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#pragma once

#include "zerocopy.h" 
#include "zerocopy_output.h"

#include <util/generic/ptr.h>

class TBuffer;
 
/** 
 * @addtogroup Streams_Buffers 
 * @{ 
 */ 
 
/** 
 * Output stream that writes into a `TBuffer`. 
 */ 
class TBufferOutput: public IZeroCopyOutput {
public:
    class TImpl;

    /** 
     * Constructs a stream that writes into an internal buffer. 
     * 
     * @param buflen                    Initial size of the internal buffer. 
     */
    TBufferOutput(size_t buflen = 1024);

    /** 
     * Constructs a stream that writes into the provided buffer. It's up to the 
     * user to make sure that the buffer doesn't get destroyed while this stream 
     * is in use. 
     * 
     * @param buffer                    Buffer to write into. 
     */
    TBufferOutput(TBuffer& buffer);

    TBufferOutput(TBufferOutput&&) noexcept; 
    TBufferOutput& operator=(TBufferOutput&&) noexcept; 

    ~TBufferOutput() override;

    /** 
     * @returns                         Buffer that this stream writes into. 
     */ 
    TBuffer& Buffer() const noexcept;

private:
    size_t DoNext(void** ptr) override;
    void DoUndo(size_t len) override;
    void DoWrite(const void* buf, size_t len) override;
    void DoWriteC(char c) override;

private:
    THolder<TImpl> Impl_;
};

/** 
 * Input stream that reads from an external `TBuffer`. 
 */ 
class TBufferInput: public IZeroCopyInputFastReadTo {
public:
    /** 
     * Constructs a stream that reads from an external buffer. It's up to the 
     * user to make sure that the buffer doesn't get destroyed before this 
     * stream. 
     * 
     * @param buffer                    External buffer to read from. 
     */ 
    TBufferInput(const TBuffer& buffer); 

    ~TBufferInput() override;

    const TBuffer& Buffer() const noexcept;
 
    void Rewind() noexcept;

protected: 
    size_t DoNext(const void** ptr, size_t len) override;
    void DoUndo(size_t len) override;
 
private:
    const TBuffer& Buf_;
    size_t Readed_;
};

/** 
 * Input/output stream that works with a `TBuffer`. 
 */ 
class TBufferStream: public TBufferOutput, public TBufferInput {
public:
    /** 
     * Constructs a stream that works with an internal buffer. 
     * 
     * @param buflen                    Initial size of the internal buffer. 
     */ 
    inline TBufferStream(size_t buflen = 1024)
        : TBufferOutput(buflen)
        , TBufferInput(TBufferOutput::Buffer()) 
    {
    }

    /** 
     * Constructs a stream that works with the provided buffer. 
     * 
     * @param buffer                    Buffer to work with. 
     */ 
    inline TBufferStream(TBuffer& buffer)
        : TBufferOutput(buffer)
        , TBufferInput(TBufferOutput::Buffer()) 
    {
    }

    ~TBufferStream() override = default;
 
    using TBufferOutput::Buffer; 
};

/** @} */