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#pragma once

#include "input.h" 
#include "output.h" 

#include <util/system/pipe.h>
#include <util/generic/ptr.h>
#include <util/generic/string.h>

/** 
 * @addtogroup Streams_Pipes 
 * @{ 
 */ 
 
/** 
 * Base class for starting a process and communicating with it via pipes. 
 */ 
class TPipeBase {
protected:
    /** 
     * Starts a new process and opens a pipe. 
     * 
     * @param command                   Command line to start a process with. 
     * @param mode                      Data transfer mode for the pipe. Use 
     *                                  "r" for reading and "w" for writing. 
     */ 
    TPipeBase(const TString& command, const char* mode);
    virtual ~TPipeBase();

protected:
    class TImpl;
    THolder<TImpl> Impl_;
};

/** 
 * Input stream that binds to a standard output stream of a newly started process. 
 * 
 * Note that if the process ends with non-zero exit status, `Read` function will 
 * throw an exception. 
 */ 
class TPipeInput: protected TPipeBase, public IInputStream {
public:
    /** 
     * Starts a new process and opens a pipe. 
     * 
     * @param command                   Command line to start a process with. 
     */ 
    TPipeInput(const TString& command);

private:
    size_t DoRead(void* buf, size_t len) override;
};

/** 
 * Output stream that binds to a standard input stream of a newly started process. 
 * 
 * Note that if the process ends with non-zero exit status, `Close` function will 
 * throw an exception. 
 */ 
class TPipeOutput: protected TPipeBase, public IOutputStream {
public:
    /** 
     * Starts a new process and opens a pipe. 
     * 
     * @param command                   Command line to start a process with. 
     */ 
    TPipeOutput(const TString& command);
 
    /** 
     * Waits for the process to terminate and throws an exception if it ended 
     * with a non-zero exit status. 
     */ 
    void Close();

private:
    void DoWrite(const void* buf, size_t len) override;
};

class TPipedBase {
protected:
    TPipedBase(PIPEHANDLE fd);
    virtual ~TPipedBase();

protected:
    TPipeHandle Handle_;
};

/** 
 * Input stream that binds to a standard output stream of an existing process. 
 */ 
class TPipedInput: public TPipedBase, public IInputStream {
public:
    TPipedInput(PIPEHANDLE fd);
    ~TPipedInput() override;

private:
    size_t DoRead(void* buf, size_t len) override;
};

/** 
 * Output stream that binds to a standard input stream of an existing process. 
 */ 
class TPipedOutput: public TPipedBase, public IOutputStream {
public:
    TPipedOutput(PIPEHANDLE fd);
    ~TPipedOutput() override;

private:
    void DoWrite(const void* buf, size_t len) override;
};

/** @} */