/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.update.configuration;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.update.core.IFeature;

/**
 * Local Site.
 * Represents the local installation. It consists of the current
 * configuration and the configuration history. A local site
 * manages the number of configuration histories kept. It also allows
 * specific configuration histories to be saved.
 * <p>
 * <b>Note:</b> This class/interface is part of an interim API that is still under development and expected to
 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
 * (repeatedly) as the API evolves.
 * </p> 
 * @since 2.0
 */
public interface ILocalSite extends IAdaptable {

	/**
	 * Return the current configuration.
	 * 
	 * @return current configuration
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	IInstallConfiguration getCurrentConfiguration();

	/**
	 * Return configuration history.
	 * 
	 * @return an array of configurations, or an empty array.
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public IInstallConfiguration[] getConfigurationHistory();

	/**
	 * Reverts the local site to use the specified configuration.
	 * The result of this operation is a new configuration that
	 * contains the same configured features as the specified configuration.
	 * The new configuration becomes the current configuration.
	 * 
	 * @param configuration configuration state to revert to
	 * @param monitor progress monitor
	 * @param handler problem handler
	 * @exception CoreException
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public void revertTo(
		IInstallConfiguration configuration,
		IProgressMonitor monitor,
		IProblemHandler handler)
		throws CoreException;

	/**
	 * Creates a new configuration containing the same state as the 
	 * specified configuration. The new configuration is not added to
	 * this lical site.
	 * 
	 * @return cloned configuration
	 * @exception CoreException
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public IInstallConfiguration cloneCurrentConfiguration() throws CoreException;

	/**
	 * Adds the specified configuration to this local site.
	 * The new configuration becomes the current one.
	 * 
	 * @param config the configuration
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public void addConfiguration(IInstallConfiguration config);

	/**
	 * Saves the local site state
	 * 
	 * @exception CoreException
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 * @return true if a restart is needed. This return code was added in 3.0.
	 */
	public boolean save() throws CoreException;

	/**
	 * Indicates how many configuration histories should be maintained.
	 * Histories beyond the specified count are automatically deleted.
	 * 
	 * @return number of past configurations to keep as history
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public int getMaximumHistoryCount();

	/**
	 * Sets the number of past configurations to keep in history
	 * 
	 * @param history number of configuration to keep
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public void setMaximumHistoryCount(int history);

	/**
	 * Adds a site change listener
	 * 
	 * @param listener the listener
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public void addLocalSiteChangedListener(ILocalSiteChangedListener listener);

	/**
	 * Removes a site listener
	 * 
	 * @param listener the listener
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public void removeLocalSiteChangedListener(ILocalSiteChangedListener listener);

	/**
	 * Save the specified configuration. Saved configurations are 
	 * not deleted based on the history count. They must be explicitly
	 * removed.
	 * 
	 * @param configuration the configuration to save
	 * @return the preserved configuration or <code>null</code> if the configuration to save is <code>null</code>
	 * @exception CoreException
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public IInstallConfiguration addToPreservedConfigurations(IInstallConfiguration configuration)
		throws CoreException;

	/**
	 * Removes the specified configuration from the list of previously
	 * saved configurations.
	 * 
	 * @param configuration the configuration to remove
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public void removeFromPreservedConfigurations(IInstallConfiguration configuration);

	/**
	 * Return the list of saved configurations
	 * 
	 * @return an array of configurations, or an empty array.
	 * @since 2.0 
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public IInstallConfiguration[] getPreservedConfigurations();
	
	/**
	 * Indicates if the 'state' of the specified feature and its children features.
	 * 
	 * A feature is considered to be 'unhappy' in the context of this site,
	 * if some of the plug-ins referenced by the feature, or any of its children,
	 *  are not installed on this site.
	 * 
	 * A feature is considered to be 'happy' in the context of a local site
	 * if all the plug-ins referenced by the feature, or any of its children,
	 * are installed on the site and no other version of any of the plug-ins
	 * are installed on any other site of the local site.
	 * 
	 * A feature is considered to be 'ambiguous' in the context of a local site
	 * if all the plug-ins referenced by the feature, or any of its children,
	 * are installed on the site and other version of any of the plug-ins
	 * are installed on any other site of the local site.
	 * 
	 * @param feature the feature
	 * @see IFeature#STATUS_HAPPY
	 * @see IFeature#STATUS_UNHAPPY
	 * @see IFeature#STATUS_AMBIGUOUS
	 * @return the state of the feature
	 * @exception CoreException
	 * @since 2.0
	 * <p>
	 * <b>Note:</b> This method is part of an interim API that is still under development and expected to
	 * change significantly before reaching stability. It is being made available at this early stage to solicit feedback
	 * from pioneering adopters on the understanding that any code that uses this API will almost certainly be broken
	 * (repeatedly) as the API evolves.
	 * </p>
	 */
	public IStatus getFeatureStatus(IFeature feature) throws CoreException ;	

}
