// Licensed to 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. Apache Software Foundation (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 meter

import (
	"context"
	"fmt"
	"io"
	"reflect"

	v3 "skywalking.apache.org/repo/goapi/collect/language/agent/v3"
	v1 "skywalking.apache.org/repo/goapi/satellite/data/v1"

	"google.golang.org/grpc"

	"github.com/apache/skywalking-satellite/internal/pkg/config"
	"github.com/apache/skywalking-satellite/internal/pkg/log"
	"github.com/apache/skywalking-satellite/internal/satellite/event"
)

const Name = "meter-grpc-forwarder"

type Forwarder struct {
	config.CommonFields
	meterClient v3.MeterReportServiceClient
}

func (f *Forwarder) Name() string {
	return Name
}

func (f *Forwarder) Description() string {
	return "This is a synchronization meter grpc forwarder with the SkyWalking meter protocol."
}

func (f *Forwarder) DefaultConfig() string {
	return ``
}

func (f *Forwarder) Prepare(connection interface{}) error {
	client, ok := connection.(*grpc.ClientConn)
	if !ok {
		return fmt.Errorf("the %s is only accepet the grpc client, but receive a %s",
			f.Name(), reflect.TypeOf(connection).String())
	}
	f.meterClient = v3.NewMeterReportServiceClient(client)
	return nil
}

func (f *Forwarder) Forward(batch event.BatchEvents) error {
	stream, err := f.meterClient.Collect(context.Background())
	if err != nil {
		log.Logger.Errorf("open grpc stream error %v", err)
		return err
	}
	for _, e := range batch {
		data, ok := e.GetData().(*v1.SniffData_Meter)
		if !ok {
			continue
		}
		err := stream.Send(data.Meter)
		if err != nil {
			log.Logger.Errorf("%s send meter data error: %v", f.Name(), err)
			err = closeStream(stream)
			if err != nil {
				log.Logger.Errorf("%s close stream error: %v", f.Name(), err)
			}
			return err
		}
	}
	return closeStream(stream)
}

func closeStream(stream v3.MeterReportService_CollectClient) error {
	_, err := stream.CloseAndRecv()
	if err != nil && err != io.EOF {
		return err
	}
	return nil
}

func (f *Forwarder) ForwardType() v1.SniffType {
	return v1.SniffType_MeterType
}