/*

 * Copyright (C) 2020 Igalia, S.L.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public License

 * along with this library; see the file COPYING.LIB.  If not, write to

 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#include <stdlib.h>

#include "soup-date-utils.h"

#include "soup-date-utils-private.h"

/**

 * soup_date_time_is_past:

 * @date: a #GDateTime

 *

 * Determines if @date is in the past.

 *

 * Returns: %TRUE if @date is in the past

 */

gboolean

soup_date_time_is_past (GDateTime *date)

{

        g_return_val_if_fail (date != NULL, TRUE);

  /* optimization */

  if (g_date_time_get_year (date) < 2025)

    return TRUE;

  return g_date_time_to_unix (date) < time (NULL);

}

/**

 * SoupDateFormat:

 * @SOUP_DATE_HTTP: RFC 1123 format, used by the HTTP "Date" header. Eg

 *   "Sun, 06 Nov 1994 08:49:37 GMT".

 * @SOUP_DATE_COOKIE: The format for the "Expires" timestamp in the

 *   Netscape cookie specification. Eg, "Sun, 06-Nov-1994 08:49:37 GMT".

 *

 * Date formats that [func@date_time_to_string] can use.

 *

 * @SOUP_DATE_HTTP and @SOUP_DATE_COOKIE always coerce the time to

 * UTC.

 *

 * This enum may be extended with more values in future releases.

 **/

/* Do not internationalize */

static const char *const months[] = {

  "Jan", "Feb", "Mar", "Apr", "May", "Jun",

  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"

};

/* Do not internationalize */

static const char *const days[] = {

  "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"

};

/**

 * soup_date_time_to_string:

 * @date: a #GDateTime

 * @format: the format to generate the date in

 *

 * Converts @date to a string in the format described by @format.

 *

 * Returns: (transfer full): @date as a string or %NULL

 **/

char *

soup_date_time_to_string (GDateTime      *date,

                          SoupDateFormat  format)

{

  g_return_val_if_fail (date != NULL, NULL);

  if (format == SOUP_DATE_HTTP || format == SOUP_DATE_COOKIE) {

    /* HTTP and COOKIE formats require UTC timestamp, so coerce

     * @date if it's non-UTC.

     */

    GDateTime *utcdate = g_date_time_to_utc (date);

                char *date_format;

                char *formatted_date;

                if (!utcdate)

                        return NULL;

                // We insert days/months ourselves to avoid locale specific formatting

                if (format == SOUP_DATE_HTTP) {

      /* "Sun, 06 Nov 1994 08:49:37 GMT" */

                        date_format = g_strdup_printf ("%s, %%d %s %%Y %%T GMT",

                                                       days[g_date_time_get_day_of_week (utcdate) - 1],

                                                       months[g_date_time_get_month (utcdate) - 1]);

                } else {

      /* "Sun, 06-Nov-1994 08:49:37 GMT" */

                        date_format = g_strdup_printf ("%s, %%d-%s-%%Y %%T GMT",

                                                       days[g_date_time_get_day_of_week (utcdate) - 1],

                                                       months[g_date_time_get_month (utcdate) - 1]);

    }

                formatted_date = g_date_time_format (utcdate, (const char*)date_format);

                g_date_time_unref (utcdate);

                g_free (date_format);

                return formatted_date;

  }

        g_return_val_if_reached (NULL);

}

static inline gboolean

parse_day (int *day, const char **date_string)

{

  char *end;

  *day = strtoul (*date_string, &end, 10);

  if (end == (char *)*date_string)

    return FALSE;

  while (*end == ' ' || *end == '-')

    end++;

  *date_string = end;

  return *day >= 1 && *day <= 31;

}

static inline gboolean

parse_month (int *month, const char **date_string)

{

  int i;

  for (i = 0; i < G_N_ELEMENTS (months); i++) {

    if (!g_ascii_strncasecmp (*date_string, months[i], 3)) {

      *month = i + 1;

      *date_string += 3;

      while (**date_string == ' ' || **date_string == '-')

        (*date_string)++;

      return TRUE;

    }

  }

  return FALSE;

}

static inline gboolean

parse_year (int *year, const char **date_string)

{

  char *end;

  *year = strtoul (*date_string, &end, 10);

  if (end == (char *)*date_string)

    return FALSE;

  if (end == (char *)*date_string + 2) {

    if (*year < 70)

      *year += 2000;

    else

      *year += 1900;

  } else if (end == (char *)*date_string + 3)

    *year += 1900;

  while (*end == ' ' || *end == '-')

    end++;

  *date_string = end;

  return *year > 0 && *year < 9999;

}

static inline gboolean

parse_time (int *hour, int *minute, int *second, const char **date_string)

{

  char *p, *end;

  *hour = strtoul (*date_string, &end, 10);

  if (end == (char *)*date_string || *end++ != ':')

    return FALSE;

  p = end;

  *minute = strtoul (p, &end, 10);

  if (end == p || *end++ != ':')

    return FALSE;

  p = end;

  *second = strtoul (p, &end, 10);

  if (end == p)

    return FALSE;

  p = end;

  while (*p == ' ')

    p++;

  *date_string = p;

  return *hour >= 0 && *hour < 24 && *minute >= 0 && *minute < 60 && *second >= 0 && *second < 60;

}

static inline gboolean

parse_timezone (GTimeZone **timezone, const char **date_string)

{

        gint32 offset_minutes;

        gboolean utc;

  if (!**date_string) {

                utc = FALSE;

    offset_minutes = 0;

  } else if (**date_string == '+' || **date_string == '-') {

    gulong val;

    int sign = (**date_string == '+') ? 1 : -1;

    val = strtoul (*date_string + 1, (char **)date_string, 10);

    if (val > 9999)

      return FALSE;

    if (**date_string == ':') {

      gulong val2 = strtoul (*date_string + 1, (char **)date_string, 10);

      if (val > 99 || val2 > 99)

        return FALSE;

      val = 60 * val + val2;

    } else

      val =  60 * (val / 100) + (val % 100);

    offset_minutes = sign * val;

    utc = (sign == -1) && !val;

  } else if (**date_string == 'Z') {

    offset_minutes = 0;

    utc = TRUE;

    (*date_string)++;

  } else if (!strcmp (*date_string, "GMT") ||

       !strcmp (*date_string, "UTC")) {

    offset_minutes = 0;

    utc = TRUE;

    (*date_string) += 3;

  } else if (strchr ("ECMP", **date_string) &&

       ((*date_string)[1] == 'D' || (*date_string)[1] == 'S') &&

       (*date_string)[2] == 'T') {

    offset_minutes = -60 * (5 * strcspn ("ECMP", *date_string));

    if ((*date_string)[1] == 'D')

      offset_minutes += 60;

                utc = FALSE;

  } else

    return FALSE;

        if (utc)

                *timezone = g_time_zone_new_utc ();

        else

                *timezone = g_time_zone_new_offset (offset_minutes * 60);

  return TRUE;

}

static GDateTime *

parse_textual_date (const char *date_string)

{

        int month, day, year, hour, minute, second;

        GTimeZone *tz = NULL;

        GDateTime *date;

  /* If it starts with a word, it must be a weekday, which we skip */

  if (g_ascii_isalpha (*date_string)) {

    while (g_ascii_isalpha (*date_string))

      date_string++;

    if (*date_string == ',')

      date_string++;

    while (g_ascii_isspace (*date_string))

      date_string++;

  }

  /* If there's now another word, this must be an asctime-date */

  if (g_ascii_isalpha (*date_string)) {

    /* (Sun) Nov  6 08:49:37 1994 */

    if (!parse_month (&month, &date_string) ||

        !parse_day (&day, &date_string) ||

        !parse_time (&hour, &minute, &second, &date_string) ||

        !parse_year (&year, &date_string) ||

        !g_date_valid_dmy (day, month, year))

      return NULL;

    /* There shouldn't be a timezone, but check anyway */

    parse_timezone (&tz, &date_string);

  } else {

    /* Non-asctime date, so some variation of

     * (Sun,) 06 Nov 1994 08:49:37 GMT

     */

    if (!parse_day (&day, &date_string) ||

        !parse_month (&month, &date_string) ||

        !parse_year (&year, &date_string) ||

        !parse_time (&hour, &minute, &second, &date_string) ||

        !g_date_valid_dmy (day, month, year))

      return NULL;

    /* This time there *should* be a timezone, but we

     * survive if there isn't.

     */

    parse_timezone (&tz, &date_string);

  }

        if (!tz)

                tz = g_time_zone_new_utc ();

        date = g_date_time_new (tz, year, month, day, hour, minute, second);

        g_time_zone_unref (tz);

        return date;

}

/**

 * soup_date_time_new_from_http_string:

 * @date_string: The date as a string

 *

 * Parses @date_string and tries to extract a date from it.

 *

 * This recognizes all of the "HTTP-date" formats from RFC 2616, RFC 2822 dates,

 * and reasonable approximations thereof. (Eg, it is lenient about whitespace,

 * leading "0"s, etc.)

 *

 * Returns: (nullable): a new #GDateTime, or %NULL if @date_string

 *   could not be parsed.

 **/

GDateTime *

soup_date_time_new_from_http_string (const char *date_string)

{

        g_return_val_if_fail (date_string != NULL, NULL);

  while (g_ascii_isspace (*date_string))

    date_string++;

        /* If it starts with a digit, it's either an ISO 8601 date, or

         * an RFC2822 date without the optional weekday; in the later

         * case, there will be a month name later on, so look for one

         * of the month-start letters.

         * Previous versions of this library supported parsing iso8601 strings

         * however g_date_time_new_from_iso8601() should be used now. Just

         * catch those in case for testing.

         */

  if (G_UNLIKELY (g_ascii_isdigit (*date_string) && !strpbrk (date_string, "JFMASOND"))) {

                g_debug ("Unsupported format passed to soup_date_time_new_from_http_string(): %s", date_string);

                return NULL;

        }

  return parse_textual_date (date_string);

}