edge/pkg/module/cast/cast.go

package cast

import (
	"context"
	"net"
	"sync"
	"time"

	"github.com/barnybug/go-cast"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

type Device struct {
	UUID string `goja:"uuid" json:"uuid"`
	Host net.IP `goja:"host" json:"host"`
	Port int    `goja:"port" json:"port"`
	Name string `goja:"name" json:"name"`
}

type CachedDevice struct {
	Device
	UpdatedAt time.Time
}

func (d CachedDevice) Expired() bool {
	return d.UpdatedAt.Add(30 * time.Minute).Before(time.Now())
}

type DeviceStatus struct {
	CurrentApp DeviceStatusCurrentApp `goja:"currentApp" json:"currentApp"`
	Volume     DeviceStatusVolume     `goja:"volume" json:"volume"`
}

type DeviceStatusCurrentApp struct {
	ID          string `goja:"id" json:"id"`
	DisplayName string `goja:"displayName" json:"displayName"`
	StatusText  string `goja:"statusText" json:"statusText"`
}

type DeviceStatusVolume struct {
	Level float64 `goja:"level" json:"level"`
	Muted bool    `goja:"muted" json:"muted"`
}

const (
	serviceDiscoveryPollingInterval time.Duration = 500 * time.Millisecond
)

var cache sync.Map

func getCachedDevice(uuid string) (Device, bool) {
	value, exists := cache.Load(uuid)
	if !exists {
		return Device{}, false
	}

	cachedDevice, ok := value.(CachedDevice)
	if !ok {
		return Device{}, false
	}

	if cachedDevice.Expired() {
		return Device{}, false
	}

	return cachedDevice.Device, true
}

func cacheDevice(dev Device) {
	cache.Store(dev.UUID, CachedDevice{
		Device:    dev,
		UpdatedAt: time.Now(),
	})
}

func getDeviceClientByUUID(ctx context.Context, uuid string) (*cast.Client, error) {
	device, err := FindDeviceByUUID(ctx, uuid)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	client := cast.NewClient(device.Host, device.Port)

	return client, nil
}

func FindDeviceByUUID(ctx context.Context, uuid string) (Device, error) {
	device, exists := getCachedDevice(uuid)
	if exists {
		return device, nil
	}

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	devices, err := SearchDevices(ctx)
	if err != nil {
		return Device{}, nil
	}

	for dev := range devices {
		if dev.UUID == uuid {
			return dev, nil
		}
	}

	return Device{}, errors.Errorf("could not find device '%s'", uuid)
}

func ListDevices(ctx context.Context, refresh bool) ([]Device, error) {
	devices := make([]Device, 0)

	if !refresh {
		cache.Range(func(key, value any) bool {
			cached, ok := value.(CachedDevice)
			if !ok || cached.Expired() {
				return true
			}

			devices = append(devices, cached.Device)
			return true
		})

		return devices, nil
	}

	ch, err := SearchDevices(ctx)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	for dev := range ch {
		devices = append(devices, dev)
	}

	return devices, nil
}

var searchDevicesMutex sync.Mutex

func SearchDevices(ctx context.Context) (chan Device, error) {
	service := NewService(ctx)
	defer service.Stop()

	go func() {
		searchDevicesMutex.Lock()
		defer searchDevicesMutex.Unlock()

		if err := service.Run(ctx, serviceDiscoveryPollingInterval); err != nil && !errors.Is(err, context.DeadlineExceeded) {
			logger.Error(ctx, "error while running cast service discovery", logger.CapturedE(errors.WithStack(err)))
		}
	}()

	devices := make(chan Device)

	go func() {
		defer close(devices)

		found := make(map[string]struct{})

	LOOP:
		for {
			select {
			case c := <-service.Found():
				dev := Device{
					Host: c.IP().To4(),
					Port: c.Port(),
					Name: c.Name(),
					UUID: c.Uuid(),
				}

				if _, exists := found[dev.UUID]; !exists {
					devices <- dev

					found[dev.UUID] = struct{}{}
				}

				cacheDevice(dev)

			case <-ctx.Done():
				break LOOP
			}
		}
	}()

	return devices, nil
}

var loadURLMutex sync.Mutex

func LoadURL(ctx context.Context, deviceUUID string, url string) error {
	loadURLMutex.Lock()
	defer loadURLMutex.Unlock()

	client, err := getDeviceClientByUUID(ctx, deviceUUID)
	if err != nil {
		return errors.WithStack(err)
	}

	if err := client.Connect(ctx); err != nil {
		return errors.WithStack(err)
	}
	defer client.Close()

	controller, err := client.URL(ctx)
	if err != nil {
		return errors.WithStack(err)
	}

	// Ignore context.DeadlineExceeded errors. github.com/barnybug/go-cast bug ?
	if _, err := controller.LoadURL(ctx, url); err != nil && !isLoadURLContextExceeded(err) {
		return errors.WithStack(err)
	}

	return nil
}

// False positive workaround.
func isLoadURLContextExceeded(err error) bool {
	return err.Error() == "Failed to send load command: context deadline exceeded"
}

var stopCastMutex sync.Mutex

func StopCast(ctx context.Context, deviceUUID string) error {
	stopCastMutex.Lock()
	defer stopCastMutex.Unlock()

	client, err := getDeviceClientByUUID(ctx, deviceUUID)
	if err != nil {
		return errors.WithStack(err)
	}

	if err := client.Connect(ctx); err != nil {
		return errors.WithStack(err)
	}
	defer client.Close()

	if _, err := client.Receiver().QuitApp(ctx); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

var getStatusMutex sync.Mutex

func getStatus(ctx context.Context, deviceUUID string) (*DeviceStatus, error) {
	getStatusMutex.Lock()
	defer getStatusMutex.Unlock()

	client, err := getDeviceClientByUUID(ctx, deviceUUID)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	if err := client.Connect(ctx); err != nil {
		return nil, errors.WithStack(err)
	}
	defer client.Close()

	ctrlStatus, err := client.Receiver().GetStatus(ctx)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	status := &DeviceStatus{
		CurrentApp: DeviceStatusCurrentApp{
			ID:          "",
			DisplayName: "",
			StatusText:  "",
		},
		Volume: DeviceStatusVolume{
			Level: *ctrlStatus.Volume.Level,
			Muted: *ctrlStatus.Volume.Muted,
		},
	}

	if len(ctrlStatus.Applications) > 0 {
		status.CurrentApp.ID = *ctrlStatus.Applications[0].AppID
		status.CurrentApp.DisplayName = *ctrlStatus.Applications[0].DisplayName
		status.CurrentApp.StatusText = *ctrlStatus.Applications[0].StatusText
	}

	return status, nil
}