#ifndef IOUTILITIES_COPY_H
#define IOUTILITIES_COPY_H

#include "../application/global.h"

#include <iostream>
#include <functional>

namespace IoUtilities {

/*!
 * \class IoUtilities::CopyHelper
 * \brief The copy helper class helps to copy bytes from one stream to another.
 * \tparam Specifies the buffer size.
 */
template<std::size_t bufferSize>
class LIB_EXPORT CopyHelper
{
public:
    CopyHelper();
    void copy(std::istream &input, std::ostream &output, std::size_t count);
    void callbackCopy(std::istream &input, std::ostream &output, std::size_t count, const std::function<bool (void)> &isAborted, const std::function<void (double)> &callback);
    char *buffer();
private:
    char m_buffer[bufferSize];
};

/*!
 * \brief Constructs a new copy helper.
 */
template<std::size_t bufferSize>
CopyHelper<bufferSize>::CopyHelper()
{}

/*!
 * \brief Copies \a count bytes from \a input to \a output.
 * \remarks Set an exception mask using std::ios::exceptions() to get
 *          a std::ios_base::failure exception when an IO error occurs.
 */
template<std::size_t bufferSize>
void CopyHelper<bufferSize>::copy(std::istream &input, std::ostream &output, std::size_t count)
{
    while(count > bufferSize) {
        input.read(m_buffer, bufferSize);
        output.write(m_buffer, bufferSize);
        count -= bufferSize;
    }
    input.read(m_buffer, count);
    output.write(m_buffer, count);
}


/*!
 * \brief Copies \a count bytes from \a input to \a output. The procedure might be abortet. Progress updates will be reportet.
 *
 * Copying is aborted when \a isAborted returns true. The current progress is reported by calling the specified \a callback function.
 *
 * \remarks Set an exception mask using std::ios::exceptions() to get a std::ios_base::failure exception when an IO error occurs.
 */
template<std::size_t bufferSize>
void CopyHelper<bufferSize>::callbackCopy(std::istream &input, std::ostream &output, std::size_t count, const std::function<bool (void)> &isAborted, const std::function<void (double)> &callback)
{
    std::size_t totalBytes = count;
    while(count > bufferSize) {
        input.read(m_buffer, bufferSize);
        output.write(m_buffer, bufferSize);
        count -= bufferSize;
        if(isAborted()) {
            return;
        }
        callback(static_cast<double>(totalBytes - count) / totalBytes);
    }
    input.read(m_buffer, count);
    output.write(m_buffer, count);
    callback(1.0);
}

/*!
 * \brief Returns the internal buffer.
 */
template<std::size_t bufferSize>
char *CopyHelper<bufferSize>::buffer()
{
    return m_buffer;
}

}

#endif // IOUTILITIES_COPY_H