/*
 * Copyright (C) 2004-2008 Jive Software. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.jivesoftware.openfire.user;

import java.util.Collection;
import java.util.Date;
import java.util.Set;

/**
 * Provider interface for the user system.
 *
 * @author Matt Tucker
 */
public interface UserProvider {

    /**
     * Loads the specified user by username.
     *
     * @param username the username
     * @return the User.
     * @throws UserNotFoundException if the User could not be loaded.
     */
    User loadUser( String username ) throws UserNotFoundException;

    /**
     * Creates a new user. This method should throw an
     * UnsupportedOperationException if this operation is not
     * supporte by the backend user store.
     *
     * @param username the username.
     * @param password the plain-text password.
     * @param name the user's name, which can be {@code null}, unless isNameRequired is set to true.
     * @param email the user's email address, which can be {@code null}, unless isEmailRequired is set to true.
     * @return a new User.
     * @throws UserAlreadyExistsException if the username is already in use.
     */
    User createUser( String username, String password, String name, String email )
            throws UserAlreadyExistsException;

    /**
     * Delets a user. This method should throw an
     * UnsupportedOperationException if this operation is not
     * supported by the backend user store.
     *
     * @param username the username to delete.
     */
    void deleteUser( String username );

    /**
     * Returns the number of users in the system.
     *
     * @return the total number of users.
     */
    int getUserCount();

    /**
     * Returns an unmodifiable Collections of all users in the system. The
     * {@link UserCollection} class can be used to assist in the implementation
     * of this method. It takes a String [] of usernames and presents it as a
     * Collection of User objects (obtained with calls to
     * {@link UserManager#getUser(String)}.
     *
     * @return an unmodifiable Collection of all users.
     */
    Collection<User> getUsers();

    /**
     * Returns an unmodifiable Collection of usernames of all users in the system.
     *
     * @return an unmodifiable Collection of all usernames in the system.
     */
    Collection<String> getUsernames();

    /**
     * Returns an unmodifiable Collections of users in the system within the
     * specified range. The {@link UserCollection} class can be used to assist
     * in the implementation of this method. It takes a String [] of usernames
     * and presents it as a  Collection of User objects (obtained with calls to
     * {@link UserManager#getUser(String)}.<p>
     *
     * It is possible that the number of results returned will be less than that
     * specified by {@code numResults} if {@code numResults} is greater than the
     * number of records left to display.
     *
     * @param startIndex the beginning index to start the results at.
     * @param numResults the total number of results to return.
     * @return an unmodifiable Collection of users within the specified range.
     */
    Collection<User> getUsers( int startIndex, int numResults );

    /**
     * Sets the user's name. This method should throw an UnsupportedOperationException
     * if this operation is not supported by the backend user store.
     *
     * @param username the username.
     * @param name the name.
     * @throws UserNotFoundException if the user could not be found.
     */
    void setName( String username, String name ) throws UserNotFoundException;

    /**
     * Sets the user's email address. This method should throw an
     * UnsupportedOperationException if this operation is not supported
     * by the backend user store.
     *
     * @param username the username.
     * @param email the email address.
     * @throws UserNotFoundException if the user could not be found.
     */
    void setEmail( String username, String email ) throws UserNotFoundException;

    /**
     * Sets the date the user was created. This method should throw an
     * UnsupportedOperationException if this operation is not supported
     * by the backend user store.
     *
     * @param username the username.
     * @param creationDate the date the user was created.
     * @throws UserNotFoundException if the user could not be found.
     */
    void setCreationDate( String username, Date creationDate ) throws UserNotFoundException;

    /**
     * Sets the date the user was last modified. This method should throw an
     * UnsupportedOperationException if this operation is not supported
     * by the backend user store.
     *
     * @param username the username.
     * @param modificationDate the date the user was last modified.
     * @throws UserNotFoundException if the user could not be found.
     */
    void setModificationDate( String username, Date modificationDate )
            throws UserNotFoundException;

    /**
     * Returns the set of fields that can be used for searching for users. Each field
     * returned must support wild-card and keyword searching. For example, an
     * implementation might send back the set {"Username", "Name", "Email"}. Any of
     * those three fields can then be used in a search with the
     * {@link #findUsers(Set,String)} method.<p>
     *
     * This method should throw an UnsupportedOperationException if this
     * operation is not supported by the backend user store.
     *
     * @return the valid search fields.
     * @throws UnsupportedOperationException if the provider does not
     *      support the operation (this is an optional operation).
     */
    Set<String> getSearchFields() throws UnsupportedOperationException;

    /**
     * Searches for users based on a set of fields and a query string. The fields must
     * be taken from the values returned by {@link #getSearchFields()}. The query can
     * include wildcards. For example, a search on the field "Name" with a query of "Ma*"
     * might return user's with the name "Matt", "Martha" and "Madeline".<p>
     *
     * This method should throw an UnsupportedOperationException if this
     * operation is not supported by the backend user store. 
     *
     * @param fields the fields to search on.
     * @param query the query string.
     * @return a Collection of users that match the search.
     * @throws UnsupportedOperationException if the provider does not
     *      support the operation (this is an optional operation).
     */
    Collection<User> findUsers( Set<String> fields, String query )
            throws UnsupportedOperationException;

    /**
     * Searches for users based on a set of fields and a query string. The fields must
     * be taken from the values returned by {@link #getSearchFields()}. The query can
     * include wildcards. For example, a search on the field "Name" with a query of "Ma*"
     * might return user's with the name "Matt", "Martha" and "Madeline".<p>
     *
     * The startIndex and numResults parameters are used to page through search
     * results. For example, if the startIndex is 0 and numResults is 10, the first
     * 10 search results will be returned. Note that numResults is a request for the
     * number of results to return and that the actual number of results returned
     * may be fewer.<p>
     *
     * This method should throw an UnsupportedOperationException if this
     * operation is not supported by the backend user store.
     *
     * @param fields the fields to search on.
     * @param query the query string.
     * @param startIndex the starting index in the search result to return.
     * @param numResults the number of users to return in the search result.
     * @return a Collection of users that match the search.
     * @throws UnsupportedOperationException if the provider does not
     *      support the operation (this is an optional operation).
     */
    Collection<User> findUsers( Set<String> fields, String query, int startIndex,
                                int numResults ) throws UnsupportedOperationException;

    /**
     * Returns true if this UserProvider is read-only. When read-only,
     * users can not be created, deleted, or modified.
     *
     * @return true if the user provider is read-only.
     */
    boolean isReadOnly();

    /**
     * Returns true if this UserProvider requires a name to be set on User objects.
     *
     * @return true if an name is required with this provider.
     */
    boolean isNameRequired();

    /**
     * Returns true if this UserProvider requires an email address to be set on User objects.
     *
     * @return true if an email address is required with this provider.
     */
    boolean isEmailRequired();

}
