/*	isearch.c
 *
 * The functions in this file implement commands that perform incremental
 * searches in the forward and backward directions.  This "ISearch" command
 * is intended to emulate the same command from the original EMACS
 * implementation (ITS).  Contains references to routines internal to
 * SEARCH.C.
 *
 * REVISION HISTORY:
 *
 *	D. R. Banks 9-May-86
 *	- added ITS EMACSlike ISearch
 *
 *	John M. Gamble 5-Oct-86
 *	- Made iterative search use search.c's scanner() routine.
 *	  This allowed the elimination of bakscan().
 *	- Put isearch constants into estruct.h
 *	- Eliminated the passing of 'status' to scanmore() and
 *	  checknext(), since there were no circumstances where
 *	  it ever equalled FALSE.
 *
 *	Modified by Petri Kutvonen
 */

#include <stdio.h>

#include "estruct.h"
#include "edef.h"
#include "efunc.h"
#include "line.h"

#if	ISRCH

static int echo_char(int c, int col);

/* A couple of "own" variables for re-eat */

static int (*saved_get_char) (void);	/* Get character routine */
static int eaten_char = -1;		/* Re-eaten char */

/* A couple more "own" variables for the command string */

static int cmd_buff[CMDBUFLEN];	/* Save the command args here */
static int cmd_offset;			/* Current offset into command buff */
static int cmd_reexecute = -1;		/* > 0 if re-executing command */


/*
 * Subroutine to do incremental reverse search.  It actually uses the
 * same code as the normal incremental search, as both can go both ways.
 */
int risearch(int f, int n)
{
	struct line *curline;		/* Current line on entry              */
	int curoff;		/* Current offset on entry            */

	/* remember the initial . on entry: */

	curline = curwp->w_dotp;	/* Save the current line pointer      */
	curoff = curwp->w_doto;	/* Save the current offset            */

	/* Make sure the search doesn't match where we already are:               */

	backchar(TRUE, 1);	/* Back up a character                */

	if (!(isearch(f, -n))) {	/* Call ISearch backwards       *//* If error in search:                */
		curwp->w_dotp = curline;	/* Reset the line pointer             */
		curwp->w_doto = curoff;	/*  and the offset to original value  */
		curwp->w_flag |= WFMOVE;	/* Say we've moved                    */
		update(FALSE);	/* And force an update                */
		mlwrite("(search failed)");	/* Say we died                        */
#if	PKCODE
		matchlen = strlen(pat);
#endif
	} else
		mlerase();	/* If happy, just erase the cmd line  */
#if	PKCODE
	matchlen = strlen(pat);
#endif
	return TRUE;
}

/*
 * Again, but for the forward direction
 */
int fisearch(int f, int n)
{
	struct line *curline;		/* Current line on entry              */
	int curoff;		/* Current offset on entry            */

	/* remember the initial . on entry: */

	curline = curwp->w_dotp;	/* Save the current line pointer      */
	curoff = curwp->w_doto;	/* Save the current offset            */

	/* do the search */

	if (!(isearch(f, n))) {	/* Call ISearch forwards        *//* If error in search:                */
		curwp->w_dotp = curline;	/* Reset the line pointer             */
		curwp->w_doto = curoff;	/*  and the offset to original value  */
		curwp->w_flag |= WFMOVE;	/* Say we've moved                    */
		update(FALSE);	/* And force an update                */
		mlwrite("(search failed)");	/* Say we died                        */
#if	PKCODE
		matchlen = strlen(pat);
#endif
	} else
		mlerase();	/* If happy, just erase the cmd line  */
#if	PKCODE
	matchlen = strlen(pat);
#endif
	return TRUE;
}

/*
 * Subroutine to do an incremental search.  In general, this works similarly
 * to the older micro-emacs search function, except that the search happens
 * as each character is typed, with the screen and cursor updated with each
 * new search character.
 *
 * While searching forward, each successive character will leave the cursor
 * at the end of the entire matched string.  Typing a Control-S or Control-X
 * will cause the next occurrence of the string to be searched for (where the
 * next occurrence does NOT overlap the current occurrence).  A Control-R will
 * change to a backwards search, META will terminate the search and Control-G
 * will abort the search.  Rubout will back up to the previous match of the
 * string, or if the starting point is reached first, it will delete the
 * last character from the search string.
 *
 * While searching backward, each successive character will leave the cursor
 * at the beginning of the matched string.  Typing a Control-R will search
 * backward for the next occurrence of the string.  Control-S or Control-X
 * will revert the search to the forward direction.  In general, the reverse
 * incremental search is just like the forward incremental search inverted.
 *
 * In all cases, if the search fails, the user will be feeped, and the search
 * will stall until the pattern string is edited back into something that
 * exists (or until the search is aborted).
 */

int isearch(int f, int n)
{
	int status;		/* Search status */
	int col;		/* prompt column */
	int cpos;	/* character number in search string  */
	int c;		/* current input character */
	int expc;	/* function expanded input char       */
	char pat_save[NPAT];	/* Saved copy of the old pattern str  */
	struct line *curline;		/* Current line on entry              */
	int curoff;		/* Current offset on entry            */
	int init_direction;	/* The initial search direction       */

	/* Initialize starting conditions */

	cmd_reexecute = -1;	/* We're not re-executing (yet?)      */
	cmd_offset = 0;		/* Start at the beginning of the buff */
	cmd_buff[0] = '\0';	/* Init the command buffer            */
	strncpy(pat_save, pat, NPAT);	/* Save the old pattern string        */
	curline = curwp->w_dotp;	/* Save the current line pointer      */
	curoff = curwp->w_doto;	/* Save the current offset            */
	init_direction = n;	/* Save the initial search direction  */

	/* This is a good place to start a re-execution: */

      start_over:

	/* ask the user for the text of a pattern */
	col = promptpattern("ISearch: ");	/* Prompt, remember the col   */

	cpos = 0;		/* Start afresh               */
	status = TRUE;		/* Assume everything's cool   */

	/*
	   Get the first character in the pattern.  If we get an initial Control-S
	   or Control-R, re-use the old search string and find the first occurrence
	 */

	c = ectoc(expc = get_char());	/* Get the first character    */
	if ((c == IS_FORWARD) || (c == IS_REVERSE) || (c == IS_VMSFORW)) {	/* Reuse old search string?   */
		for (cpos = 0; pat[cpos] != 0; cpos++)	/* Yup, find the length           */
			col = echo_char(pat[cpos], col);	/*  and re-echo the string    */
		if (c == IS_REVERSE) {	/* forward search?            */
			n = -1;	/* No, search in reverse      */
			backchar(TRUE, 1);	/* Be defensive about EOB     */
		} else
			n = 1;	/* Yes, search forward        */
		status = scanmore(pat, n);	/* Do the search              */
		c = ectoc(expc = get_char());	/* Get another character      */
	}

	/* Top of the per character loop */

	for (;;) {		/* ISearch per character loop */
		/* Check for special characters first: */
		/* Most cases here change the search */

		if (expc == metac)	/* Want to quit searching?    */
			return TRUE;	/* Quit searching now         */

		switch (c) {	/* dispatch on the input char */
		case IS_ABORT:	/* If abort search request    */
			return FALSE;	/* Quit searching again       */

		case IS_REVERSE:	/* If backward search         */
		case IS_FORWARD:	/* If forward search          */
		case IS_VMSFORW:	/*  of either flavor          */
			if (c == IS_REVERSE)	/* If reverse search              */
				n = -1;	/* Set the reverse direction  */
			else	/* Otherwise,                     */
				n = 1;	/*  go forward                */
			status = scanmore(pat, n);	/* Start the search again     */
			c = ectoc(expc = get_char());	/* Get the next char          */
			continue;	/* Go continue with the search */

		case IS_NEWLINE:	/* Carriage return            */
			c = '\n';	/* Make it a new line         */
			break;	/* Make sure we use it        */

		case IS_QUOTE:	/* Quote character            */
		case IS_VMSQUOTE:	/*  of either variety         */
			c = ectoc(expc = get_char());	/* Get the next char          */

		case IS_TAB:	/* Generically allowed        */
		case '\n':	/*  controlled characters     */
			break;	/* Make sure we use it        */

		case IS_BACKSP:	/* If a backspace:            */
		case IS_RUBOUT:	/*  or if a Rubout:           */
			if (cmd_offset <= 1)	/* Anything to delete?            */
				return TRUE;	/* No, just exit              */
			--cmd_offset;	/* Back up over the Rubout    */
			cmd_buff[--cmd_offset] = '\0';	/* Yes, delete last char   */
			curwp->w_dotp = curline;	/* Reset the line pointer     */
			curwp->w_doto = curoff;	/*  and the offset            */
			n = init_direction;	/* Reset the search direction */
			strncpy(pat, pat_save, NPAT);	/* Restore the old search str */
			cmd_reexecute = 0;	/* Start the whole mess over  */
			goto start_over;	/* Let it take care of itself */

			/* Presumably a quasi-normal character comes here */

		default:	/* All other chars            */
			if (c < ' ') {	/* Is it printable?             *//* Nope.                      */
				reeat(c);	/* Re-eat the char            */
				return TRUE;	/* And return the last status */
			}
		}		/* Switch */

		/* I guess we got something to search for, so search for it           */

		pat[cpos++] = c;	/* put the char in the buffer */
		if (cpos >= NPAT) {	/* too many chars in string?  *//* Yup.  Complain about it    */
			mlwrite("? Search string too long");
			return TRUE;	/* Return an error            */
		}
		pat[cpos] = 0;	/* null terminate the buffer  */
		col = echo_char(c, col);	/* Echo the character         */
		if (!status) {	/* If we lost last time       */
			TTputc(BELL);	/* Feep again                 */
			TTflush();	/* see that the feep feeps    */
		} else /* Otherwise, we must have won */ if (!(status = checknext(c, pat, n)))	/* See if match         */
			status = scanmore(pat, n);	/*  or find the next match    */
		c = ectoc(expc = get_char());	/* Get the next char          */
	}			/* for {;;} */
}

/*
 * Trivial routine to insure that the next character in the search string is
 * still true to whatever we're pointing to in the buffer.  This routine will
 * not attempt to move the "point" if the match fails, although it will 
 * implicitly move the "point" if we're forward searching, and find a match,
 * since that's the way forward isearch works.
 *
 * If the compare fails, we return FALSE and assume the caller will call
 * scanmore or something.
 *
 * char chr;		Next char to look for
 * char *patrn;		The entire search string (incl chr)
 * int dir;		Search direction
 */
int checknext(char chr, char *patrn, int dir)	/* Check next character in search string */
{
	struct line *curline;	/* current line during scan           */
	int curoff;	/* position within current line       */
	int buffchar;	/* character at current position      */
	int status;		/* how well things go                 */


	/* setup the local scan pointer to current "." */

	curline = curwp->w_dotp;		/* Get the current line structure     */
	curoff = curwp->w_doto;			/* Get the offset within that line    */

	if (dir > 0) {				/* If searching forward                 */
		if (curoff == llength(curline)) {		/* If at end of line                    */
			curline = lforw(curline);		/* Skip to the next line              */
			if (curline == curbp->b_linep)
				return FALSE;			/* Abort if at end of buffer          */
			curoff = 0;				/* Start at the beginning of the line */
			buffchar = '\n';			/* And say the next char is NL        */
		} else
			buffchar = lgetc(curline, curoff++);	/* Get the next char         */
		if ((status = eq(buffchar, chr)) != 0) {	/* Is it what we're looking for?      */
			curwp->w_dotp = curline;		/* Yes, set the buffer's point        */
			curwp->w_doto = curoff;			/*  to the matched character          */
			curwp->w_flag |= WFMOVE;		/* Say that we've moved               */
		}
		return status;		/* And return the status              */
	} else					/* Else, if reverse search:       */
		return match_pat(patrn);	/* See if we're in the right place    */
}

/*
 * This hack will search for the next occurrence of <pat> in the buffer, either
 * forward or backward.  It is called with the status of the prior search
 * attempt, so that it knows not to bother if it didn't work last time.  If
 * we can't find any more matches, "point" is left where it was before.  If
 * we do find a match, "point" will be at the end of the matched string for
 * forward searches and at the beginning of the matched string for reverse
 * searches.
 *
 * char *patrn;			string to scan for
 * int dir;			direction to search
 */
int scanmore(char *patrn, int dir)	/* search forward or back for a pattern           */
{
	int sts;		/* search status                      */

	if (dir < 0) {		/* reverse search?              */
		rvstrcpy(tap, patrn);	/* Put reversed string in tap */
		sts = scanner(tap, REVERSE, PTBEG);
	} else
		sts = scanner(patrn, FORWARD, PTEND);	/* Nope. Go forward   */

	if (!sts) {
		TTputc(BELL);	/* Feep if search fails       */
		TTflush();	/* see that the feep feeps    */
	}

	return sts;		/* else, don't even try       */
}

/*
 * The following is a worker subroutine used by the reverse search.  It
 * compares the pattern string with the characters at "." for equality. If
 * any characters mismatch, it will return FALSE.
 *
 * This isn't used for forward searches, because forward searches leave "."
 * at the end of the search string (instead of in front), so all that needs to
 * be done is match the last char input.
 *
 * char *patrn;			String to match to buffer
 */
int match_pat(char *patrn)	/* See if the pattern string matches string at "."   */
{
	int i;		/* Generic loop index/offset          */
	int buffchar;	/* character at current position      */
	struct line *curline;	/* current line during scan           */
	int curoff;	/* position within current line       */

	/* setup the local scan pointer to current "." */

	curline = curwp->w_dotp;	/* Get the current line structure     */
	curoff = curwp->w_doto;	/* Get the offset within that line    */

	/* top of per character compare loop: */

	for (i = 0; i < strlen(patrn); i++) {	/* Loop for all characters in patrn   */
		if (curoff == llength(curline)) {	/* If at end of line                    */
			curline = lforw(curline);	/* Skip to the next line              */
			curoff = 0;	/* Start at the beginning of the line */
			if (curline == curbp->b_linep)
				return FALSE;	/* Abort if at end of buffer          */
			buffchar = '\n';	/* And say the next char is NL        */
		} else
			buffchar = lgetc(curline, curoff++);	/* Get the next char         */
		if (!eq(buffchar, patrn[i]))	/* Is it what we're looking for?      */
			return FALSE;	/* Nope, just punt it then            */
	}
	return TRUE;		/* Everything matched? Let's celebrate */
}

/*
 * Routine to prompt for I-Search string.
 */
int promptpattern(char *prompt)
{
	char tpat[NPAT + 20];

	strcpy(tpat, prompt);	/* copy prompt to output string */
	strcat(tpat, " (");	/* build new prompt string */
	expandp(pat, &tpat[strlen(tpat)], NPAT / 2);	/* add old pattern */
	strcat(tpat, ")<Meta>: ");

	/* check to see if we are executing a command line */
	if (!clexec) {
		mlwrite(tpat);
	}
	return strlen(tpat);
}

/*
 * routine to echo i-search characters
 *
 * int c;		character to be echoed
 * int col;		column to be echoed in
 */
static int echo_char(int c, int col)
{
	movecursor(term.t_nrow, col);	/* Position the cursor        */
	if ((c < ' ') || (c == 0x7F)) {	/* Control character?           */
		switch (c) {	/* Yes, dispatch special cases */
		case '\n':	/* Newline                    */
			TTputc('<');
			TTputc('N');
			TTputc('L');
			TTputc('>');
			col += 3;
			break;

		case '\t':	/* Tab                        */
			TTputc('<');
			TTputc('T');
			TTputc('A');
			TTputc('B');
			TTputc('>');
			col += 4;
			break;

		case 0x7F:	/* Rubout:                    */
			TTputc('^');	/* Output a funny looking     */
			TTputc('?');	/*  indication of Rubout      */
			col++;	/* Count the extra char       */
			break;

		default:	/* Vanilla control char       */
			TTputc('^');	/* Yes, output prefix         */
			TTputc(c + 0x40);	/* Make it "^X"               */
			col++;	/* Count this char            */
		}
	} else
		TTputc(c);	/* Otherwise, output raw char */
	TTflush();		/* Flush the output           */
	return ++col;		/* return the new column no   */
}

/*
 * Routine to get the next character from the input stream.  If we're reading
 * from the real terminal, force a screen update before we get the char. 
 * Otherwise, we must be re-executing the command string, so just return the
 * next character.
 */
int get_char(void)
{
	int c;			/* A place to get a character         */

	/* See if we're re-executing: */

	if (cmd_reexecute >= 0)	/* Is there an offset?                    */
		if ((c = cmd_buff[cmd_reexecute++]) != 0)
			return c;	/* Yes, return any character          */

	/* We're not re-executing (or aren't any more).  Try for a real char      */

	cmd_reexecute = -1;	/* Say we're in real mode again       */
	update(FALSE);		/* Pretty up the screen               */
	if (cmd_offset >= CMDBUFLEN - 1) {	/* If we're getting too big ...         */
		mlwrite("? command too long");	/* Complain loudly and bitterly       */
		return metac;	/* And force a quit                   */
	}
	c = get1key();		/* Get the next character             */
	cmd_buff[cmd_offset++] = c;	/* Save the char for next time        */
	cmd_buff[cmd_offset] = '\0';	/* And terminate the buffer           */
	return c;		/* Return the character               */
}

/*
 * Hacky routine to re-eat a character.  This will save the character to be
 * re-eaten by redirecting the input call to a routine here.  Hack, etc.
 */

/* Come here on the next term.t_getchar call: */

int uneat(void)
{
	int c;

	term.t_getchar = saved_get_char;	/* restore the routine address        */
	c = eaten_char;		/* Get the re-eaten char              */
	eaten_char = -1;	/* Clear the old char                 */
	return c;		/* and return the last char           */
}

void reeat(int c)
{
	if (eaten_char != -1)	/* If we've already been here             */
		return /*(NULL) */ ;	/* Don't do it again                  */
	eaten_char = c;		/* Else, save the char for later      */
	saved_get_char = term.t_getchar;	/* Save the char get routine          */
	term.t_getchar = uneat;	/* Replace it with ours               */
}
#else
int isearch(int f, int n)
{
}
#endif