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

// Unmarshal unmarshals the REST component of a response in a REST service.
func Unmarshal(r *service.Request) {
	if r.DataFilled() {
		v := reflect.Indirect(reflect.ValueOf(r.Data))
		unmarshalBody(r, v)
		unmarshalLocationElements(r, v)
	}
}

// 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 *service.Request) {
	// If the request does not need to be signed ignore the signing of the
	// request if the AnonymousCredentials object is used.
	if req.Service.Config.Credentials == credentials.AnonymousCredentials {
		return
	}

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

	name := req.Service.SigningName
	if name == "" {
		name = req.Service.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.Service.Config.Credentials,
		Debug:       req.Service.Config.LogLevel.Value(),
		Logger:      req.Service.Config.Logger,
	}

	req.Error = s.sign()
}

func buildQueryString(r *service.Request, v reflect.Value, name string, query url.Values) {
	str, err := convertType(v)
	if err != nil {
		r.Error = awserr.New("SerializationError", "failed to encode REST request", err)
	} else if str != nil {
		query.Set(name, *str)
	}
}

func buildHeader(r *service.Request, v reflect.Value, name string) {
	str, err := convertType(v)
	if err != nil {
		r.Error = awserr.New("SerializationError", "failed to encode REST request", err)
	} else if str != nil {
		r.HTTPRequest.Header.Add(name, *str)
	}
}

func unmarshalError(r *service.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 buildHeaderMap(r *service.Request, v reflect.Value, prefix string) {
	for _, key := range v.MapKeys() {
		str, err := convertType(v.MapIndex(key))
		if err != nil {
			r.Error = awserr.New("SerializationError", "failed to encode REST request", err)
		} else if str != nil {
			r.HTTPRequest.Header.Add(prefix+key.String(), *str)
		}
	}
}

func unmarshalHandler(r *service.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)
}

func buildURI(r *service.Request, v reflect.Value, name string) {
	value, err := convertType(v)
	if err != nil {
		r.Error = awserr.New("SerializationError", "failed to encode REST request", err)
	} else if value != nil {
		uri := r.HTTPRequest.URL.Path
		uri = strings.Replace(uri, "{"+name+"}", EscapePath(*value, true), -1)
		uri = strings.Replace(uri, "{"+name+"+}", EscapePath(*value, false), -1)
		r.HTTPRequest.URL.Path = uri
	}
}

func unmarshalBody(r *service.Request, v reflect.Value) {
	if field, ok := v.Type().FieldByName("SDKShapeTraits"); 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 *service.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 buildBody(r *service.Request, v reflect.Value) {
	if field, ok := v.Type().FieldByName("SDKShapeTraits"); 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 *service.Request) {
	if r.Service.Endpoint == "" {
		r.Error = service.ErrMissingEndpoint
	}
}