/*	$OpenBSD: window.c,v 1.20 2005/12/13 06:01:27 kjell Exp $	*/

/* This file is in the public domain. */

/*
 *		Window handling.
 */

#include "def.h"

struct mgwin *
new_window(struct buffer *bp)
{
	struct mgwin *wp;

	wp = calloc(1, sizeof(struct mgwin));
	if (wp == NULL)
		return (NULL);

	wp->w_bufp = bp;
	wp->w_dotp = NULL;
	wp->w_doto = 0;
	wp->w_markp = NULL;
	wp->w_marko = 0;
	wp->w_flag = 0;
	wp->w_force = 0;
	wp->w_wrapline = NULL;
	if (bp)
		bp->b_nwnd++;
	return (wp);
}

/*
 * Reposition dot in the current window to line "n".  If the argument is
 * positive, it is that line.  If it is negative it is that line from the
 * bottom.  If it is 0 the window is centered (this is what the standard
 * redisplay code does).  If GOSREC is undefined, default is 0, so it acts
 * like GNU.  If GOSREC is defined, with no argument it defaults to 1 and
 * works like in Gosling.
 */
/* ARGSUSED */
int
reposition(int f, int n)
{
#ifndef GOSREC
	curwp->w_force = (f & FFARG) ? (n >= 0 ? n + 1 : n) : 0;
#else /* !GOSREC */
	curwp->w_force = n;
#endif /* !GOSREC */
	curwp->w_flag |= WFFORCE;
	sgarbf = TRUE;
	return (TRUE);
}

/*
 * Refresh the display.  A call is made to the "ttresize" entry in the
 * terminal handler, which tries to reset "nrow" and "ncol".  They will,
 * however, never be set outside of the NROW or NCOL range.  If the display
 * changed size, arrange that everything is redone, then call "update" to
 * fix the display.  We do this so the new size can be displayed.  In the
 * normal case the call to "update" in "main.c" refreshes the screen, and
 * all of the windows need not be recomputed.  Note that when you get to the
 * "display unusable" message, the screen will be messed up. If you make the
 * window bigger again, and send another command, everything will get fixed!
 */
/* ARGSUSED */
int
redraw(int f, int n)
{
	struct mgwin	*wp;
	int		 oldnrow, oldncol;

	oldnrow = nrow;
	oldncol = ncol;
	ttresize();
	if (nrow != oldnrow || ncol != oldncol) {

		/* find last */
		wp = wheadp;
		while (wp->w_wndp != NULL)
			wp = wp->w_wndp;

		/* check if too small */
		if (nrow < wp->w_toprow + 3) {
			ewprintf("Display unusable");
			return (FALSE);
		}
		wp->w_ntrows = nrow - wp->w_toprow - 2;
		sgarbf = TRUE;
		update();
	} else
		sgarbf = TRUE;
	return (TRUE);
}

/*
 * The command to make the next window (next => down the screen) the current
 * window. There are no real errors, although the command does nothing if
 * there is only 1 window on the screen.
 */
/* ARGSUSED */
int
nextwind(int f, int n)
{
	struct mgwin	*wp;

	if ((wp = curwp->w_wndp) == NULL)
		wp = wheadp;
	curwp = wp;
	curbp = wp->w_bufp;
	return (TRUE);
}

/* not in Gnu Emacs */
/*
 * This command makes the previous window (previous => up the screen) the
 * current window. There are no errors, although the command does not do
 * a lot if there is only 1 window.
 */
/* ARGSUSED */
int
prevwind(int f, int n)
{
	struct mgwin	*wp1, *wp2;

	wp1 = wheadp;
	wp2 = curwp;
	if (wp1 == wp2)
		wp2 = NULL;
	while (wp1->w_wndp != wp2)
		wp1 = wp1->w_wndp;
	curwp = wp1;
	curbp = wp1->w_bufp;
	return (TRUE);
}

/*
 * This command makes the current window the only window on the screen.  Try
 * to set the framing so that "." does not have to move on the display.  Some
 * care has to be taken to keep the values of dot and mark in the buffer
 * structures right if the destruction of a window makes a buffer become
 * undisplayed.
 */
/* ARGSUSED */
int
onlywind(int f, int n)
{
	struct mgwin	*wp;
	struct line	*lp;
	int		 i;

	while (wheadp != curwp) {
		wp = wheadp;
		wheadp = wp->w_wndp;
		if (--wp->w_bufp->b_nwnd == 0) {
			wp->w_bufp->b_dotp = wp->w_dotp;
			wp->w_bufp->b_doto = wp->w_doto;
			wp->w_bufp->b_markp = wp->w_markp;
			wp->w_bufp->b_marko = wp->w_marko;
		}
		free(wp);
	}
	while (curwp->w_wndp != NULL) {
		wp = curwp->w_wndp;
		curwp->w_wndp = wp->w_wndp;
		if (--wp->w_bufp->b_nwnd == 0) {
			wp->w_bufp->b_dotp = wp->w_dotp;
			wp->w_bufp->b_doto = wp->w_doto;
			wp->w_bufp->b_markp = wp->w_markp;
			wp->w_bufp->b_marko = wp->w_marko;
		}
		free(wp);
	}
	lp = curwp->w_linep;
	i = curwp->w_toprow;
	while (i != 0 && lback(lp) != curbp->b_linep) {
		--i;
		lp = lback(lp);
	}
	curwp->w_toprow = 0;

	/* 2 = mode, echo */
	curwp->w_ntrows = nrow - 2;
	curwp->w_linep = lp;
	curwp->w_flag |= WFMODE | WFHARD;
	return (TRUE);
}

/*
 * Split the current window.  A window smaller than 3 lines cannot be split.
 * The only other error that is possible is a "malloc" failure allocating the
 * structure for the new window.
 */
/* ARGSUSED */
int
splitwind(int f, int n)
{
	struct mgwin	*wp, *wp1, *wp2;
	struct line	*lp;
	int		 ntru, ntrd, ntrl;

	if (curwp->w_ntrows < 3) {
		ewprintf("Cannot split a %d line window", curwp->w_ntrows);
		return (FALSE);
	}
	wp = new_window(curbp);
	if (wp == NULL) {
		ewprintf("Unable to create a window");
		return (FALSE);
	}

	/* use the current dot and mark */
	wp->w_dotp = curwp->w_dotp;
	wp->w_doto = curwp->w_doto;
	wp->w_markp = curwp->w_markp;
	wp->w_marko = curwp->w_marko;

	/* figure out which half of the screen we're in */
	ntru = (curwp->w_ntrows - 1) / 2;	/* Upper size */
	ntrl = (curwp->w_ntrows - 1) - ntru;	/* Lower size */

	for (lp = curwp->w_linep, ntrd = 0; lp != curwp->w_dotp;
	    lp = lforw(lp))
		ntrd++;

	lp = curwp->w_linep;

	/* old is upper window */
	if (ntrd <= ntru) {
		/* hit mode line */
		if (ntrd == ntru)
			lp = lforw(lp);
		curwp->w_ntrows = ntru;
		wp->w_wndp = curwp->w_wndp;
		curwp->w_wndp = wp;
		wp->w_toprow = curwp->w_toprow + ntru + 1;
		wp->w_ntrows = ntrl;
	/* old is lower window */
	} else {
		wp1 = NULL;
		wp2 = wheadp;
		while (wp2 != curwp) {
			wp1 = wp2;
			wp2 = wp2->w_wndp;
		}
		if (wp1 == NULL)
			wheadp = wp;
		else
			wp1->w_wndp = wp;
		wp->w_wndp = curwp;
		wp->w_toprow = curwp->w_toprow;
		wp->w_ntrows = ntru;

		/* mode line */
		++ntru;
		curwp->w_toprow += ntru;
		curwp->w_ntrows = ntrl;
		while (ntru--)
			lp = lforw(lp);
	}

	/* adjust the top lines if necessary */
	curwp->w_linep = lp;
	wp->w_linep = lp;

	curwp->w_flag |= WFMODE | WFHARD;
	wp->w_flag |= WFMODE | WFHARD;
	return (TRUE);
}

/*
 * Enlarge the current window.  Find the window that loses space.  Make sure
 * it is big enough.  If so, hack the window descriptions, and ask redisplay
 * to do all the hard work.  You don't just set "force reframe" because dot
 * would move.
 */
/* ARGSUSED */
int
enlargewind(int f, int n)
{
	struct mgwin	*adjwp;
	struct line	*lp;
	int		 i;

	if (n < 0)
		return (shrinkwind(f, -n));
	if (wheadp->w_wndp == NULL) {
		ewprintf("Only one window");
		return (FALSE);
	}
	if ((adjwp = curwp->w_wndp) == NULL) {
		adjwp = wheadp;
		while (adjwp->w_wndp != curwp)
			adjwp = adjwp->w_wndp;
	}
	if (adjwp->w_ntrows <= n) {
		ewprintf("Impossible change");
		return (FALSE);
	}

	/* shrink below */
	if (curwp->w_wndp == adjwp) {
		lp = adjwp->w_linep;
		for (i = 0; i < n && lp != adjwp->w_bufp->b_linep; ++i)
			lp = lforw(lp);
		adjwp->w_linep = lp;
		adjwp->w_toprow += n;
	/* shrink above */
	} else {
		lp = curwp->w_linep;
		for (i = 0; i < n && lback(lp) != curbp->b_linep; ++i)
			lp = lback(lp);
		curwp->w_linep = lp;
		curwp->w_toprow -= n;
	}
	curwp->w_ntrows += n;
	adjwp->w_ntrows -= n;
	curwp->w_flag |= WFMODE | WFHARD;
	adjwp->w_flag |= WFMODE | WFHARD;
	return (TRUE);
}

/*
 * Shrink the current window.  Find the window that gains space.  Hack at the
 * window descriptions. Ask the redisplay to do all the hard work.
 */
int
shrinkwind(int f, int n)
{
	struct mgwin	*adjwp;
	struct line	*lp;
	int		 i;

	if (n < 0)
		return (enlargewind(f, -n));
	if (wheadp->w_wndp == NULL) {
		ewprintf("Only one window");
		return (FALSE);
	}
	/*
	 * Bit of flakiness - KRANDOM means it was an internal call, and
	 * to be trusted implicitly about sizes.
	 */
	if (!(f & FFRAND) && curwp->w_ntrows <= n) {
		ewprintf("Impossible change");
		return (FALSE);
	}
	if ((adjwp = curwp->w_wndp) == NULL) {
		adjwp = wheadp;
		while (adjwp->w_wndp != curwp)
			adjwp = adjwp->w_wndp;
	}

	/* grow below */
	if (curwp->w_wndp == adjwp) {
		lp = adjwp->w_linep;
		for (i = 0; i < n && lback(lp) != adjwp->w_bufp->b_linep; ++i)
			lp = lback(lp);
		adjwp->w_linep = lp;
		adjwp->w_toprow -= n;
	/* grow above */
	} else {
		lp = curwp->w_linep;
		for (i = 0; i < n && lp != curbp->b_linep; ++i)
			lp = lforw(lp);
		curwp->w_linep = lp;
		curwp->w_toprow += n;
	}
	curwp->w_ntrows -= n;
	adjwp->w_ntrows += n;
	curwp->w_flag |= WFMODE | WFHARD;
	adjwp->w_flag |= WFMODE | WFHARD;
	return (TRUE);
}

/*
 * Delete current window. Call shrink-window to do the screen updating, then
 * throw away the window.
 */
/* ARGSUSED */
int
delwind(int f, int n)
{
	struct mgwin	*wp, *nwp;

	wp = curwp;		/* Cheap...		 */

	/* shrinkwind returning false means only one window... */
	if (shrinkwind(FFRAND, wp->w_ntrows + 1) == FALSE)
		return (FALSE);
	if (--wp->w_bufp->b_nwnd == 0) {
		wp->w_bufp->b_dotp = wp->w_dotp;
		wp->w_bufp->b_doto = wp->w_doto;
		wp->w_bufp->b_markp = wp->w_markp;
		wp->w_bufp->b_marko = wp->w_marko;
	}

	/* since shrinkwind did't crap out, we know we have a second window */
	if (wp == wheadp)
		wheadp = curwp = wp->w_wndp;
	else if ((curwp = wp->w_wndp) == NULL)
		curwp = wheadp;
	curbp = curwp->w_bufp;
	for (nwp = wheadp; nwp != NULL; nwp = nwp->w_wndp)
		if (nwp->w_wndp == wp) {
			nwp->w_wndp = wp->w_wndp;
			break;
		}
	free(wp);
	return (TRUE);
}

/*
 * Pick a window for a pop-up.  Split the screen if there is only one window.
 * Pick the uppermost window that isn't the current window. An LRU algorithm
 * might be better. Return a pointer, or NULL on error.
 */
struct mgwin *
wpopup(void)
{
	struct mgwin	*wp;

	if (wheadp->w_wndp == NULL &&
	    splitwind(FFRAND, 0) == FALSE)
		return (NULL);

	/* find a window to use */
	wp = wheadp;

	while (wp != NULL && wp == curwp)
		wp = wp->w_wndp;
	return (wp);
}