/*
 * 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.cassandra.schema;

import java.util.Iterator;
import java.util.function.Predicate;
import java.util.stream.Stream;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.MapDifference;
import com.google.common.collect.Maps;

public final class Keyspaces implements Iterable<KeyspaceMetadata>
{
    private final ImmutableMap<String, KeyspaceMetadata> keyspaces;

    private Keyspaces(Builder builder)
    {
        keyspaces = builder.keyspaces.build();
    }

    public static Builder builder()
    {
        return new Builder();
    }

    public static Keyspaces none()
    {
        return builder().build();
    }

    public static Keyspaces of(KeyspaceMetadata... keyspaces)
    {
        return builder().add(keyspaces).build();
    }

    public Iterator<KeyspaceMetadata> iterator()
    {
        return keyspaces.values().iterator();
    }

    public Stream<KeyspaceMetadata> stream()
    {
        return keyspaces.values().stream();
    }

    public Keyspaces filter(Predicate<KeyspaceMetadata> predicate)
    {
        Builder builder = builder();
        stream().filter(predicate).forEach(builder::add);
        return builder.build();
    }

    MapDifference<String, KeyspaceMetadata> diff(Keyspaces other)
    {
        return Maps.difference(keyspaces, other.keyspaces);
    }

    @Override
    public boolean equals(Object o)
    {
        return this == o || (o instanceof Keyspaces && keyspaces.equals(((Keyspaces) o).keyspaces));
    }

    @Override
    public int hashCode()
    {
        return keyspaces.hashCode();
    }

    @Override
    public String toString()
    {
        return keyspaces.values().toString();
    }

    public static final class Builder
    {
        private final ImmutableMap.Builder<String, KeyspaceMetadata> keyspaces = new ImmutableMap.Builder<>();

        private Builder()
        {
        }

        public Keyspaces build()
        {
            return new Keyspaces(this);
        }

        public Builder add(KeyspaceMetadata keyspace)
        {
            keyspaces.put(keyspace.name, keyspace);
            return this;
        }

        public Builder add(KeyspaceMetadata... keyspaces)
        {
            for (KeyspaceMetadata keyspace : keyspaces)
                add(keyspace);
            return this;
        }

        public Builder add(Iterable<KeyspaceMetadata> keyspaces)
        {
            keyspaces.forEach(this::add);
            return this;
        }
    }
}