#include "texturemanager.h"
#include "texture.h"
#include "singleton.h"
#include "gltextureformattraits.h"

#include "opengljobprocessor.h"

#define ENABLE_TEXTURE_POOL

namespace {
    /// private class to format iostream to use points as a thousands separator
    class PointSeparator : public std::numpunct<char>
    {
    public:
        PointSeparator(std::size_t refs) : std::numpunct<char>(refs) {}
    protected:
        char do_thousands_sep() const { return '.'; }
        std::string do_grouping() const { return "\03"; }
    };
}

const std::string cgt::TextureManager::loggerCat_("cgt.TextureManager");

cgt::TextureManager::TextureManager()
    : RunnableWithConditionalWait("Texture Manager")
    , activeAllocatedMemory_(0)
    , texturePoolMemory_(0)
{
#ifdef ENABLE_TEXTURE_POOL
    // start the garbage collection thread
    start();
#endif ENABLE_TEXTURE_POOl
}

cgt::TextureManager::~TextureManager()
{
#ifdef ENABLE_TEXTURE_POOL
    // stop the GC thread and clear the pool
    stop();
    forceClearPool();
#endif ENABLE_TEXTURE_POOL

    cgtAssert(texturePool_.empty(), "Texture pool not empty at the end of texture manager's life!");
    cgtAssert(activeAllocatedMemory_ == 0, "There are still Textures in use after the Texture Manager is destroyed! This most likely means you are leaking cgt::Texture instances!");
}

void cgt::TextureManager::clearPool()
{
    std::stringstream dbgOut;
    dbgOut.imbue(std::locale(std::cout.getloc(), new PointSeparator(1)));

    dbgOut << texturePoolMemory_ << " Bytes of in texture pool, additionally " << activeAllocatedMemory_ << " Bytes still in use.";
    LDEBUG(dbgOut.str());
    LDEBUG("releasing texture pool with " << texturePool_.size() << " textures...");
    size_t totalBytes = 0;

    std::stringstream ss;
    for (auto& it : texturePool_)
    {
        auto tft = GLTextureFormatTraits::get(it.first.internalFormat);
        cgt::svec3 size(it.first.size_x, it.first.size_y, it.first.size_z);
        GLenum textureType = it.first.type;
        ss << "\t * [" << size.x << "," << size.y << "," << size.z
            << "] " << textureTypeToStr(textureType) << " " << tft.internalFormatName() << std::endl;

        glDeleteTextures(1, &it.second.first);

        totalBytes += textureByteSize(it.first);
        texturePoolMemory_ -= textureByteSize(it.first);
    }
    texturePool_.clear();

    std::stringstream ss3;
    ss3 << "Released " << totalBytes << " Bytes of texture data:" << std::endl << ss.str();
    LDEBUG(ss3.str());
}

void cgt::TextureManager::performGarbageCollection()
{
    std::stringstream dbgOut;
    dbgOut.imbue(std::locale(std::cout.getloc(), new PointSeparator(1)));

    dbgOut << texturePoolMemory_ << " Bytes of in texture pool, additionally " << activeAllocatedMemory_ << " Bytes still in use." << std::endl;
    size_t releasedBytes = 0;

    std::stringstream ss;
    std::vector<GLuint> idsToRelease;
    for (auto it = texturePool_.begin(); it != texturePool_.end(); )
    {
        auto tft = GLTextureFormatTraits::get(it->first.internalFormat);
        cgt::svec3 size(it->first.size_x, it->first.size_y, it->first.size_z);
        GLenum textureType = it->first.type;

        // Check if pool entry has expired
        if (++(it->second.second) >= garbageLifetime) {
            ss << "\t * [" << size.x << "," << size.y << "," << size.z
                << "] " << textureTypeToStr(textureType) << " " << tft.internalFormatName() << std::endl;

            releasedBytes += textureByteSize(it->first);
            texturePoolMemory_ -= textureByteSize(it->first);

            idsToRelease.push_back(it->second.first);
            it = texturePool_.erase(it);
        }
        else
            ++it;
    }

    if (!idsToRelease.empty()) {
        dbgOut << "Released " << releasedBytes << " Bytes of texture data:" << std::endl << ss.str();
        std::string debugMessage = dbgOut.str();
        GLJobProc.enqueueJob([=] {
            glDeleteTextures(static_cast<GLsizei>(idsToRelease.size()), idsToRelease.data());
            LDEBUG(debugMessage);
        });
    }
}

void cgt::TextureManager::forceGarbageCollection()
{
#ifdef ENABLE_TEXTURE_POOL
    std::lock_guard<std::mutex> scope_lock(accessMutex_);

    performGarbageCollection();
#endif ENABLE_TEXTURE_POOL
}

void cgt::TextureManager::forceClearPool()
{
#ifdef ENABLE_TEXTURE_POOL
    std::lock_guard<std::mutex> scope_lock(accessMutex_);

    clearPool();
#endif ENABLE_TEXTURE_POOL
}

GLuint cgt::TextureManager::generateId(GLenum type, const cgt::svec3 & dimensions, GLenum internalFormat)
{
    cache_key_t cacheKey{ type, dimensions.x, dimensions.y, dimensions.z, internalFormat };

    cgtAssert(cgt::hmul(dimensions) > 0, "At least one dimension is zero!");
    cgtAssert(type != GL_TEXTURE_1D || (dimensions.y == 1 && dimensions.z == 1), "1D texture but higher dimensions are not 1!");
    cgtAssert(type != GL_TEXTURE_2D || dimensions.z == 1, "2D texture but z is not 1!");

#ifdef ENABLE_TEXTURE_POOL
    std::lock_guard<std::mutex> scope_lock(accessMutex_);

    GLuint id;
    auto it = texturePool_.find(cacheKey);
    if (it != texturePool_.end()) {
        id = it->second.first;
        texturePool_.erase(it);

        activeAllocatedMemory_ += textureByteSize(cacheKey);
        texturePoolMemory_ -= textureByteSize(cacheKey);
    }
    else {
        glGenTextures(1, &id);

        glBindTexture(type, id);

        switch (type) {
        case GL_TEXTURE_1D:
            glTexImage1D(type, 0, internalFormat, static_cast<GLsizei>(dimensions.x), 0,
                Texture::calcMatchingPixelFormat(internalFormat), Texture::calcMatchingPixelDataType(internalFormat), nullptr);
            break;

        case GL_TEXTURE_1D_ARRAY: // fallthrough
        case GL_TEXTURE_2D:
            glTexImage2D(type, 0, internalFormat, static_cast<GLsizei>(dimensions.x), static_cast<GLsizei>(dimensions.y), 0,
                Texture::calcMatchingPixelFormat(internalFormat), Texture::calcMatchingPixelDataType(internalFormat), nullptr);
            break;

        case GL_TEXTURE_2D_ARRAY: // fallthrough
        case GL_TEXTURE_3D:
            glTexImage3D(type, 0, internalFormat, static_cast<GLsizei>(dimensions.x), static_cast<GLsizei>(dimensions.y), static_cast<GLsizei>(dimensions.z), 0,
                Texture::calcMatchingPixelFormat(internalFormat), Texture::calcMatchingPixelDataType(internalFormat), nullptr);
            break;
        }
        LGL_ERROR;

        activeAllocatedMemory_ += textureByteSize(cacheKey);
    }
#else
    GLuint id;
    glGenTextures(1, &id);

    glBindTexture(type, id);

    switch (type) {
    case GL_TEXTURE_1D:
        glTexImage1D(type, 0, internalFormat, static_cast<GLsizei>(dimensions.x), 0,
            Texture::calcMatchingPixelFormat(internalFormat), Texture::calcMatchingPixelDataType(internalFormat), nullptr);
        break;

    case GL_TEXTURE_1D_ARRAY: // fallthrough
    case GL_TEXTURE_2D:
        glTexImage2D(type, 0, internalFormat, static_cast<GLsizei>(dimensions.x), static_cast<GLsizei>(dimensions.y), 0,
            Texture::calcMatchingPixelFormat(internalFormat), Texture::calcMatchingPixelDataType(internalFormat), nullptr);
        break;

    case GL_TEXTURE_2D_ARRAY: // fallthrough
    case GL_TEXTURE_3D:
        glTexImage3D(type, 0, internalFormat, static_cast<GLsizei>(dimensions.x), static_cast<GLsizei>(dimensions.y), static_cast<GLsizei>(dimensions.z), 0,
            Texture::calcMatchingPixelFormat(internalFormat), Texture::calcMatchingPixelDataType(internalFormat), nullptr);
        break;
    }
    LGL_ERROR;

    activeAllocatedMemory_ += textureByteSize(cacheKey);

#endif
    return id;
}

void cgt::TextureManager::releaseId(GLuint id, GLenum type, const cgt::svec3 & dimensions, GLenum internalFormat)
{
    cache_key_t cacheKey{ type, dimensions.x, dimensions.y, dimensions.z, internalFormat };
#ifdef ENABLE_TEXTURE_POOL
    std::lock_guard<std::mutex> scope_lock(accessMutex_);
    texturePool_.insert(std::make_pair(cacheKey, std::make_pair(id, 0)));
    activeAllocatedMemory_ -= textureByteSize(cacheKey);
    texturePoolMemory_ += textureByteSize(cacheKey);
#else
    glDeleteTextures(1, &id);
    activeAllocatedMemory_ -= textureByteSize(cacheKey);
#endif
}

void cgt::TextureManager::run()
{
    std::unique_lock<std::mutex> scope_lock(accessMutex_);

    while (!_stopExecution) {
        _evaluationCondition.wait_for(scope_lock, std::chrono::milliseconds(garbageCollectionDelayMs));

        // could have changed in the meantime
        if(!_stopExecution)
            performGarbageCollection();
    }
}

size_t cgt::TextureManager::textureByteSize(const cache_key_t & key)
{
     return key.size_x * key.size_y * key.size_z * GLTextureFormatTraits::get(key.internalFormat).bpp();
}

std::string cgt::TextureManager::textureTypeToStr(GLenum tt)
{
    switch (tt) {
    case GL_TEXTURE_1D:
        return "GL_TEXTURE_1D";
    case GL_TEXTURE_1D_ARRAY:
        return "GL_TEXTURE_1D_ARRAY";
    case GL_TEXTURE_2D:
        return "GL_TEXTURE_2D";
    case GL_TEXTURE_2D_ARRAY:
        return "GL_TEXTURE_2D_ARRAY";
    case GL_TEXTURE_3D:
        return "GL_TEXTURE_3D";
    default:
        return "Unknown";
    }
}