package kafka

import (
	"fmt"
	"io"
	"reflect"
	"time"

	"github.com/up9inc/mizu/tap/api"
)

type Response struct {
	Size          int32       `json:"size"`
	CorrelationID int32       `json:"correlationID"`
	Payload       interface{} `json:"payload"`
	CaptureTime   time.Time   `json:"captureTime"`
}

func ReadResponse(r io.Reader, tcpID *api.TcpID, superTimer *api.SuperTimer, emitter api.Emitter) (err error) {
	d := &decoder{reader: r, remain: 4}
	size := d.readInt32()

	if size > 1000000 {
		return fmt.Errorf("A Kafka message cannot be bigger than 1MB")
	}

	if size < 4 {
		return fmt.Errorf("A Kafka response header cannot be smaller than 8 bytes")
	}

	if err = d.err; err != nil {
		err = dontExpectEOF(err)
		return err
	}

	d.remain = int(size)
	correlationID := d.readInt32()
	var payload interface{}
	response := &Response{
		Size:          size,
		CorrelationID: correlationID,
		Payload:       payload,
		CaptureTime:   superTimer.CaptureTime,
	}

	key := fmt.Sprintf(
		"%s:%s->%s:%s::%d",
		tcpID.DstIP,
		tcpID.DstPort,
		tcpID.SrcIP,
		tcpID.SrcPort,
		correlationID,
	)
	reqResPair := reqResMatcher.registerResponse(key, response)
	if reqResPair == nil {
		return fmt.Errorf("Couldn't match a Kafka response to a Kafka request in 3 seconds!")
	}
	apiKey := reqResPair.Request.ApiKey
	apiVersion := reqResPair.Request.ApiVersion

	switch apiKey {
	case Metadata:
		var mt interface{}
		var metadataResponse interface{}
		if apiVersion >= 11 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV11{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV11{}
		} else if apiVersion >= 10 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV10{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV10{}
		} else if apiVersion >= 8 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV8{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV8{}
		} else if apiVersion >= 7 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV7{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV7{}
		} else if apiVersion >= 5 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV5{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV5{}
		} else if apiVersion >= 3 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV3{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV3{}
		} else if apiVersion >= 2 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV2{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV2{}
		} else if apiVersion >= 1 {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV1{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV1{}
		} else {
			types := makeTypes(reflect.TypeOf(&MetadataResponseV0{}).Elem())
			mt = types[0]
			metadataResponse = &MetadataResponseV0{}
		}
		mt.(messageType).decode(d, valueOf(metadataResponse))
		reqResPair.Response.Payload = metadataResponse
		break
	case ApiVersions:
		var mt interface{}
		var apiVersionsResponse interface{}
		if apiVersion >= 1 {
			types := makeTypes(reflect.TypeOf(&ApiVersionsResponseV1{}).Elem())
			mt = types[0]
			apiVersionsResponse = &ApiVersionsResponseV1{}
		} else {
			types := makeTypes(reflect.TypeOf(&ApiVersionsResponseV0{}).Elem())
			mt = types[0]
			apiVersionsResponse = &ApiVersionsResponseV0{}
		}
		mt.(messageType).decode(d, valueOf(apiVersionsResponse))
		reqResPair.Response.Payload = apiVersionsResponse
		break
	case Produce:
		var mt interface{}
		var produceResponse interface{}
		if apiVersion >= 8 {
			types := makeTypes(reflect.TypeOf(&ProduceResponseV8{}).Elem())
			mt = types[0]
			produceResponse = &ProduceResponseV8{}
		} else if apiVersion >= 5 {
			types := makeTypes(reflect.TypeOf(&ProduceResponseV5{}).Elem())
			mt = types[0]
			produceResponse = &ProduceResponseV5{}
		} else if apiVersion >= 2 {
			types := makeTypes(reflect.TypeOf(&ProduceResponseV2{}).Elem())
			mt = types[0]
			produceResponse = &ProduceResponseV2{}
		} else if apiVersion >= 1 {
			types := makeTypes(reflect.TypeOf(&ProduceResponseV1{}).Elem())
			mt = types[0]
			produceResponse = &ProduceResponseV1{}
		} else {
			types := makeTypes(reflect.TypeOf(&ProduceResponseV0{}).Elem())
			mt = types[0]
			produceResponse = &ProduceResponseV0{}
		}
		mt.(messageType).decode(d, valueOf(produceResponse))
		reqResPair.Response.Payload = produceResponse
		break
	case Fetch:
		var mt interface{}
		var fetchResponse interface{}
		if apiVersion >= 11 {
			types := makeTypes(reflect.TypeOf(&FetchResponseV11{}).Elem())
			mt = types[0]
			fetchResponse = &FetchResponseV11{}
		} else if apiVersion >= 7 {
			types := makeTypes(reflect.TypeOf(&FetchResponseV7{}).Elem())
			mt = types[0]
			fetchResponse = &FetchResponseV7{}
		} else if apiVersion >= 5 {
			types := makeTypes(reflect.TypeOf(&FetchResponseV5{}).Elem())
			mt = types[0]
			fetchResponse = &FetchResponseV5{}
		} else if apiVersion >= 4 {
			types := makeTypes(reflect.TypeOf(&FetchResponseV4{}).Elem())
			mt = types[0]
			fetchResponse = &FetchResponseV4{}
		} else if apiVersion >= 1 {
			types := makeTypes(reflect.TypeOf(&FetchResponseV1{}).Elem())
			mt = types[0]
			fetchResponse = &FetchResponseV1{}
		} else {
			types := makeTypes(reflect.TypeOf(&FetchResponseV0{}).Elem())
			mt = types[0]
			fetchResponse = &FetchResponseV0{}
		}
		mt.(messageType).decode(d, valueOf(fetchResponse))
		reqResPair.Response.Payload = fetchResponse
		break
	case ListOffsets:
		var mt interface{}
		var listOffsetsResponse interface{}
		if apiVersion >= 4 {
			types := makeTypes(reflect.TypeOf(&ListOffsetsResponseV4{}).Elem())
			mt = types[0]
			listOffsetsResponse = &ListOffsetsResponseV4{}
		} else if apiVersion >= 2 {
			types := makeTypes(reflect.TypeOf(&ListOffsetsResponseV2{}).Elem())
			mt = types[0]
			listOffsetsResponse = &ListOffsetsResponseV2{}
		} else if apiVersion >= 1 {
			types := makeTypes(reflect.TypeOf(&ListOffsetsResponseV1{}).Elem())
			mt = types[0]
			listOffsetsResponse = &ListOffsetsResponseV1{}
		} else {
			types := makeTypes(reflect.TypeOf(&ListOffsetsResponseV0{}).Elem())
			mt = types[0]
			listOffsetsResponse = &ListOffsetsResponseV0{}
		}
		mt.(messageType).decode(d, valueOf(listOffsetsResponse))
		reqResPair.Response.Payload = listOffsetsResponse
	case CreateTopics:
		var mt interface{}
		var createTopicsResponse interface{}
		if apiVersion >= 7 {
			types := makeTypes(reflect.TypeOf(&CreateTopicsResponseV0{}).Elem())
			mt = types[0]
			createTopicsResponse = &CreateTopicsResponseV0{}
		} else if apiVersion >= 5 {
			types := makeTypes(reflect.TypeOf(&CreateTopicsResponseV5{}).Elem())
			mt = types[0]
			createTopicsResponse = &CreateTopicsResponseV5{}
		} else if apiVersion >= 2 {
			types := makeTypes(reflect.TypeOf(&CreateTopicsResponseV2{}).Elem())
			mt = types[0]
			createTopicsResponse = &CreateTopicsResponseV2{}
		} else if apiVersion >= 1 {
			types := makeTypes(reflect.TypeOf(&CreateTopicsResponseV1{}).Elem())
			mt = types[0]
			createTopicsResponse = &CreateTopicsResponseV1{}
		} else {
			types := makeTypes(reflect.TypeOf(&CreateTopicsResponseV0{}).Elem())
			mt = types[0]
			createTopicsResponse = &CreateTopicsResponseV0{}
		}
		mt.(messageType).decode(d, valueOf(createTopicsResponse))
		reqResPair.Response.Payload = createTopicsResponse
		break
	case DeleteTopics:
		var mt interface{}
		var deleteTopicsResponse interface{}
		if apiVersion >= 6 {
			types := makeTypes(reflect.TypeOf(&DeleteTopicsReponseV6{}).Elem())
			mt = types[0]
			deleteTopicsResponse = &DeleteTopicsReponseV6{}
		} else if apiVersion >= 5 {
			types := makeTypes(reflect.TypeOf(&DeleteTopicsReponseV5{}).Elem())
			mt = types[0]
			deleteTopicsResponse = &DeleteTopicsReponseV5{}
		} else if apiVersion >= 1 {
			types := makeTypes(reflect.TypeOf(&DeleteTopicsReponseV1{}).Elem())
			mt = types[0]
			deleteTopicsResponse = &DeleteTopicsReponseV1{}
		} else {
			types := makeTypes(reflect.TypeOf(&DeleteTopicsReponseV0{}).Elem())
			mt = types[0]
			deleteTopicsResponse = &DeleteTopicsReponseV0{}
		}
		mt.(messageType).decode(d, valueOf(deleteTopicsResponse))
		reqResPair.Response.Payload = deleteTopicsResponse
	default:
		return fmt.Errorf("(Response) Not implemented: %s", apiKey)
	}

	connectionInfo := &api.ConnectionInfo{
		ClientIP:   tcpID.SrcIP,
		ClientPort: tcpID.SrcPort,
		ServerIP:   tcpID.DstIP,
		ServerPort: tcpID.DstPort,
		IsOutgoing: true,
	}

	item := &api.OutputChannelItem{
		Protocol:       _protocol,
		Timestamp:      reqResPair.Request.CaptureTime.UnixNano() / int64(time.Millisecond),
		ConnectionInfo: connectionInfo,
		Pair: &api.RequestResponsePair{
			Request: api.GenericMessage{
				IsRequest:   true,
				CaptureTime: reqResPair.Request.CaptureTime,
				Payload: KafkaPayload{
					Data: &KafkaWrapper{
						Method:  apiNames[apiKey],
						Url:     "",
						Details: reqResPair.Request,
					},
				},
			},
			Response: api.GenericMessage{
				IsRequest:   false,
				CaptureTime: reqResPair.Response.CaptureTime,
				Payload: KafkaPayload{
					Data: &KafkaWrapper{
						Method:  apiNames[apiKey],
						Url:     "",
						Details: reqResPair.Response,
					},
				},
			},
		},
	}
	emitter.Emit(item)

	if i := int(apiKey); i < 0 || i >= len(apiTypes) {
		err = fmt.Errorf("unsupported api key: %d", i)
		return err
	}

	t := &apiTypes[apiKey]
	if t == nil {
		err = fmt.Errorf("unsupported api: %s", apiNames[apiKey])
		return err
	}

	d.discardAll()

	return nil
}

func WriteResponse(w io.Writer, apiVersion int16, correlationID int32, msg Message) error {
	apiKey := msg.ApiKey()

	if i := int(apiKey); i < 0 || i >= len(apiTypes) {
		return fmt.Errorf("unsupported api key: %d", i)
	}

	t := &apiTypes[apiKey]
	if t == nil {
		return fmt.Errorf("unsupported api: %s", apiNames[apiKey])
	}

	minVersion := t.minVersion()
	maxVersion := t.maxVersion()

	if apiVersion < minVersion || apiVersion > maxVersion {
		return fmt.Errorf("unsupported %s version: v%d not in range v%d-v%d", apiKey, apiVersion, minVersion, maxVersion)
	}

	r := &t.responses[apiVersion-minVersion]
	v := valueOf(msg)
	b := newPageBuffer()
	defer b.unref()

	e := &encoder{writer: b}
	e.writeInt32(0) // placeholder for the response size
	e.writeInt32(correlationID)
	r.encode(e, v)
	err := e.err

	if err == nil {
		size := packUint32(uint32(b.Size()) - 4)
		b.WriteAt(size[:], 0)
		_, err = b.WriteTo(w)
	}

	return err
}