#include "stdafx.h"

#include "InputOutputStream.h"

// Creates ByteArrayInputStream that uses buf as its buffer array. The initial value of pos is offset and
// the initial value of count is the minimum of offset+length and buf.length. The buffer array is not copied.
// The buffer's mark is set to the specified offset.
// Parameters:
// buf - the input buffer.
// offset - the offset in the buffer of the first byte to read.
// length - the maximum number of bytes to read from the buffer.
ByteArrayInputStream::ByteArrayInputStream(byteArray buf, unsigned int offset, unsigned int length)
    : pos(offset), mark(offset)
{
    if (offset > buf.length)
    {
        count = buf.length;
    }
    else if (length > buf.length - offset)
    {
        count = buf.length;
    }
    else
    {
        count = offset + length;
    }
    this->buf = buf;
}

// Creates a ByteArrayInputStream so that it uses buf as its buffer array. The buffer array is not copied.
// The initial value of pos is 0 and the initial value of count is the length of buf.
// Parameters:
// buf - the input buffer.
ByteArrayInputStream::ByteArrayInputStream(byteArray buf)
    : pos(0), count(buf.length), mark(0)
{
    this->buf = buf;
}

// Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255.
// If no byte is available because the end of the stream has been reached, the value -1 is returned.
// This read method cannot block.
// Returns:
// the next byte of data, or -1 if the end of the stream has been reached.
int ByteArrayInputStream::read()
{
    if (pos >= count)
    {
        return -1;
    }
    else
    {
        return buf[pos++];
    }
}

// Reads some number of bytes from the input stream and stores them into the buffer array b.
// The number of bytes actually read is returned as an integer. This method blocks until input data is available,
// end of file is detected, or an exception is thrown.
// If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte.
// If no byte is available because the stream is at the end of the file, the value -1 is returned; otherwise,
// at least one byte is read and stored into b.
//
// The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is,
// at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1],
// leaving elements b[k] through b[b.length-1] unaffected.
//
// The read(b) method for class InputStream has the same effect as:
//
//  read(b, 0, b.length)
// Parameters:
// b - the buffer into which the data is read.
// Returns:
// the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.
int ByteArrayInputStream::read(byteArray b)
{
    return read(b, 0, b.length);
}

// Reads up to len bytes of data into an array of bytes from this input stream. If pos equals count,
// then -1 is returned to indicate end of file. Otherwise, the number k of bytes read is equal to the smaller of len and count-pos.
// If k is positive, then bytes buf[pos] through buf[pos+k-1] are copied into b[off] through b[off+k-1] in the manner
// performed by System.arraycopy. The value k is added into pos and k is returned.
// This read method cannot block.
// Parameters:
// b - the buffer into which the data is read.
// off - the start offset in the destination array b
// len - the maximum number of bytes read.
// Returns:
// the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
int ByteArrayInputStream::read(byteArray b, unsigned int offset, unsigned int length)
{
    if (pos == count)
    {
        return -1;
    }

    int k = min(length, count - pos);
    XMemCpy(&b[offset], &buf[pos], k);
    // std::copy( buf->data+pos, buf->data+pos+k, b->data + offset ); // Or this instead?

    pos += k;

    return k;
}

// Closing a ByteArrayInputStream has no effect.
// The methods in this class can be called after the stream has been closed without generating an IOException.
void ByteArrayInputStream::close()
{
    return;
}

// Skips n bytes of input from this input stream. Fewer bytes might be skipped if the end of the input stream is reached. The actual number k of bytes to be skipped is equal to the smaller of n and count-pos. The value k is added into pos and k is returned.
// Overrides:
// skip in class InputStream
// Parameters:
// n - the number of bytes to be skipped.
// Returns:
// the actual number of bytes skipped.
__int64 ByteArrayInputStream::skip(__int64 n)
{
    int newPos = pos + n;

    if (newPos > count)
    {
        newPos = count;
    }

    int k = newPos - pos;
    pos = newPos;

    return k;
}

ByteArrayInputStream::~ByteArrayInputStream()
{
    if (buf.data != NULL)
    {
        delete[] buf.data;
    }
}