repeater/internal/wifi/iwd/backend.go

package iwd

import (
	"fmt"

	"github.com/godbus/dbus/v5"
	"github.com/nemunaire/repeater/internal/wifi/backend"
)

const (
	AgentPath = "/com/github/nemunaire/repeater/agent"
)

// IWDBackend implements the WiFiBackend interface for iwd (Intel Wireless Daemon)
type IWDBackend struct {
	conn          *dbus.Conn
	manager       *Manager
	station       *Station
	agent         *Agent
	agentManager  *AgentManager
	signalMonitor *SignalMonitor
	interfaceName string
	callbacks     backend.EventCallbacks
}

// NewIWDBackend creates a new IWD backend instance
func NewIWDBackend() *IWDBackend {
	return &IWDBackend{}
}

// Initialize initializes the iwd backend with the given interface name
func (b *IWDBackend) Initialize(interfaceName string) error {
	b.interfaceName = interfaceName
	var err error

	// Connect to D-Bus
	b.conn, err = dbus.SystemBus()
	if err != nil {
		return fmt.Errorf("échec de connexion à D-Bus: %v", err)
	}

	// Find station for interface
	b.manager = NewManager(b.conn)
	b.station, err = b.manager.FindStation(interfaceName)
	if err != nil {
		return fmt.Errorf("impossible de trouver la station pour %s: %v", interfaceName, err)
	}

	// Create and register agent for credential callbacks
	b.agent = NewAgent(b.conn, dbus.ObjectPath(AgentPath))
	if err := b.agent.Export(); err != nil {
		return fmt.Errorf("échec de l'export de l'agent: %v", err)
	}

	b.agentManager = NewAgentManager(b.conn)
	if err := b.agentManager.RegisterAgent(dbus.ObjectPath(AgentPath)); err != nil {
		b.agent.Unexport()
		return fmt.Errorf("échec de l'enregistrement de l'agent: %v", err)
	}

	return nil
}

// Close closes the D-Bus connection and unregisters the agent
func (b *IWDBackend) Close() error {
	if b.agentManager != nil && b.agent != nil {
		b.agentManager.UnregisterAgent(dbus.ObjectPath(AgentPath))
		b.agent.Unexport()
	}
	if b.conn != nil {
		b.conn.Close()
	}
	return nil
}

// ScanNetworks triggers a network scan
func (b *IWDBackend) ScanNetworks() error {
	err := b.station.Scan()
	if err != nil {
		return fmt.Errorf("erreur lors du scan: %v", err)
	}
	return nil
}

// GetOrderedNetworks returns networks sorted by signal strength in backend-agnostic format
func (b *IWDBackend) GetOrderedNetworks() ([]backend.BackendNetwork, error) {
	networkInfos, err := b.station.GetOrderedNetworks()
	if err != nil {
		return nil, fmt.Errorf("erreur lors de la récupération des réseaux: %v", err)
	}

	var networks []backend.BackendNetwork
	seenSSIDs := make(map[string]bool)

	for _, netInfo := range networkInfos {
		network := NewNetwork(b.conn, netInfo.Path)
		props, err := network.GetProperties()
		if err != nil {
			continue
		}

		if props.Name == "" || seenSSIDs[props.Name] {
			continue
		}
		seenSSIDs[props.Name] = true

		// Convert iwd network to backend-agnostic format
		backendNet := backend.BackendNetwork{
			SSID:         props.Name,
			SignalDBm:    netInfo.Signal / 100, // iwd provides 100*dBm, convert to dBm
			SecurityType: props.Type,
			BSSID:        generateSyntheticBSSID(props.Name), // iwd doesn't expose BSSID
			Frequency:    0,                                  // iwd doesn't expose frequency in GetOrderedNetworks
		}

		networks = append(networks, backendNet)
	}

	return networks, nil
}

// IsScanning checks if a scan is currently in progress
func (b *IWDBackend) IsScanning() (bool, error) {
	return b.station.IsScanning()
}

// Connect connects to a WiFi network
func (b *IWDBackend) Connect(ssid, password string) error {
	// Store passphrase in agent for callback
	if password != "" {
		b.agent.SetPassphrase(ssid, password)
	}

	// Ensure passphrase is cleared after connection attempt
	defer func() {
		if password != "" {
			b.agent.ClearPassphrase(ssid)
		}
	}()

	// Get network object
	network, err := b.station.GetNetwork(ssid)
	if err != nil {
		return fmt.Errorf("réseau '%s' non trouvé: %v", ssid, err)
	}

	// Connect - iwd will call agent.RequestPassphrase() if needed
	if err := network.Connect(); err != nil {
		return fmt.Errorf("erreur lors de la connexion: %v", err)
	}

	return nil
}

// Disconnect disconnects from the current WiFi network
func (b *IWDBackend) Disconnect() error {
	if err := b.station.Disconnect(); err != nil {
		return fmt.Errorf("erreur lors de la déconnexion: %v", err)
	}
	return nil
}

// GetConnectionState returns the current WiFi connection state
func (b *IWDBackend) GetConnectionState() (backend.ConnectionState, error) {
	state, err := b.station.GetState()
	if err != nil {
		return backend.StateDisconnected, err
	}
	return mapIWDState(state), nil
}

// GetConnectedSSID returns the SSID of the currently connected network
func (b *IWDBackend) GetConnectedSSID() string {
	network, err := b.station.GetConnectedNetwork()
	if err != nil {
		return ""
	}

	props, err := network.GetProperties()
	if err != nil {
		return ""
	}

	return props.Name
}

// StartEventMonitoring starts monitoring WiFi events
func (b *IWDBackend) StartEventMonitoring(callbacks backend.EventCallbacks) error {
	b.callbacks = callbacks

	// Create signal monitor
	b.signalMonitor = NewSignalMonitor(b.conn, b.station)

	// Register callbacks - wrap to convert iwd types to backend types
	b.signalMonitor.OnStateChange(func(state StationState, ssid string) {
		if b.callbacks.OnStateChange != nil {
			b.callbacks.OnStateChange(mapIWDState(state), ssid)
		}
	})

	b.signalMonitor.OnScanComplete(func() {
		if b.callbacks.OnScanComplete != nil {
			b.callbacks.OnScanComplete()
		}
	})

	// Start monitoring
	return b.signalMonitor.Start()
}

// StopEventMonitoring stops monitoring WiFi events
func (b *IWDBackend) StopEventMonitoring() {
	if b.signalMonitor != nil {
		b.signalMonitor.Stop()
	}
}

// mapIWDState maps iwd-specific states to backend-agnostic states
func mapIWDState(state StationState) backend.ConnectionState {
	switch state {
	case StateConnected:
		return backend.StateConnected
	case StateConnecting:
		return backend.StateConnecting
	case StateDisconnecting:
		return backend.StateDisconnecting
	case StateDisconnected:
		return backend.StateDisconnected
	case StateRoaming:
		// Map roaming to connected since we're still connected during roaming
		return backend.StateConnected
	default:
		return backend.StateDisconnected
	}
}

// generateSyntheticBSSID generates a consistent fake BSSID from SSID
// (iwd doesn't expose real BSSID)
func generateSyntheticBSSID(ssid string) string {
	// Use a simple hash approach - consistent per SSID
	hash := 0
	for _, c := range ssid {
		hash = ((hash << 5) - hash) + int(c)
	}

	// Generate 6 bytes for MAC address
	b1 := byte((hash >> 0) & 0xff)
	b2 := byte((hash >> 8) & 0xff)
	b3 := byte((hash >> 16) & 0xff)
	b4 := byte((hash >> 24) & 0xff)
	b5 := byte(len(ssid) & 0xff)
	b6 := byte((len(ssid) >> 8) & 0xff)

	return fmt.Sprintf("%02x:%02x:%02x:%02x:%02x:%02x", b1, b2, b3, b4, b5, b6)
}