// Echo Stream: an input stream with line echo.
//
// File:	estream.cc
// Author:	course
// Version:	2

#include "estream.h"
#include <fstream.h>
#include <unistd.h>	// isatty for g++
#include <stdlib.h>	// isatty for ObjectCenter

estream ein (cin, cout);

int estreambuf::echo()
{
    if (echo_enable < 0) echo_enable =
	! isatty (((filebuf *) (in->rdbuf())) -> fd());
    return echo_enable;
}

int estreambuf::underflow ()
{
    // In case we are called with characters left in the
    // get buffer.
    //
    if (in_avail()) return (unsigned char) *gptr();

    // Leave 4 character positions at the beginning of
    // the get buffer for putback, and two at the end
    // for line feed and NUL.
    //
    char * buffer = base() + 4;
    char * ebuffer = ebuf() - 2;

    int count = 0;

    while ( ! in->eof() )
    {
	char c = in->get();

	if ( c == '\n' || c == EOF )
		break;
	else
		buffer[count++] = c;
    }

    buffer[count] = '\0';

    if (count == 0 && in->eof())
    {
	// End of file.  Indicate no more input
	// available.
	//
	setg (NULL, NULL, NULL);
	return EOF;
    }
    else
    {
	// Not end of file.  Count does not include
	// the '\0' at the end of the buffer, and does
	// NOT include any '\n' (which was discarded).

	ebuffer		= buffer + count;

	// If echo is automatic, set it.
	//
	if (echo_enable < 0) echo();

	// Echo line if echo switch on.
	//
	if (echo_enable) *out << buffer << endl;

	// Return buffer to estream, complete with '\n'.
	//
	* ebuffer ++	= '\n';
	setg (buffer, buffer, ebuffer);
	return (unsigned char) *buffer;
    }
}