/* GTK - The GIMP Toolkit
 * Copyright (C) 2020, Red Hat, Inc
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"

#include "gtkdragsource.h"
#include "gtkdroptarget.h"
#include "gtkeditablelabel.h"
#include "gtkeditable.h"
#include "gtklabel.h"
#include "gtkstack.h"
#include "gtktext.h"
#include "gtkbinlayout.h"
#include "gtkgestureclick.h"
#include "gtkprivate.h"
#include "gtkshortcut.h"
#include "gtkshortcuttrigger.h"
#include "gtkwidgetprivate.h"
#include "gtkeventcontrollerfocus.h"

/**
 * GtkEditableLabel:
 *
 * A `GtkEditableLabel` is a label that allows users to
 * edit the text by switching to an “edit mode”.
 *
 * ![An example GtkEditableLabel](editable-label.png)
 *
 * `GtkEditableLabel` does not have API of its own, but it
 * implements the [iface@Gtk.Editable] interface.
 *
 * The default bindings for activating the edit mode is
 * to click or press the Enter key. The default bindings
 * for leaving the edit mode are the Enter key (to save
 * the results) or the Escape key (to cancel the editing).
 *
 * # Shortcuts and Gestures
 *
 * `GtkEditableLabel` supports the following keyboard shortcuts:
 *
 * - <kbd>Enter</kbd> starts editing.
 * - <kbd>Escape</kbd> stops editing.
 *
 * # Actions
 *
 * `GtkEditableLabel` defines a set of built-in actions:
 *
 * - `editing.starts` switches the widget into editing mode.
 * - `editing.stop` switches the widget out of editing mode.
 *
 * # CSS nodes
 *
 * ```
 * editablelabel[.editing]
 * ╰── stack
 *     ├── label
 *     ╰── text
 * ```
 *
 * `GtkEditableLabel` has a main node with the name editablelabel.
 * When the entry is in editing mode, it gets the .editing style
 * class.
 *
 * For all the subnodes added to the text node in various situations,
 * see [class@Gtk.Text].
 */

struct _GtkEditableLabel
{
  GtkWidget parent_instance;

  GtkWidget *stack;
  GtkWidget *label;
  GtkWidget *entry;

  guint stop_editing_soon_id;
};

struct _GtkEditableLabelClass
{
  GtkWidgetClass parent_class;
};

enum
{
  PROP_EDITING = 1,
  NUM_PROPERTIES
};

static GParamSpec *properties[NUM_PROPERTIES] = { NULL, };

static GtkEditable *
gtk_editable_label_get_delegate (GtkEditable *editable)
{
  GtkEditableLabel *self = GTK_EDITABLE_LABEL (editable);

  return GTK_EDITABLE (self->entry);
}

static void
gtk_editable_label_editable_init (GtkEditableInterface *iface)
{
  iface->get_delegate = gtk_editable_label_get_delegate;
}


G_DEFINE_TYPE_WITH_CODE (GtkEditableLabel, gtk_editable_label, GTK_TYPE_WIDGET,
                         G_IMPLEMENT_INTERFACE (GTK_TYPE_EDITABLE,
                                                gtk_editable_label_editable_init))

static void
start_editing (GtkWidget  *widget,
               const char *action_name,
               GVariant   *parameters)
{
  gtk_editable_label_start_editing (GTK_EDITABLE_LABEL (widget));
}

static void
stop_editing (GtkWidget  *widget,
              const char *action_name,
              GVariant   *parameters)
{
  gtk_editable_label_stop_editing (GTK_EDITABLE_LABEL (widget),
                                   g_variant_get_boolean (parameters));
}

static void
clicked_cb (GtkWidget *self)
{
  gtk_widget_activate_action (self, "editing.start", NULL);
}

static void
activate_cb (GtkWidget *self)
{
  gtk_widget_activate_action (self, "editing.stop", "b", TRUE);
}

static void
text_changed (GtkEditableLabel *self)
{
  /* Sync the entry text to the label, unless we are editing.
   *
   * This is necessary to catch apis like gtk_editable_insert_text(),
   * which don't go through the text property.
   */
  if (!gtk_editable_label_get_editing (self))
    {
      const char *text = gtk_editable_get_text (GTK_EDITABLE (self->entry));
      gtk_label_set_label (GTK_LABEL (self->label), text);
    }
}

static gboolean
gtk_editable_label_drag_accept (GtkDropTarget    *dest,
                                GdkDrop          *drop,
                                GtkEditableLabel *self)
{
  if (!gtk_editable_get_editable (GTK_EDITABLE (self)))
    return FALSE;

  if ((gdk_drop_get_actions (drop) & gtk_drop_target_get_actions (dest)) == 0)
    return FALSE;

  return gdk_content_formats_match (gtk_drop_target_get_formats (dest), gdk_drop_get_formats (drop));
}

static gboolean
gtk_editable_label_drag_drop (GtkDropTarget    *dest,
                              const GValue     *value,
                              double            x,
                              double            y,
                              GtkEditableLabel *self)
{
  if (!gtk_editable_get_editable (GTK_EDITABLE (self)))
    return FALSE;

  gtk_editable_set_text (GTK_EDITABLE (self), g_value_get_string (value));

  return TRUE;
}

static GdkContentProvider *
gtk_editable_label_prepare_drag (GtkDragSource    *source,
                                 double            x,
                                 double            y,
                                 GtkEditableLabel *self)
{
  if (!gtk_editable_get_editable (GTK_EDITABLE (self)))
    return NULL;

  return gdk_content_provider_new_typed (G_TYPE_STRING,
                                         gtk_label_get_label (GTK_LABEL (self->label)));
}

static gboolean
stop_editing_soon (gpointer data)
{
  GtkEventController *controller = data;
  GtkEditableLabel *self = GTK_EDITABLE_LABEL (gtk_event_controller_get_widget (controller));

  if (!gtk_event_controller_focus_contains_focus (GTK_EVENT_CONTROLLER_FOCUS (controller)))
    gtk_editable_label_stop_editing (self, TRUE);

  self->stop_editing_soon_id = 0;

  return FALSE;
}

static void
gtk_editable_label_focus_out (GtkEventController *controller,
                              GtkEditableLabel   *self)
{
  if (self->stop_editing_soon_id == 0)
    self->stop_editing_soon_id = g_timeout_add (100, stop_editing_soon, controller);
}

static void
gtk_editable_label_init (GtkEditableLabel *self)
{
  GtkGesture *gesture;
  GtkDropTarget *target;
  GtkDragSource *source;
  GtkEventController *controller;

  gtk_widget_set_focusable (GTK_WIDGET (self), TRUE);

  self->stack = gtk_stack_new ();
  self->label = gtk_label_new ("");
  gtk_label_set_xalign (GTK_LABEL (self->label), 0.0);
  self->entry = gtk_text_new ();

  gtk_stack_add_named (GTK_STACK (self->stack), self->label, "label");
  gtk_stack_add_named (GTK_STACK (self->stack), self->entry, "entry");

  gtk_widget_set_parent (self->stack, GTK_WIDGET (self));

  gesture = gtk_gesture_click_new ();
  g_signal_connect_swapped (gesture, "released", G_CALLBACK (clicked_cb), self);
  gtk_widget_add_controller (self->label, GTK_EVENT_CONTROLLER (gesture));

  g_signal_connect_swapped (self->entry, "activate", G_CALLBACK (activate_cb), self);
  g_signal_connect_swapped (self->entry, "notify::text", G_CALLBACK (text_changed), self);

  target = gtk_drop_target_new (G_TYPE_STRING, GDK_ACTION_COPY | GDK_ACTION_MOVE);
  g_signal_connect (target, "accept", G_CALLBACK (gtk_editable_label_drag_accept), self);
  g_signal_connect (target, "drop", G_CALLBACK (gtk_editable_label_drag_drop), self);
  gtk_widget_add_controller (self->label, GTK_EVENT_CONTROLLER (target));

  source = gtk_drag_source_new ();
  g_signal_connect (source, "prepare", G_CALLBACK (gtk_editable_label_prepare_drag), self);
  gtk_widget_add_controller (self->label, GTK_EVENT_CONTROLLER (source));

  controller = gtk_event_controller_focus_new ();
  g_signal_connect (controller, "leave", G_CALLBACK (gtk_editable_label_focus_out), self);
  gtk_widget_add_controller (GTK_WIDGET (self), controller);

  gtk_editable_init_delegate (GTK_EDITABLE (self));
}

static gboolean
gtk_editable_label_grab_focus (GtkWidget *widget)
{
  GtkEditableLabel *self = GTK_EDITABLE_LABEL (widget);

  if (gtk_editable_label_get_editing (self))
    return gtk_widget_grab_focus (self->entry);
  else
    return gtk_widget_grab_focus_self (widget);
}

static void
gtk_editable_label_set_property (GObject      *object,
                                 guint         prop_id,
                                 const GValue *value,
                                 GParamSpec   *pspec)
{
  GtkEditableLabel *self = GTK_EDITABLE_LABEL (object);

  if (gtk_editable_delegate_set_property (object, prop_id, value, pspec))
    {
      switch (prop_id)
        {
        case NUM_PROPERTIES + GTK_EDITABLE_PROP_TEXT:
          gtk_label_set_label (GTK_LABEL (self->label), g_value_get_string (value));
          break;

        case NUM_PROPERTIES + GTK_EDITABLE_PROP_WIDTH_CHARS:
          gtk_label_set_width_chars (GTK_LABEL (self->label), g_value_get_int (value));
          break;

        case NUM_PROPERTIES + GTK_EDITABLE_PROP_MAX_WIDTH_CHARS:
          gtk_label_set_max_width_chars (GTK_LABEL (self->label), g_value_get_int (value));
          break;

        case NUM_PROPERTIES + GTK_EDITABLE_PROP_XALIGN:
          gtk_label_set_xalign (GTK_LABEL (self->label), g_value_get_float (value));
          break;

        case NUM_PROPERTIES + GTK_EDITABLE_PROP_EDITABLE:
          {
            gboolean editable;

            editable = g_value_get_boolean (value);
            if (!editable)
              gtk_editable_label_stop_editing (self, FALSE);

            gtk_widget_action_set_enabled (GTK_WIDGET (self), "editing.start", editable);
            gtk_widget_action_set_enabled (GTK_WIDGET (self), "editing.stop", editable);
          }
          break;

         default: ;
        }
      return;
    }

  switch (prop_id)
    {
    case PROP_EDITING:
      if (g_value_get_boolean (value))
        gtk_editable_label_start_editing (self);
      else
        gtk_editable_label_stop_editing (self, FALSE);
      break;

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

static void
gtk_editable_label_get_property (GObject     *object,
                                 guint        prop_id,
                                 GValue      *value,
                                 GParamSpec  *pspec)
{
  GtkEditableLabel *self = GTK_EDITABLE_LABEL (object);

  if (gtk_editable_delegate_get_property (object, prop_id, value, pspec))
    return;

  switch (prop_id)
    {
    case PROP_EDITING:
      g_value_set_boolean (value, gtk_editable_label_get_editing (self));
      break;

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

static void
gtk_editable_label_dispose (GObject *object)
{
  GtkEditableLabel *self = GTK_EDITABLE_LABEL (object);

  gtk_editable_finish_delegate (GTK_EDITABLE (self));

  g_clear_pointer (&self->stack, gtk_widget_unparent);

  self->entry = NULL;
  self->label = NULL;

  g_clear_handle_id (&self->stop_editing_soon_id, g_source_remove);

  G_OBJECT_CLASS (gtk_editable_label_parent_class)->dispose (object);
}

static void
gtk_editable_label_class_init (GtkEditableLabelClass *class)
{
  GObjectClass *object_class = G_OBJECT_CLASS (class);
  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
  GtkShortcut *shortcut;
  GtkShortcutTrigger *trigger;
  GtkShortcutAction *action;

  object_class->set_property = gtk_editable_label_set_property;
  object_class->get_property = gtk_editable_label_get_property;
  object_class->dispose = gtk_editable_label_dispose;

  widget_class->grab_focus = gtk_editable_label_grab_focus;

  /**
   * GtkEditableLabel:editing: (attributes org.gtk.Property.get=gtk_editable_label_get_editing)
   *
   * This property is %TRUE while the widget is in edit mode.
   */
  properties[PROP_EDITING] =
    g_param_spec_boolean ("editing", NULL, NULL,
                          FALSE,
                          GTK_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY);

  g_object_class_install_properties (object_class, NUM_PROPERTIES, properties);

  gtk_editable_install_properties (object_class, NUM_PROPERTIES);

  /**
   * GtkEditableLabel|editing.start:
   *
   * Switch the widget into editing mode, so that the
   * user can make changes to the text.
   *
   * The default bindings for this action are clicking
   * on the widget and the <kbd>Enter</kbd> key.
   *
   * This action is disabled when `GtkEditableLabel:editing`
   * is %FALSE.
   */
  gtk_widget_class_install_action (widget_class, "editing.start", NULL, start_editing);

  /**
   * GtkEditableLabel|editing.stop:
   * @commit: Whether the make changes permanent
   *
   * Switch the widget out of editing mode. If @commit
   * is %TRUE, then the results of the editing are taken
   * as the new value of `GtkEditable:text`.
   *
   * The default binding for this action is the Escape
   * key.
   *
   * This action is disabled when `GtkEditableLabel:editing`
   * is %FALSE.
   */
  gtk_widget_class_install_action (widget_class, "editing.stop", "b", stop_editing);

  trigger = gtk_alternative_trigger_new (
                gtk_alternative_trigger_new (
                    gtk_keyval_trigger_new (GDK_KEY_Return, 0),
                    gtk_keyval_trigger_new (GDK_KEY_ISO_Enter, 0)),
                    gtk_keyval_trigger_new (GDK_KEY_KP_Enter, 0));
  action = gtk_named_action_new ("editing.start");
  shortcut = gtk_shortcut_new (trigger, action);
  gtk_widget_class_add_shortcut (widget_class, shortcut);
  g_object_unref (shortcut);

  gtk_widget_class_add_binding_action (widget_class,
                                       GDK_KEY_Escape, 0,
                                       "editing.stop",
                                       "b", FALSE);

  gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_BIN_LAYOUT);
  gtk_widget_class_set_css_name (widget_class, "editablelabel");
}

/**
 * gtk_editable_label_new:
 * @str: the text for the label
 *
 * Creates a new `GtkEditableLabel` widget.
 *
 * Returns: the new `GtkEditableLabel`
 */
GtkWidget *
gtk_editable_label_new (const char *str)
{
  return g_object_new (GTK_TYPE_EDITABLE_LABEL,
                       "text", str,
                       NULL);
}

/**
 * gtk_editable_label_get_editing: (attributes org.gtk.Method.get_property=editing)
 * @self: a `GtkEditableLabel`
 *
 * Returns whether the label is currently in “editing mode”.
 *
 * Returns: %TRUE if @self is currently in editing mode
 */
gboolean
gtk_editable_label_get_editing (GtkEditableLabel *self)
{
  g_return_val_if_fail (GTK_IS_EDITABLE_LABEL (self), FALSE);

  return gtk_stack_get_visible_child (GTK_STACK (self->stack)) == self->entry;
}

/**
 * gtk_editable_label_start_editing:
 * @self: a `GtkEditableLabel`
 *
 * Switches the label into “editing mode”.
 */
void
gtk_editable_label_start_editing (GtkEditableLabel *self)
{
  g_return_if_fail (GTK_IS_EDITABLE_LABEL (self));

  if (gtk_editable_label_get_editing (self))
    return;

  gtk_stack_set_visible_child_name (GTK_STACK (self->stack), "entry");
  gtk_widget_grab_focus (self->entry);

  gtk_widget_add_css_class (GTK_WIDGET (self), "editing");

  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_EDITING]);
}

/**
 * gtk_editable_label_stop_editing:
 * @self: a `GtkEditableLabel`
 * @commit: whether to set the edited text on the label
 *
 * Switches the label out of “editing mode”.
 *
 * If @commit is %TRUE, the resulting text is kept as the
 * [property@Gtk.Editable:text] property value, otherwise the
 * resulting text is discarded and the label will keep its
 * previous [property@Gtk.Editable:text] property value.
 */
void
gtk_editable_label_stop_editing (GtkEditableLabel *self,
                                 gboolean          commit)
{
  g_return_if_fail (GTK_IS_EDITABLE_LABEL (self));

  if (!gtk_editable_label_get_editing (self))
    return;

  if (commit)
    {
      gtk_label_set_label (GTK_LABEL (self->label),
                           gtk_editable_get_text (GTK_EDITABLE (self->entry)));
      gtk_stack_set_visible_child_name (GTK_STACK (self->stack), "label");
    }
  else
    {
      gtk_stack_set_visible_child_name (GTK_STACK (self->stack), "label");
      gtk_editable_set_text (GTK_EDITABLE (self->entry),
                             gtk_label_get_label (GTK_LABEL (self->label)));
    }

  gtk_widget_grab_focus (GTK_WIDGET (self));

  gtk_widget_remove_css_class (GTK_WIDGET (self), "editing");

  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_EDITING]);
}
