#pragma once

// External
#include <mutex>
#include <string>

// Internal
#include "BufferedFrame2D.hpp"
#include "DEN/DenFileInfo.hpp"
#include "Frame2DI.hpp"
#include "Frame2DReaderI.hpp"

namespace CTL {
namespace io {
    /**
     * Implementation of the ProjectionReader for projections and projection matrices stored in the
     * den files.
     */
    template <typename T>
    class DenFrame2DReader : virtual public Frame2DReaderI<T>
    // Frame2DReaderI<T> will be only once in the family tree
    {

    public:
        /**Constructs DenFrame2DReader from file name.
         *
         *
         * @param denFile
         * @param denFile File in a DEN format to read by frames.
         * @param additionalBufferNum Number of additional buffers to allocate. Defaults to 0 for 1
         * default buffer.
         */
        DenFrame2DReader(std::string denFile, uint32_t additionalBufferNum = 0);
        /// Destructor
        ~DenFrame2DReader();
        /// Copy constructor
        DenFrame2DReader(const DenFrame2DReader<T>& b);
        // Copy assignment with copy and swap
        DenFrame2DReader<T>& operator=(DenFrame2DReader<T> b);
        static void swap(DenFrame2DReader<T>& a, DenFrame2DReader<T>& b);
        // Move constructor
        DenFrame2DReader(DenFrame2DReader<T>&& b);
        // Move assignment
        DenFrame2DReader<T>& operator=(DenFrame2DReader<T>&& other);
        std::shared_ptr<io::Frame2DI<T>> readFrame(unsigned int i) override;
        std::shared_ptr<io::BufferedFrame2D<T>> readBufferedFrame(unsigned int i);
        void readFrameIntoBuffer(unsigned int frameID, T* outside_buffer);
        uint32_t dimx() const override;
        uint32_t dimy() const override;
        uint32_t dimz() const override;
        std::string getFileName() const;
        /**Returns file name of the underlying DEN file.**/
	protected:
        std::string denFile;
        uint64_t offset;
        // protected: // Visible in inheritance structure
        uint32_t sizex, sizey, sizez;
        DenSupportedType dataType;
        int elementByteSize;
    private:
        mutable std::mutex* consistencyMutexes;
        uint8_t** buffers;
        T** buffer_copys;
        uint32_t additionalBufferNum;
    };

    template <typename T>
    DenFrame2DReader<T>::DenFrame2DReader(std::string denFile, uint32_t additionalBufferNum)
        : denFile(denFile)
        , additionalBufferNum(additionalBufferNum)
    {
        DenFileInfo pi = DenFileInfo(this->denFile);
        this->offset = pi.getOffset();
        this->sizex = pi.dimx();
        this->sizey = pi.dimy();
        this->sizez = pi.dimz();
        this->dataType = pi.getDataType();
        this->elementByteSize = pi.elementByteSize();
        this->consistencyMutexes = new std::mutex[1 + additionalBufferNum];
        this->buffers = new uint8_t*[1 + additionalBufferNum];
        this->buffer_copys = new T*[1 + additionalBufferNum];
        for(uint32_t i = 0; i != 1 + additionalBufferNum; i++)
        {
            this->buffers[i] = new uint8_t[elementByteSize * sizex * sizey];
            this->buffer_copys[i] = new T[sizex * sizey];
        }
        // Buffers are used for the alocation of new frames. Since this class uses the instance that
        // copies memory, this memory might me reused.
    }

    // This mumbo jumbo is for correctly deleting object after move assignment operation was
    // performed to be able to delete such object with stealed internals where its buffers are
    // nullptr.
    template <typename T>
    DenFrame2DReader<T>::~DenFrame2DReader()
    {
        if(consistencyMutexes != nullptr)
        {
            delete[] consistencyMutexes;
        }
        consistencyMutexes = nullptr;
        if(buffers != nullptr)
        {
            for(uint32_t i = 0; i != 1 + additionalBufferNum; i++)
            {
                if(buffers[i] != nullptr)
                {
                    delete buffers[i];
                }
                buffers[i] = nullptr;
            }
            delete[] buffers;
        }
        buffers = nullptr;
        if(buffer_copys != nullptr)
        {
            for(uint32_t i = 0; i != 1 + additionalBufferNum; i++)
            {
                if(buffer_copys[i] != nullptr)
                {
                    delete buffer_copys[i];
                }
                buffer_copys[i] = nullptr;
            }
            delete[] buffer_copys;
        }
        buffer_copys = nullptr;
    }

    /**Copy constructor of DenFrame2DReader from another element.
     *Basically contructs everything from scratch by probing file on the disk.
     */
    template <typename T>
    DenFrame2DReader<T>::DenFrame2DReader(const DenFrame2DReader<T>& b)
        : DenFrame2DReader<T>::DenFrame2DReader(b.denFile, b.additionalBufferNum)
    {
    }

    template <typename T>
    void DenFrame2DReader<T>::swap(DenFrame2DReader<T>& a, DenFrame2DReader<T>& b)
    {
        std::swap(a.denFile, b.denFile);
        std::swap(a.offset, b.offset);
        std::swap(a.sizex, b.sizex);
        std::swap(a.sizey, b.sizey);
        std::swap(a.sizez, b.sizez);
        std::swap(a.dataType, b.dataType);
        std::swap(a.elementByteSize, b.elementByteSize);
        std::swap(a.additionalBufferNum, b.additionalBufferNum);
        // It will probably work just to swap pointers to the starts of respective arrays
        std::swap(a.buffers, b.buffers);
        std::swap(a.buffer_copys, b.buffer_coppys);
        std::swap(a.consistencyMutexes, b.consistencyMutexes);
    }

    /**Copy assignment
     *
     */
    template <typename T>
    DenFrame2DReader<T>& DenFrame2DReader<T>::operator=(DenFrame2DReader<T> b)
    {
        swap(*this, b);
        return *this;
    }

    template <typename T>
    DenFrame2DReader<T>::DenFrame2DReader(DenFrame2DReader<T>&& b)
    {
        this->denFile = b.denFile;
        this->offset = b.offset;
        this->sizex = b.sizex;
        this->sizey = b.sizey;
        this->sizez = b.sizez;
        this->dataType = b.dataType;
        this->elementByteSize = b.elementByteSize;
        this->additionalBufferNum = b.additionalBufferNum;
        this->consistencyMutexes = std::exchange(b.consistencyMutexes, nullptr);
        this->buffers = std::exchange(b.buffers, nullptr);
        this->buffer_copys = std::exchange(b.buffer_copys, nullptr);
    } // Move constructor to steal resources from another object

    template <typename T>
    DenFrame2DReader<T>& DenFrame2DReader<T>::operator=(DenFrame2DReader<T>&& b)
    {
        if(&b != this) // To elegantly solve situation when assigning to itself
        {
            this->denFile = b.denFile;
            this->offset = b.offset;
            this->sizex = b.sizex;
            this->sizey = b.sizey;
            this->sizez = b.sizez;
            this->dataType = b.dataType;
            this->elementByteSize = b.elementByteSize;
            this->additionalBufferNum = b.additionalBufferNum;
            if(consistencyMutexes != nullptr)
            {
                delete[] consistencyMutexes;
            }
            consistencyMutexes = nullptr;
            if(buffers != nullptr)
            {
                for(uint32_t i = 0; i != 1 + additionalBufferNum; i++)
                {
                    if(buffers[i] != nullptr)
                    {
                        delete buffers[i];
                    }
                    buffers[i] = nullptr;
                }
                delete[] buffers;
            }
            buffers = nullptr;
            if(buffer_copys != nullptr)
            {
                for(uint32_t i = 0; i != 1 + additionalBufferNum; i++)
                {
                    if(buffer_copys[i] != nullptr)
                    {
                        delete buffer_copys[i];
                    }
                    buffer_copys[i] = nullptr;
                }
                delete[] buffer_copys;
            }
            buffer_copys = nullptr;
            this->consistencyMutexes = std::exchange(b.consistencyMutexes, nullptr);
            this->buffers = std::exchange(b.buffers, nullptr);
            this->buffer_copys = std::exchange(b.buffer_copys, nullptr);
        }
        return *this;
    } // Move assignment

    template <typename T>
    std::string DenFrame2DReader<T>::getFileName() const
    {
        return this->denFile;
    }

    template <typename T>
    uint32_t DenFrame2DReader<T>::dimx() const
    {
        return sizex;
    }

    template <typename T>
    uint32_t DenFrame2DReader<T>::dimy() const
    {
        return sizey;
    }

    template <typename T>
    uint32_t DenFrame2DReader<T>::dimz() const
    {
        return sizez;
    }

    template <typename T>
    std::shared_ptr<io::Frame2DI<T>> DenFrame2DReader<T>::readFrame(unsigned int sliceNum)
    {
        std::shared_ptr<Frame2DI<T>> ps = readBufferedFrame(sliceNum);
        return ps;
    }

    template <typename T>
    std::shared_ptr<io::BufferedFrame2D<T>>
    DenFrame2DReader<T>::readBufferedFrame(unsigned int sliceNum)
    {
        std::unique_lock<std::mutex> l;
        bool locked = false;
        uint32_t mutexnum = 0;
        for(uint32_t i = 0; i != 1 + additionalBufferNum; i++)
        {
            l = std::unique_lock<std::mutex>(consistencyMutexes[i], std::try_to_lock);
            if(l.owns_lock())
            {
                locked = true;
                mutexnum = i;
                break;
            }
        }
        if(!locked)
        {
            l = std::unique_lock<std::mutex>(consistencyMutexes[0]);
            mutexnum = 0;
        }
        // Mutex will be released as this goes out of scope.
        // To protect calling this method from another thread using the same block of memory
        uint8_t* buffer = buffers[mutexnum];
        T* buffer_copy = buffer_copys[mutexnum];
        uint32_t elmCount = sizex * sizey;
        uint64_t position = this->offset + uint64_t(sliceNum) * elementByteSize * elmCount;
        io::readBytesFrom(this->denFile, position, buffer, elementByteSize * elmCount);
        for(uint32_t a = 0; a != elmCount; a++)
        {
            buffer_copy[a] = util::getNextElement<T>(&buffer[a * elementByteSize], dataType);
        }
        std::shared_ptr<BufferedFrame2D<T>> ps
            = std::make_shared<BufferedFrame2D<T>>(buffer_copy, sizex, sizey);
        return ps;
    }

    template <typename T>
    void DenFrame2DReader<T>::readFrameIntoBuffer(unsigned int frameID, T* outside_buffer)
    {
        std::unique_lock<std::mutex> l;
        bool locked = false;
        uint32_t mutexnum = 0;
        for(uint32_t i = 0; i != 1 + additionalBufferNum; i++)
        {
            l = std::unique_lock<std::mutex>(consistencyMutexes[i], std::try_to_lock);
            if(l.owns_lock())
            {
                locked = true;
                mutexnum = i;
                break;
            }
        }
        if(!locked)
        {
            l = std::unique_lock<std::mutex>(consistencyMutexes[0]);
            mutexnum = 0;
        }
        // Mutex will be released as this goes out of scope.
        // To protect calling this method from another thread using the same block of memory
        uint8_t* buffer = buffers[mutexnum];
        uint32_t elmCount = sizex * sizey;
        uint64_t position = this->offset + uint64_t(frameID) * elementByteSize * elmCount;
        io::readBytesFrom(this->denFile, position, buffer, elementByteSize * elmCount);
        for(uint32_t a = 0; a != elmCount; a++)
        {
            outside_buffer[a] = util::getNextElement<T>(&buffer[a * elementByteSize], dataType);
        }
    }
} // namespace io
} // namespace CTL