/*****************************************************************************************
 *                                                                                       *
 * OpenSpace                                                                             *
 *                                                                                       *
 * Copyright (c) 2014-2017                                                               *
 *                                                                                       *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this  *
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 * permit persons to whom the Software is furnished to do so, subject to the following   *
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 * The above copyright notice and this permission notice shall be included in all copies *
 * or substantial portions of the Software.                                              *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,   *
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A         *
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT    *
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 ****************************************************************************************/

#include <modules/globebrowsing/rendering/layershadermanager.h>
#include <modules/globebrowsing/globes/renderableglobe.h>
#include <modules/globebrowsing/globes/chunkedlodglobe.h>
#include <modules/globebrowsing/chunk/chunk.h>
#include <modules/globebrowsing/tile/rawtiledatareader/rawtiledatareader.h>
#include <modules/globebrowsing/rendering/layer/layermanager.h>
#include <modules/globebrowsing/rendering/layer/layergroup.h>

#include <openspace/engine/openspaceengine.h>
#include <openspace/rendering/renderengine.h>

#include <ghoul/opengl/programobject.h>

namespace openspace::globebrowsing {

bool LayerShaderManager::LayerShaderPreprocessingData::LayerGroupPreprocessingData::operator==(
    const LayerGroupPreprocessingData& other) const {
    return layerType == other.layerType &&
        blendMode == other.blendMode &&
        layerAdjustmentType == other.layerAdjustmentType &&
        lastLayerIdx == other.lastLayerIdx &&
        layerBlendingEnabled == other.layerBlendingEnabled;
}

bool LayerShaderManager::LayerShaderPreprocessingData::operator==(
    const LayerShaderPreprocessingData& other) const {
    if (layeredTextureInfo.size() != other.layeredTextureInfo.size() ||
        keyValuePairs.size() != other.keyValuePairs.size()) {
        return false;
    }
    else {
        bool equal = true;
        for (size_t i = 0; i < layeredTextureInfo.size(); i++) {
            equal &= (layeredTextureInfo[i] == other.layeredTextureInfo[i]);
        }
        for (size_t i = 0; i < keyValuePairs.size(); i++) {
            equal &= (keyValuePairs[i] == other.keyValuePairs[i]);
        }
        return equal;
    }
}

LayerShaderManager::LayerShaderPreprocessingData
    LayerShaderManager::LayerShaderPreprocessingData::get(
    const RenderableGlobe& globe)
{
    LayerShaderManager::LayerShaderPreprocessingData preprocessingData;

    std::shared_ptr<LayerManager> layerManager = globe.chunkedLodGlobe()->layerManager();
    for (size_t i = 0; i < layergroupid::NUM_LAYER_GROUPS; i++) {
        LayerShaderManager::LayerShaderPreprocessingData::LayerGroupPreprocessingData
            layeredTextureInfo;

        const LayerGroup& layerGroup = layerManager->layerGroup(i);
        std::vector<std::shared_ptr<Layer>> layers = layerGroup.activeLayers();
        
        // This check was implicit before;  not sure if it will fire or will be handled
        // elsewhere
        //ghoul_assert(
        //    !layerGroup.activeLayers().empty(),
        //    "If activeLayers is empty the following line will lead to an overflow"
        //);
        layeredTextureInfo.lastLayerIdx = static_cast<int>(
            layerGroup.activeLayers().size() - 1
        );
        layeredTextureInfo.layerBlendingEnabled = layerGroup.layerBlendingEnabled();

        for (const std::shared_ptr<Layer>& layer : layers) {
            layeredTextureInfo.layerType.push_back(layer->type());
            layeredTextureInfo.blendMode.push_back(layer->blendMode());
            layeredTextureInfo.layerAdjustmentType.push_back(layer->layerAdjustment().type());
        }

        preprocessingData.layeredTextureInfo[i] = layeredTextureInfo;
    }
        
    const RenderableGlobe::GeneralProperties& generalProps = globe.generalProperties();
    const RenderableGlobe::DebugProperties& debugProps = globe.debugProperties();
    auto& pairs = preprocessingData.keyValuePairs;
        
    pairs.emplace_back("useAccurateNormals",
        std::to_string(generalProps.useAccurateNormals)
    );
    pairs.emplace_back("useAtmosphere", std::to_string(generalProps.atmosphereEnabled));
    pairs.emplace_back("performShading", std::to_string(generalProps.performShading));
    pairs.emplace_back("showChunkEdges", std::to_string(debugProps.showChunkEdges));
    pairs.emplace_back("showHeightResolution",
        std::to_string(debugProps.showHeightResolution)
    );
    pairs.emplace_back("showHeightIntensities",
        std::to_string(debugProps.showHeightIntensities)
    );
    pairs.emplace_back("defaultHeight", std::to_string(Chunk::DEFAULT_HEIGHT));

    pairs.emplace_back("tilePaddingStart",
        "ivec2(" +
        std::to_string(RawTileDataReader::padding.start.x) + "," +
        std::to_string(RawTileDataReader::padding.start.y) + ")"
    );
    pairs.emplace_back("tilePaddingSizeDiff",
        "ivec2(" +
        std::to_string(RawTileDataReader::padding.numPixels.x) + "," +
        std::to_string(RawTileDataReader::padding.numPixels.y) + ")"
    );

    return preprocessingData;
}

LayerShaderManager::LayerShaderManager(const std::string& shaderName,
                                       const std::string& vsPath,
                                       const std::string& fsPath)
    : _shaderName(shaderName)
    , _vsPath(vsPath)
    , _fsPath(fsPath)
    , _updatedOnLastCall(false)
{}
    
LayerShaderManager::~LayerShaderManager() {
    if (_programObject) {
        RenderEngine& renderEngine = OsEng.renderEngine();
        renderEngine.removeRenderProgram(_programObject);
        _programObject = nullptr;
    }
}

ghoul::opengl::ProgramObject* LayerShaderManager::programObject() const {
    ghoul_assert(_programObject, "Program does not exist. Needs to be compiled!");
    return _programObject.get();
}

void LayerShaderManager::recompileShaderProgram(
                                           LayerShaderPreprocessingData preprocessingData)
{
    _preprocessingData = preprocessingData;
    ghoul::Dictionary shaderDictionary;

    // Different layer types can be height layers or color layers for example.
    // These are used differently within the shaders.
    auto textureTypes = _preprocessingData.layeredTextureInfo;
    for (size_t i = 0; i < textureTypes.size(); i++) {
        // lastLayerIndex must be at least 0 for the shader to compile,
        // the layer type is inactivated by setting use to false
        std::string groupName = layergroupid::LAYER_GROUP_NAMES[i];
        shaderDictionary.setValue(
            "lastLayerIndex" + groupName,
            glm::max(textureTypes[i].lastLayerIdx, 0)
        );
        shaderDictionary.setValue(
            "use" + groupName,
            textureTypes[i].lastLayerIdx >= 0
        );
        shaderDictionary.setValue(
            "blend" + groupName,
            textureTypes[i].layerBlendingEnabled
        );

        // This is to avoid errors from shader preprocessor
        std::string keyLayerType = groupName + "0" + "LayerType";
        shaderDictionary.setValue(keyLayerType, 0);

        for (int j = 0; j < textureTypes[i].lastLayerIdx + 1; ++j) {
            std::string key = groupName + std::to_string(j) + "LayerType";
            shaderDictionary.setValue(key, static_cast<int>(textureTypes[i].layerType[j]));
        }

        // This is to avoid errors from shader preprocessor
        std::string keyBlendMode = groupName + "0" + "BlendMode";
        shaderDictionary.setValue(keyBlendMode, 0);

        for (int j = 0; j < textureTypes[i].lastLayerIdx + 1; ++j) {
            std::string key = groupName + std::to_string(j) + "BlendMode";
            shaderDictionary.setValue(key, static_cast<int>(textureTypes[i].blendMode[j]));
        }

        // This is to avoid errors from shader preprocessor
        std::string keyLayerAdjustmentType = groupName + "0" + "LayerAdjustmentType";
        shaderDictionary.setValue(keyLayerAdjustmentType, 0);

        for (int j = 0; j < textureTypes[i].lastLayerIdx + 1; ++j) {
            std::string key = groupName + std::to_string(j) + "LayerAdjustmentType";
            shaderDictionary.setValue(key, static_cast<int>(textureTypes[i].layerAdjustmentType[j]));
        }
    }

    ghoul::Dictionary layerGroupNames;
    for (int i = 0; i < layergroupid::NUM_LAYER_GROUPS; ++i) {
        layerGroupNames.setValue(std::to_string(i), layergroupid::LAYER_GROUP_NAMES[i]);
    }
    shaderDictionary.setValue("layerGroups", layerGroupNames);

    // Other settings such as "useAtmosphere"
    auto keyValuePairs = _preprocessingData.keyValuePairs;
    for (size_t i = 0; i < keyValuePairs.size(); i++) {
        shaderDictionary.setValue(keyValuePairs[i].first, keyValuePairs[i].second);
    }

    // Remove old program
    OsEng.renderEngine().removeRenderProgram(_programObject);

    _programObject = OsEng.renderEngine().buildRenderProgram(
        _shaderName,
        _vsPath,
        _fsPath,
        shaderDictionary
    );

    ghoul_assert(_programObject != nullptr, "Failed to initialize programObject!");
    using IgnoreError = ghoul::opengl::ProgramObject::ProgramObject::IgnoreError;
    _programObject->setIgnoreSubroutineUniformLocationError(IgnoreError::Yes);
    _updatedOnLastCall = true;
}

bool LayerShaderManager::updatedOnLastCall() {
    return _updatedOnLastCall;
}

} // namespace openspace::globebrowsing