// Build builds the REST component of a service request.
func Build(r *request.Request) {
	if r.ParamsFilled() {
		v := reflect.ValueOf(r.Params).Elem()
		buildLocationElements(r, v)
		buildBody(r, v)
	}
}

// UnmarshalError unmarshals a response error for the REST JSON protocol.
func UnmarshalError(r *request.Request) {
	code := r.HTTPResponse.Header.Get("X-Amzn-Errortype")
	bodyBytes, err := ioutil.ReadAll(r.HTTPResponse.Body)
	if err != nil {
		r.Error = awserr.New("SerializationError", "failed reading REST JSON error response", err)
		return
	}
	if len(bodyBytes) == 0 {
		r.Error = awserr.NewRequestFailure(
			awserr.New("SerializationError", r.HTTPResponse.Status, nil),
			r.HTTPResponse.StatusCode,
			"",
		)
		return
	}
	var jsonErr jsonErrorResponse
	if err := json.Unmarshal(bodyBytes, &jsonErr); err != nil {
		r.Error = awserr.New("SerializationError", "failed decoding REST JSON error response", err)
		return
	}

	if code == "" {
		code = jsonErr.Code
	}

	code = strings.SplitN(code, ":", 2)[0]
	r.Error = awserr.NewRequestFailure(
		awserr.New(code, jsonErr.Message, nil),
		r.HTTPResponse.StatusCode,
		r.RequestID,
	)
}

// Build builds a JSON payload for a JSON RPC request.
func Build(req *request.Request) {
	var buf []byte
	var err error
	if req.ParamsFilled() {
		buf, err = jsonutil.BuildJSON(req.Params)
		if err != nil {
			req.Error = awserr.New("SerializationError", "failed encoding JSON RPC request", err)
			return
		}
	} else {
		buf = emptyJSON
	}

	if req.ClientInfo.TargetPrefix != "" || string(buf) != "{}" {
		req.SetBufferBody(buf)
	}

	if req.ClientInfo.TargetPrefix != "" {
		target := req.ClientInfo.TargetPrefix + "." + req.Operation.Name
		req.HTTPRequest.Header.Add("X-Amz-Target", target)
	}
	if req.ClientInfo.JSONVersion != "" {
		jsonVersion := req.ClientInfo.JSONVersion
		req.HTTPRequest.Header.Add("Content-Type", "application/x-amz-json-"+jsonVersion)
	}
}

// UnmarshalError unmarshals an error response for a JSON RPC service.
func UnmarshalError(req *request.Request) {
	defer req.HTTPResponse.Body.Close()
	bodyBytes, err := ioutil.ReadAll(req.HTTPResponse.Body)
	if err != nil {
		req.Error = awserr.New("SerializationError", "failed reading JSON RPC error response", err)
		return
	}
	if len(bodyBytes) == 0 {
		req.Error = awserr.NewRequestFailure(
			awserr.New("SerializationError", req.HTTPResponse.Status, nil),
			req.HTTPResponse.StatusCode,
			"",
		)
		return
	}
	var jsonErr jsonErrorResponse
	if err := json.Unmarshal(bodyBytes, &jsonErr); err != nil {
		req.Error = awserr.New("SerializationError", "failed decoding JSON RPC error response", err)
		return
	}

	codes := strings.SplitN(jsonErr.Code, "#", 2)
	req.Error = awserr.NewRequestFailure(
		awserr.New(codes[len(codes)-1], jsonErr.Message, nil),
		req.HTTPResponse.StatusCode,
		req.RequestID,
	)
}

func verifySendMessage(r *request.Request) {
	if r.DataFilled() && r.ParamsFilled() {
		in := r.Params.(*SendMessageInput)
		out := r.Data.(*SendMessageOutput)
		err := checksumsMatch(in.MessageBody, out.MD5OfMessageBody)
		if err != nil {
			setChecksumError(r, err.Error())
		}
	}
}

// Unmarshal unmarshals a response for a JSON RPC service.
func Unmarshal(req *request.Request) {
	defer req.HTTPResponse.Body.Close()
	if req.DataFilled() {
		err := jsonutil.UnmarshalJSON(req.Data, req.HTTPResponse.Body)
		if err != nil {
			req.Error = awserr.New("SerializationError", "failed decoding JSON RPC response", err)
		}
	}
	return
}

// UnmarshalMeta unmarshals the REST metadata of a response in a REST service
func UnmarshalMeta(r *request.Request) {
	r.RequestID = r.HTTPResponse.Header.Get("X-Amzn-Requestid")
	if r.RequestID == "" {
		// Alternative version of request id in the header
		r.RequestID = r.HTTPResponse.Header.Get("X-Amz-Request-Id")
	}
	if r.DataFilled() {
		v := reflect.Indirect(reflect.ValueOf(r.Data))
		unmarshalLocationElements(r, v)
	}
}

// Unmarshal unmarshals a response for an AWS Query service.
func Unmarshal(r *request.Request) {
	defer r.HTTPResponse.Body.Close()
	if r.DataFilled() {
		decoder := xml.NewDecoder(r.HTTPResponse.Body)
		err := xmlutil.UnmarshalXML(r.Data, decoder, r.Operation.Name+"Result")
		if err != nil {
			r.Error = awserr.New("SerializationError", "failed decoding Query response", err)
			return
		}
	}
}

func verifyReceiveMessage(r *request.Request) {
	if r.DataFilled() && r.ParamsFilled() {
		ids := []string{}
		out := r.Data.(*ReceiveMessageOutput)
		for _, msg := range out.Messages {
			err := checksumsMatch(msg.Body, msg.MD5OfBody)
			if err != nil {
				ids = append(ids, *msg.MessageId)
			}
		}
		if len(ids) > 0 {
			setChecksumError(r, "invalid messages: %s", strings.Join(ids, ", "))
		}
	}
}

// Sign requests with signature version 4.
//
// Will sign the requests with the service config's Credentials object
// Signing is skipped if the credentials is the credentials.AnonymousCredentials
// object.
func Sign(req *request.Request) {
	// If the request does not need to be signed ignore the signing of the
	// request if the AnonymousCredentials object is used.
	if req.Config.Credentials == credentials.AnonymousCredentials {
		return
	}

	region := req.ClientInfo.SigningRegion
	if region == "" {
		region = aws.StringValue(req.Config.Region)
	}

	name := req.ClientInfo.SigningName
	if name == "" {
		name = req.ClientInfo.ServiceName
	}

	s := signer{
		Request:     req.HTTPRequest,
		Time:        req.Time,
		ExpireTime:  req.ExpireTime,
		Query:       req.HTTPRequest.URL.Query(),
		Body:        req.Body,
		ServiceName: name,
		Region:      region,
		Credentials: req.Config.Credentials,
		Debug:       req.Config.LogLevel.Value(),
		Logger:      req.Config.Logger,
	}

	req.Error = s.sign()
}

func unmarshalError(r *request.Request) {
	defer r.HTTPResponse.Body.Close()
	_, err := ioutil.ReadAll(r.HTTPResponse.Body)
	if err != nil {
		r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata error respose", err)
	}

	// TODO extract the error...
}

func unmarshalHandler(r *request.Request) {
	defer r.HTTPResponse.Body.Close()
	b, err := ioutil.ReadAll(r.HTTPResponse.Body)
	if err != nil {
		r.Error = awserr.New("SerializationError", "unable to unmarshal EC2 metadata respose", err)
	}

	data := r.Data.(*metadataOutput)
	data.Content = string(b)
}

// UnmarshalError unmarshals an error response for an AWS Query service.
func UnmarshalError(r *request.Request) {
	defer r.HTTPResponse.Body.Close()

	resp := &xmlErrorResponse{}
	err := xml.NewDecoder(r.HTTPResponse.Body).Decode(resp)
	if err != nil && err != io.EOF {
		r.Error = awserr.New("SerializationError", "failed to decode query XML error response", err)
	} else {
		reqID := resp.RequestID
		if reqID == "" {
			reqID = r.RequestID
		}
		r.Error = awserr.NewRequestFailure(
			awserr.New(resp.Code, resp.Message, nil),
			r.HTTPResponse.StatusCode,
			reqID,
		)
	}
}

func unmarshalBody(r *request.Request, v reflect.Value) {
	if field, ok := v.Type().FieldByName("_"); ok {
		if payloadName := field.Tag.Get("payload"); payloadName != "" {
			pfield, _ := v.Type().FieldByName(payloadName)
			if ptag := pfield.Tag.Get("type"); ptag != "" && ptag != "structure" {
				payload := v.FieldByName(payloadName)
				if payload.IsValid() {
					switch payload.Interface().(type) {
					case []byte:
						b, err := ioutil.ReadAll(r.HTTPResponse.Body)
						if err != nil {
							r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
						} else {
							payload.Set(reflect.ValueOf(b))
						}
					case *string:
						b, err := ioutil.ReadAll(r.HTTPResponse.Body)
						if err != nil {
							r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
						} else {
							str := string(b)
							payload.Set(reflect.ValueOf(&str))
						}
					default:
						switch payload.Type().String() {
						case "io.ReadSeeker":
							payload.Set(reflect.ValueOf(aws.ReadSeekCloser(r.HTTPResponse.Body)))
						case "aws.ReadSeekCloser", "io.ReadCloser":
							payload.Set(reflect.ValueOf(r.HTTPResponse.Body))
						default:
							r.Error = awserr.New("SerializationError",
								"failed to decode REST response",
								fmt.Errorf("unknown payload type %s", payload.Type()))
						}
					}
				}
			}
		}
	}
}

func unmarshalLocationElements(r *request.Request, v reflect.Value) {
	for i := 0; i < v.NumField(); i++ {
		m, field := v.Field(i), v.Type().Field(i)
		if n := field.Name; n[0:1] == strings.ToLower(n[0:1]) {
			continue
		}

		if m.IsValid() {
			name := field.Tag.Get("locationName")
			if name == "" {
				name = field.Name
			}

			switch field.Tag.Get("location") {
			case "statusCode":
				unmarshalStatusCode(m, r.HTTPResponse.StatusCode)
			case "header":
				err := unmarshalHeader(m, r.HTTPResponse.Header.Get(name))
				if err != nil {
					r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
					break
				}
			case "headers":
				prefix := field.Tag.Get("locationName")
				err := unmarshalHeaderMap(m, r.HTTPResponse.Header, prefix)
				if err != nil {
					r.Error = awserr.New("SerializationError", "failed to decode REST response", err)
					break
				}
			}
		}
		if r.Error != nil {
			return
		}
	}
}

func verifySendMessageBatch(r *request.Request) {
	if r.DataFilled() && r.ParamsFilled() {
		entries := map[string]*SendMessageBatchResultEntry{}
		ids := []string{}

		out := r.Data.(*SendMessageBatchOutput)
		for _, entry := range out.Successful {
			entries[*entry.Id] = entry
		}

		in := r.Params.(*SendMessageBatchInput)
		for _, entry := range in.Entries {
			if e := entries[*entry.Id]; e != nil {
				err := checksumsMatch(entry.MessageBody, e.MD5OfMessageBody)
				if err != nil {
					ids = append(ids, *e.MessageId)
				}
			}
		}
		if len(ids) > 0 {
			setChecksumError(r, "invalid messages: %s", strings.Join(ids, ", "))
		}
	}
}

func buildLocationElements(r *request.Request, v reflect.Value) {
	query := r.HTTPRequest.URL.Query()

	for i := 0; i < v.NumField(); i++ {
		m := v.Field(i)
		if n := v.Type().Field(i).Name; n[0:1] == strings.ToLower(n[0:1]) {
			continue
		}

		if m.IsValid() {
			field := v.Type().Field(i)
			name := field.Tag.Get("locationName")
			if name == "" {
				name = field.Name
			}
			if m.Kind() == reflect.Ptr {
				m = m.Elem()
			}
			if !m.IsValid() {
				continue
			}

			var err error
			switch field.Tag.Get("location") {
			case "headers": // header maps
				err = buildHeaderMap(&r.HTTPRequest.Header, m, field.Tag.Get("locationName"))
			case "header":
				err = buildHeader(&r.HTTPRequest.Header, m, name)
			case "uri":
				err = buildURI(r.HTTPRequest.URL, m, name)
			case "querystring":
				err = buildQueryString(query, m, name)
			}
			r.Error = err
		}
		if r.Error != nil {
			return
		}
	}

	r.HTTPRequest.URL.RawQuery = query.Encode()
	updatePath(r.HTTPRequest.URL, r.HTTPRequest.URL.Path)
}

func buildBody(r *request.Request, v reflect.Value) {
	if field, ok := v.Type().FieldByName("_"); ok {
		if payloadName := field.Tag.Get("payload"); payloadName != "" {
			pfield, _ := v.Type().FieldByName(payloadName)
			if ptag := pfield.Tag.Get("type"); ptag != "" && ptag != "structure" {
				payload := reflect.Indirect(v.FieldByName(payloadName))
				if payload.IsValid() && payload.Interface() != nil {
					switch reader := payload.Interface().(type) {
					case io.ReadSeeker:
						r.SetReaderBody(reader)
					case []byte:
						r.SetBufferBody(reader)
					case string:
						r.SetStringBody(reader)
					default:
						r.Error = awserr.New("SerializationError",
							"failed to encode REST request",
							fmt.Errorf("unknown payload type %s", payload.Type()))
					}
				}
			}
		}
	}
}

func validateEndpointHandler(r *request.Request) {
	if r.ClientInfo.Endpoint == "" {
		r.Error = aws.ErrMissingEndpoint
	}
}

// ShouldRetry returns if the request should be retried.
func (d DefaultRetryer) ShouldRetry(r *request.Request) bool {
	if r.HTTPResponse.StatusCode >= 500 {
		return true
	}
	return r.IsErrorRetryable()
}