#include <stdio.h>
#include <unistd.h>
#include "arraylen.h"

/* Thanks to u/smcameron on Reddit. */

#define TAB_WIDTH 8

/* Changing ENUM to DEFINE will make this output the traditional BSD header
 * verbatim, without copyright notice. I don't have any idea if that's a
 * copyright violation, but let's keep this as ENUM to skirt by that little
 * technicality.
 * I implemented sysexits(3) in the enum method before reading the BSD 4.0
 * source to see how they did it. */
#define ENUM 1

static char *program_name = "sysexits";

static const char comment_prefix[] = "/* ";
static const char comment_prefix_ongoing[] = " * ";
static const char comment_suffix[] = " */\n";

static const char header_prefix[] =
	"#ifndef _SYSEXITS_H\n"
	"#\tdefine _SYSEXITS_H\n"
	"enum{\n"
;

/* ASSUMPTIONS:
 * - This array is always organized.
 * - All characters in descriptions are one space wide.
 * - The only whitespace in descriptions is ASCII_SP. */
static const struct {
	char *desc;
	char *name;
	int status;
}sysexits[] = {
	/* sysexit descriptions copied from FreeBSD's sysexits(3). */

	{ "All is well.", /* except this one */
	"EX_OK", 0 },

	{ "The command was used incorrectly, e.g., with the wrong number of"
	" arguments, a bad flag, a bad syntax in a parameter, or whatever.",
	"EX_USAGE", 64 },

	{ "The input data was incorrect in some way. This should only be used"
	" for user's data and not system files.",
	"EX_DATAERR", 65 },

	{ "An input file (not a system file) did not exist or was not readable."
	" This could also include errors like \"No message\" to a mailer (if it"
	" cared to catch it).",
	 "EX_NOINPUT", 66 },

	{ "The user specified did not exist. This might be used for mail"
	" addresses or remote logins.",
	 "EX_NOUSER", 67 },

	{ "The host specified did not exist. This is used in mail addresses or"
	" network requests.",
	 "EX_NOHOST", 68 },

	{ "A service is unavailable. This can occur if a support program or"
	" file does not exist. This can also be used as a catchall message"
	" when something you wanted to do does not work, but you do not know"
	" why.",
	"EX_UNAVAILABLE", 69 },

	{ "An internal software error has been detected. This should be limited"
	" to non-operating system related errors as possible.",
	"EX_SOFTWARE", 70 },

	{ "An operating system error has been detected. This is intended to be"
	" used for such things as \"cannot fork\", \"cannot create pipe\", or"
	" the like. It includes things like getuid returning a user that does"
	" not exist in the passwd file.",
	"EX_OSERR", 71 },

	{ "Some system file (e.g., /etc/passwd, /var/run/utx.active, etc.) does"
	" not exist, cannot be opened, or has some sort of error (e.g., syntax"
	" error).",
	"EX_OSFILE", 72 },

	{ "A (user specified) output file cannot be created.",
	"EX_CANTCREAT", 73 },

	{ "An error occurred while doing I/O on some file.",
	"EX_IOERR", 74 },

	{ "Temporary failure, indicating something that is not really an error."
	" In sendmail, this means that a mailer (e.g.) could not create a"
	" connection, and the request should be reattempted later.",
	"EX_TEMPFAIL", 75 },

	{ "The remote system returned something that was \"not possible\" during a"
	" protocol exchange.",
	"EX_PROTOCOL", 76 },

	{ "You did not have sufficient permission to perform the operation."
	" This is not intended for file system problems, which should use"
	" EX_NOINPUT or EX_CANTCREAT, but rather for higher level"
	" permissions.",
	"EX_NOPERM", 77 },

	{ "Something was found in an unconfigured or misconfigured state.",
	"EX_CONFIG", 78 }
};

static const char header_suffix[] =
	"};\n"
	"#endif /* ifndef _SYSEXITS_H */\n"
;

static size_t i;

static int findbyint(int status){
	for(i = 0; i < ARRAYLEN(sysexits); ++i)
		if(sysexits[i].status == status)
			return i;
	return -1;
}

static void output_comment(int fd, int indentation, int width, char *comment){
	size_t word_start;
	size_t line_start;

	for(i = 0, line_start = 0, word_start = 0; ; ++i)
		switch(comment[i]){
		case '\0':
			while(		i - line_start 
					+ ARRAYLEN(comment_suffix)
					+ indentation * TAB_WIDTH
					> width){
				i = word_start - 2; /* - current char, - space */
				write(
					fd, comment_prefix_ongoing,
					ARRAYLEN(comment_prefix_ongoing)
				);
				write(fd, comment + line_start, i - line_start);
				i += 2; /* + space, + next word char */
				write(fd, "\n", 1);
			}
			write(fd, comment + line_start, i - line_start);
			write(fd, comment_suffix, ARRAYLEN(comment_suffix));
			break;
		}

	return;
}

static void output_header(void){
	write(1, header_prefix, ARRAYLEN(header_prefix) - 1);
	for(i = 0; i < ARRAYLEN(sysexits); ++i){
		//output_comment(1, 1 * TAB_WIDTH, 80, sysexits[i].desc);
		#ifdef ENUM
		fprintf(stdout, "\t%s = %d%s",
			sysexits[i].name,
			sysexits[i].status,
			i < ARRAYLEN(sysexits) - 1 ? ",\n" : "\n"
		);
		#endif /* ifdef ENUM */
		#ifdef DEFINE
		fprintf(stdout, "#\tdefine %s %d\n",
			sysexits[i].name,
			sysexits[i].status
		);
		#endif /* ifdef DEFINE */
	}
	fflush(stdout);
	write(1, header_suffix, ARRAYLEN(header_suffix) - 1);
}

int main(int argc, char *argv[]){
	if(argv[0] == NULL){
		argv[0] = program_name;
		++argc;
	}

	output_header();
	return 0;
}