// This may look like C code, but it's really -*- C++ -*-
/*
 * Copyright (C) 2008 Emweb bvba, Kessel-Lo, Belgium.
 *
 * See the LICENSE file for terms of use.
 */
#ifndef WDIALOG_H_
#define WDIALOG_H_

#include <Wt/WPopupWidget>
#include <Wt/WContainerWidget>
#include <Wt/WJavaScript>

namespace Wt {

class WTable;
class WTemplate;
class WText;

/*! \class WDialog Wt/WDialog Wt/WDialog
 *  \brief A %WDialog shows a dialog.
 *
 * By default, the dialog is <i>modal</i>. A modal window blocks the
 * user interface, and does not allow the user to interact with any
 * other part of the user interface until the dialog is closed (this
 * is enforced at the server side, so you may rely on this behavior).
 *
 * A modal dialog can be instantiated synchronously or
 * asynchronously. A non-modal dialog can only be instantiated
 * asynchronously.
 * 
 * When using a dialog asynchronously, there is no API call that waits
 * for the dialog to be closed. Then, the usage is similar to
 * instantiating any other widget. The dialog may be closed by calling
 * accept(), reject() or done() (or connecting a signal to one of
 * these methods). This will hide the dialog and emit the finished()
 * signal, which you then can listen for to process the dialog result
 * and delete the dialog. Unlike other widgets, a dialog does not need
 * to be added to a parent widget, but is hidden by default. You must
 * use the method show() or \link setHidden() setHidden(false)\endlink
 * to show the dialog.
 *
 * The synchronous use of a dialog involves a call to exec() which
 * will block (suspend the thread) until the dialog window is closed,
 * and return the dialog result. Events within dialog are handled
 * using a so-called recursive event loop. Typically, an OK button
 * will be connected to accept(), and in some cases a Cancel button to
 * reject(). This solution has the drawback that it is not scalable to
 * many concurrent sessions, since for every session with a recursive
 * event loop, a thread is locked until exec() returns. A thread that is
 * locked by a recursive event loop cannot be used to process requests
 * from another sessions. When all threads in the threadpool are locked in
 * recursive event loops, the server will be unresponsive to requests
 * from any other session. In practical terms, this means you must not
 * use exec(), unless your application will never be used by more
 * concurrent users than the amount of threads in your threadpool (like on
 * some intranets or extranets).  \if java This functionality is only
 * available on Servlet 3.0 compatible servlet containers.  \endif
 *
 *
 * Use \link setModal() setModal(false)\endlink  to create a non-modal
 * dialog. A non-modal dialog does not block the underlying user interface:
 * the user must not first deal with the dialog before interacting with the
 * rest of the user interface.
 *
 * Contents for the dialog is defined by adding it to the contents()
 * widget.
 *
 * \if cpp
 * Usage example, using the exec() method (not recommended):
 * \code
 * Wt::WDialog dialog("Personalia");
 *
 * new Wt::WText("Enter your name: ", dialog.contents());
 * Wt::WLineEdit edit(dialog.contents());
 * new Wt::WBreak(dialog.contents());
 *
 * Wt::WPushButton ok("Ok", dialog.contents());
 *
 * // these events will accept() the Dialog
 * edit.enterPressed().connect(&dialog, &Wt::WDialog::accept);
 * ok.clicked().connect(&dialog, &Wt::WDialog::accept);
 *
 * if (dialog.exec() == Wt::WDialog::Accepted)
 *   setStatus("Welcome, " + edit.text());
 * \endcode
 *
 * Usage example, using the asynchronous method (recommended):
 * \code
 * void MyClass::showDialog()
 * {
 *   dialog_ = new WDialog("Personalia");
 *  
 *   new Wt::WText("Enter your name: ", dialog_->contents());
 *   Wt::WLineEdit *edit = new Wt::WLineEdit(dialog_->contents());
 *   new Wt::WBreak(dialog_->contents());
 *  
 *   Wt::WPushButton *ok = new Wt::WPushButton("Ok", dialog_->contents());
 *
 *   // these events will accept() the Dialog
 *   edit->enterPressed().connect(dialog_, &Wt::WDialog::accept);
 *   ok->clicked().connect(dialog_, &Wt::WDialog::accept);
 *  
 *   dialog_->finished().connect(this, &MyClass::dialogDone);
 *   dialog_->show();
 * }
 *
 * void MyClass::dialogDone(DialogCode code)
 * {
 *   if (code == Wt::WDialog::Accepted)
 *     setStatus("Welcome, " + edit_->text());
 *   delete dialog_;
 * }
 * \endcode
 * \endif
 *
 * This dialog looks like this (using the default css themes):
 *
 * <TABLE border="0" align="center"> <TR> <TD> 
 * \image html WDialog-default-1.png "A simple custom dialog (default)" 
 * </TD> <TD>
 * \image html WDialog-polished-1.png "A simple custom dialog (polished)" 
 * </TD> </TR> </TABLE>
 *
 * \note For the dialog (or rather, the silkscreen covering the user
 *       interface below) to render properly in IE, the "html body"
 *       margin is set to 0 (if it wasn't already).
 */
class WT_API WDialog : public WPopupWidget
{
public:
  /*! \brief The result of a modal dialog execution.
   */
  enum DialogCode { Rejected, //!< Dialog closed with reject()
		    Accepted  //!< Dialog closed with accept()
  };

  /*! \brief Constructs a new dialog.
   *
   * Unlike other widgets, the dialog does not require a parent
   * container since it is a top-level widget. You may however still
   * provide a parent object to let the dialog be deleted together
   * with its parent.
   */
  WDialog(WObject *parent = 0);

  /*! \brief Constructs a dialog with a given window title.
   *
   * Unlike other widgets, the dialog does not require a parent
   * container since it is a top-level widget. You may however still
   * provide a parent object to let the dialog be deleted together
   * with its parent.
   */
  WDialog(const WString& windowTitle, WObject *parent = 0);

  /*! \brief Deletes a dialog.
   */
  ~WDialog();

  /*! \brief Sets the dialog window title.
   *
   * The window title is displayed in the title bar.
   *
   * \sa setTitleBarEnabled()
   */
  void setWindowTitle(const WString& title);

  /*! \brief Returns the dialog window title.
   *
   * \sa setWindowTitle()
   */
  WString windowTitle() const;

#ifndef WT_DEPRECATED_3_0_0
  /*! \brief Sets the dialog caption (<b>deprecated</b>).
   *
   * \deprecated Use setWindowTitle() instead.
   */
  void setCaption(const WString& caption);

  /*! \brief Returns the dialog caption (<b>deprecated</b>).
   *
   * \deprecated Use windowTitle() instead.
   */
  WString caption() const;
#endif // WT_DEPRECATED_3_0_0

  /*! \brief Enables or disables the title bar.
   *
   * The titlebar is enabled by default.
   */
  void setTitleBarEnabled(bool enabled);

  /*! \brief Returns whether the title bar is enabled.
   *
   * \sa setTitleBarEnabled()
   */
  bool isTitleBarEnabled() const { return !titleBar_->isHidden(); }

  /*! \brief Returns the dialog title bar container.
   *
   * The title bar contains a single text that contains the
   * caption. You may customize the title bar by for example adding
   * other content.
   */
  WContainerWidget *titleBar() const { return titleBar_; }

  /*! \brief Returns the dialog contents container.
   *
   * Content to the dialog window may be added to this container widget. 
   */
  WContainerWidget *contents() const { return contents_; }

  /*! \brief Returns the dialog footer container.
   *
   * This is an optional section which is typically used for buttons.
   */
  WContainerWidget *footer() const;

  /*! \brief Executes the dialog in a recursive event loop.
   *
   * Executes the dialog synchronously. This blocks the current thread
   * of execution until one of done(DialogCode), accept() or reject()
   * is called.
   *
   * <i>Warning: using exec() does not scale to many concurrent
   * sessions, since the thread is locked until exec returns, so the
   * entire server will be unresponsive when the thread pool is
   * exhausted.</i>
   *
   * \if java 
   * <i>This functionality is only available on Servlet 3.0 compatible 
   * servlet containers.</i>
   * \endif
   *
   * \sa done(DialogCode r), accept(), reject()
   */
  DialogCode exec(const WAnimation& animation = WAnimation());

  /*! \brief Stops the dialog.
   *
   * Sets the dialog result, and emits the finished() signal.
   *
   * \if cpp
   * If a recursive event loop was started using the exec() method, it
   * is ended.
   * \endif
   *
   * \sa finished(), result()
   */
  virtual void done(DialogCode r);

  /*! \brief Closes the dialog, with result is Accepted.
   *
   * \sa done(DialogCode r), reject()
   */
  virtual void accept();

  /*! \brief Closes the dialog, with result is Rejected.
   *
   * \sa done(DialogCode r), accept()
   */
  virtual void reject();

  /*! \brief Lets pressing the escape key reject the dialog.
   *
   * Before %Wt 3.1.5, pressing escape automatically rejected the dialog.
   * Since 3.1.4 this behaviour is no longer the default since it may
   * interfere with other functionality in the dialog. Use this method
   * to enable this behaviour.
   *
   * \sa reject()
   */
  void rejectWhenEscapePressed();
  
  /*! \brief %Signal emitted when the dialog is closed.
   *
   * \sa done(DialogCode r), accept(), reject()
   */
  Signal<DialogCode>& finished() { return finished_; }

  /*! \brief Returns the result that was set for this dialog.
   *
   * \sa done(DialogCode r)
   */
  DialogCode result() const { return result_; }

  /*! \brief Sets whether the dialog is modal.
   *
   * A modal dialog will block the underlying user interface. A modal dialog
   * can be shown synchronously or asynchronously. A non-modal dialog can only
   * be shown asynchronously.
   *
   * By default a dialog is modal.
   */
  void setModal(bool modal);

  /*! \brief Returns whether the dialog is modal.
   *
   * \sa setModal()
   */
  bool isModal() const { return modal_; }

  /*! \brief Adds a resize handle to the dialog.
   *
   * The resize handle is shown in the bottom right corner of the dialog,
   * and allows the user to resize the dialog (but not smaller than the
   * content allows).
   *
   * This also sets the minimum width and height to WLength::Auto to
   * use the initial width and height as minimum sizes. You may want
   * to provide other values for minimum width and height to allow the
   * dialog to be reduced in size.
   *
   * \sa setMinimumSize(), setMaximumSize()
   */
  void setResizable(bool resizable);

  /*! \brief Returns whether the dialog has a resize handle.
   *
   * \sa setResizable()
   */
  bool resizable() const { return resizable_; }

  /*! \brief Adds a close button to the titlebar.
   *
   * The close button is shown in the title bar. Clicking the close button
   * will reject the dialog.
   */
  void setClosable(bool closable);

  /*! \brief Returns whether the dialog can be closed.
   */
  bool closable() const { return closeIcon_ != 0; }

  virtual void setHidden(bool hidden,
			 const WAnimation& animation = WAnimation());

  virtual void positionAt(const WWidget *widget,
			  Orientation orientation = Vertical);

  virtual void setMinimumSize(const WLength& width, const WLength& height);
  virtual void setMaximumSize(const WLength& width, const WLength& height);

protected:
  void render(WFlags<RenderFlag> flags);

private:
  WTemplate        *impl_;
  WText            *caption_;
  WText            *closeIcon_;
  WContainerWidget *titleBar_;
  WContainerWidget *contents_;
  mutable WContainerWidget *footer_;
  bool              modal_, resizable_;

  int               coverPreviousZIndex_;
  bool              coverWasHidden_;

  Signal<DialogCode> finished_;

  DialogCode result_;

  bool recursiveEventLoop_;

  bool initialized_;

  void create();
  void saveCoverState(WApplication *app, WContainerWidget *cover);
  void restoreCoverState(WApplication *app, WContainerWidget *cover);
};

}

#endif // WDIALOG_H_
