/* -*- mode: c; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 * gcal-utils.c
 *
 * Copyright (C) 2012 - Erick Pérez Castellanos
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#define G_LOG_DOMAIN "Utils"

#include "gcal-utils.h"
#include "gcal-event-widget.h"
#include "gcal-view.h"

#include <libecal/libecal.h>
#include <libedataserver/libedataserver.h>

#include <glib/gi18n.h>

#include <langinfo.h>

#include <string.h>
#include <math.h>

/**
 * SECTION:gcal-utils
 * @short_description: Utility functions
 * @title:Utility functions
 */

static const gint
ab_day[7] =
{
  ABDAY_1,
  ABDAY_2,
  ABDAY_3,
  ABDAY_4,
  ABDAY_5,
  ABDAY_6,
  ABDAY_7,
};

static const gint
month_item[12] =
{
  MON_1,
  MON_2,
  MON_3,
  MON_4,
  MON_5,
  MON_6,
  MON_7,
  MON_8,
  MON_9,
  MON_10,
  MON_11,
  MON_12
};

#define SCROLL_HARDNESS 10.0

G_DEFINE_BOXED_TYPE (icaltimetype, icaltime, gcal_dup_icaltime, g_free)

/**
 * datetime_compare_date:
 * @dt1: (nullable): a #GDateTime
 * @dt2: (nullable): a #GDateTime
 *
 * Compares the dates of @dt1 and @dt2. The times are
 * ignored.
 *
 * Returns: negative, 0 or positive
 */
gint
datetime_compare_date (GDateTime *dt1,
                       GDateTime *dt2)
{
  if (!dt1 && !dt2)
    return 0;
  else if (!dt1)
    return -1;
  else if (!dt2)
    return 1;

  if (g_date_time_get_year (dt1) != g_date_time_get_year (dt2))
    return (g_date_time_get_year (dt1) - g_date_time_get_year (dt2)) * 360;

  if (g_date_time_get_month (dt1) != g_date_time_get_month (dt2))
    return (g_date_time_get_month (dt1) - g_date_time_get_month (dt2)) * 30;

  if (g_date_time_get_day_of_month (dt1) != g_date_time_get_day_of_month (dt2))
    return g_date_time_get_day_of_month (dt1) - g_date_time_get_day_of_month (dt2);

  return 0;
}

/**
 * datetime_to_icaltime:
 * @dt: a #GDateTime
 *
 * Converts the #GDateTime's @dt to an #icaltimetype.
 *
 * Returns: (transfer full): a #icaltimetype.
 */
icaltimetype*
datetime_to_icaltime (GDateTime *dt)
{
  icaltimetype *idt;

  if (!dt)
    return NULL;

  idt = g_new0 (icaltimetype, 1);

  idt->year = g_date_time_get_year (dt);
  idt->month = g_date_time_get_month (dt);
  idt->day = g_date_time_get_day_of_month (dt);
  idt->hour = g_date_time_get_hour (dt);
  idt->minute = g_date_time_get_minute (dt);
  idt->second = g_date_time_get_seconds (dt);
  idt->is_date = (idt->hour == 0 &&
                  idt->minute == 0 &&
                  idt->second == 0);

  return idt;
}

/**
 * icaltime_to_datetime:
 * @date: an #icaltimetype
 *
 * Converts the #icaltimetype's @date to a #GDateTime. The
 * timezone is preserved.
 *
 * Returns: (transfer full): a #GDateTime.
 */
GDateTime*
icaltime_to_datetime (const icaltimetype  *date)
{
  GDateTime *dt;
  GTimeZone *tz;

  tz = date->zone ? g_time_zone_new (icaltime_get_tzid (*date)) : g_time_zone_new_utc ();
  dt = g_date_time_new (tz,
                        date->year,
                        date->month,
                        date->day,
                        date->is_date ? 0 : date->hour,
                        date->is_date ? 0 : date->minute,
                        date->is_date ? 0 : date->second);

  g_clear_pointer (&tz, g_time_zone_unref);

  return dt;
}

/**
 * datetime_is_date:
 * @dt: a #GDateTime
 *
 * Checks if @dt represents a date. A pure date
 * has the values of hour, minutes and seconds set
 * to 0.
 *
 * Returns: %TRUE if @dt is a date, %FALSE if it's a
 * timed datetime.
 */
gboolean
datetime_is_date (GDateTime *dt)
{
  return g_date_time_get_hour (dt) == 0 &&
         g_date_time_get_minute (dt) == 0 &&
         g_date_time_get_seconds (dt) == 0;
}

/**
 * gcal_dup_icaltime:
 * @date: an #icaltimetype
 *
 * Creates an exact copy of @date.
 *
 * Returns: (transfer full): an #icaltimetype
 */
icaltimetype*
gcal_dup_icaltime (const icaltimetype *date)
{
  icaltimetype *new_date;

  if (date == NULL)
    return NULL;

  new_date= g_new (icaltimetype, 1);
  new_date->year = date->year;
  new_date->month = date->month;
  new_date->day = date->day;
  new_date->hour = date->hour;
  new_date->minute = date->minute;
  new_date->second = date->second;
  new_date->is_utc = date->is_utc;
  new_date->is_date = date->is_date;
  new_date->is_daylight = date->is_daylight;
  new_date->zone = date->zone;

  return new_date;
}

/**
 * gcal_get_weekday:
 * @i: the weekday index
 *
 * Retrieves the weekday name.
 *
 * Returns: (transfer full): the weekday name
 */
gchar*
gcal_get_weekday (gint i)
{
  return nl_langinfo (ab_day[i]);
}

/**
 * gcal_get_month_name:
 * @i: the month index
 *
 * Retrieves the month name.
 *
 * Returns: (transfer full): the month name
 */
gchar*
gcal_get_month_name (gint i)
{
  return nl_langinfo (month_item[i]);
}

/**
 * gcal_get_surface_from_color:
 * @color: a #GdkRGBA
 * @size: the size of the surface
 *
 * Creates a squared surface filled with @color. The
 * surface is always @size x @size.
 *
 * Returns: (transfer full): a #cairo_surface_t
 */
cairo_surface_t*
gcal_get_surface_from_color (GdkRGBA  *color,
                             gint      size)
{
  cairo_surface_t *surface;
  cairo_t *cr;

  /* TODO: review size here, maybe not hardcoded */
  surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, size, size);
  cr = cairo_create (surface);

  cairo_set_source_rgba (cr,
                         color->red,
                         color->green,
                         color->blue,
                         color->alpha);
  cairo_rectangle (cr, 0, 0, size, size);
  cairo_fill (cr);
  cairo_destroy (cr);

  return surface;
}

/**
 * get_circle_surface_from_color:
 * @color: a #GdkRGBA
 * @size: the size of the surface
 *
 * Creates a circular surface filled with @color. The
 * surface is always @size x @size.
 *
 * Returns: (transfer full): a #cairo_surface_t
 */
cairo_surface_t*
get_circle_surface_from_color (GdkRGBA *color,
                               gint     size)
{
  cairo_surface_t *surface;
  cairo_t *cr;

  surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, size, size);
  cr = cairo_create (surface);

  cairo_set_source_rgba (cr,
                         color->red,
                         color->green,
                         color->blue,
                         color->alpha);
  cairo_arc (cr, size / 2.0, size / 2.0, size / 2.0, 0., 2 * M_PI);
  cairo_fill (cr);
  cairo_destroy (cr);

  return surface;
}

/**
 * get_color_name_from_source:
 * @source: an #ESource
 * @out_color: return value for the color
 *
 * Utility function to retrieve the color from @source.
 */
void
get_color_name_from_source (ESource *source,
                            GdkRGBA *out_color)
{
  ESourceSelectable *extension = E_SOURCE_SELECTABLE (e_source_get_extension (source, E_SOURCE_EXTENSION_CALENDAR));

  /* FIXME: We should handle calendars colours better */
  if (!gdk_rgba_parse (out_color, e_source_selectable_get_color (extension)))
    gdk_rgba_parse (out_color, "#becedd"); /* calendar default colour */
}

/**
 * get_desc_from_component:
 * @component: an #ECalComponent
 * @joint_char: the character to use when merging event comments
 *
 * Utility method to handle the extraction of the description from an
 * #ECalComponent. This cycle through the list of #ECalComponentText
 * and concatenate each string into one.
 *
 * Returns: (nullable)(transfer full) a new allocated string with the
 * description
 **/
gchar*
get_desc_from_component (ECalComponent *component,
                         const gchar   *joint_char)
{
  GSList *text_list;
  GSList *l;

  gchar *desc = NULL;
  e_cal_component_get_description_list (component, &text_list);

  for (l = text_list; l != NULL; l = l->next)
    {
      if (l->data != NULL)
        {
          ECalComponentText *text;
          gchar *carrier;
          text = l->data;

          if (desc != NULL)
            {
              carrier = g_strconcat (desc, joint_char, text->value, NULL);
              g_free (desc);
              desc = carrier;
            }
          else
            {
              desc = g_strdup (text->value);
            }
        }
    }

  e_cal_component_free_text_list (text_list);
  return desc != NULL ? g_strstrip (desc) : NULL;
}

/**
 * get_uuid_from_component:
 * @source: an {@link ESource}
 * @component: an {@link ECalComponent}
 *
 * Obtains the uuid from a component in the form
 * "source_uid:event_uid:event_rid" or "source:uid:event_uid" if the
 * component doesn't hold a recurrence event
 *
 * Returns: (Transfer full) a new allocated string with the description
 **/
gchar*
get_uuid_from_component (ESource       *source,
                         ECalComponent *component)
{
  gchar *uuid;
  ECalComponentId *id;

  id = e_cal_component_get_id (component);
  if (id->rid != NULL)
    {
      uuid = g_strdup_printf ("%s:%s:%s",
                              e_source_get_uid (source),
                              id->uid,
                              id->rid);
    }
  else
    {
      uuid = g_strdup_printf ("%s:%s",
                              e_source_get_uid (source),
                              id->uid);
    }
  e_cal_component_free_id (id);

  return uuid;
}

/**
 * get_first_weekday:
 *
 * Copied from Clocks, which by itself is
 * copied from GtkCalendar.
 *
 * Returns: the first weekday, from 0 to 6
 */
gint
get_first_weekday (void)
{
  int week_start;
#ifdef HAVE__NL_TIME_FIRST_WEEKDAY
  union { unsigned int word; char *string; } langinfo;
  int week_1stday = 0;
  int first_weekday = 1;
  guint week_origin;
#else
  char *gtk_week_start;
#endif

#ifdef HAVE__NL_TIME_FIRST_WEEKDAY
  langinfo.string = nl_langinfo (_NL_TIME_FIRST_WEEKDAY);
  first_weekday = langinfo.string[0];
  langinfo.string = nl_langinfo (_NL_TIME_WEEK_1STDAY);
  week_origin = langinfo.word;
  if (week_origin == 19971130) /* Sunday */
    week_1stday = 0;
  else if (week_origin == 19971201) /* Monday */
    week_1stday = 1;
  else
    g_warning ("Unknown value of _NL_TIME_WEEK_1STDAY.\n");

  week_start = (week_1stday + first_weekday - 1) % 7;
#else
  /* Use a define to hide the string from xgettext */
# define GTK_WEEK_START "calendar:week_start:0"
  gtk_week_start = dgettext ("gtk30", GTK_WEEK_START);

  if (strncmp (gtk_week_start, "calendar:week_start:", 20) == 0)
    week_start = *(gtk_week_start + 20) - '0';
  else
    week_start = -1;

  if (week_start < 0 || week_start > 6)
    {
      g_warning ("Whoever translated calendar:week_start:0 for GTK+ "
                 "did so wrongly.\n");
      week_start = 0;
    }
#endif

  return week_start;
}

/**
 * build_component_from_details:
 * @summary:
 * @initial_date:
 * @final_date:
 *
 * Create a component with the provided details
 *
 * Returns: (transfer full): an {@link ECalComponent} object
 **/
ECalComponent*
build_component_from_details (const gchar *summary,
                              GDateTime   *initial_date,
                              GDateTime   *final_date)
{
  ECalComponent *event;
  ECalComponentDateTime dt;
  ECalComponentText summ;
  icaltimezone *zone;
  gboolean all_day;

  event = e_cal_component_new ();
  e_cal_component_set_new_vtype (event, E_CAL_COMPONENT_EVENT);

  /*
   * Check if the event is all day. Notice that it can be all day even
   * without the final date.
   */
  all_day = datetime_is_date (initial_date) && (final_date ? datetime_is_date (final_date) : TRUE);

  /*
   * When the event is all day, we consider UTC timezone by default. Otherwise,
   * we always use the system timezone to create new events
   */
  if (all_day)
    {
      zone = icaltimezone_get_utc_timezone ();
    }
  else
    {
      gchar *system_tz = e_cal_system_timezone_get_location ();

      zone = icaltimezone_get_builtin_timezone (system_tz);

      g_free (system_tz);
    }

  /* Start date */
  dt.value = datetime_to_icaltime (initial_date);
  icaltime_set_timezone (dt.value, zone);
  dt.value->is_date = all_day;
  dt.tzid = icaltimezone_get_tzid (zone);
  e_cal_component_set_dtstart (event, &dt);

  g_free (dt.value);

  /* End date */
  if (!final_date)
    final_date = g_date_time_add_days (initial_date, 1);

  dt.value = datetime_to_icaltime (final_date);
  icaltime_set_timezone (dt.value, zone);
  dt.value->is_date = all_day;
  dt.tzid = icaltimezone_get_tzid (zone);
  e_cal_component_set_dtend (event, &dt);

  g_free (dt.value);

  /* Summary */
  summ.altrep = NULL;
  summ.value = summary;
  e_cal_component_set_summary (event, &summ);

  e_cal_component_commit_sequence (event);

  return event;
}

/**
 * icaltime_compare_date:
 * @date1: an #icaltimetype
 * @date2: an #icaltimetype
 *
 * Compare date parts of #icaltimetype objects. Returns negative value,
 * 0 or positive value accordingly if @date1 is before, same day of
 * after date2.
 *
 * As a bonus it returns the amount of days passed between two days on the
 * same year.
 *
 * Returns: negative, 0 or positive
 **/
gint
icaltime_compare_date (const icaltimetype *date1,
                       const icaltimetype *date2)
{
  if (date2 == NULL)
    return 0;

  if (date1->year < date2->year)
    return -1;
  else if (date1->year > date2->year)
    return 1;
  else
    return time_day_of_year (date1->day, date1->month - 1, date1->year) -
           time_day_of_year (date2->day, date2->month - 1, date2->year);
}

/**
 * icaltime_compare_with_current:
 * @date1: an #icaltimetype
 * @date2: an #icaltimetype
 * @current_time_t: the current time
 *
 * Compares @date1 and @date2 against the current time. Dates
 * closer to the current date are sorted before.
 *
 * Returns: negative if @date1 comes after @date2, 0 if they're
 * equal, positive otherwise
 */
gint
icaltime_compare_with_current (const icaltimetype *date1,
                               const icaltimetype *date2,
                               time_t             *current_time_t)
{
  gint result = 0;

  time_t start1, start2, diff1, diff2;
  start1 = icaltime_as_timet_with_zone (*date1, date1->zone != NULL ? date1->zone : e_cal_util_get_system_timezone ());
  start2 = icaltime_as_timet_with_zone (*date2, date2->zone != NULL ? date2->zone : e_cal_util_get_system_timezone ());
  diff1 = start1 - *current_time_t;
  diff2 = start2 - *current_time_t;

  if (diff1 != diff2)
    {
      if (diff1 == 0)
        result = -1;
      else if (diff2 == 0)
        result = 1;

      if (diff1 > 0 && diff2 < 0)
        result = -1;
      else if (diff2 > 0 && diff1 < 0)
        result = 1;
      else if (diff1 < 0 && diff2 < 0)
        result = ABS (diff1) - ABS (diff2);
      else if (diff1 > 0 && diff2 > 0)
        result = diff1 - diff2;
    }

  return result;
}

/**
 * get_start_of_week:
 * @date: an #icaltimetype
 *
 * Retrieves the start of the week that @date
 * falls in. This function already takes the
 * first weekday into account.
 *
 * Returns: (transfer full): a #GDateTime with
 * the start of the week.
 */
GDateTime*
get_start_of_week (icaltimetype *date)
{
  icaltimetype *new_date;
  GDateTime *dt;

  new_date = g_new0 (icaltimetype, 1);
  *new_date = icaltime_from_day_of_year (icaltime_start_doy_week (*date, get_first_weekday () + 1),
                                         date->year);
  new_date->is_date = 0;
  new_date->hour = 0;
  new_date->minute = 0;
  new_date->second = 0;

  dt = g_date_time_new_local (new_date->year,
                              new_date->month,
                              new_date->day,
                              0, 0, 0);

  g_clear_pointer (&new_date, g_free);

  return dt;
}

/**
 * get_end_of_week:
 * @date: an #icaltimetype
 *
 * Retrieves the end of the week that @date
 * falls in. This function already takes the
 * first weekday into account.
 *
 * Returns: (transfer full): a #GDateTime with
 * the end of the week.
 */
GDateTime*
get_end_of_week (icaltimetype *date)
{
  GDateTime *week_start, *week_end;

  week_start = get_start_of_week (date);
  week_end = g_date_time_add_days (week_start, 7);

  g_clear_pointer (&week_start, g_date_time_unref);

  return week_end;
}

/**
 * is_clock_format_24h:
 *
 * Retrieves whether the current clock format is
 * 12h or 24h based.
 *
 * Returns: %TRUE if the clock format is 24h, %FALSE
 * otherwise.
 */
gboolean
is_clock_format_24h (void)
{
  static GSettings *settings = NULL;
  g_autofree gchar *clock_format = NULL;

  if (!settings)
    settings = g_settings_new ("org.gnome.desktop.interface");

  clock_format = g_settings_get_string (settings, "clock-format");

  return g_strcmp0 (clock_format, "24h") == 0;
}

/**
 * e_strftime_fix_am_pm:
 *
 * Function to do a last minute fixup of the AM/PM stuff if the locale
 * and gettext haven't done it right. Most English speaking countries
 * except the USA use the 24 hour clock (UK, Australia etc). However
 * since they are English nobody bothers to write a language
 * translation (gettext) file. So the locale turns off the AM/PM, but
 * gettext does not turn on the 24 hour clock. Leaving a mess.
 *
 * This routine checks if AM/PM are defined in the locale, if not it
 * forces the use of the 24 hour clock.
 *
 * The function itself is a front end on strftime and takes exactly
 * the same arguments.
 *
 * TODO: Actually remove the '%p' from the fixed up string so that
 * there isn't a stray space.
 */
gsize
e_strftime_fix_am_pm (gchar *str,
                      gsize max,
                      const gchar *fmt,
                      const struct tm *tm)
{
  gchar buf[10];
  gchar *sp;
  gchar *ffmt;
  gsize ret;

  if (strstr(fmt, "%p")==NULL && strstr(fmt, "%P")==NULL) {
    /* No AM/PM involved - can use the fmt string directly */
    ret = e_strftime (str, max, fmt, tm);
  } else {
    /* Get the AM/PM symbol from the locale */
    e_strftime (buf, 10, "%p", tm);

    if (buf[0]) {
      /* AM/PM have been defined in the locale
       * so we can use the fmt string directly. */
      ret = e_strftime (str, max, fmt, tm);
    } else {
      /* No AM/PM defined by locale
       * must change to 24 hour clock. */
      ffmt = g_strdup (fmt);
      for (sp=ffmt; (sp=strstr(sp, "%l")); sp++) {
        /* Maybe this should be 'k', but I have never
         * seen a 24 clock actually use that format. */
        sp[1]='H';
      }
      for (sp=ffmt; (sp=strstr(sp, "%I")); sp++) {
        sp[1]='H';
      }
      ret = e_strftime (str, max, ffmt, tm);
      g_free (ffmt);
    }
  }

  return (ret);
}

/**
 * e_utf8_strftime_fix_am_pm:
 *
 * Stolen from Evolution codebase. Selects the
 * correct time format.
 *
 * Returns: the size of the string
 */
gsize
e_utf8_strftime_fix_am_pm (gchar *str,
                           gsize max,
                           const gchar *fmt,
                           const struct tm *tm)
{
  gsize sz, ret;
  gchar *locale_fmt, *buf;

  locale_fmt = g_locale_from_utf8 (fmt, -1, NULL, &sz, NULL);
  if (!locale_fmt)
    return 0;

  ret = e_strftime_fix_am_pm (str, max, locale_fmt, tm);
  if (!ret) {
    g_free (locale_fmt);
    return 0;
  }

  buf = g_locale_to_utf8 (str, ret, NULL, &sz, NULL);
  if (!buf) {
    g_free (locale_fmt);
    return 0;
  }

  if (sz >= max) {
    gchar *tmp = buf + max - 1;
    tmp = g_utf8_find_prev_char (buf, tmp);
    if (tmp)
      sz = tmp - buf;
    else
      sz = 0;
  }
  memcpy (str, buf, sz);
  str[sz] = '\0';
  g_free (locale_fmt);
  g_free (buf);
  return sz;
}


/**
 * fix_popover_menu_icons:
 * @window: a #GtkPopover
 *
 * Hackish code that inspects the popover's children,
 * retrieve the hidden GtkImage buried under lots of
 * widgets, and make it visible again.
 *
 * Hopefully, we'll find a better way to do this in
 * the long run.
 *
 */
void
fix_popover_menu_icons (GtkPopover *popover)
{
  GtkWidget *popover_stack;
  GtkWidget *menu_section;
  GtkWidget *menu_section_box;
  GList *stack_children;
  GList *menu_section_children;
  GList *menu_section_box_children, *aux;

  popover_stack = gtk_bin_get_child (GTK_BIN (popover));
  stack_children = gtk_container_get_children (GTK_CONTAINER (popover_stack));

  /**
   * At the moment, the popover stack surely contains only
   * one child of type GtkMenuSectionBox, which contains
   * a single GtkBox.
   */
  menu_section = stack_children->data;
  menu_section_children = gtk_container_get_children (GTK_CONTAINER (menu_section));

	/**
	 * Get the unique box's children.
	 */
  menu_section_box = menu_section_children->data;
  menu_section_box_children = gtk_container_get_children (GTK_CONTAINER (menu_section_box));

  gtk_style_context_add_class (gtk_widget_get_style_context (menu_section_box), "calendars-list");

  /**
   * Iterate through the GtkModelButtons inside the menu section box.
   */
  for (aux = menu_section_box_children; aux != NULL; aux = aux->next)
    {
      GtkWidget *button_box;
      GList *button_box_children, *aux2;

      button_box = gtk_bin_get_child (GTK_BIN (aux->data));
      button_box_children = gtk_container_get_children (GTK_CONTAINER (button_box));

      /**
       * Since there is no guarantee that the first child is
       * the GtkImage we're looking for, we have to iterate
       * through the children and check if the types match.
       */
      for (aux2 = button_box_children; aux2 != NULL; aux2 = aux2->next)
        {
          GtkWidget *button_box_child;
          button_box_child = aux2->data;

          if (g_type_is_a (G_OBJECT_TYPE (button_box_child), GTK_TYPE_IMAGE))
            {
              gtk_style_context_add_class (gtk_widget_get_style_context (button_box_child), "calendar-color-image");
              gtk_widget_show (button_box_child);
              break;
            }
        }

      g_list_free (button_box_children);
    }

  g_list_free (stack_children);
  g_list_free (menu_section_children);
  g_list_free (menu_section_box_children);
}

/**
 * uri_get_fields:
 * @uri: the URI
 * @schema: (nullable): return location for the schema of the URI
 * @host: (nullable): return location for the host of the URI
 * @path: (nullable): return location for the resource path
 *
 * Split the given URI into the fields.
 *
 * Returns: #TRUE if @uri could be parsed, #FALSE otherwise
 */
gboolean
uri_get_fields (const gchar  *uri,
                gchar       **schema,
                gchar       **host,
                gchar       **path,
                gboolean     *is_file)
{
  GRegex *regex;
  GMatchInfo *match;
  gboolean valid;

  g_return_val_if_fail (uri != NULL, FALSE);

  match = NULL;
  valid = FALSE;

  regex = g_regex_new ("([a-zA-Z0-9\\+\\.\\-]*:\\/\\/){0,1}([-a-zA-Z0-9@:%._\\+~#=]{2,256}\\.[a-z]{2,6}\\b)([-a-zA-Z0-9@:%_\\+.//=]*)",
                       G_REGEX_CASELESS, 0, NULL);

  /*
   * Retrieved matching URI. The whole url is
   * checked and the regex groups are:
   * 1. schema
   * 2. host
   * 3. server path
   */
  if (g_regex_match (regex, uri, 0, &match))
    {
      valid = TRUE;

      if (schema != NULL)
        *schema = g_match_info_fetch (match, 1);

      if (host != NULL)
        *host = g_match_info_fetch (match, 2);

      if (path != NULL)
        *path = g_match_info_fetch (match, 3);

      g_match_info_free (match);
    }
  else
    {
      if (schema != NULL)
        *schema = NULL;

      if (host != NULL)
        *host = NULL;

      if (path != NULL)
        *path = NULL;
    }

  /* File extension */
  if (is_file)
    {
      GRegex *extension_regex;

      extension_regex = g_regex_new ("(\\.[a-zA-Z0-9]+)$", G_REGEX_CASELESS, 0, NULL);

      *is_file = g_regex_match (extension_regex, uri, 0, NULL);

      g_regex_unref (extension_regex);
    }

  g_regex_unref (regex);
  return valid;
}

/**
 * get_source_parent_name_color:
 * @manager: a #GcalManager
 * @source: an #ESource
 * @name: (nullable): return location for the name
 * @color: (nullable): return location for the color
 *
 * Retrieves the name and the color of the #ESource that is
 * parent of @source.
 */
void
get_source_parent_name_color (GcalManager  *manager,
                              ESource      *source,
                              gchar       **name,
                              gchar       **color)
{
  ESource *parent_source;

  g_assert (source && E_IS_SOURCE (source));

  parent_source = gcal_manager_get_source (manager, e_source_get_parent (source));

  if (name != NULL)
    *name = e_source_dup_display_name (parent_source);

  if (color != NULL)
    {
      GdkRGBA c;

      get_color_name_from_source (parent_source, &c);

      *color = gdk_rgba_to_string (&c);
    }
}

/**
 * format_utc_offset:
 * @offset: an UTC offset
 *
 * Formats the UTC offset to a string that GTimeZone can
 * parse. E.g. "-0300" or "+0530".
 *
 * Returns: (transfer full): a string representing the
 * offset
 */
gchar*
format_utc_offset (gint64 offset)
{
  const char *sign = "+";
  gint hours, minutes, seconds;

  if (offset < 0) {
      offset = -offset;
      sign = "-";
  }

  /* offset can be seconds or microseconds */
  if (offset >= 1000000)
    offset = offset / 1000000;

  hours = offset / 3600;
  minutes = (offset % 3600) / 60;
  seconds = offset % 60;

  if (seconds > 0)
    return g_strdup_printf ("%s%02i%02i%02i", sign, hours, minutes, seconds);
  else
    return g_strdup_printf ("%s%02i%02i", sign, hours, minutes);
}

/**
 * get_alarm_trigger_minutes:
 * @event: a #GcalEvent
 * @alarm: a #ECalComponentAlarm
 *
 * Calculates the number of minutes before @event's
 * start time that the alarm should be triggered.
 *
 * Returns: the number of minutes before the event
 * start that @alarm will be triggered.
 */
gint
get_alarm_trigger_minutes (GcalEvent          *event,
                           ECalComponentAlarm *alarm)
{
  ECalComponentAlarmTrigger trigger;
  GDateTime *alarm_dt;
  gint diff;

  e_cal_component_alarm_get_trigger (alarm, &trigger);

  /*
   * We only support alarms relative to the start date, and solely
   * ignore whetever different it may be.
   */
  if (trigger.type != E_CAL_COMPONENT_ALARM_TRIGGER_RELATIVE_START)
    return -1;

  alarm_dt = g_date_time_add_full (gcal_event_get_date_start (event),
                                   0,
                                   0,
                                   - (trigger.u.rel_duration.days + trigger.u.rel_duration.weeks * 7),
                                   - trigger.u.rel_duration.hours,
                                   - trigger.u.rel_duration.minutes,
                                   - trigger.u.rel_duration.seconds);

  diff = g_date_time_difference (gcal_event_get_date_start (event), alarm_dt) / G_TIME_SPAN_MINUTE;

  g_clear_pointer (&alarm_dt, g_date_time_unref);

  return diff;
}

/**
 * should_change_date_for_scroll:
 * @scroll_value: the current scroll value
 * @scroll_event: the #GdkEventScroll that is being parsed
 *
 * Utility function to check if the date should change based
 * on the scroll. The date is changed when the user scrolls
 * too much on touchpad, or performs a rotation of the scroll
 * button in a mouse.
 *
 * Returns: %TRUE if the date should change, %FALSE otherwise.
 */
gboolean
should_change_date_for_scroll (gdouble        *scroll_value,
                               GdkEventScroll *scroll_event)
{
  gdouble delta_y;

  switch (scroll_event->direction)
    {
    case GDK_SCROLL_DOWN:
      *scroll_value = SCROLL_HARDNESS;
      break;

    case GDK_SCROLL_UP:
      *scroll_value = -SCROLL_HARDNESS;
      break;

    case GDK_SCROLL_SMOOTH:
      gdk_event_get_scroll_deltas ((GdkEvent*) scroll_event, NULL, &delta_y);
      *scroll_value += delta_y;
      break;

    /* Ignore horizontal scrolling for now */
    case GDK_SCROLL_LEFT:
    case GDK_SCROLL_RIGHT:
    default:
      break;
    }

  if (*scroll_value <= -SCROLL_HARDNESS || *scroll_value >= SCROLL_HARDNESS)
    return TRUE;

  return FALSE;
}

/**
 * is_source_enabled:
 * @source: an #ESource
 *
 * Retrieves whether the @source is enabled or not.
 * Disabled sources don't show their events.
 *
 * Returns: %TRUE if @source is enabled, %FALSE otherwise.
 */
gboolean
is_source_enabled (ESource *source)
{
  ESourceSelectable *selectable;

  g_return_val_if_fail (E_IS_SOURCE (source), FALSE);

  selectable = e_source_get_extension (source, E_SOURCE_EXTENSION_CALENDAR);

  return e_source_selectable_get_selected (selectable);
}
