/*
 * 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 failsafe

import (
	"context"
)

import (
	"github.com/dubbogo/gost/log/logger"
)

import (
	"dubbo.apache.org/dubbo-go/v3/cluster/cluster/base"
	"dubbo.apache.org/dubbo-go/v3/cluster/directory"
	"dubbo.apache.org/dubbo-go/v3/common/constant"
	"dubbo.apache.org/dubbo-go/v3/common/extension"
	protocolbase "dubbo.apache.org/dubbo-go/v3/protocol/base"
	"dubbo.apache.org/dubbo-go/v3/protocol/result"
)

/**
 * When invoke fails, log the error message and ignore this error by returning an empty Result.
 * Usually used to write audit logs and other operations
 *
 * <a href="http://en.wikipedia.org/wiki/Fail-safe">Fail-safe</a>
 *
 */
type failsafeClusterInvoker struct {
	base.BaseClusterInvoker
}

func newFailsafeClusterInvoker(directory directory.Directory) protocolbase.Invoker {
	return &failsafeClusterInvoker{
		BaseClusterInvoker: base.NewBaseClusterInvoker(directory),
	}
}

func (invoker *failsafeClusterInvoker) Invoke(ctx context.Context, invocation protocolbase.Invocation) result.Result {
	invokers := invoker.Directory.List(invocation)

	err := invoker.CheckInvokers(invokers, invocation)
	if err != nil {
		return &result.RPCResult{}
	}

	url := invokers[0].GetURL()
	methodName := invocation.MethodName()
	// Get the service loadbalance config
	lb := url.GetParam(constant.LoadbalanceKey, constant.DefaultLoadBalance)
	// Get the service method loadbalance config if have
	if v := url.GetMethodParam(methodName, constant.LoadbalanceKey, ""); v != "" {
		lb = v
	}
	loadbalance := extension.GetLoadbalance(lb)

	invoked := make([]protocolbase.Invoker, 0)
	var res result.Result

	ivk := invoker.DoSelect(loadbalance, invocation, invokers, invoked)
	// DO INVOKE
	res = ivk.Invoke(ctx, invocation)
	if res.Error() != nil {
		// ignore
		logger.Errorf("Failsafe ignore exception: %v.\n", res.Error().Error())
		return &result.RPCResult{}
	}
	return res
}
