/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.action;


import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.swt.events.HelpListener;
import org.eclipse.swt.widgets.Event;

/**
 * An action represents the non-UI side of a command which can be triggered
 * by the end user. Actions are typically associated with buttons, menu items,
 * and items in tool bars. The controls for a command are built by some container,
 * which furnished the context where these controls appear and configures 
 * them with data from properties declared by the action. When the end user
 * triggers the command via its control, the action's <code>run</code>
 * method is invoked to do the real work.
 * <p>
 * Actions support a predefined set of properties (and possibly others as well).
 * Clients of an action may register property change listeners so that they get 
 * notified whenever the value of a property changes.
 * </p>
 * <p>
 * Clients should subclass the abstract base class <code>Action</code> to define 
 * concrete actions rather than implementing <code>IAction</code> from scratch.
 * </p>
 * <p>
 * This interface exists only to define the API for actions.
 * It is not intended to be implemented by clients.
 * </p>
 * 
 * @see Action
 */
public interface IAction {

	/**
	 * Action style constant (value <code>0</code>) indicating action style 
	 * is not specified yet. By default, the action will assume a push button
	 * style. If <code>setChecked</code> is called, then the style will change
	 * to a check box, or if <code>setMenuCreator</code> is called, then the
	 * style will change to a drop down menu.
	 * 
	 * @since 2.1
	 */
	public static int AS_UNSPECIFIED = 0x00;

	/**
	 * Action style constant (value <code>1</code>) indicating action is 
	 * a simple push button.
	 */
	public static int AS_PUSH_BUTTON = 0x01;

	/**
	 * Action style constant (value <code>2</code>) indicating action is 
	 * a check box (or a toggle button).
	 */
	public static int AS_CHECK_BOX = 0x02;

	/**
	 * Action style constant (value <code>4</code>) indicating action is 
	 * a drop down menu.
	 */
	public static int AS_DROP_DOWN_MENU = 0x04;

	/**
	 * Action style constant (value <code>8</code>) indicating action is 
	 * a radio button.
	 * 
	 * @since 2.1
	 */
	public static int AS_RADIO_BUTTON = 0x08;

	/**
	 * Property name of an action's text (value <code>"text"</code>).
	 */
	public static final String TEXT= "text"; //$NON-NLS-1$
	
	
	/**
	 * Property name of an action's enabled state
	 * (value <code>"enabled"</code>).
	 */
	public static final String ENABLED= "enabled"; //$NON-NLS-1$

	
	/**
	 * Property name of an action's image (value <code>"image"</code>).
	 */
	public static final String IMAGE= "image"; //$NON-NLS-1$
	
	/**
	 * Property name of an action's tooltip text (value <code>"toolTipText"</code>).
	 */
	public static final String TOOL_TIP_TEXT= "toolTipText"; //$NON-NLS-1$

	
	/**
	 * Property name of an action's description (value <code>"description"</code>).
	 * Typically the description is shown as a (longer) help text in the status line.
	 */
	public static final String DESCRIPTION= "description"; //$NON-NLS-1$
	
	/**
	 * Property name of an action's checked status (value
	 * <code>"checked"</code>). Applicable when the style is
	 * <code>AS_CHECK_BOX</code> or <code>AS_RADIO_BUTTON</code>.
	 */
	public static final String CHECKED= "checked"; //$NON-NLS-1$

	/**
	 * Property name of an action's success/fail result
	 * (value <code>"result"</code>). The values are
	 * <code>Boolean.TRUE</code> if running the action succeeded and 
	 * <code>Boolean.FALSE</code> if running the action failed or did not
	 * complete.
	 * <p>
	 * Not all actions report whether they succeed or fail. This property
	 * is provided for use by actions that may be invoked by clients that can
	 * take advantage of this information when present (for example, actions
	 * used in cheat sheets). Clients should always assume that running the
	 * action succeeded in the absence of notification to the contrary. 
	 * </p>
	 * 
	 * @since 3.0
	 */
	public static final String RESULT= "result"; //$NON-NLS-1$

/**
 * Adds a property change listener to this action.
 * Has no effect if an identical listener is already registered.
 *
 * @param listener a property change listener
 */
public void addPropertyChangeListener(IPropertyChangeListener listener);
/**
 * Returns the accelerator keycode for this action.
 * The result is the bit-wise OR of zero or more modifier masks
 * and a key, as explained in <code>MenuItem.getAccelerator</code>.
 *
 * @return the accelerator keycode
 * @see org.eclipse.swt.widgets.MenuItem#getAccelerator()
 */
public int getAccelerator();
/**
 * Returns the action definition id of this action.
 * 
 * @return the action definition id of this action, or
 * <code>null</code> if none
 * @since 2.0
 */
public String getActionDefinitionId();
/**
 * Returns the action's description if it has one.
 * Otherwise it returns <code>getToolTipText()</code>.
 */
public String getDescription();
/**
 * Returns the disabled image for this action as an image descriptor.
 * <p>
 * This method is associated with the <code>IMAGE</code> property;
 * property change events are reported when its value changes.
 * </p>
 *
 * @return the image, or <code>null</code> if this action has no image
 * @see #IMAGE
 */
public ImageDescriptor getDisabledImageDescriptor();
/**
 * Returns a help listener for this action. 
 *
 * @return a help listener for this action
 */
public HelpListener getHelpListener();
/**
 * Returns the hover image for this action as an image descriptor.
 * <p>
 * Hover images will be used on platforms that support changing the image
 * when the user hovers over the item. This method is associated with 
 * the <code>IMAGE</code> property;
 * property change events are reported when its value changes.
 * </p>
 *
 * @return the image, or <code>null</code> if this action has no image
 * @see #IMAGE
 */
public ImageDescriptor getHoverImageDescriptor();
/**
 * Returns a unique identifier for this action, or <code>null</code> if it has
 * none.
 *
 * @return the action id, or <code>null</code> if none
 */
public String getId();
/**
 * Returns the image for this action as an image descriptor.
 * <p>
 * This method is associated with the <code>IMAGE</code> property;
 * property change events are reported when its value changes.
 * </p>
 *
 * @return the image, or <code>null</code> if this action has no image
 * @see #IMAGE
 */
public ImageDescriptor getImageDescriptor();
/**
 * Returns the menu creator for this action.
 *
 * @return the menu creator, or <code>null</code> if none
 */
public IMenuCreator getMenuCreator();
/**
 * Return this action's style.
 *
 * @return one of <code>AS_PUSH_BUTTON</code>, <code>AS_CHECK_BOX</code>,
 * <code>AS_RADIO_BUTTON</code> and <code>AS_DROP_DOWN_MENU</code>.
 */
public int getStyle();
/**
 * Returns the text for this action.
 * <p>
 * This method is associated with the <code>TEXT</code> property;
 * property change events are reported when its value changes.
 * </p>
 *
 * @return the text, or <code>null</code> if none
 * @see #TEXT
 */
public String getText();
/**
 * Returns the tool tip text for this action.
 * <p>
 * This method is associated with the <code>TOOL_TIP_TEXT</code> property;
 * property change events are reported when its value changes.
 * </p>
 *
 * @return the tool tip text, or <code>null</code> if none
 * @see #TOOL_TIP_TEXT
 */
public String getToolTipText();
/**
 * Returns the checked status of this action. Applicable only if the style is
 * <code>AS_CHECK_BOX</code> or <code>AS_RADIO_BUTTON</code>.
 * <p>
 * This method is associated with the <code>CHECKED</code> property;
 * property change events are reported when its value changes.
 * </p>
 *
 * @return the checked status
 * @see #CHECKED
 */
public boolean isChecked();
/**
 * Returns whether this action is enabled.
 * <p>
 * This method is associated with the <code>ENABLED</code> property;
 * property change events are reported when its value changes.
 * </p>
 *
 * @return <code>true</code> if enabled, and
 *   <code>false</code> if disabled
 * @see #ENABLED
 */
public boolean isEnabled();
/**
 * Removes the given listener from this action.
 * Has no effect if an identical listener is not registered.
 *
 * @param listener a property change listener
 */
public void removePropertyChangeListener(IPropertyChangeListener listener);

/**
 * Runs this action.
 * Each action implementation must define the steps needed to carry out this action.
 * The default implementation of this method in <code>Action</code>
 * does nothing.
 */
public void run();

/**
 * Runs this action, passing the triggering SWT event.
 * As of 2.0, <code>ActionContributionItem</code> calls this method
 * instead of <code>run()</code>.  
 * The default implementation of this method in <code>Action</code>
 * simply calls <code>run()</code> for backwards compatibility.
 * 
 * @param event the SWT event which triggered this action being run 
 * @since 2.0
 */
public void runWithEvent(Event event);
/**
 * Sets the action definition id of this action.
 * 
 * @param id the action definition id
 * @since 2.0
 */
public void setActionDefinitionId(String id);
/**
 * Sets the checked status of this action. Applicable for the styles
 * <code>AS_CHECK_BOX</code> or <code>AS_RADIO_BUTTON</code>.
 * <p>
 * Fires a property change event for the <code>CHECKED</code> property
 * if the checked status actually changes as a consequence.
 * </p>
 *
 * @param checked the new checked status
 * @see #CHECKED
 */
public void setChecked(boolean checked);
/**
 * Sets this action's description.
 * Typically the description is shown as a (longer) help text in the status line.
 * <p>
 * Fires a property change event for the <code>DESCRIPTION</code> property
 * if the description actually changes as a consequence.
 * </p>
 *
 * @param text the description, or <code>null</code> to clear the description
 * @see #DESCRIPTION
 */
public void setDescription(String text);
/**
 * Sets the disabled image for this action, as an image descriptor.
 * <p>
 * Disabled images will be used on platforms that support changing the image
 * when the item is disabled.Fires a property change event for 
 * the <code>IMAGE</code> property
 * if the image actually changes as a consequence.
 * </p>
 *
 * @param newImage the image, or <code>null</code> if this 
 *   action should not have an image
 * @see #IMAGE
 */
public void setDisabledImageDescriptor(ImageDescriptor newImage);
/**
 * Sets the enabled state of this action.
 * <p>
 * When an action is in the enabled state, the control associated with 
 * it is active; triggering it will end up inkoking this action's 
 * <code>run</code> method.
 * </p>
 * <p>
 * Fires a property change event for the <code>ENABLED</code> property
 * if the enabled state actually changes as a consequence.
 * </p>
 *
 * @param enabled <code>true</code> to enable, and
 *   <code>false</code> to disable
 * @see #ENABLED
 */
public void setEnabled(boolean enabled);
/**
 * Sets a help listener for this action. 
 *
 * @param listener a help listener for this action
 */
public void setHelpListener(HelpListener listener);
/**
 * Sets the hover image for this action, as an image descriptor.
 * <p>
 * Hover images will be used on platforms that support changing the image
 * when the user hovers over the item.Fires a property change event for 
 * the <code>IMAGE</code> property
 * if the image actually changes as a consequence.
 * </p>
 *
 * @param newImage the image, or <code>null</code> if this 
 *   action should not have an image
 * @see #IMAGE
 */
public void setHoverImageDescriptor(ImageDescriptor newImage);
/**
 * Sets the unique identifier for this action. This is used to identify actions
 * when added to a contribution manager.
 * It should be set when the action is created.  It should not be modified once
 * the action is part of an action contribution item.
 *
 * @param id the action id
 *
 * @see ActionContributionItem
 * @see IContributionItem#getId
 */
public void setId(String id);
/**
 * Sets the image for this action, as an image descriptor.
 * <p>
 * Fires a property change event for the <code>IMAGE</code> property
 * if the image actually changes as a consequence.
 * </p>
 *
 * @param newImage the image, or <code>null</code> if this 
 *   action should not have an image
 * @see #IMAGE
 */
public void setImageDescriptor(ImageDescriptor newImage);
/**
 * Sets the menu creator for this action. Applicable for style
 * <code>AS_DROP_DOWN_MENU</code>.
 *
 * @param creator the menu creator, or <code>null</code> if none
 */
public void setMenuCreator(IMenuCreator creator); 
/**
 * Sets the text for this action.
 * <p>
 * An accelerator specification may follow the actual text, separated from it by
 * an '@' or a '\t' character.  An accelerator specification consists of zero or more 
 * modifier tokens followed by a key code token.  The tokens are separated by a '+' character.
 * </p>
 * <p>
 * Fires a property change event for the <code>TEXT</code> property
 * if the text actually changes as a consequence.
 * </p>
 *
 * @param text the text, or <code>null</code> if none
 * @see #TEXT
 * @see Action#findModifier
 * @see Action#findKeyCode
 */
public void setText(String text);
/**
 * Sets the tool tip text for this action.
 * <p>
 * Fires a property change event for the <code>TOOL_TIP_TEXT</code> property
 * if the tool tip text actually changes as a consequence.
 * </p>
 *
 * @param text the tool tip text, or <code>null</code> if none
 * @see #TOOL_TIP_TEXT
 */
public void setToolTipText(String text);

/**
 * <p>
 * Sets the accelerator keycode that this action maps to. This is a bitwise OR
 * of zero or more SWT key modifier masks (i.e. SWT.CTRL or SWT.ALT) and a
 * character code. For example, for Ctrl+Z, use <code>SWT.CTRL | 'Z'</code>.
 * Use 0 for no accelerator.
 * </p>
 * <p>
 * This method should no longer be used for actions in the Eclipse workbench.
 * <code>IWorkbenchCommandSupport</code> and
 * <code>IWorkbenchContextSupport</code> provide all the functionality
 * required for key bindings. If you set an accelerator using this method, then
 * it will not work in the workbench if it conflicts any existing key binding,
 * or if there is a different key binding defined for this action's definition
 * id.
 * </p>
 * 
 * @param keycode
 *            the keycode to be accepted.
 */
public void setAccelerator(int keycode);
}