[gnome-calendar/wip/gbsneto/dnd: 9/14] month-view: save the event when dragged and dropped

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 220d7c88bd31aac48d5200e0770c8da0feea13e5
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Sat May 21 17:32:53 2016 -0300

    month-view: save the event when dragged and dropped
    
    This magical commit finally implements the Drag n' Drop
    feature for Month view by changing the start and end dates
    of the events according to the cell where the user drops
    the event.

 src/gcal-month-view.c |   70 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 70 insertions(+), 0 deletions(-)
---
diff --git a/src/gcal-month-view.c b/src/gcal-month-view.c
index 7578685..49cffbd 100644
--- a/src/gcal-month-view.c
+++ b/src/gcal-month-view.c
@@ -847,6 +847,74 @@ gcal_month_view_drag_motion (GtkWidget      *widget,
   return priv->dnd_cell != -1;
 }
 
+static gboolean
+gcal_month_view_drag_drop (GtkWidget      *widget,
+                           GdkDragContext *context,
+                           gint            x,
+                           gint            y,
+                           guint           time)
+{
+  GcalMonthViewPrivate *priv = gcal_month_view_get_instance_private (GCAL_MONTH_VIEW (widget));
+  GtkWidget *event_widget;
+  GDateTime *start_dt, *end_dt;
+  GcalEvent *event;
+  gint cell, diff;
+
+  cell = get_dnd_cell (widget, x, y);
+  event_widget = gtk_drag_get_source_widget (context);
+  event = gcal_event_widget_get_event (GCAL_EVENT_WIDGET (event_widget));
+
+  /* Move the event's date */
+  start_dt = gcal_event_get_date_start (event);
+  end_dt = gcal_event_get_date_end (event);
+
+  diff = cell - g_date_time_get_day_of_month (start_dt) + 1;
+
+  if (diff != 0)
+    {
+      GDateTime *new_start = g_date_time_add_days (start_dt, diff);
+
+      gcal_event_set_date_start (event, new_start);
+
+      /* The event may have a NULL end date, so we have to check it here */
+      if (end_dt)
+        {
+          GDateTime *new_end = g_date_time_add_days (end_dt, diff);
+
+          gcal_event_set_date_end (event, new_end);
+          g_clear_pointer (&new_end, g_date_time_unref);
+        }
+
+      gcal_manager_update_event (priv->manager, event);
+
+      g_clear_pointer (&new_start, g_date_time_unref);
+    }
+
+  /* Cancel the DnD */
+  priv->dnd_cell = -1;
+  gtk_drag_unhighlight (widget);
+
+  gtk_drag_finish (context, TRUE, FALSE, time);
+
+  gtk_widget_queue_draw (widget);
+
+  return TRUE;
+}
+
+static void
+gcal_month_view_drag_leave (GtkWidget      *widget,
+                            GdkDragContext *context,
+                            guint           time)
+{
+  GcalMonthViewPrivate *priv = gcal_month_view_get_instance_private (GCAL_MONTH_VIEW (widget));
+
+  /* Cancel the drag */
+  priv->dnd_cell = -1;
+  gtk_drag_unhighlight (widget);
+
+  gtk_widget_queue_draw (widget);
+}
+
 static void
 add_new_event_button_cb (GtkWidget *button,
                          gpointer   user_data)
@@ -892,6 +960,8 @@ gcal_month_view_class_init (GcalMonthViewClass *klass)
   widget_class->direction_changed = gcal_month_view_direction_changed;
   widget_class->key_press_event = gcal_month_view_key_press;
   widget_class->drag_motion = gcal_month_view_drag_motion;
+  widget_class->drag_drop = gcal_month_view_drag_drop;
+  widget_class->drag_leave = gcal_month_view_drag_leave;
 
   subscriber_view_class = GCAL_SUBSCRIBER_VIEW_CLASS (klass);
   subscriber_view_class->get_child_cell = gcal_month_view_get_child_cell;