data_rate.go

// Copyright © 2017 The Things Network
// Use of this source code is governed by the MIT license that can be found in the LICENSE file.

package types

import (
	"fmt"
	"regexp"
	"strconv"

	"github.com/TheThingsNetwork/ttn/utils/errors"

	"github.com/brocaar/lorawan/band"
)

type DataRate struct {
	SpreadingFactor uint `json:"spreading_factor,omitempty"`
	Bandwidth       uint `json:"bandwidth,omitempty"`
}

// ParseDataRate parses a 32-bit hex-encoded string to a Devdatr
func ParseDataRate(input string) (datr *DataRate, err error) {
	re := regexp.MustCompile("SF(7|8|9|10|11|12)BW(125|250|500)")
	matches := re.FindStringSubmatch(input)
	if len(matches) != 3 {
		return nil, errors.New("ttn/core: Invalid DataRate")
	}

	sf, _ := strconv.ParseUint(matches[1], 10, 64)
	bw, _ := strconv.ParseUint(matches[2], 10, 64)

	return &DataRate{
		SpreadingFactor: uint(sf),
		Bandwidth:       uint(bw),
	}, nil
}

func ConvertDataRate(input band.DataRate) (datr *DataRate, err error) {
	if input.Modulation != band.LoRaModulation {
		err = errors.New(fmt.Sprintf("ttn/core: %s can not be converted to a LoRa DataRate", input.Modulation))
	}
	datr = &DataRate{
		SpreadingFactor: uint(input.SpreadFactor),
		Bandwidth:       uint(input.Bandwidth),
	}
	return
}

// Bytes returns the DataRate as a byte slice
func (datr DataRate) Bytes() []byte {
	return []byte(datr.String())
}

// String implements the Stringer interface.
func (datr DataRate) String() string {
	return fmt.Sprintf("SF%dBW%d", datr.SpreadingFactor, datr.Bandwidth)
}

// GoString implements the GoStringer interface.
func (datr DataRate) GoString() string {
	return datr.String()
}

// MarshalText implements the TextMarshaler interface.
func (datr DataRate) MarshalText() ([]byte, error) {
	return []byte(datr.String()), nil
}

// UnmarshalText implements the TextUnmarshaler interface.
func (datr *DataRate) UnmarshalText(data []byte) error {
	parsed, err := ParseDataRate(string(data))
	if err != nil {
		return err
	}
	*datr = *parsed
	return nil
}

// MarshalBinary implements the BinaryMarshaler interface.
func (datr DataRate) MarshalBinary() ([]byte, error) {
	return datr.MarshalText()
}

// UnmarshalBinary implements the BinaryUnmarshaler interface.
func (datr *DataRate) UnmarshalBinary(data []byte) error {
	return datr.UnmarshalText(data)
}

// MarshalTo is used by Protobuf
func (datr DataRate) MarshalTo(b []byte) (int, error) {
	copy(b, datr.Bytes())
	return len(datr.Bytes()), nil
}

// Size is used by Protobuf
func (datr DataRate) Size() int {
	return len(datr.Bytes())
}

// Marshal implements the Marshaler interface.
func (datr DataRate) Marshal() ([]byte, error) {
	return datr.MarshalBinary()
}

// Unmarshal implements the Unmarshaler interface.
func (datr *DataRate) Unmarshal(data []byte) error {
	*datr = DataRate{} // Reset the receiver
	return datr.UnmarshalBinary(data)
}