/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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 com.googlecode.android_scripting.jsonrpc;

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import com.googlecode.android_scripting.facade.FacadeManager;
import com.googlecode.android_scripting.Log;
import com.googlecode.android_scripting.rpc.MethodDescriptor;

public abstract class RpcReceiverManager {

    private final Map<Class<? extends RpcReceiver>, RpcReceiver> mReceivers;

    /**
     * A map of strings to known RPCs.
     */
    private final Map<String, MethodDescriptor> mKnownRpcs = new HashMap<String, MethodDescriptor>();

    public RpcReceiverManager(Collection<Class<? extends RpcReceiver>> classList) {
        mReceivers = new HashMap<Class<? extends RpcReceiver>, RpcReceiver>();
        for (Class<? extends RpcReceiver> receiverClass : classList) {
            mReceivers.put(receiverClass, null);
            Collection<MethodDescriptor> methodList = MethodDescriptor.collectFrom(receiverClass);
            for (MethodDescriptor m : methodList) {
                if (mKnownRpcs.containsKey(m.getName())) {
                    // We already know an RPC of the same name. We don't catch this anywhere because
                    // this is a programming error.
                    throw new RuntimeException("An RPC with the name " + m.getName()
                            + " is already known.");
                }
                mKnownRpcs.put(m.getName(), m);
            }
        }
    }

    public Collection<Class<? extends RpcReceiver>> getRpcReceiverClasses() {
        return mReceivers.keySet();
    }

    private RpcReceiver get(Class<? extends RpcReceiver> clazz) {
        RpcReceiver object = mReceivers.get(clazz);
        if (object != null) {
            return object;
        }

        Constructor<? extends RpcReceiver> constructor;
        try {
            constructor = clazz.getConstructor(FacadeManager.class);
            object = constructor.newInstance(this);
            mReceivers.put(clazz, object);
        } catch (Exception e) {
            Log.e(e);
        }

        return object;
    }

    public <T extends RpcReceiver> T getReceiver(Class<T> clazz) {
        RpcReceiver receiver = get(clazz);
        return clazz.cast(receiver);
    }

    public MethodDescriptor getMethodDescriptor(String methodName) {
        return mKnownRpcs.get(methodName);
    }

    public Object invoke(Class<? extends RpcReceiver> clazz, Method method, Object[] args)
            throws Exception {
        RpcReceiver object = get(clazz);
        return method.invoke(object, args);
    }

    public void shutdown() {
        for (RpcReceiver receiver : mReceivers.values()) {
            try {
                if (receiver != null) {
                    receiver.shutdown();
                }
            } catch (Exception e) {
                Log.e("Failed to shut down an RpcReceiver", e);
            }
        }
    }
}