/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.

This file is part of Tremulous.

Tremulous is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.

Tremulous is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Tremulous; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/

#include "../qcommon/q_shared.h"
#include "../qcommon/qcommon.h"

#include <unistd.h>
#include <signal.h>
#include <termios.h>
#include <fcntl.h>

/*
=============================================================
tty console routines

NOTE: if the user is editing a line when something gets printed to the early
console then it won't look good so we provide TTY_Hide and TTY_Show to be
called before and after a stdout or stderr output
=============================================================
*/

// general flag to tell about tty console mode
static qboolean ttycon_on = qfalse;
static int ttycon_hide = 0;

// some key codes that the terminal may be using, initialised on start up
static int TTY_erase;
static int TTY_eof;

static struct termios TTY_tc;

static field_t TTY_con;

// This is somewhat of aduplicate of the graphical console history
// but it's safer more modular to have our own here
#define TTY_HISTORY 32
static field_t ttyEditLines[ TTY_HISTORY ];
static int hist_current = -1, hist_count = 0;

/*
==================
TTY_FlushIn

Flush stdin, I suspect some terminals are sending a LOT of shit
FIXME relevant?
==================
*/
static void TTY_FlushIn( void )
{
	char key;
	while (read(0, &key, 1)!=-1);
}

/*
==================
TTY_Back

Output a backspace

NOTE: it seems on some terminals just sending '\b' is not enough so instead we
send "\b \b"
(FIXME there may be a way to find out if '\b' alone would work though)
==================
*/
static void TTY_Back( void )
{
	char key;
	key = '\b';
	write(1, &key, 1);
	key = ' ';
	write(1, &key, 1);
	key = '\b';
	write(1, &key, 1);
}

/*
==================
TTY_Hide

Clear the display of the line currently edited
bring cursor back to beginning of line
==================
*/
void TTY_Hide( void )
{
	if( ttycon_on )
	{
		int i;
		if (ttycon_hide)
		{
			ttycon_hide++;
			return;
		}
		if (TTY_con.cursor>0)
		{
			for (i=0; i<TTY_con.cursor; i++)
			{
				TTY_Back();
			}
		}
		TTY_Back(); // Delete "]"
		ttycon_hide++;
	}
}

/*
==================
TTY_Show

Show the current line
FIXME need to position the cursor if needed?
==================
*/
void TTY_Show( void )
{
	if( ttycon_on )
	{
		int i;

		assert(ttycon_hide>0);
		ttycon_hide--;
		if (ttycon_hide == 0)
		{
			write( 1, "]", 1 );
			if (TTY_con.cursor)
			{
				for (i=0; i<TTY_con.cursor; i++)
				{
					write(1, TTY_con.buffer+i, 1);
				}
			}
		}
	}
}

/*
==================
TTY_Shutdown

Never exit without calling this, or your terminal will be left in a pretty bad state
==================
*/
void TTY_Shutdown( void )
{
	if (ttycon_on)
	{
		TTY_Back(); // Delete "]"
		tcsetattr (0, TCSADRAIN, &TTY_tc);

		// Restore blocking to stdin reads
		fcntl( 0, F_SETFL, fcntl( 0, F_GETFL, 0 ) & ~O_NDELAY );
	}
}

/*
==================
Hist_Add
==================
*/
void Hist_Add(field_t *field)
{
	int i;
	assert(hist_count <= TTY_HISTORY);
	assert(hist_count >= 0);
	assert(hist_current >= -1);
	assert(hist_current <= hist_count);
	// make some room
	for (i=TTY_HISTORY-1; i>0; i--)
	{
		ttyEditLines[i] = ttyEditLines[i-1];
	}
	ttyEditLines[0] = *field;
	if (hist_count<TTY_HISTORY)
	{
		hist_count++;
	}
	hist_current = -1; // re-init
}

/*
==================
Hist_Prev
==================
*/
field_t *Hist_Prev( void )
{
	int hist_prev;
	assert(hist_count <= TTY_HISTORY);
	assert(hist_count >= 0);
	assert(hist_current >= -1);
	assert(hist_current <= hist_count);
	hist_prev = hist_current + 1;
	if (hist_prev >= hist_count)
	{
		return NULL;
	}
	hist_current++;
	return &(ttyEditLines[hist_current]);
}

/*
==================
Hist_Next
==================
*/
field_t *Hist_Next( void )
{
	assert(hist_count <= TTY_HISTORY);
	assert(hist_count >= 0);
	assert(hist_current >= -1);
	assert(hist_current <= hist_count);
	if (hist_current >= 0)
	{
		hist_current--;
	}
	if (hist_current == -1)
	{
		return NULL;
	}
	return &(ttyEditLines[hist_current]);
}

/*
==================
TTY_Init

Initialize the console input (tty mode if possible)
==================
*/
void TTY_Init( void )
{
	struct termios tc;

	// If the process is backgrounded (running non interactively)
	// then SIGTTIN or SIGTOU is emitted, if not caught, turns into a SIGSTP
	signal(SIGTTIN, SIG_IGN);
	signal(SIGTTOU, SIG_IGN);

	// Make stdin reads non-blocking
	fcntl( 0, F_SETFL, fcntl( 0, F_GETFL, 0 ) | O_NDELAY );

	if (isatty(STDIN_FILENO)!=1)
	{
		Com_Printf( "stdin is not a tty, tty console mode disabled\n");
		ttycon_on = qfalse;
		return;
	}

	Field_Clear(&TTY_con);
	tcgetattr (0, &TTY_tc);
	TTY_erase = TTY_tc.c_cc[VERASE];
	TTY_eof = TTY_tc.c_cc[VEOF];
	tc = TTY_tc;

	/*
	ECHO: don't echo input characters
	ICANON: enable canonical mode.  This  enables  the  special
	characters  EOF,  EOL,  EOL2, ERASE, KILL, REPRINT,
	STATUS, and WERASE, and buffers by lines.
	ISIG: when any of the characters  INTR,  QUIT,  SUSP,  or
	DSUSP are received, generate the corresponding sig­
	nal
	*/
	tc.c_lflag &= ~(ECHO | ICANON);

	/*
	ISTRIP strip off bit 8
	INPCK enable input parity checking
	*/
	tc.c_iflag &= ~(ISTRIP | INPCK);
	tc.c_cc[VMIN] = 1;
	tc.c_cc[VTIME] = 0;
	tcsetattr (0, TCSADRAIN, &tc);
	ttycon_on = qtrue;
}

/*
==================
TTY_ConsoleInput
==================
*/
char *TTY_ConsoleInput( void )
{
	// we use this when sending back commands
	static char text[256];
	int avail;
	char key;
	field_t *history;

	if( ttycon_on )
	{
		avail = read(0, &key, 1);
		if (avail != -1)
		{
			// we have something
			// backspace?
			// NOTE TTimo testing a lot of values .. seems it's the only way to get it to work everywhere
			if ((key == TTY_erase) || (key == 127) || (key == 8))
			{
				if (TTY_con.cursor > 0)
				{
					TTY_con.cursor--;
					TTY_con.buffer[TTY_con.cursor] = '\0';
					TTY_Back();
				}
				return NULL;
			}
			// check if this is a control char
			if ((key) && (key) < ' ')
			{
				if (key == '\n')
				{
					// push it in history
					Hist_Add(&TTY_con);
					strcpy(text, TTY_con.buffer);
					Field_Clear(&TTY_con);
					key = '\n';
					write(1, &key, 1);
					write( 1, "]", 1 );
					return text;
				}
				if (key == '\t')
				{
					TTY_Hide();
					Field_AutoComplete( &TTY_con );
					TTY_Show();
					return NULL;
				}
				avail = read(0, &key, 1);
				if (avail != -1)
				{
					// VT 100 keys
					if (key == '[' || key == 'O')
					{
						avail = read(0, &key, 1);
						if (avail != -1)
						{
							switch (key)
							{
								case 'A':
									history = Hist_Prev();
									if (history)
									{
										TTY_Hide();
										TTY_con = *history;
										TTY_Show();
									}
									TTY_FlushIn();
									return NULL;
									break;
								case 'B':
									history = Hist_Next();
									TTY_Hide();
									if (history)
									{
										TTY_con = *history;
									} else
									{
										Field_Clear(&TTY_con);
									}
									TTY_Show();
									TTY_FlushIn();
									return NULL;
									break;
								case 'C':
									return NULL;
								case 'D':
									return NULL;
							}
						}
					}
				}
				Com_DPrintf("droping ISCTL sequence: %d, TTY_erase: %d\n", key, TTY_erase);
				TTY_FlushIn();
				return NULL;
			}
			// push regular character
			TTY_con.buffer[TTY_con.cursor] = key;
			TTY_con.cursor++;
			// print the current line (this is differential)
			write(1, &key, 1);
		}

		return NULL;
	}
	else
	{
		int     len;
		fd_set  fdset;
		struct timeval timeout;
		static qboolean stdin_active;

		if (!com_dedicated || !com_dedicated->value)
			return NULL;

		if (!stdin_active)
			return NULL;

		FD_ZERO(&fdset);
		FD_SET(0, &fdset); // stdin
		timeout.tv_sec = 0;
		timeout.tv_usec = 0;
		if (select (1, &fdset, NULL, NULL, &timeout) == -1 || !FD_ISSET(0, &fdset))
		{
			return NULL;
		}

		len = read (0, text, sizeof(text));
		if (len == 0)
		{ // eof!
			stdin_active = qfalse;
			return NULL;
		}

		if (len < 1)
			return NULL;
		text[len-1] = 0;    // rip off the /n and terminate

		return text;
	}
}