/*
 * Copyright (C) 1995.  Bill Brown <brown@gis.uiuc.edu> & Michael Shapiro
 *
 * This program is free software under the GPL (>=v2)
 * Read the file GPL.TXT coming with GRASS for details.
 */
#include <stdio.h>
#include <string.h>
#include <grass/datetime.h>


static char *months[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
			 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

/*!
 * \brief
 *
 * formats DateTime structure as a human-readable string
 * returns 0 when successful and 'buf' is filled with the string
 * returns a negative number on error
 *
 * \param dt
 * \param buf
 * \return int
 */

int datetime_format ( const DateTime *dt, char *buf)
{
/* Format the DateTime structure as a human-readable string */
/*  Returns 0 when successful, and buf is filled with the
      formatted data.
    Returns a negative number as an error code if the DateTime
      structure is not valid.
*/
    char temp[128];
    int n;
    double sec;

    *buf = 0;
    if(!datetime_is_valid_type(dt))
	return datetime_error_code();
    
    if(datetime_is_absolute(dt))
    {
	if (datetime_get_day(dt, &n) == 0)
	{
	    sprintf (temp, "%d", n);
	    strcat (buf, temp);
	}

	if (datetime_get_month(dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    strcat (buf, months[n-1]);
	}

	if (datetime_get_year (dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    sprintf (temp, "%d", n);
	    strcat (buf, temp);
	    if (datetime_is_negative(dt))
		strcat (buf, " bc");
	}

	if (datetime_get_hour(dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    sprintf (temp, "%02d", n);
	    strcat (buf, temp);
	}

	if (datetime_get_minute(dt, &n) == 0)
	{
	    if (*buf) strcat (buf, ":");
	    sprintf (temp, "%02d", n);
	    strcat (buf, temp);
	}

	if (datetime_get_second(dt, &sec) == 0)
	{
	    if (*buf) strcat (buf, ":");
	    if (datetime_get_fracsec(dt, &n) != 0)
		n = 0;
	    sprintf (temp, "%02.*f", n, sec);
	    strcat (buf, temp);
	}

	if (datetime_get_timezone (dt, &n) == 0)
	{
	    int hour, minute;

	    if (*buf) strcat (buf, " ");
	    datetime_decompose_timezone (n, &hour, &minute);
	    sprintf (temp, "%s%02d%02d", n<0?"-":"+",hour,minute);
	    strcat (buf, temp);
	}
    }

    if(datetime_is_relative(dt))
    {
	if (datetime_is_negative(dt))
	    strcat (buf, "-");

	if (datetime_get_year (dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    sprintf (temp, "%d year%s", n, n==1?"":"s");
	    strcat (buf, temp);
	}

	if (datetime_get_month(dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    sprintf (temp, "%d month%s", n, n==1?"":"s");
	    strcat (buf, temp);
	}

	if (datetime_get_day(dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    sprintf (temp, "%d day%s", n, n==1?"":"s");
	    strcat (buf, temp);
	}

	if (datetime_get_hour(dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    sprintf (temp, "%d hour%s", n, n==1?"":"s");
	    strcat (buf, temp);
	}

	if (datetime_get_minute(dt, &n) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    sprintf (temp, "%d minute%s", n, n==1?"":"s");
	    strcat (buf, temp);
	}

	if (datetime_get_second(dt, &sec) == 0)
	{
	    if (*buf) strcat (buf, " ");
	    if (datetime_get_fracsec(dt, &n) != 0)
		n = 0;
	    sprintf (temp, "%.*f second%s", n, sec, (sec==1.0&&n==0)?"":"s");
	    strcat (buf, temp);
	}
    }

    return 0;
}
