/*
 * Copyright (c) 1988 Mark Nudleman
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Mark Nudleman and the University of California, Berkeley.  The
 * name of Mark Nudleman or the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)command.c	5.9 (Berkeley) 09/23/88";
#endif /* not lint */

/*
 * User-level command processor.
 */

#include "less.h"
#include "position.h"
#include "cmd.h"

#define	NO_MCA		0
#define	MCA_DONE	1
#define	MCA_MORE	2

extern int erase_char, kill_char;
extern int ispipe;
extern int sigs;
extern int quit_at_eof;
extern int hit_eof;
extern int sc_width;
extern int sc_height;
extern int sc_window;
extern int curr_ac;
extern int ac;
extern int quitting;
extern int scroll;
extern char *first_cmd;
extern char *every_first_cmd;
extern char *current_file;
extern int screen_trashed;	/* The screen has been overwritten */

static char cmdbuf[120];	/* Buffer for holding a multi-char command */
static char *cp;		/* Pointer into cmdbuf */
static int cmd_col;		/* Current column of the multi-char command */
static int mca;			/* The multicharacter command (action) */
static int last_mca;		/* The previous mca */
static int number;		/* The number typed by the user */
static int wsearch;		/* Search for matches (1) or non-matches (0) */

/*
 * Reset command buffer (to empty).
 */
cmd_reset()
{
	cp = cmdbuf;
}

/*
 * Backspace in command buffer.
 */
	static int
cmd_erase()
{
	if (cp == cmdbuf)
		/*
		 * Backspace past beginning of the string:
		 * this usually means abort the command.
		 */
		return (1);

	if (control_char(*--cp))
	{
		/*
		 * Erase an extra character, for the carat.
		 */
		backspace();
		cmd_col--;
	}
	backspace();
	cmd_col--;
	return (0);
}

/*
 * Set up the display to start a new multi-character command.
 */
start_mca(action, prompt)
	int action;
	char *prompt;
{
	lower_left();
	clear_eol();
	putstr(prompt);
	cmd_col = strlen(prompt);
	mca = action;
}

/*
 * Process a single character of a multi-character command, such as
 * a number, or the pattern of a search command.
 */
	static int
cmd_char(c)
	int c;
{
	if (c == erase_char)
	{
		if (cmd_erase())
			return (1);
	} else if (c == kill_char)
	{
		/* {{ Could do this faster, but who cares? }} */
		while (cmd_erase() == 0)
			;
	} else if (cp >= &cmdbuf[sizeof(cmdbuf)-1])
	{
		/*
		 * No room in the command buffer.
		 */
		bell();
	} else if (cmd_col >= sc_width-3)
	{
		/*
		 * No room on the screen.
		 * {{ Could get fancy here; maybe shift the displayed
		 *    line and make room for more chars, like ksh. }}
		 */
		bell();
	} else
	{
		/*
		 * Append the character to the string.
		 */
		*cp++ = c;
		if (control_char(c))
		{
			putchr('^');
			cmd_col++;
			c = carat_char(c);
		}
		putchr(c);
		cmd_col++;
	}
	return (0);
}

/*
 * Return the number currently in the command buffer.
 */
	static int
cmd_int()
{
	*cp = '\0';
	cp = cmdbuf;
	return (atoi(cmdbuf));
}

/*
 * Move the cursor to lower left before executing a command.
 * This looks nicer if the command takes a long time before
 * updating the screen.
 */
	static void
cmd_exec()
{
	lower_left();
	flush();
}

/*
 * Display the appropriate prompt.
 */
	static void
prompt()
{
	register char *p;

	if (first_cmd != NULL && *first_cmd != '\0')
	{
		/*
		 * No prompt necessary if commands are from first_cmd
		 * rather than from the user.
		 */
		return;
	}

	/*
	 * If nothing is displayed yet, display starting from line 1.
	 */
	if (position(TOP) == NULL_POSITION)
		jump_back(1);
	else if (screen_trashed)
		repaint();

	/*
	 * If the -E flag is set and we've hit EOF on the last file, quit.
	 */
	if (quit_at_eof == 2 && hit_eof && curr_ac + 1 >= ac)
		quit();

	/*
	 * Select the proper prompt and display it.
	 */
	lower_left();
	clear_eol();
	p = pr_string();
	if (p == NULL)
		putchr(':');
	else
	{
		so_enter();
		putstr(p);
		so_exit();
	}
}

/*
 * Get command character.
 * The character normally comes from the keyboard,
 * but may come from the "first_cmd" string.
 */
	static int
getcc()
{
	if (first_cmd == NULL)
		return (getchr());

	if (*first_cmd == '\0')
	{
		/*
		 * Reached end of first_cmd input.
		 */
		first_cmd = NULL;
		if (cp > cmdbuf && position(TOP) == NULL_POSITION)
		{
			/*
			 * Command is incomplete, so try to complete it.
			 * There are only two cases:
			 * 1. We have "/string" but no newline.  Add the \n.
			 * 2. We have a number but no command.  Treat as #g.
			 * (This is all pretty hokey.)
			 */
			if (mca != A_DIGIT)
				/* Not a number; must be search string */
				return ('\n'); 
			else
				/* A number; append a 'g' */
				return ('g');
		}
		return (getchr());
	}
	return (*first_cmd++);
}

/*
 * Execute a multicharacter command.
 */
	static void
exec_mca()
{
	register char *p;

	*cp = '\0';
	cmd_exec();
	switch (mca)
	{
	case A_F_SEARCH:
		search(1, cmdbuf, number, wsearch);
		break;
	case A_B_SEARCH:
		search(0, cmdbuf, number, wsearch);
		break;
	case A_FIRSTCMD:
		/*
		 * Skip leading spaces or + signs in the string.
		 */
		for (p = cmdbuf;  *p == '+' || *p == ' ';  p++)
			;
		if (every_first_cmd != NULL)
			free(every_first_cmd);
		if (*p == '\0')
			every_first_cmd = NULL;
		else
			every_first_cmd = save(p);
		break;
	case A_TOGGLE_OPTION:
		toggle_option(cmdbuf, 1);
		break;
	case A_EXAMINE:
		/*
		 * Ignore leading spaces in the filename.
		 */
		for (p = cmdbuf;  *p == ' ';  p++)
			;
		edit(glob(p));
		break;
	}
}

/*
 * Add a character to a multi-character command.
 */
	static int
mca_char(c)
	int c;
{
	switch (mca)
	{
	case 0:
		/*
		 * Not in a multicharacter command.
		 */
		return (NO_MCA);

	case A_PREFIX:
		/*
		 * In the prefix of a command.
		 */
		return (NO_MCA);

	case A_DIGIT:
		/*
		 * Entering digits of a number.
		 * Terminated by a non-digit.
		 */
		if ((c < '0' || c > '9') &&
			c != erase_char && c != kill_char)
		{
			/*
			 * Not part of the number.
			 * Treat as a normal command character.
			 */
			number = cmd_int();
			mca = 0;
			return (NO_MCA);
		}
		break;

	case A_TOGGLE_OPTION:
		/*
		 * Special case for the TOGGLE_OPTION command.
		 * if the option letter which was entered is a
		 * single-char option, execute the command immediately,
		 * so he doesn't have to hit RETURN.
		 */
		if (cp == cmdbuf && c != erase_char && c != kill_char &&
		    single_char_option(c))
		{
			cmdbuf[0] = c;
			cmdbuf[1] = '\0';
			toggle_option(cmdbuf, 1);
			return (MCA_DONE);
		}
		break;
	}

	/*
	 * Any other multicharacter command
	 * is terminated by a newline.
	 */
	if (c == '\n' || c == '\r')
	{
		/*
		 * Execute the command.
		 */
		exec_mca();
		return (MCA_DONE);
	}
	/*
	 * Append the char to the command buffer.
	 */
	if (cmd_char(c))
		/*
		 * Abort the multi-char command.
		 */
		return (MCA_DONE);
	/*
	 * Need another character.
	 */
	return (MCA_MORE);
}

/*
 * Main command processor.
 * Accept and execute commands until a quit command, then return.
 */
	public void
commands()
{
	register int c;
	register int action;

	last_mca = 0;
	scroll = (sc_height + 1) / 2;

	for (;;)
	{
		mca = 0;
		number = 0;

		/*
		 * See if any signals need processing.
		 */
		if (sigs)
		{
			psignals();
			if (quitting)
				quit();
		}
		/*
		 * Display prompt and accept a character.
		 */
		cmd_reset();
		prompt();
		noprefix();
		c = getcc();

again:		if (sigs)
			continue;

		/*
		 * If we are in a multicharacter command, call mca_char.
		 * Otherwise we call cmd_decode to determine the
		 * action to be performed.
		 */
		if (mca)
			switch (mca_char(c))
			{
			case MCA_MORE:
				/*
				 * Need another character.
				 */
				c = getcc();
				goto again;
			case MCA_DONE:
				/*
				 * Command has been handled by mca_char.
				 * Start clean with a prompt.
				 */
				continue;
			case NO_MCA:
				/*
				 * Not a multi-char command
				 * (at least, not anymore).
				 */
				break;
			}

		/*
		 * Decode the command character and decide what to do.
		 */
		switch (action = cmd_decode(c))
		{
		case A_DIGIT:
			/*
			 * First digit of a number.
			 */
			start_mca(A_DIGIT, ":");
			goto again;

		case A_F_SCREEN:
			/*
			 * Forward one screen.
			 */
			if (number <= 0)
				number = sc_window;
			if (number <= 0)
				number = sc_height - 1;
			cmd_exec();
			forward(number, 1);
			break;

		case A_B_SCREEN:
			/*
			 * Backward one screen.
			 */
			if (number <= 0)
				number = sc_window;
			if (number <= 0)
				number = sc_height - 1;
			cmd_exec();
			backward(number, 1);
			break;

		case A_F_LINE:
			/*
			 * Forward N (default 1) line.
			 */
			if (number <= 0)
				number = 1;
			cmd_exec();
			forward(number, 0);
			break;

		case A_B_LINE:
			/*
			 * Backward N (default 1) line.
			 */
			if (number <= 0)
				number = 1;
			cmd_exec();
			backward(number, 0);
			break;

		case A_F_SCROLL:
			/*
			 * Forward N lines 
			 * (default same as last 'd' or 'u' command).
			 */
			if (number > 0)
				scroll = number;
			cmd_exec();
			forward(scroll, 0);
			break;

		case A_B_SCROLL:
			/*
			 * Forward N lines 
			 * (default same as last 'd' or 'u' command).
			 */
			if (number > 0)
				scroll = number;
			cmd_exec();
			backward(scroll, 0);
			break;

		case A_FREPAINT:
			/*
			 * Flush buffers, then repaint screen.
			 * Don't flush the buffers on a pipe!
			 */
			if (!ispipe)
			{
				ch_init(0, 0);
				clr_linenum();
			}
			/* FALLTHRU */
		case A_REPAINT:
			/*
			 * Repaint screen.
			 */
			cmd_exec();
			repaint();
			break;

		case A_GOLINE:
			/*
			 * Go to line N, default beginning of file.
			 */
			if (number <= 0)
				number = 1;
			cmd_exec();
			jump_back(number);
			break;

		case A_PERCENT:
			/*
			 * Go to a specified percentage into the file.
			 */
			if (number < 0)
				number = 0;
			if (number > 100)
				number = 100;
			cmd_exec();
			jump_percent(number);
			break;

		case A_GOEND:
			/*
			 * Go to line N, default end of file.
			 */
			cmd_exec();
			if (number <= 0)
				jump_forw();
			else
				jump_back(number);
			break;

		case A_STAT:
			/*
			 * Print file name, etc.
			 */
			cmd_exec();
			lower_left();
			clear_eol();
			putstr(eq_message());
			lower_left();
			c = getcc();
			goto again;
		case A_QUIT:
			/*
			 * Exit.
			 */
			quit();

		case A_F_SEARCH:
		case A_B_SEARCH:
			/*
			 * Search for a pattern.
			 * Accept chars of the pattern until \n.
			 */
			if (number <= 0)
				number = 1;
			start_mca(action, (action==A_F_SEARCH) ? "/" : "?");
			last_mca = mca;
			wsearch = 1;
			c = getcc();
			if (c == '!')
			{
				/*
				 * Invert the sense of the search.
				 * Set wsearch to 0 and get a new
				 * character for the start of the pattern.
				 */
				start_mca(action, 
					(action==A_F_SEARCH) ? "!/" : "!?");
				wsearch = 0;
				c = getcc();
			}
			goto again;

		case A_AGAIN_SEARCH:
			/*
			 * Repeat previous search.
			 */
			if (number <= 0)
				number = 1;
			if (wsearch)
				start_mca(last_mca, 
					(last_mca==A_F_SEARCH) ? "/" : "?");
			else
				start_mca(last_mca, 
					(last_mca==A_F_SEARCH) ? "!/" : "!?");
			cmd_exec();
			search(mca==A_F_SEARCH, (char *)NULL, number, wsearch);
			break;

		case A_HELP:
			/*
			 * Help.
			 */
			lower_left();
			clear_eol();
			putstr("help");
			cmd_exec();
			help();
			break;

		case A_EXAMINE:
			/*
			 * Edit a new file.  Get the filename.
			 */
			cmd_reset();
			start_mca(A_EXAMINE, "Examine: ");
			c = getcc();
			goto again;
			
		case A_VISUAL:
			/*
			 * Invoke an editor on the input file.
			 */
			if (ispipe)
			{
				error("Cannot edit standard input");
				break;
			}
			cmd_exec();
			editfile();
			ch_init(0, 0);
			clr_linenum();
			break;

		case A_NEXT_FILE:
			/*
			 * Examine next file.
			 */
			if (number <= 0)
				number = 1;
			next_file(number);
			break;

		case A_PREV_FILE:
			/*
			 * Examine previous file.
			 */
			if (number <= 0)
				number = 1;
			prev_file(number);
			break;

		case A_TOGGLE_OPTION:
			/*
			 * Toggle a flag setting.
			 */
			cmd_reset();
			start_mca(A_TOGGLE_OPTION, "-");
			c = getcc();
			goto again;

		case A_DISP_OPTION:
			/*
			 * Report a flag setting.
			 */
			cmd_reset();
			start_mca(A_DISP_OPTION, "_");
			c = getcc();
			if (c == erase_char || c == kill_char)
				break;
			cmdbuf[0] = c;
			cmdbuf[1] = '\0';
			toggle_option(cmdbuf, 0);
			break;

		case A_FIRSTCMD:
			/*
			 * Set an initial command for new files.
			 */
			cmd_reset();
			start_mca(A_FIRSTCMD, "+");
			c = getcc();
			goto again;

		case A_SETMARK:
			/*
			 * Set a mark.
			 */
			lower_left();
			clear_eol();
			start_mca(A_SETMARK, "mark: ");
			c = getcc();
			if (c == erase_char || c == kill_char)
				break;
			setmark(c);
			break;

		case A_GOMARK:
			/*
			 * Go to a mark.
			 */
			lower_left();
			clear_eol();
			start_mca(A_GOMARK, "goto mark: ");
			c = getcc();
			if (c == erase_char || c == kill_char)
				break;
			gomark(c);
			break;

		case A_PREFIX:
			/*
			 * The command is incomplete (more chars are needed).
			 * Display the current char so the user knows
			 * what's going on and get another character.
			 */
			if (mca != A_PREFIX)
				start_mca(A_PREFIX, "& ");
			if (control_char(c))
			{
				putchr('^');
				c = carat_char(c);
			}
			putchr(c);
			c = getcc();
			goto again;

		default:
			bell();
			break;
		}
	}
}

static
editfile()
{
	static int dolinenumber;
	static char *editor;
	int c;
	char buf[MAXPATHLEN], *getenv();

	if (editor == NULL) {
		editor = getenv("EDITOR");
		/* pass the line number to vi */
		if (editor == NULL || *editor == '\0') {
			editor = "/usr/ucb/vi";
			dolinenumber = 1;
		}
		else
			dolinenumber = 0;
	}
	if (dolinenumber && (c = currline(MIDDLE)))
		(void)sprintf(buf, "%s +%d %s", editor, c, current_file);
	else
		(void)sprintf(buf, "%s %s", editor, current_file);
	lsystem(buf);
}