/* File: z-form.c */

/* Purpose: Low level text formatting -BEN- */

#include "z-form.h"

#include "z-util.h"

#include <stdlib.h>

/*
 * Here is some information about the routines in this file.
 *
 * In general, the following routines take a "buffer", a "max length",
 * a "format string", and some "arguments", and use the format string
 * and the arguments to create a (terminated) string in the buffer
 * (using only the first "max length" bytes), and return the "length"
 * of the resulting string, not including the (mandatory) terminator.
 *
 * The format strings allow the basic "sprintf()" format sequences,
 * though some of them are processed slightly more carefully or
 * portably, as well as a few "special" sequences, including the
 * "capilitization" sequences of "%C", "%S", and "%V".
 *
 * Note that some "limitations" are enforced by the current implementation,
 * for example, no "format sequence" can exceed 100 characters, including any
 * "length" restrictions, and the result of combining and "format sequence"
 * with the relevent "arguments" must not exceed 1000 characters.
 *
 * These limitations could be fixed by stealing some of the code from,
 * say, "vsprintf()" and placing it into my "vstrnfmt()" function.
 *
 * Note that a "^" inside a "format sequence" causes the first non-space
 * character in the string resulting from the combination of the format
 * sequence and the argument(s) to be "capitalized" if possible.  Note
 * that the "^" character is removed before the "standard" formatting
 * routines are called.  Likewise, a "*" inside a "format sequence" is
 * removed from the "format sequence", and replaced by the textual form
 * of the next argument in the argument list.  See examples below.
 *
 * Legal format characters: %,n,p,c,s,d,i,o,u,X,x,E,e,F,f,G,g,r,v.
 *
 * Format("%%")
 *   Append the literal "%".
 *   No legal modifiers.
 *
 * Format("%n", int *np)
 *   Save the current length into (*np).
 *   No legal modifiers.
 *
 * Format("%p", vptr v)
 *   Append the pointer "v" (implementation varies).
 *   No legal modifiers.
 *
 * Format("%E", double r)
 * Format("%F", double r)
 * Format("%G", double r)
 * Format("%e", double r)
 * Format("%f", double r)
 * Format("%g", double r)
 *   Append the double "r", in various formats.
 *
 * Format("%ld", long int i)
 *   Append the long integer "i".
 *
 * Format("%d", int i)
 *   Append the integer "i".
 *
 * Format("%lu", unsigned long int i)
 *   Append the unsigned long integer "i".
 *
 * Format("%u", unsigned int i)
 *   Append the unsigned integer "i".
 *
 * Format("%lo", unsigned long int i)
 *   Append the unsigned long integer "i", in octal.
 *
 * Format("%o", unsigned int i)
 *   Append the unsigned integer "i", in octal.
 *
 * Format("%lX", unsigned long int i)
 *   Note -- use all capital letters
 * Format("%lx", unsigned long int i)
 *   Append the unsigned long integer "i", in hexidecimal.
 *
 * Format("%X", unsigned int i)
 *   Note -- use all capital letters
 * Format("%x", unsigned int i)
 *   Append the unsigned integer "i", in hexidecimal.
 *
 * Format("%c", char c)
 *   Append the character "c".
 *   Do not use the "+" or "0" flags.
 *
 * Format("%s", cptr s)
 *   Append the string "s".
 *   Do not use the "+" or "0" flags.
 *   Note that a "NULL" value of "s" is converted to the empty string.
 *
 * Format("%V", vptr v)
 *   Note -- possibly significant mode flag
 *
 *
 * For examples below, assume "int n = 0; int m = 100; char buf[100];",
 * plus "char *s = NULL;", and unknown values "char *txt; int i;".
 *
 * For example: "n = strnfmt(buf, -1, "(Max %d)", i);" will have a
 * similar effect as "sprintf(buf, "(Max %d)", i); n = strlen(buf);".
 *
 * For example: "(void)strnfmt(buf, 16, "%s", txt);" will have a similar
 * effect as "strncpy(buf, txt, 16); buf[15] = '\0';".
 *
 * For example: "if (strnfmt(buf, 16, "%s", txt) < 16) ..." will have
 * a similar effect as "strcpy(buf, txt)" but with bounds checking.
 *
 * For example: "s = buf; s += vstrnfmt(s, -1, ...); ..." will allow
 * multiple "appends" to "buf" (at the cost of losing the max-length info).
 *
 * For example: "s = buf; n = vstrnfmt(s+n, 100-n, ...); ..." will allow
 * multiple bounded "appends" to "buf", with constant access to "strlen(buf)".
 *
 * For example: "format("%^-.*s", i, txt)" will produce a string containing
 * the first "i" characters of "txt", left justified, with the first non-space
 * character capitilized, if reasonable.
 */




/*
 * Basic "vararg" format function.
 *
 * This function takes a buffer, a max byte count, a format string, and
 * a va_list of arguments to the format string, and uses the format string
 * and the arguments to create a string to the buffer.  The string is
 * derived from the format string and the arguments in the manner of the
 * "sprintf()" function, but with some extra "format" commands.  Note that
 * this function will never use more than the given number of bytes in the
 * buffer, preventing messy invalid memory references.  This function then
 * returns the total number of non-null bytes written into the buffer.
 *
 * Method: Let "str" be the (unlimited) created string, and let "len" be the
 * smaller of "max-1" and "strlen(str)".  We copy the first "len" chars of
 * "str" into "buf", place "\0" into buf[len], and return "len".
 *
 * In English, we do a sprintf() into "buf", a buffer with size "max",
 * and we return the resulting value of "strlen(buf)", but we allow some
 * special format commands, and we are more careful than "sprintf()".
 *
 * Typically, "max" is in fact the "size" of "buf", and thus represents
 * the "number" of chars in "buf" which are ALLOWED to be used.  An
 * alternative definition would have required "buf" to hold at least
 * "max+1" characters, and would have used that extra character only
 * in the case where "buf" was too short for the result.  This would
 * give an easy test for "overflow", but a less "obvious" semantics.
 *
 * Note that if the buffer was "too short" to hold the result, we will
 * always return "max-1", but we also return "max-1" if the buffer was
 * "just long enough".  We could have returned "max" if the buffer was
 * too short, not written a null, and forced the programmer to deal with
 * this special case, but I felt that it is better to at least give a
 * "usable" result when the buffer was too long instead of either giving
 * a memory overwrite like "sprintf()" or a non-terminted string like
 * "strncpy()".  Note that "strncpy()" also "null-pads" the result.
 *
 * Note that in most cases "just long enough" is probably "too short".
 *
 * We should also consider extracting and processing the "width" and other
 * "flags" by hand, it might be more "accurate", and it would allow us to
 * remove the limit (1000 chars) on the result of format sequences.
 *
 * Also, some sequences, such as "%+d" by hand, do not work on all machines,
 * and could thus be correctly handled here.
 *
 * Error detection in this routine is not very graceful, in particular,
 * if an error is detected in the format string, we simply "pre-terminate"
 * the given buffer to a length of zero, and return a "length" of zero.
 * The contents of "buf", except for "buf[0]", may then be undefined.
 */
uint vstrnfmt(char *buf, uint max, cptr fmt, va_list vp)
{
	cptr s;

	/* The argument is "long" */
	bool_ do_long;

	/* The argument needs "processing" */
	bool_ do_xtra;

	/* Bytes used in buffer */
	uint n;

	/* Bytes used in format sequence */
	uint q;

	/* Format sequence */
	char aux[128];

	/* Resulting string */
	char tmp[1024];


	/* Mega-Hack -- treat "illegal" length as "infinite" */
	if (!max) max = 32767;

	/* Mega-Hack -- treat "no format" as "empty string" */
	if (!fmt) fmt = "";


	/* Begin the buffer */
	n = 0;

	/* Begin the format string */
	s = fmt;

	/* Scan the format string */
	while (TRUE)
	{
		/* All done */
		if (!*s) break;

		/* Normal character */
		if (*s != '%')
		{
			/* Check total length */
			if (n == max - 1) break;

			/* Save the character */
			buf[n++] = *s++;

			/* Continue */
			continue;
		}

		/* Skip the "percent" */
		s++;

		/* Pre-process "%%" */
		if (*s == '%')
		{
			/* Check total length */
			if (n == max - 1) break;

			/* Save the percent */
			buf[n++] = '%';

			/* Skip the "%" */
			s++;

			/* Continue */
			continue;
		}

		/* Pre-process "%n" */
		if (*s == 'n')
		{
			int *arg;

			/* Access the next argument */
			arg = va_arg(vp, int *);

			/* Save the current length */
			(*arg) = n;

			/* Skip the "n" */
			s++;

			/* Continue */
			continue;
		}


		/* Begin the "aux" string */
		q = 0;

		/* Save the "percent" */
		aux[q++] = '%';

		/* Assume no "long" argument */
		do_long = FALSE;

		/* Assume no "xtra" processing */
		do_xtra = FALSE;

		/* Build the "aux" string */
		while (TRUE)
		{
			/* Error -- format sequence is not terminated */
			if (!*s)
			{
				/* Terminate the buffer */
				buf[0] = '\0';

				/* Return "error" */
				return (0);
			}

			/* Error -- format sequence may be too long */
			if (q > 100)
			{
				/* Terminate the buffer */
				buf[0] = '\0';

				/* Return "error" */
				return (0);
			}

			/* Handle "alphabetic" chars */
			if (isalpha(*s))
			{
				/* Hack -- handle "long" request */
				if (*s == 'l')
				{
					/* Save the character */
					aux[q++] = *s++;

					/* Note the "long" flag */
					do_long = TRUE;
				}

				/* Mega-Hack -- handle "extra-long" request */
				else if (*s == 'L')
				{
					/* Error -- illegal format char */
					buf[0] = '\0';

					/* Return "error" */
					return (0);
				}

				/* Handle normal end of format sequence */
				else
				{
					/* Save the character */
					aux[q++] = *s++;

					/* Stop processing the format sequence */
					break;
				}
			}

			/* Handle "non-alphabetic" chars */
			else
			{
				/* Hack -- Handle 'star' (for "variable length" argument) */
				if (*s == '*')
				{
					int arg;

					/* Access the next argument */
					arg = va_arg(vp, int);

					/* Hack -- append the "length" */
					sprintf(aux + q, "%d", arg);

					/* Hack -- accept the "length" */
					while (aux[q]) q++;

					/* Skip the "*" */
					s++;
				}

				/* Mega-Hack -- Handle 'caret' (for "uppercase" request) */
				else if (*s == '^')
				{
					/* Note the "xtra" flag */
					do_xtra = TRUE;

					/* Skip the "^" */
					s++;
				}

				/* Collect "normal" characters (digits, "-", "+", ".", etc) */
				else
				{
					/* Save the character */
					aux[q++] = *s++;
				}
			}
		}


		/* Terminate "aux" */
		aux[q] = '\0';

		/* Clear "tmp" */
		tmp[0] = '\0';

		/* Process the "format" char */
		switch (aux[q - 1])
		{
			/* Simple Character -- standard format */
		case 'c':
			{
				int arg;

				/* Access next argument */
				arg = va_arg(vp, int);

				/* Format the argument */
				sprintf(tmp, aux, arg);

				/* Done */
				break;
			}

			/* Signed Integers -- standard format */
		case 'd':
		case 'i':
			{
				if (do_long)
				{
					long arg;

					/* Access next argument */
					arg = va_arg(vp, long);

					/* Format the argument */
					sprintf(tmp, aux, arg);
				}
				else
				{
					int arg;

					/* Access next argument */
					arg = va_arg(vp, int);

					/* Format the argument */
					sprintf(tmp, aux, arg);
				}

				/* Done */
				break;
			}

			/* Unsigned Integers -- various formats */
		case 'u':
		case 'o':
		case 'x':
		case 'X':
			{
				if (do_long)
				{
					unsigned long arg;

					/* Access next argument */
					arg = va_arg(vp, unsigned long);

					/* Format the argument */
					sprintf(tmp, aux, arg);
				}
				else
				{
					unsigned int arg;

					/* Access next argument */
					arg = va_arg(vp, unsigned int);

					/* Format the argument */
					sprintf(tmp, aux, arg);
				}

				/* Done */
				break;
			}

			/* Floating Point -- various formats */
		case 'f':
		case 'e':
		case 'E':
		case 'g':
		case 'G':
			{
				double arg;

				/* Access next argument */
				arg = va_arg(vp, double);

				/* Format the argument */
				sprintf(tmp, aux, arg);

				/* Done */
				break;
			}

			/* Pointer -- implementation varies */
		case 'p':
			{
				vptr arg;

				/* Access next argument */
				arg = va_arg(vp, vptr);

				/* Format the argument */
				sprintf(tmp, aux, arg);

				/* Done */
				break;
			}

			/* String */
		case 's':
			{
				cptr arg;

				/* Access next argument */
				arg = va_arg(vp, cptr);

				/* Hack -- convert NULL to EMPTY */
				if (!arg) arg = "";

				/* Format the argument */
				sprintf(tmp, aux, arg);

				/* Done */
				break;
			}

			/* Oops */
		default:
			{
				/* Error -- illegal format char */
				buf[0] = '\0';

				/* Return "error" */
				return (0);
			}
		}


		/* Mega-Hack -- handle "capitilization" */
		if (do_xtra)
		{
			capitalize(tmp);
		}

		/* Now append "tmp" to "buf" */
		for (q = 0; tmp[q]; q++)
		{
			/* Check total length */
			if (n == max - 1) break;

			/* Save the character */
			buf[n++] = tmp[q];
		}
	}


	/* Terminate buffer */
	buf[n] = '\0';

	/* Return length */
	return (n);
}


/*
 * Do a vstrnfmt (see above) into a (growable) static buffer.
 * This buffer is usable for very short term formatting of results.
 */
static char *vformat(cptr fmt, va_list vp)
{
	static char *format_buf = NULL;
	static size_t format_len = 0;

	/* Initial allocation */
	if (!format_buf)
	{
		format_len = 1024;
		format_buf = calloc(format_len, sizeof(char));
		if (format_buf == NULL)
		{
			abort(); // Nothing sensible we can do
		}
	}

	/* Null format yields last result */
	if (!fmt) return (format_buf);

	/* Keep going until successful */
	while (1)
	{
		uint len;

		/* Build the string */
		len = vstrnfmt(format_buf, format_len, fmt, vp);

		/* Success */
		if (len < format_len - 1) break;

		/* Grow the buffer */
		free(format_buf);
		format_len = format_len * 2;
		format_buf = calloc(format_len, sizeof(char));
		if (format_buf == NULL)
		{
			abort(); // Nothing sensible we can do
		}
	}

	/* Return the new buffer */
	return (format_buf);
}



/*
 * Do a vstrnfmt (see above) into a buffer of a given size.
 */
uint strnfmt(char *buf, uint max, cptr fmt, ...)
{
	uint len;

	va_list vp;

	/* Begin the Varargs Stuff */
	va_start(vp, fmt);

	/* Do a virtual fprintf to stderr */
	len = vstrnfmt(buf, max, fmt, vp);

	/* End the Varargs Stuff */
	va_end(vp);

	/* Return the number of bytes written */
	return (len);
}




/*
 * Do a vstrnfmt() into (see above) into a (growable) static buffer.
 * This buffer is usable for very short term formatting of results.
 * Note that the buffer is (technically) writable, but only up to
 * the length of the string contained inside it.
 */
char *format(cptr fmt, ...)
{
	char *res;
	va_list vp;

	/* Begin the Varargs Stuff */
	va_start(vp, fmt);

	/* Format the args */
	res = vformat(fmt, vp);

	/* End the Varargs Stuff */
	va_end(vp);

	/* Return the result */
	return (res);
}




/*
 * Vararg interface to quit()
 */
void quit_fmt(cptr fmt, ...)
{
	char *res;
	va_list vp;

	/* Begin the Varargs Stuff */
	va_start(vp, fmt);

	/* Format */
	res = vformat(fmt, vp);

	/* End the Varargs Stuff */
	va_end(vp);

	/* Call quit() */
	quit(res);
}