  size, -size, 1.f, 0.f },
        {  size,  size, 1.f, 1.f },
    };

    glBindVertexArray(_quad);
    glBindBuffer(GL_ARRAY_BUFFER, _vertexPositionBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(data), data, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(
        0,
        2,
        GL_FLOAT,
        GL_FALSE,
        sizeof(VertexData),
        nullptr
    );
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(
        1,
        2,
        GL_FLOAT,
        GL_FALSE,
        sizeof(VertexData),
        reinterpret_cast<void*>(offsetof(VertexData, s)) // NOLINT
    );
}

void RingsComponent::compileShadowShader() {
    ghoul::Dictionary dict;
    dict.setValue("nShadowSamples", std::to_string(_nShadowSamples - 1));

    try {
        global::renderEngine.removeRenderProgram(_shader.get());
        _shader = global::renderEngine.buildRenderProgram(
            "RingsProgram",
            absPath("${MODULE_GLOBEBROWSING}/shaders/rings_vs.glsl"),
            absPath("${MODULE_GLOBEBROWSING}/shaders/rings_fs.glsl"),
            dict
        );
    }
    catch (const ghoul::RuntimeError& e) {
        LERROR(e.message);
    }
    ghoul::opengl::updateUniformLocations(*_shader, _uniformCache, UniformNames);
}

bool RingsComponent::isEnabled() const {
    return _enabled;
}

} // namespace openspace