ble.go

// ble.go contains the transport-layer specifics of the device

package gorileylink

import (
	"fmt"
	"log"
	"regexp"
	"strings"
	"time"

	"github.com/currantlabs/ble"
	"github.com/currantlabs/ble/linux"
	"golang.org/x/net/context"
)

var (
	// from gatt.xml
	rileyLinkSvc  = ble.MustParse("0235733b-99c5-4197-b856-69219c2a3845")
	dataChr       = ble.MustParse("c842e849-5028-42e2-867c-016adada9155")
	timerTickChr  = ble.MustParse("6e6c7910-b89e-43a5-78af-50c5e2b86f7e")
	customNameChr = ble.MustParse("d93b2af0-1e28-11e4-8c21-0800200c9a66")
	versionChr    = ble.MustParse("30d99dc9-7c91-4295-a051-0a104d238cf2")
	ledModeChr    = ble.MustParse("c6d84241-f1a7-4f9c-a25f-fce16732f14e")
	// notifier
	respCountChr             = ble.MustParse("6e6c7910-b89e-43a5-a0fe-50c5e2b81f4a")
	btRegex                  = regexp.MustCompile("([0-9A-Fa-f]{2}):([0-9A-Fa-f]{2}):([0-9A-Fa-f]{2}):([0-9A-Fa-f]{2}):([0-9A-Fa-f]{2}):([0-9A-Fa-f]{2})")
	enableNotificationValue  = []byte{0x01, 0x00}
	disableNotificationValue = []byte{0x00, 0x00}
)

// on respCountChr notification, dataChr should be read out
func (crl *ConnectedRileyLink) gattNotifyCallback(data []byte) {
	fmt.Printf("notify callback occured: %v\n", data)
}

// OpenBLE creates a bluetooth context
func OpenBLE(timeout time.Duration) (*linux.Device, context.Context) {
	var (
		err error
		hci *linux.Device
		ctx context.Context
	)
	hci, err = linux.NewDevice()
	if err != nil {
		log.Fatalf("can't NewDevice: %s", err)
	}
	ble.SetDefaultDevice(hci)
	ctx = ble.WithSigHandler(context.WithTimeout(context.Background(), timeout))
	return hci, ctx
}

// ConnectNameOrAddress binds a RileyLink based on address or name input
func ConnectNameOrAddress(ctx context.Context, nameoraddress string) (ble.Client, error) {
	if btRegex.MatchString(nameoraddress) {
		return ConnectAddress(ctx, strings.ToLower(nameoraddress))
	} else {
		return ConnectName(ctx, nameoraddress)
	}
}

// ConnectAddress binds a RileyLink via BT address
func ConnectAddress(ctx context.Context, address string) (ble.Client, error) {
	var (
		blec   ble.Client
		err    error
		filter func(adv ble.Advertisement) bool
	)
	filter = func(adv ble.Advertisement) bool {
		return adv.Address().String() == address
	}
	blec, err = ble.Connect(ctx, filter)
	if err != nil {
		log.Fatalf("couldn't connect to %v: %v", address, err)
	}
	return blec, nil
}

// ConnectName binds a RileyLink via local (custom) name
func ConnectName(ctx context.Context, name string) (ble.Client, error) {
	var (
		blec   ble.Client
		err    error
		filter func(adv ble.Advertisement) bool
	)
	filter = func(adv ble.Advertisement) bool {
		return adv.LocalName() == name
	}
	blec, err = ble.Connect(ctx, filter)
	if err != nil {
		log.Fatalf("couldn't connect to %v: %v", name, err)
	}
	return blec, nil
}