/* -*- c -*- */
/* See LICENSE file for copyright and license details. */
#include "libgamma-error.h"


#include <stddef.h>
#include <sys/types.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>



$>set -u
$>cd src/extract
$>export PATH=".:${PATH}"



/**
 * Group that the user needs to be a member of if
 * `LIBGAMMA_DEVICE_REQUIRE_GROUP` is returned
 */
#ifndef __WIN32__
__thread gid_t libgamma_group_gid = 0;
gid_t
libgamma_group_gid_get(void)
{
	return libgamma_group_gid;
}
void
libgamma_group_gid_set(gid_t value)
{
	libgamma_group_gid = value;
}
#else
short libgamma_group_gid = 0;
#endif

/**
 * Group that the user needs to be a member of if
 * `LIBGAMMA_DEVICE_REQUIRE_GROUP` is returned,
 * `NULL` if the name of the group `libgamma_group_gid`
 * cannot be determined
 */
#ifndef __WIN32__
__thread const char *libgamma_group_name = NULL;
const char *
libgamma_group_name_get(void) {
	return libgamma_group_name;
}
void
libgamma_group_name_set(const char *value)
{
	libgamma_group_name = value;
}
#else
const char *libgamma_group_name = NULL;
#endif



/**
 * Prints an error to stderr in a `perror` fashion,
 * however this function will not translate the `libgamma`
 * errors into human-readable strings, it will simply
 * print the name of the error. If the value `error_code`
 * is the value of `LIBGAMMA_ERRNO_SET`, `perror` will be
 * used to print the current error stored in `errno`.
 * If `error_code` is non-negative (an `errno` value`), that
 * value will be stored in `errno` and `perror` will be
 * used to print it. Additionally, if the `error_code` is
 * the value of `LIBGAMMA_DEVICE_REQUIRE_GROUP` the
 * required group will be printed with its numerical value
 * and, if known, its name.
 * 
 * @param  name   The text to add at the beginning
 * @param  value  The error code, may be an `errno` value
 */
void
libgamma_perror(const char *name, int error_code)
{
	const char *error;
	long int gid;

	if (error_code >= 0) {
		/* Print the stored errno value */
		errno = error_code;
		perror(name);
	} else if (error_code == LIBGAMMA_ERRNO_SET) {
		/* Print errno */
		perror(name);
	} else if (error_code == LIBGAMMA_DEVICE_REQUIRE_GROUP) {
		/* Print the error name and the required group membership */
		error = libgamma_name_of_error(error_code);
		gid = (long int)libgamma_group_gid;
		if (!libgamma_group_name) {
			/* Group name unknown */
			if (name && *name)
				fprintf(stderr, "%s: %s: %ld\n", name, error, gid);
			else
				fprintf(stderr, "%s: %ld\n", error, gid);
		} else {
			/* Group name known, ID is second class */
			if (name && *name)
				fprintf(stderr, "%s: %s: %s (%ld)\n", name, error, libgamma_group_name, gid);
			else
				fprintf(stderr, "%s: %s (%ld)\n", error, libgamma_group_name, gid);
		}
	} else if (error_code < LIBGAMMA_ERROR_MIN) {
		/* If the error code does not exist, print "(?)" */
		if (name && *name)
			fprintf(stderr, "%s: (?)\n", name);
		else
			fprintf(stderr, "(?)\n");
	} else {
		/* Print the name of the error */
		if (name && *name)
			fprintf(stderr, "%s: %s\n", name, libgamma_name_of_error(error_code));
		else
			fprintf(stderr, "%s\n", libgamma_name_of_error(error_code));
	}
}


/**
 * Returns the name of the definition associated with a `libgamma` error code
 * 
 * @param   value  The error code
 * @return         The name of the definition associated with the error code,
 *                 `NULL` if the error code does not exist; the return string
 *                 should not be `free`:d
 */
const char *
libgamma_name_of_error(int value)
{
	/* Map from error codes to error names.
	   The output of $(libgamma-error-extract --list)
	   is sorted by error code in decreasing order */
	static const char* error_names[] = {
$>for error in $(libgamma-error-extract --list); do
		"${error}",
$>done
	};

	/* Return `NULL` if the error code is invalid */
	if (value < LIBGAMMA_ERROR_MIN || value >= 0)
		return NULL;

	/* Convert error code from {-1, -2, -3, ...} to {0, 1, 2, ...}
	 * and look up the error's name and return it */
	return error_names[-value - 1];
}


/**
 * Return the value of a `libgamma` error definition refered to by name
 * 
 * @param   name  The name of the definition associated with the error code
 * @return        The error code, zero if the name does is `NULL`
 *                or does not refer to a `libgamma` error
 */
int
libgamma_value_of_error(const char *name)
{
	/* Return 0 (not a valid error code) if the error name is `NULL` */
	if (!name)
		return 0;

	/* Test error names against `name` and return the value of the match error */
$>for error in $(libgamma-error-extract --list); do
	if (!strcmp(name, "${error}"))
		return ${error};
$>done

	/* Return 0 (not a valid error code) if the error name is unknown */
	return 0;
}