/*
 * 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.shardingsphere.proxy.frontend.state;

import io.netty.channel.ChannelHandlerContext;
import lombok.AccessLevel;
import lombok.NoArgsConstructor;
import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
import org.apache.shardingsphere.proxy.frontend.spi.DatabaseProtocolFrontendEngine;
import org.apache.shardingsphere.proxy.frontend.state.impl.CircuitBreakProxyState;
import org.apache.shardingsphere.proxy.frontend.state.impl.LockProxyState;
import org.apache.shardingsphere.proxy.frontend.state.impl.OKProxyState;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicReference;

/**
 * Proxy state machine.
 */
@NoArgsConstructor(access = AccessLevel.PRIVATE)
public final class ProxyStateMachine {
    
    private static final Map<ProxyStateType, ProxyState> PROXY_STATE_MAP = new ConcurrentHashMap<>(3, 1);
    
    private static final AtomicReference<ProxyState> CURRENT_STATE = new AtomicReference<>();
    
    static {
        PROXY_STATE_MAP.put(ProxyStateType.OK, new OKProxyState());
        PROXY_STATE_MAP.put(ProxyStateType.LOCK, new LockProxyState());
        PROXY_STATE_MAP.put(ProxyStateType.CIRCUIT_BREAK, new CircuitBreakProxyState());
        CURRENT_STATE.set(PROXY_STATE_MAP.get(ProxyStateType.OK));
    }
    
    /**
     * Execute command.
     *
     * @param context channel handler context
     * @param message message
     * @param databaseProtocolFrontendEngine database protocol frontend engine
     * @param backendConnection backend connection
     */
    public static void execute(final ChannelHandlerContext context, final Object message, 
                               final DatabaseProtocolFrontendEngine databaseProtocolFrontendEngine, final BackendConnection backendConnection) {
        CURRENT_STATE.get().execute(context, message, databaseProtocolFrontendEngine, backendConnection);
    }
    
    /**
     * Switch proxy state.
     * 
     * @param type proxy state type
     */
    public static void switchState(final ProxyStateType type) {
        CURRENT_STATE.set(PROXY_STATE_MAP.get(type));
    }
}