ble/ble_android.go

//go:generate mkdir -p classes
//go:generate javac -bootclasspath $ANDROID_HOME/platforms/android-29/android.jar -classpath blessed-full.jar -d classes BlessedConnect.java
//go:generate jar cf Ble.jar -C classes .
//go:generate rm -rf classes

package ble

import (
	"log"
	"sync"
	"unsafe"

	"gioui.org/app"
	_ "gioui.org/app/permission/bluetooth"

	"git.wow.st/gmp/ble/gatt"
)

/*
#include "jni_android.h"
*/
import "C"

// Types required for ble.go

type bleHandle struct {
	BlessedConnect C.jobject
	state int
}

type bleState string

type Peripheral struct {
	Name string
	RSSI int
	Identifier string
	peripheral C.jobject
}

type Service struct {
	UUID string
	service C.jobject
}

type Characteristic struct {
	UUID string
	characteristic C.jobject
}

// Internal global variables

var (
	gBLE *BLE // FIXME: move to lookup tables as in ble_darwin.go?

	// FIXME: lifecycle, this may need to fire again? Or can I depend
	// on my Fragment re-starting? Or call setRetained(true) from the
	// fragment so we don't have to re-discover our BluetoothGatt and
	// BluetoothDevice objects?
	installCompleteOnce sync.Once
	waitch chan struct{}
)

const (
	// https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html
	// FIXME: create a type for these?
	STATE_OFF int = 10
	STATE_TURNING_ON = 11
	STATE_ON = 12
	STATE_TURNING_OFF = 13
)

func init() {
	waitch = make(chan struct{})
}

func connect() {
	<-waitch
}

// Functions required by API

//peripheralLookup returns a pointer to a BLE struct related to the given
//Peripheral.
func peripheralLookup(p Peripheral) *BLE {
	return gBLE
}

//newPeripheral creates a new Peripheral struct
// FIXME: check what happens with "incomplete" Peripherals that have only
// an Identifier set. Do the other functions on Peripherals do something
// sensible?
func newPeripheral(name, id string, rssi int, peripheral C.jobject) Peripheral {
	return Peripheral{
		Name: name,
		RSSI: rssi,
		Identifier: id,
		peripheral: peripheral,
	}
}

func (p Peripheral) IsIncomplete() bool {
	if p.peripheral == 0 {
		return true
	} else {
		return false
	}
}

// FIXME: should I call NewGlobalRef() here?
func (p Peripheral) Retain() {
}

//stringState returns a string version of the BLE state
func (b *BLE) stringState() string {
	switch b.handle.state {
	case STATE_OFF:
		return "powered off"
	case STATE_TURNING_ON:
		return "turning on"
	case STATE_ON:
		return "powered on"
	case STATE_TURNING_OFF:
		return "turning off"
	default:
		return "no state"
	}
}

//readyToScan returns true if the hardware is ready to initiate a scan
func (b *BLE) readyToScan() bool {
	connect()
	var ret bool
	runInJVM(func(env *C.JNIEnv) {
		ret = C.enabled(env, b.handle.BlessedConnect) == C.JNI_TRUE
	})
	return ret
}

//scan puts the BLE hardware into scanning mode
func (b *BLE) scan() {
	connect()
	runInJVM(func(env *C.JNIEnv) {
		C.scan(env, b.handle.BlessedConnect);
	})
}

//stopScan stops a scan in progress
func (b *BLE) stopScan() {
	connect()
	runInJVM(func(env *C.JNIEnv) {
		C.stopScan(env, b.handle.BlessedConnect);
	})
}

//connectPeripheral attempts to connect to a Peripheral
func (b *BLE) connectPeripheral(x Peripheral) {
	runInJVM(func(env *C.JNIEnv) {
		C.connect(env, b.handle.BlessedConnect, x.peripheral)
	})
}

//cancelConnection cancels an in-progress connection attempt
func (b *BLE) cancelConnection(p Peripheral) {
	connect()
	runInJVM(func(env *C.JNIEnv) {
		C.disconnect(env, b.handle.BlessedConnect, p.peripheral)
	})
}

//knownPeripheral returns a Peripheral that is known to the system without
//scanning
//Not implemented for Android
func (b *BLE) knownPeripheral(p Peripheral) (Peripheral, bool) {
	return Peripheral{}, false
}

//DiscoverServices asks a Peripheral for its Services
func (p Peripheral) DiscoverServices() {
	//launch a goroutine because this function calls back directly
	//from the same thread (the underlying Java call is synchronous)
	go func() {
		connect()
		log.Printf("discovering services")
		runInJVM(func(env *C.JNIEnv) {
			C.discoverServices(env, gBLE.handle.BlessedConnect, p.peripheral)
		})
	}()
}

//DiscoverCharacteristics asks a Peripheral for the Characteristics related
//to a Service
func (p Peripheral) DiscoverCharacteristics(serv Service) {
	//launch a goroutine because this function calls back directly
	//from the same thread (the underlying Java call is synchronous)
	go func() {
		connect()
		log.Printf("discovering characteristics")
		runInJVM(func(env *C.JNIEnv) {
			C.discoverCharacteristics(env, gBLE.handle.BlessedConnect, p.peripheral, serv.service)
		})
	}()
}

//SetNotifyValue subscribes to a characteristic
func (p Peripheral) SetNotifyValue(c Characteristic) {
	runInJVM(func(env *C.JNIEnv) {
		result := (C.setCharacteristicNotification(env, gBLE.handle.BlessedConnect, p.peripheral, c.characteristic) == C.JNI_TRUE)
		if (!result) {
			log.Printf("setCharacteristicNotification: %s failed", c.UUID)
		}
	})
}

//NewBLE returns a pointer to a BLE struct after setting up the OS
//Bluetooth API.
func NewBLE() *BLE {
	ps := Peripherals{items: make([]PeripheralListItem, 0)}
	gBLE = &BLE{
		events: make(chan interface{}),
		peripherals: ps,
	}
	return gBLE
}

//Enable
func (b *BLE) Enable(view uintptr) {
	log.Printf("ble.Enable()")
	setJVM(app.JavaVM())
	runInJVM(func(env *JNIEnv) {
		log.Printf("ble.Enable(): inside runInJVM()")
		C.registerFragment(env, (C.jobject)(unsafe.Pointer(view)))
	})
}

// Go callbacks from Java

//export Java_st_wow_git_ble_BlessedConnect_installComplete
func Java_st_wow_git_ble_BlessedConnect_installComplete(env *C.JNIEnv, class C.jclass, b C.jobject) {
	log.Printf("installComplete()")
	if (b == 0) {
		log.Printf("BlessedConnect object is nil!")
	}
	gBLE.handle.BlessedConnect = (C.NewGlobalRef)(env,b)
	if C.enabled(env, gBLE.handle.BlessedConnect) == C.JNI_TRUE {
		gBLE.handle.state = STATE_ON
		gBLE.ready = true
		gBLE.events <- UpdateStateEvent{State: gBLE.stringState()}
	}
	installCompleteOnce.Do(func() {
		close(waitch)
	})
	log.Printf("installComplete() returning")
}

//export Java_st_wow_git_ble_BlessedConnect_updateState
func Java_st_wow_git_ble_BlessedConnect_updateState(env *C.JNIEnv, class C.jclass, s C.jint) {
	log.Printf("UpdateState: %d", s)
	gBLE.handle.state = (int)(s)
	if gBLE.handle.state == STATE_ON {
		gBLE.ready = true
	}
	gBLE.events <- UpdateStateEvent{State: gBLE.stringState()}
}

//export goOnScan
func goOnScan(cname, cid *C.char, rssi C.int, dev C.jobject) {
	name := C.GoString(cname);
	id := C.GoString(cid);
	if name == "" {
		return
	}
	peripheral := newPeripheral(name, id, (int)(rssi), dev)
	if ok := gBLE.peripherals.Add(peripheral); ok {
		gBLE.events <- DiscoverPeripheralEvent{Peripheral: peripheral}
	}
}

//export goOnConnect
func goOnConnect(p C.jobject, cid *C.char) {
	id := C.GoString(cid)

	peripheral := gBLE.retrievePeripheral(id, p)

	if peripheral.peripheral == 0 {
		log.Printf("goOnConnect(): peripheral == null")
	}

	gBLE.connections.UpdateState(peripheral, "connected")
	gBLE.events <- ConnectEvent{peripheral}
	log.Printf("Go: goOnConnect returning\n")
}

//export goOnDisconnect
func goOnDisconnect(p C.jobject, cid *C.char) {
	id := C.GoString(cid)

	peripheral := gBLE.retrievePeripheral(id)

	if peripheral.peripheral == 0 {
		log.Printf("goOnDisconnect(): peripheral == null")
	}

	go func() {
		gBLE.connections.UpdateState(peripheral, "cancel")
		gBLE.events <- DisconnectEvent{peripheral}
	}()
	log.Printf("Go: goOnDisconnect returning\n")
}

//export goOnDiscoverService
func goOnDiscoverService(cid, cuuid *C.char, serv C.jobject) {
	id := C.GoString(cid)
	uuid := C.GoString(cuuid)

	peripheral := gBLE.retrievePeripheral(id)

	service := Service{
		UUID: uuid,
		service: serv,
	}
	gBLE.events <- DiscoverServiceEvent{
		Peripheral: peripheral,
		Gatt: gatt.Service{uuid},
		Service: service,
	}
}

//export goOnDiscoverCharacteristic
func goOnDiscoverCharacteristic(cid, csuuid *C.char, serv C.jobject, ccuuid *C.char, characteristic C.jobject) {
	id := C.GoString(cid)
	suuid := C.GoString(csuuid)
	cuuid := C.GoString(ccuuid)
	log.Printf("goOnDiscoverCharacteristic: %s", cuuid)

	peripheral := gBLE.retrievePeripheral(id)

	service := Service{
		UUID: suuid,
		service: serv,
	}

	ch := Characteristic{
		UUID: cuuid,
		characteristic: characteristic,
	}

	gBLE.events <- DiscoverCharacteristicEvent{
		Peripheral: peripheral,
		Service: service,
		Characteristic: ch,
		Gatt: gatt.Characteristic{cuuid},
	}
}

//export goOnCharacteristicChanged
func goOnCharacteristicChanged(cid, ccuuid *C.char, characteristic C.jobject, cvalue *C.char, length C.jint) {
	id := C.GoString(cid)
	cuuid := C.GoString(ccuuid)

	peripheral := gBLE.retrievePeripheral(id)

	ch := Characteristic{
		UUID: cuuid,
		characteristic: characteristic,
	}

	gBLE.events <- UpdateValueEvent{
		Peripheral: peripheral,
		Characteristic: ch,
		Data: C.GoBytes(unsafe.Pointer(cvalue), length),
	}
}

// internal convenience functions

func (b *BLE) retrievePeripheral(id string, devs ...C.jobject) Peripheral {
	var dev C.jobject
	if len(devs) > 0 {
		dev = devs[0]
	}

	found := false
	var peripheral Peripheral

	gBLE.peripherals.Lock()
	for i, item := range gBLE.peripherals.items {
		if item.p.Identifier == id {
			peripheral = item.p
			if dev != 0 {
				peripheral.peripheral = dev
			}
			found = true
			gBLE.peripherals.items[i].p = peripheral
			break
		}
	}
	gBLE.peripherals.Unlock()

	if !found {
		log.Printf("Go: peripheral not found!")
	}
	return peripheral
}