/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 * gcal-date-selector.c
 * Copyright (C) 2014 Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
 *
 * gnome-calendar 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 3 of the License, or
 * (at your option) any later version.
 *
 * gnome-calendar 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 "gcal-date-selector.h"

#include <locale.h>
#include <langinfo.h>
#include <stdlib.h>
#include <glib/gi18n.h>

enum
{
  DAY,
  MONTH,
  YEAR,
  NUM_ENTRIES
};

struct _GcalDateSelector
{
  GtkMenuButton parent;

  /* widgets */
  GtkWidget   *date_label;
  GtkWidget   *calendar;
  GtkWidget   *grid;

  GtkWidget   *entries[NUM_ENTRIES];

  /* date */
  GDateTime   *date;

  /* misc */
  const gchar *mask;

  /* index in the mask starting by 0 */
  guint        day_pos;
  guint        month_pos;
  guint        year_pos;
};

enum
{
  PROP_0,
  PROP_DATE,
  LAST_PROP
};

static void     calendar_day_selected                             (GtkCalendar          *calendar,
                                                                   GcalDateSelector     *selector);

static gboolean date_entry_focus_out                              (GtkWidget            *widget,
                                                                   GdkEvent             *event,
                                                                   gpointer              user_data);

static void     entry_activated                                   (GtkEntry             *entry,
                                                                   gpointer              user_data);

static void     parse_entries                                     (GcalDateSelector     *selector);

static void     text_inserted                                     (GtkEditable          *editable,
                                                                   gchar                *new_text,
                                                                   gint                  new_text_length,
                                                                   gint                 *position,
                                                                   gpointer              user_data);

static void     gcal_date_selector_constructed                    (GObject              *object);

G_DEFINE_TYPE (GcalDateSelector, gcal_date_selector, GTK_TYPE_MENU_BUTTON);

static void
calendar_day_selected (GtkCalendar      *calendar,
                       GcalDateSelector *selector)
{
  GDateTime *new_date;
  guint day, month, year;

  gtk_calendar_get_date (calendar, &year, &month, &day);

  new_date = g_date_time_new_local (year, month + 1, day, 0, 0, 0);

  /**
   * Block signal handler to avoid an infinite
   * recursion, exploding the proccess stack.
   */
  g_signal_handlers_block_by_func (selector->calendar, calendar_day_selected, selector);

  gcal_date_selector_set_date (selector, new_date);

  g_signal_handlers_unblock_by_func (selector->calendar, calendar_day_selected, selector);

  g_clear_pointer (&new_date, g_date_time_unref);
}

static gboolean
date_entry_focus_out (GtkWidget *widget,
                      GdkEvent  *event,
                      gpointer   user_data)
{
  parse_entries (GCAL_DATE_SELECTOR (user_data));
  return FALSE;
}

static void
entry_activated (GtkEntry *entry,
                 gpointer  user_data)
{
  parse_entries (GCAL_DATE_SELECTOR (user_data));
}

static void
parse_entries (GcalDateSelector *selector)
{
  GDateTime *new_date;
  gint day, month, year;

  day = atoi (gtk_entry_get_text (GTK_ENTRY (selector->entries[DAY])));
  month = atoi (gtk_entry_get_text (GTK_ENTRY (selector->entries[MONTH])));
  year = atoi (gtk_entry_get_text (GTK_ENTRY (selector->entries[YEAR])));

  new_date = g_date_time_new_local (year, month, day, 0, 0, 0);

  /* select the date */
  g_signal_handlers_block_by_func (selector->calendar, calendar_day_selected, selector);

  gcal_date_selector_set_date (selector, new_date);

  g_signal_handlers_unblock_by_func (selector->calendar, calendar_day_selected, selector);

  g_clear_pointer (&new_date, g_date_time_unref);
}

static void
text_inserted (GtkEditable *editable,
               gchar       *new_text,
               gint         new_text_length,
               gint        *position,
               gpointer     user_data)
{
  GtkEntryBuffer *buffer;
  gchar* new_label;
  gint i;
  gint current_length, max_length;
  gboolean valid;

  valid = TRUE;
  buffer = gtk_entry_get_buffer (GTK_ENTRY (editable));
  current_length = gtk_entry_buffer_get_length (buffer);
  max_length = gtk_entry_get_max_length (GTK_ENTRY (editable));

  /* honor max length property */
  if (current_length + new_text_length > max_length)
    return;

  /* stop the default implementation */
  g_signal_stop_emission (editable, g_signal_lookup ("insert-text", GTK_TYPE_ENTRY), 0);

  for (i = 0; i < new_text_length; i++)
    {
      gchar c;
      c = *(new_text + i);

      /* trying to insert a non-numeric char */
      if (c < '0' || c > '9')
        {
          valid = FALSE;
          break;
        }
    }

  if (!valid)
    return;

  new_label = g_strdup_printf ("%s%s", gtk_entry_buffer_get_text (buffer), new_text);
  gtk_entry_buffer_set_text (buffer, new_label, current_length + new_text_length);
  *position = *position + new_text_length;

  g_free (new_label);
}

static void
gcal_date_selector_get_property (GObject    *object,
                                 guint       prop_id,
                                 GValue     *value,
                                 GParamSpec *pspec)
{
  GcalDateSelector *self = (GcalDateSelector*) object;

  switch (prop_id)
    {
    case PROP_DATE:
      g_value_set_boxed (value, self->date);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
gcal_date_selector_set_property (GObject      *object,
                                 guint         prop_id,
                                 const GValue *value,
                                 GParamSpec   *pspec)
{
  GcalDateSelector *self = (GcalDateSelector*) object;

  switch (prop_id)
    {
    case PROP_DATE:
      gcal_date_selector_set_date (self, g_value_get_boxed (value));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
gcal_date_selector_class_init (GcalDateSelectorClass *klass)
{
  GObjectClass *object_class;

  object_class = G_OBJECT_CLASS (klass);
  object_class->constructed = gcal_date_selector_constructed;
  object_class->get_property = gcal_date_selector_get_property;
  object_class->set_property = gcal_date_selector_set_property;

  /**
   * GcalDateSelector::date:
   *
   * The current date of the selector.
   */
  g_object_class_install_property (object_class,
                                   PROP_DATE,
                                   g_param_spec_boxed ("date",
                                                       "Date of the selector",
                                                       "The current date of the selector",
                                                       G_TYPE_DATE_TIME,
                                                       G_PARAM_READWRITE));

  gtk_widget_class_set_template_from_resource (GTK_WIDGET_CLASS (klass), "/org/gnome/calendar/date-selector.ui");

  gtk_widget_class_bind_template_child (GTK_WIDGET_CLASS (klass), GcalDateSelector, date_label);
  gtk_widget_class_bind_template_child (GTK_WIDGET_CLASS (klass), GcalDateSelector, calendar);
  gtk_widget_class_bind_template_child (GTK_WIDGET_CLASS (klass), GcalDateSelector, grid);

  gtk_widget_class_bind_template_callback (GTK_WIDGET_CLASS (klass), text_inserted);
  gtk_widget_class_bind_template_callback (GTK_WIDGET_CLASS (klass), date_entry_focus_out);
  gtk_widget_class_bind_template_callback (GTK_WIDGET_CLASS (klass), entry_activated);
  gtk_widget_class_bind_template_callback (GTK_WIDGET_CLASS (klass), calendar_day_selected);
}

static void
gcal_date_selector_init (GcalDateSelector *self)
{
  GDateTime *now;
  gint i, d_index, max;

  gtk_widget_set_has_window (GTK_WIDGET (self), FALSE);

  gtk_widget_init_template (GTK_WIDGET (self));

  now = g_date_time_new_now_local ();
  self->date = g_date_time_new_local (g_date_time_get_year (now),
                                      g_date_time_get_month (now),
                                      g_date_time_get_day_of_month (now),
                                      0, 0, 0);

  /* This string represents day/month/year order for each of the different
   * languages. It could possibly be default value, %m/%d/%y placing the month
   * before, or any ordering according to the translator's environment. */
  self->mask = g_dpgettext2 ("glib20", "GDateTime", "%m/%d/%y");

  /**
   * Translators: Select the day, month and year indexes. This will
   * be used later on to map the date entries to the
   * corresponding indexes. I should have added more validations here.
   */
  max = strlen (self->mask);
  if (max != 8)
    {
      /* I'll assume an error and bail out with the default values */
      self->day_pos = 0;
      self->month_pos = 1;
      self->year_pos = 2;
      return;
    }

  d_index = 0;

  for (i = 0; i < max; i++)
    {
      gchar c;

      c = *(self->mask + i);

      /* No need to check these common separators */
      if (c == '%' || c == '-' || c == '/' || c == '.')
        continue;

      switch (c)
        {
          /* day */
          case 'a':
          case 'A':
          case 'd':
          case 'e':
          case 'j':
          case 'u':
          case 'w':
            self->day_pos = d_index++;
            break;

          /* month */
          case 'b':
          case 'B':
          case 'm':
            self->month_pos = d_index++;
            break;

          /* year */
          case 'y':
          case 'Y':
            self->year_pos = d_index++;
            break;
        }
    }
}

static void
gcal_date_selector_constructed (GObject *object)
{
  GcalDateSelector *self;

  GtkWidget *label, *box;
  GList *l, *aux;

  self = GCAL_DATE_SELECTOR (object);

  /* chaining up */
  G_OBJECT_CLASS (gcal_date_selector_parent_class)->constructed (object);

  /* set labels, on the first row */
  label = gtk_grid_get_child_at (GTK_GRID (self->grid), self->day_pos, 0);
  gtk_label_set_text (GTK_LABEL (label), _("Day"));
  label = gtk_grid_get_child_at (GTK_GRID (self->grid), self->month_pos, 0);
  gtk_label_set_text (GTK_LABEL (label), _("Month"));
  label = gtk_grid_get_child_at (GTK_GRID (self->grid), self->year_pos, 0);
  gtk_label_set_text (GTK_LABEL (label), _("Year"));

  /* retrieve components from UI definition: entries */
  box = gtk_grid_get_child_at (GTK_GRID (self->grid), 0, 1);
  aux = gtk_container_get_children (GTK_CONTAINER (box));
  for (l = aux; l != NULL; l = g_list_next (l))
    {
      gint position;
      gtk_container_child_get (GTK_CONTAINER (box), l->data, "position", &position, NULL);
      if (position == self->day_pos)
        self->entries[DAY] = l->data;
      if (position == self->month_pos)
        self->entries[MONTH] = l->data;
      if (position == self->year_pos)
        self->entries[YEAR] = l->data;

      if (position == self->day_pos || position == self->month_pos)
        gtk_entry_set_max_length (GTK_ENTRY (l->data), 2);
    }
  g_list_free (aux);

  gtk_widget_set_direction (box, GTK_TEXT_DIR_LTR);
  gtk_widget_set_direction (self->grid, GTK_TEXT_DIR_LTR);
}

/* Public API */
GtkWidget*
gcal_date_selector_new (void)
{
  return g_object_new (GCAL_TYPE_DATE_SELECTOR, NULL);
}

/**
 * gcal_date_selector_set_date:
 * @selector: a #GcalDateSelector
 * @date: a valid #GDateTime
 *
 * Set the value of the shown date.
 */
void
gcal_date_selector_set_date (GcalDateSelector *selector,
                             GDateTime        *date)
{
  g_return_if_fail (GCAL_IS_DATE_SELECTOR (selector));

  if (selector->date != date)
    {
      gchar *label;

      g_clear_pointer (&selector->date, g_date_time_unref);
      selector->date = g_date_time_new_local (g_date_time_get_year (date),
                                              g_date_time_get_month (date),
                                              g_date_time_get_day_of_month (date),
                                              0, 0, 0);

      /* set calendar's date */
      g_signal_handlers_block_by_func (selector->calendar, calendar_day_selected, selector);

      g_object_set (selector->calendar,
                    "day", g_date_time_get_day_of_month (date),
                    "month", g_date_time_get_month (date) - 1,
                    "year", g_date_time_get_year (date),
                    NULL);

      g_signal_handlers_unblock_by_func (selector->calendar, calendar_day_selected, selector);

      /* rebuild the date label */
      label = g_date_time_format (date, selector->mask);

      gtk_label_set_label (GTK_LABEL (selector->date_label), label);
      g_free (label);

      /* set date entries' text */
      /* day entry */
      label = g_date_time_format (date, "%d");

      gtk_entry_set_text (GTK_ENTRY (selector->entries[DAY]), label);
      g_free (label);

      /* month entry */
      label = g_date_time_format (date, "%m");

      gtk_entry_set_text (GTK_ENTRY (selector->entries[MONTH]), label);
      g_free (label);

      /* year entry */
      label = g_date_time_format (date, "%Y");

      gtk_entry_set_text (GTK_ENTRY (selector->entries[YEAR]), label);
      g_free (label);

      /* emit the MODIFIED signal */
      g_object_notify (G_OBJECT (selector), "date");
    }
}

/**
 * gcal_date_selector_get_date:
 * @selector: a #GcalDateSelector
 *
 * Get the value of the date shown
 *
 * Returns: (transfer none): the date of the selector.
 */
GDateTime*
gcal_date_selector_get_date (GcalDateSelector *selector)
{
  g_return_val_if_fail (GCAL_IS_DATE_SELECTOR (selector), NULL);

  return selector->date;
}