#include "storage.hpp"

#include <set>

#include <osg/Image>
#include <osg/Plane>

#include <components/debug/debuglog.hpp>
#include <components/misc/resourcehelpers.hpp>
#include <components/misc/stringops.hpp>
#include <components/vfs/manager.hpp>

namespace ESMTerrain
{

    class LandCache
    {
    public:
        typedef std::map<std::pair<int, int>, osg::ref_ptr<const LandObject> > Map;
        Map mMap;
    };

    LandObject::LandObject()
        : mLand(nullptr)
        , mLoadFlags(0)
    {
    }

    LandObject::LandObject(const ESM::Land *land, int loadFlags)
        : mLand(land)
        , mLoadFlags(loadFlags)
    {
        mLand->loadData(mLoadFlags, &mData);
    }

    LandObject::LandObject(const LandObject &copy, const osg::CopyOp &copyop)
        : mLand(nullptr)
        , mLoadFlags(0)
    {
    }

    LandObject::~LandObject()
    {
    }

    const float defaultHeight = ESM::Land::DEFAULT_HEIGHT;

    Storage::Storage(const VFS::Manager *vfs, const std::string& normalMapPattern, const std::string& normalHeightMapPattern, bool autoUseNormalMaps, const std::string& specularMapPattern, bool autoUseSpecularMaps)
        : mVFS(vfs)
        , mNormalMapPattern(normalMapPattern)
        , mNormalHeightMapPattern(normalHeightMapPattern)
        , mAutoUseNormalMaps(autoUseNormalMaps)
        , mSpecularMapPattern(specularMapPattern)
        , mAutoUseSpecularMaps(autoUseSpecularMaps)
    {
    }

    bool Storage::getMinMaxHeights(float size, const osg::Vec2f &center, float &min, float &max)
    {
        assert (size <= 1 && "Storage::getMinMaxHeights, chunk size should be <= 1 cell");

        osg::Vec2f origin = center - osg::Vec2f(size/2.f, size/2.f);

        int cellX = static_cast<int>(std::floor(origin.x()));
        int cellY = static_cast<int>(std::floor(origin.y()));

        int startRow = (origin.x() - cellX) * ESM::Land::LAND_SIZE;
        int startColumn = (origin.y() - cellY) * ESM::Land::LAND_SIZE;

        int endRow = startRow + size * (ESM::Land::LAND_SIZE-1) + 1;
        int endColumn = startColumn + size * (ESM::Land::LAND_SIZE-1) + 1;

        osg::ref_ptr<const LandObject> land = getLand (cellX, cellY);
        const ESM::Land::LandData* data = land ? land->getData(ESM::Land::DATA_VHGT) : nullptr;
        if (data)
        {
            min = std::numeric_limits<float>::max();
            max = -std::numeric_limits<float>::max();
            for (int row=startRow; row<endRow; ++row)
            {
                for (int col=startColumn; col<endColumn; ++col)
                {
                    float h = data->mHeights[col*ESM::Land::LAND_SIZE+row];
                    if (h > max)
                        max = h;
                    if (h < min)
                        min = h;
                }
            }
            return true;
        }

        min = defaultHeight;
        max = defaultHeight;
        return false;
    }

    void Storage::fixNormal (osg::Vec3f& normal, int cellX, int cellY, int col, int row, LandCache& cache)
    {
        while (col >= ESM::Land::LAND_SIZE-1)
        {
            ++cellY;
            col -= ESM::Land::LAND_SIZE-1;
        }
        while (row >= ESM::Land::LAND_SIZE-1)
        {
            ++cellX;
            row -= ESM::Land::LAND_SIZE-1;
        }
        while (col < 0)
        {
            --cellY;
            col += ESM::Land::LAND_SIZE-1;
        }
        while (row < 0)
        {
            --cellX;
            row += ESM::Land::LAND_SIZE-1;
        }

        const LandObject* land = getLand(cellX, cellY, cache);
        const ESM::Land::LandData* data = land ? land->getData(ESM::Land::DATA_VNML) : nullptr;
        if (data)
        {
            normal.x() = data->mNormals[col*ESM::Land::LAND_SIZE*3+row*3];
            normal.y() = data->mNormals[col*ESM::Land::LAND_SIZE*3+row*3+1];
            normal.z() = data->mNormals[col*ESM::Land::LAND_SIZE*3+row*3+2];
            normal.normalize();
        }
        else
            normal = osg::Vec3f(0,0,1);
    }

    void Storage::averageNormal(osg::Vec3f &normal, int cellX, int cellY, int col, int row, LandCache& cache)
    {
        osg::Vec3f n1,n2,n3,n4;
        fixNormal(n1, cellX, cellY, col+1, row, cache);
        fixNormal(n2, cellX, cellY, col-1, row, cache);
        fixNormal(n3, cellX, cellY, col, row+1, cache);
        fixNormal(n4, cellX, cellY, col, row-1, cache);
        normal = (n1+n2+n3+n4);
        normal.normalize();
    }

    void Storage::fixColour (osg::Vec4ub& color, int cellX, int cellY, int col, int row, LandCache& cache)
    {
        if (col == ESM::Land::LAND_SIZE-1)
        {
            ++cellY;
            col = 0;
        }
        if (row == ESM::Land::LAND_SIZE-1)
        {
            ++cellX;
            row = 0;
        }

        const LandObject* land = getLand(cellX, cellY, cache);
        const ESM::Land::LandData* data = land ? land->getData(ESM::Land::DATA_VCLR) : nullptr;
        if (data)
        {
            color.r() = data->mColours[col*ESM::Land::LAND_SIZE*3+row*3];
            color.g() = data->mColours[col*ESM::Land::LAND_SIZE*3+row*3+1];
            color.b() = data->mColours[col*ESM::Land::LAND_SIZE*3+row*3+2];
        }
        else
        {
            color.r() = 255;
            color.g() = 255;
            color.b() = 255;
        }
    }

    void Storage::fillVertexBuffers (int lodLevel, float size, const osg::Vec2f& center,
                                            osg::ref_ptr<osg::Vec3Array> positions,
                                            osg::ref_ptr<osg::Vec3Array> normals,
                                            osg::ref_ptr<osg::Vec4ubArray> colours)
    {
        // LOD level n means every 2^n-th vertex is kept
        size_t increment = static_cast<size_t>(1) << lodLevel;

        osg::Vec2f origin = center - osg::Vec2f(size/2.f, size/2.f);

        int startCellX = static_cast<int>(std::floor(origin.x()));
        int startCellY = static_cast<int>(std::floor(origin.y()));

        size_t numVerts = static_cast<size_t>(size*(ESM::Land::LAND_SIZE - 1) / increment + 1);

        positions->resize(numVerts*numVerts);
        normals->resize(numVerts*numVerts);
        colours->resize(numVerts*numVerts);

        osg::Vec3f normal;
        osg::Vec4ub color;

        float vertY = 0;
        float vertX = 0;

        LandCache cache;

        bool alteration = useAlteration();

        float vertY_ = 0; // of current cell corner
        for (int cellY = startCellY; cellY < startCellY + std::ceil(size); ++cellY)
        {
            float vertX_ = 0; // of current cell corner
            for (int cellX = startCellX; cellX < startCellX + std::ceil(size); ++cellX)
            {
                const LandObject* land = getLand(cellX, cellY, cache);
                const ESM::Land::LandData *heightData = nullptr;
                const ESM::Land::LandData *normalData = nullptr;
                const ESM::Land::LandData *colourData = nullptr;
                if (land)
                {
                    heightData = land->getData(ESM::Land::DATA_VHGT);
                    normalData = land->getData(ESM::Land::DATA_VNML);
                    colourData = land->getData(ESM::Land::DATA_VCLR);
                }

                int rowStart = 0;
                int colStart = 0;
                // Skip the first row / column unless we're at a chunk edge,
                // since this row / column is already contained in a previous cell
                // This is only relevant if we're creating a chunk spanning multiple cells
                if (vertY_ != 0)
                    colStart += increment;
                if (vertX_ != 0)
                    rowStart += increment;

                // Only relevant for chunks smaller than (contained in) one cell
                rowStart += (origin.x() - startCellX) * ESM::Land::LAND_SIZE;
                colStart += (origin.y() - startCellY) * ESM::Land::LAND_SIZE;
                int rowEnd = std::min(static_cast<int>(rowStart + std::min(1.f, size) * (ESM::Land::LAND_SIZE-1) + 1), static_cast<int>(ESM::Land::LAND_SIZE));
                int colEnd = std::min(static_cast<int>(colStart + std::min(1.f, size) * (ESM::Land::LAND_SIZE-1) + 1), static_cast<int>(ESM::Land::LAND_SIZE));

                vertY = vertY_;
                for (int col=colStart; col<colEnd; col += increment)
                {
                    vertX = vertX_;
                    for (int row=rowStart; row<rowEnd; row += increment)
                    {
                        int srcArrayIndex = col*ESM::Land::LAND_SIZE*3+row*3;

                        assert(row >= 0 && row < ESM::Land::LAND_SIZE);
                        assert(col >= 0 && col < ESM::Land::LAND_SIZE);

                        assert (vertX < numVerts);
                        assert (vertY < numVerts);

                        float height = defaultHeight;
                        if (heightData)
                            height = heightData->mHeights[col*ESM::Land::LAND_SIZE + row];
                        if (alteration)
                            height += getAlteredHeight(col, row);
                        (*positions)[static_cast<unsigned int>(vertX*numVerts + vertY)]
                            = osg::Vec3f((vertX / float(numVerts - 1) - 0.5f) * size * Constants::CellSizeInUnits,
                                         (vertY / float(numVerts - 1) - 0.5f) * size * Constants::CellSizeInUnits,
                                         height);

                        if (normalData)
                        {
                            for (int i=0; i<3; ++i)
                                normal[i] = normalData->mNormals[srcArrayIndex+i];

                            normal.normalize();
                        }
                        else
                            normal = osg::Vec3f(0,0,1);

                        // Normals apparently don't connect seamlessly between cells
                        if (col == ESM::Land::LAND_SIZE-1 || row == ESM::Land::LAND_SIZE-1)
                            fixNormal(normal, cellX, cellY, col, row, cache);

                        // some corner normals appear to be complete garbage (z < 0)
                        if ((row == 0 || row == ESM::Land::LAND_SIZE-1) && (col == 0 || col == ESM::Land::LAND_SIZE-1))
                            averageNormal(normal, cellX, cellY, col, row, cache);

                        assert(normal.z() > 0);

                        (*normals)[static_cast<unsigned int>(vertX*numVerts + vertY)] = normal;

                        if (colourData)
                        {
                            for (int i=0; i<3; ++i)
                                color[i] = colourData->mColours[srcArrayIndex+i];
                        }
                        else
                        {
                            color.r() = 255;
                            color.g() = 255;
                            color.b() = 255;
                        }
                        if (alteration)
                            adjustColor(col, row, heightData, color); //Does nothing by default, override in OpenMW-CS

                        // Unlike normals, colors mostly connect seamlessly between cells, but not always...
                        if (col == ESM::Land::LAND_SIZE-1 || row == ESM::Land::LAND_SIZE-1)
                            fixColour(color, cellX, cellY, col, row, cache);

                        color.a() = 255;

                        (*colours)[static_cast<unsigned int>(vertX*numVerts + vertY)] = color;

                        ++vertX;
                    }
                    ++vertY;
                }
                vertX_ = vertX;
            }
            vertY_ = vertY;

            assert(vertX_ == numVerts); // Ensure we covered whole area
        }
        assert(vertY_ == numVerts);  // Ensure we covered whole area
    }

    Storage::UniqueTextureId Storage::getVtexIndexAt(int cellX, int cellY,
                                           int x, int y, LandCache& cache)
    {
        // For the first/last row/column, we need to get the texture from the neighbour cell
        // to get consistent blending at the borders
        --x;
        if (x < 0)
        {
            --cellX;
            x += ESM::Land::LAND_TEXTURE_SIZE;
        }
        while (x >= ESM::Land::LAND_TEXTURE_SIZE)
        {
            ++cellX;
            x -= ESM::Land::LAND_TEXTURE_SIZE;
        }
        while (y >= ESM::Land::LAND_TEXTURE_SIZE) // Y appears to be wrapped from the other side because why the hell not?
        {
            ++cellY;
            y -= ESM::Land::LAND_TEXTURE_SIZE;
        }

        assert(x<ESM::Land::LAND_TEXTURE_SIZE);
        assert(y<ESM::Land::LAND_TEXTURE_SIZE);

        const LandObject* land = getLand(cellX, cellY, cache);

        const ESM::Land::LandData *data = land ? land->getData(ESM::Land::DATA_VTEX) : nullptr;
        if (data)
        {
            int tex = data->mTextures[y * ESM::Land::LAND_TEXTURE_SIZE + x];
            if (tex == 0)
                return std::make_pair(0,0); // vtex 0 is always the base texture, regardless of plugin
            return std::make_pair(tex, land->getPlugin());
        }
        return std::make_pair(0,0);
    }

    std::string Storage::getTextureName(UniqueTextureId id)
    {
        static constexpr char defaultTexture[] = "textures\\_land_default.dds";
        if (id.first == 0)
            return defaultTexture; // Not sure if the default texture really is hardcoded?

        // NB: All vtex ids are +1 compared to the ltex ids
        const ESM::LandTexture* ltex = getLandTexture(id.first-1, id.second);
        if (!ltex)
        {
            Log(Debug::Warning) << "Warning: Unable to find land texture index " << id.first-1 << " in plugin " << id.second << ", using default texture instead";
            return defaultTexture;
        }

        // this is needed due to MWs messed up texture handling
        std::string texture = Misc::ResourceHelpers::correctTexturePath(ltex->mTexture, mVFS);

        return texture;
    }

    void Storage::getBlendmaps(float chunkSize, const osg::Vec2f &chunkCenter, ImageVector &blendmaps, std::vector<Terrain::LayerInfo> &layerList)
    {
        osg::Vec2f origin = chunkCenter - osg::Vec2f(chunkSize/2.f, chunkSize/2.f);
        int cellX = static_cast<int>(std::floor(origin.x()));
        int cellY = static_cast<int>(std::floor(origin.y()));

        int realTextureSize = ESM::Land::LAND_TEXTURE_SIZE+1; // add 1 to wrap around next cell

        int rowStart = (origin.x() - cellX) * realTextureSize;
        int colStart = (origin.y() - cellY) * realTextureSize;

        const int blendmapSize = (realTextureSize-1) * chunkSize + 1;
        // We need to upscale the blendmap 2x with nearest neighbor sampling to look like Vanilla
        const int imageScaleFactor = 2;
        const int blendmapImageSize = blendmapSize * imageScaleFactor;

        LandCache cache;
        std::map<UniqueTextureId, unsigned int> textureIndicesMap;

        for (int y=0; y<blendmapSize; y++)
        {
            for (int x=0; x<blendmapSize; x++)
            {
                UniqueTextureId id = getVtexIndexAt(cellX, cellY, x+rowStart, y+colStart, cache);
                std::map<UniqueTextureId, unsigned int>::iterator found = textureIndicesMap.find(id);
                if (found == textureIndicesMap.end())
                {
                    unsigned int layerIndex = layerList.size();
                    Terrain::LayerInfo info = getLayerInfo(getTextureName(id));

                    // look for existing diffuse map, which may be present when several plugins use the same texture
                    for (unsigned int i=0; i<layerList.size(); ++i)
                    {
                        if (layerList[i].mDiffuseMap == info.mDiffuseMap)
                        {
                            layerIndex = i;
                            break;
                        }
                    }

                    found = textureIndicesMap.emplace(id, layerIndex).first;

                    if (layerIndex >= layerList.size())
                    {
                        osg::ref_ptr<osg::Image> image (new osg::Image);
                        image->allocateImage(blendmapImageSize, blendmapImageSize, 1, GL_ALPHA, GL_UNSIGNED_BYTE);
                        unsigned char* pData = image->data();
                        memset(pData, 0, image->getTotalDataSize());
                        blendmaps.emplace_back(image);
                        layerList.emplace_back(info);
                    }
                }
                unsigned int layerIndex = found->second;
                unsigned char* pData = blendmaps[layerIndex]->data();
                int realY = (blendmapSize - y - 1)*imageScaleFactor;
                int realX = x*imageScaleFactor;
                pData[((realY+0)*blendmapImageSize + realX + 0)] = 255;
                pData[((realY+1)*blendmapImageSize + realX + 0)] = 255;
                pData[((realY+0)*blendmapImageSize + realX + 1)] = 255;
                pData[((realY+1)*blendmapImageSize + realX + 1)] = 255;
            }
        }

        if (blendmaps.size() == 1)
            blendmaps.clear(); // If a single texture fills the whole terrain, there is no need to blend
    }

    float Storage::getHeightAt(const osg::Vec3f &worldPos)
    {
        int cellX = static_cast<int>(std::floor(worldPos.x() / float(Constants::CellSizeInUnits)));
        int cellY = static_cast<int>(std::floor(worldPos.y() / float(Constants::CellSizeInUnits)));

        osg::ref_ptr<const LandObject> land = getLand(cellX, cellY);
        if (!land)
            return defaultHeight;

        const ESM::Land::LandData* data = land->getData(ESM::Land::DATA_VHGT);
        if (!data)
            return defaultHeight;

        // Mostly lifted from Ogre::Terrain::getHeightAtTerrainPosition

        // Normalized position in the cell
        float nX = (worldPos.x() - (cellX * Constants::CellSizeInUnits)) / float(Constants::CellSizeInUnits);
        float nY = (worldPos.y() - (cellY * Constants::CellSizeInUnits)) / float(Constants::CellSizeInUnits);

        // get left / bottom points (rounded down)
        float factor = ESM::Land::LAND_SIZE - 1.0f;
        float invFactor = 1.0f / factor;

        int startX = static_cast<int>(nX * factor);
        int startY = static_cast<int>(nY * factor);
        int endX = startX + 1;
        int endY = startY + 1;

        endX = std::min(endX, ESM::Land::LAND_SIZE-1);
        endY = std::min(endY, ESM::Land::LAND_SIZE-1);

        // now get points in terrain space (effectively rounding them to boundaries)
        float startXTS = startX * invFactor;
        float startYTS = startY * invFactor;
        float endXTS = endX * invFactor;
        float endYTS = endY * invFactor;

        // get parametric from start coord to next point
        float xParam = (nX - startXTS) * factor;
        float yParam = (nY - startYTS) * factor;

        /* For even / odd tri strip rows, triangles are this shape:
        even     odd
        3---2   3---2
        | / |   | \ |
        0---1   0---1
        */

        // Build all 4 positions in normalized cell space, using point-sampled height
        osg::Vec3f v0 (startXTS, startYTS, getVertexHeight(data, startX, startY) / float(Constants::CellSizeInUnits));
        osg::Vec3f v1 (endXTS, startYTS, getVertexHeight(data, endX, startY) / float(Constants::CellSizeInUnits));
        osg::Vec3f v2 (endXTS, endYTS, getVertexHeight(data, endX, endY) / float(Constants::CellSizeInUnits));
        osg::Vec3f v3 (startXTS, endYTS, getVertexHeight(data, startX, endY) / float(Constants::CellSizeInUnits));
        // define this plane in terrain space
        osg::Plane plane;
        // FIXME: deal with differing triangle alignment
        if (true)
        {
            // odd row
            bool secondTri = ((1.0 - yParam) > xParam);
            if (secondTri)
                plane = osg::Plane(v0, v1, v3);
            else
                plane = osg::Plane(v1, v2, v3);
        }
        /*
        else
        {
            // even row
            bool secondTri = (yParam > xParam);
            if (secondTri)
                plane.redefine(v0, v2, v3);
            else
                plane.redefine(v0, v1, v2);
        }
        */

        // Solve plane equation for z
        return (-plane.getNormal().x() * nX
                -plane.getNormal().y() * nY
                - plane[3]) / plane.getNormal().z() * Constants::CellSizeInUnits;

    }

    const LandObject* Storage::getLand(int cellX, int cellY, LandCache& cache)
    {
        LandCache::Map::iterator found = cache.mMap.find(std::make_pair(cellX, cellY));
        if (found != cache.mMap.end())
            return found->second;
        else
        {
            found = cache.mMap.insert(std::make_pair(std::make_pair(cellX, cellY), getLand(cellX, cellY))).first;
            return found->second;
        }
    }

    void Storage::adjustColor(int col, int row, const ESM::Land::LandData *heightData, osg::Vec4ub& color) const
    {
    }

    float Storage::getAlteredHeight(int col, int row) const
    {
        return 0;
    }

    Terrain::LayerInfo Storage::getLayerInfo(const std::string& texture)
    {
        std::lock_guard<std::mutex> lock(mLayerInfoMutex);

        // Already have this cached?
        std::map<std::string, Terrain::LayerInfo>::iterator found = mLayerInfoMap.find(texture);
        if (found != mLayerInfoMap.end())
            return found->second;

        Terrain::LayerInfo info;
        info.mParallax = false;
        info.mSpecular = false;
        info.mDiffuseMap = texture;

        if (mAutoUseNormalMaps)
        {
            std::string texture_ = texture;
            Misc::StringUtils::replaceLast(texture_, ".", mNormalHeightMapPattern + ".");
            if (mVFS->exists(texture_))
            {
                info.mNormalMap = texture_;
                info.mParallax = true;
            }
            else
            {
                texture_ = texture;
                Misc::StringUtils::replaceLast(texture_, ".", mNormalMapPattern + ".");
                if (mVFS->exists(texture_))
                    info.mNormalMap = texture_;
            }
        }

        if (mAutoUseSpecularMaps)
        {
            std::string texture_ = texture;
            Misc::StringUtils::replaceLast(texture_, ".", mSpecularMapPattern + ".");
            if (mVFS->exists(texture_))
            {
                info.mDiffuseMap = texture_;
                info.mSpecular = true;
            }
        }

        mLayerInfoMap[texture] = info;

        return info;
    }

    float Storage::getCellWorldSize()
    {
        return static_cast<float>(ESM::Land::REAL_SIZE);
    }

    int Storage::getCellVertices()
    {
        return ESM::Land::LAND_SIZE;
    }

    int Storage::getBlendmapScale(float chunkSize)
    {
        return ESM::Land::LAND_TEXTURE_SIZE*chunkSize;
    }

}
