/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.feedback;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

import org.apache.wicket.Component;
import org.apache.wicket.util.io.IClusterable;
import org.apache.wicket.util.string.StringList;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Holds list of feedback messages. The list can be added to, cleared, queried and filtered.
 * <p>
 * WARNING: This class should typically NOT be used directly.
 * <p>
 * 
 * @author Eelco Hillenius
 * @author Jonathan Locke
 */
public final class FeedbackMessages implements IClusterable, Iterable<FeedbackMessage>
{
        /** Log. */
        private static final Logger log = LoggerFactory.getLogger(FeedbackMessages.class);

        private static final long serialVersionUID = 1L;

        /**
         * Holds a list of {@link org.apache.wicket.feedback.FeedbackMessage}s.
         */
        private final List<FeedbackMessage> messages;

        /**
         * Construct.
         */
        public FeedbackMessages()
        {
                messages = new CopyOnWriteArrayList<>();
        }

        /**
         * Adds a message.
         * 
         * @param message
         *            the message
         */
        public final void add(FeedbackMessage message)
        {
                log.debug("Adding feedback message '{}'", message);

                synchronized (messages)
                {
                        messages.add(message);
                }
        }

        /**
         * Adds a message
         * 
         * @param reporter
         * @param message
         * @param level
         */
        public final void add(Component reporter, Serializable message, int level)
        {
                add(new FeedbackMessage(reporter, message, level));
        }

        /**
         * Adds a new ui message with level DEBUG to the current messages.
         * 
         * @param reporter
         *            the reporting component
         * @param message
         *            the actual message
         */
        public final void debug(Component reporter, Serializable message)
        {
                add(new FeedbackMessage(reporter, message, FeedbackMessage.DEBUG));
        }

        /**
         * Adds a new ui message with level INFO to the current messages.
         * 
         * @param reporter
         *            The reporting component
         * @param message
         *            The actual message
         */
        public final void info(Component reporter, Serializable message)
        {
                add(new FeedbackMessage(reporter, message, FeedbackMessage.INFO));
        }

        /**
         * Adds a new ui message with level SUCCESS to the current messages.
         * 
         * @param reporter
         *            The reporting component
         * @param message
         *            The actual message
         */
        public final void success(Component reporter, Serializable message)
        {
                add(new FeedbackMessage(reporter, message, FeedbackMessage.SUCCESS));
        }

        /**
         * Adds a new ui message with level WARNING to the current messages.
         * 
         * @param reporter
         *            the reporting component
         * @param message
         *            the actual message
         */
        public final void warn(Component reporter, Serializable message)
        {
                add(new FeedbackMessage(reporter, message, FeedbackMessage.WARNING));
        }

        /**
         * Adds a new ui message with level ERROR to the current messages.
         * 
         * @param reporter
         *            the reporting component
         * @param message
         *            the actual message
         */
        public final void error(Component reporter, Serializable message)
        {
                add(new FeedbackMessage(reporter, message, FeedbackMessage.ERROR));
        }

        /**
         * Adds a new ui message with level FATAL to the current messages.
         * 
         * @param reporter
         *            the reporting component
         * @param message
         *            the actual message
         */
        public final void fatal(Component reporter, Serializable message)
        {
                add(new FeedbackMessage(reporter, message, FeedbackMessage.FATAL));
        }

        /**
         * Clears any existing messages.
         * 
         * @return The number of messages deleted
         */
        public final int clear()
        {
                return clear(null);
        }

        /**
         * Clears all messages that are accepted by the filter.
         * 
         * @param filter
         *            Filter for selecting messages. If null, all messages will be returned
         * @return The number of messages deleted
         */
        public final int clear(final IFeedbackMessageFilter filter)
        {
                if (messages.isEmpty())
                {
                        return 0;
                }

                List<FeedbackMessage> toDelete = messages(filter);

                for (FeedbackMessage message : toDelete)
                {
                        message.detach();
                }

                synchronized(messages)
                {
                        int sizeBefore = messages.size();
                        messages.removeAll(toDelete);
                        int sizeAfter = messages.size();
                        return sizeAfter - sizeBefore;
                }
        }

        /**
         * @param filter
         *            Filter for selecting messages
         * @return True if one or more messages matches the filter
         */
        public final boolean hasMessage(final IFeedbackMessageFilter filter)
        {
                for (final FeedbackMessage message : messages)
                {
                        if (filter == null || filter.accept(message))
                        {
                                return true;
                        }
                }
                return false;
        }

        /**
         * Checks if a message of the specified {@code level} or greater was registered.<br />
         * To check for a precise {@code level} use {@link #hasMessage(IFeedbackMessageFilter)}
         * and pass it a reference to {@link org.apache.wicket.feedback.ExactLevelFeedbackMessageFilter}.
         * 
         * @param level
         *            The level of the message
         * @return {@code true} if a message with the specified {@code level} or greater was registered
         */
        public final boolean hasMessage(final int level)
        {
                for (FeedbackMessage message : messages)
                {
                        if (message.isLevel(level))
                        {
                                return true;
                        }
                }
                return false;
        }

        /**
         * Retrieves the first message
         * 
         * @return message or {@code null} if none
         */
        public final FeedbackMessage first()
        {
                return messages.size() > 0 ? messages.get(0) : null;
        }

        /**
         * Retrieves the first message that level is greater than or equal to the given level
         * 
         * @param level
         *            The minimum level of the message
         * @return a message with the same or a higher level, or {@code null} if none
         */
        public final FeedbackMessage first(final int level)
        {
                for (FeedbackMessage message : messages)
                {
                        if (message.isLevel(level))
                        {
                                return message;
                        }
                }
                return null;
        }

        /**
         * Gets an iterator over stored messages
         * 
         * @return iterator over stored messages
         */
        @Override
        public final Iterator<FeedbackMessage> iterator()
        {
                return messages.iterator();
        }

        /**
         * Gets a list of messages from the page using a filter.
         * 
         * @param filter
         *            Filter for selecting messages. If null, all messages will be returned
         * @return The messages or an empty list if no messages are found
         */
        public final List<FeedbackMessage> messages(final IFeedbackMessageFilter filter)
        {
                if (messages.isEmpty())
                {
                        return Collections.emptyList();
                }

                final List<FeedbackMessage> list = new ArrayList<FeedbackMessage>();
                for (final FeedbackMessage message : messages)
                {
                        if (filter == null || filter.accept(message))
                        {
                                list.add(message);
                        }
                }
                return list;
        }

        /**
         * Gets whether there are no messages.
         * 
         * @return True when there are no messages
         */
        public final boolean isEmpty()
        {
                return messages.isEmpty();
        }

        /**
         * Gets the number of messages
         * 
         * @return the number of messages
         */
        public final int size()
        {
                return messages.size();
        }

        /**
         * Gets the number of messages.
         * 
         * @param filter
         *            Filter for counting messages. If null, the count of all messages will be returned
         * 
         * @return the number of messages
         */
        public final int size(final IFeedbackMessageFilter filter)
        {
                int count = 0;
                for (final FeedbackMessage message : messages)
                {
                        if (filter == null || filter.accept(message))
                        {
                                count++;
                        }
                }
                return count;
        }

        /**
         * @see java.lang.Object#toString()
         */
        @Override
        public String toString()
        {
                return "[feedbackMessages = " + StringList.valueOf(messages) + ']';
        }

        /**
         * Retrieves all stored messages as an unmodifiable list
         * 
         * @return stored messages as unmodifiable list
         */
        public List<FeedbackMessage> toList()
        {
                return Collections.unmodifiableList(messages);
        }

        /**
         * Detaches each stored message
         */
        public void detach()
        {
                for (FeedbackMessage message : messages)
                {
                        message.detach();
                }
        }
}