package app

import (
	"embed"
	"log"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/nemunaire/repeater/internal/api"
	"github.com/nemunaire/repeater/internal/config"
	"github.com/nemunaire/repeater/internal/hotspot"
	"github.com/nemunaire/repeater/internal/logging"
	"github.com/nemunaire/repeater/internal/models"
	"github.com/nemunaire/repeater/internal/station"
	"github.com/nemunaire/repeater/internal/station/backend"
	"github.com/nemunaire/repeater/internal/syslog"
	"github.com/nemunaire/repeater/internal/wifi"
)

// App represents the application
type App struct {
	Status       models.SystemStatus
	StatusMutex  sync.RWMutex
	StartTime    time.Time
	Assets       embed.FS
	Config       *config.Config
	SyslogTailer *syslog.SyslogTailer

	stopCh   chan struct{}
	stopOnce sync.Once
	wg       sync.WaitGroup
}

// New creates a new application instance
func New(assets embed.FS) *App {
	return &App{
		Status: models.SystemStatus{
			Connected:       false,
			ConnectionState: "disconnected",
			ConnectedSSID:   "",
			HotspotStatus:   nil,
			ConnectedCount:  0,
			DataUsage:       0.0,
			Uptime:          0,
		},
		StartTime: time.Now(),
		Assets:    assets,
		stopCh:    make(chan struct{}),
	}
}

// Initialize initializes the application
func (a *App) Initialize(cfg *config.Config) error {
	// Store config reference
	a.Config = cfg

	// Decide whether the Ethernet uplink already provides connectivity. When
	// it does we deliberately skip every wpa_supplicant interaction below —
	// the daemon is dbus-activatable, so any call into the WiFi backend
	// would re-spawn it and undo this choice.
	eth := ensureUplink(cfg.EthernetInterface)
	a.StatusMutex.Lock()
	a.Status.EthernetStatus = eth
	a.StatusMutex.Unlock()

	if !eth.Active {
		// Initialize WiFi backend
		if err := wifi.Initialize(cfg.WifiInterface, cfg.WifiBackend); err != nil {
			return err
		}

		// Start WiFi event monitoring
		if err := wifi.StartEventMonitoring(); err != nil {
			log.Printf("Warning: WiFi event monitoring failed: %v", err)
			// Don't fail - polling fallback still works
		}
	} else {
		log.Printf("Skipping WiFi backend init: Ethernet uplink active on %s", eth.Interface)
	}

	// Initialize station backend
	stationConfig := backend.BackendConfig{
		InterfaceName:    cfg.HotspotInterface,
		ARPTablePath:     cfg.ARPTablePath,
		DHCPLeasesPath:   cfg.DHCPLeasesPath,
		HostapdInterface: cfg.HotspotInterface,
	}
	if err := station.Initialize(cfg.StationBackend, stationConfig); err != nil {
		log.Printf("Warning: Station backend initialization failed: %v", err)
		// Don't fail - will continue without station discovery
	} else {
		// Start event monitoring for station events
		if err := station.StartEventMonitoring(backend.EventCallbacks{
			OnStationConnected:    a.handleStationConnected,
			OnStationDisconnected: a.handleStationDisconnected,
			OnStationUpdated:      a.handleStationUpdated,
		}); err != nil {
			log.Printf("Warning: Station event monitoring failed: %v", err)
			// Don't fail - polling fallback still works
		}
	}

	// Start syslog tailing if enabled
	if cfg.SyslogEnabled {
		a.SyslogTailer = syslog.NewSyslogTailer(
			cfg.SyslogPath,
			cfg.SyslogFilter,
			cfg.SyslogSource,
		)
		if err := a.SyslogTailer.Start(); err != nil {
			log.Printf("Warning: Failed to start syslog tailing: %v", err)
			// Don't fail - app continues without syslog
		}
	}

	// Start periodic tasks
	a.wg.Add(2)
	go a.periodicStatusUpdate()
	go a.periodicDeviceUpdate()

	logging.AddLog("Système", "Application initialisée")
	return nil
}

// Run starts the HTTP server
func (a *App) Run(addr string) error {
	router := api.SetupRouter(&a.Status, &a.StatusMutex, a.Config, a.Assets)

	logging.AddLog("Système", "Serveur API démarré sur "+addr)
	return router.Run(addr)
}

// Shutdown gracefully shuts down the application. Idempotent — main wires
// it both to a signal handler and a defer, and the second call must be a
// no-op (channel close panics otherwise; backend Close paths assume single
// invocation).
func (a *App) Shutdown() {
	a.stopOnce.Do(func() {
		// Signal periodic loops to exit, then wait for them so we don't
		// race with backends being closed below.
		close(a.stopCh)
		a.wg.Wait()

		// Stop syslog tailing if running
		if a.SyslogTailer != nil {
			a.SyslogTailer.Stop()
		}

		// Stop station monitoring and close backend
		station.StopEventMonitoring()
		station.Close()

		wifi.StopEventMonitoring()
		wifi.Close()
		logging.AddLog("Système", "Application arrêtée")
	})
}

// getSystemUptime reads system uptime from /proc/uptime
func getSystemUptime() int64 {
	data, err := os.ReadFile("/proc/uptime")
	if err != nil {
		log.Printf("Error reading /proc/uptime: %v", err)
		return 0
	}

	fields := strings.Fields(string(data))
	if len(fields) == 0 {
		return 0
	}

	uptime, err := strconv.ParseFloat(fields[0], 64)
	if err != nil {
		log.Printf("Error parsing uptime: %v", err)
		return 0
	}

	return int64(uptime)
}

// getInterfaceBytes reads rx and tx bytes for a network interface
func getInterfaceBytes(interfaceName string) (rxBytes, txBytes int64) {
	rxPath := "/sys/class/net/" + interfaceName + "/statistics/rx_bytes"
	txPath := "/sys/class/net/" + interfaceName + "/statistics/tx_bytes"

	// Read RX bytes
	rxData, err := os.ReadFile(rxPath)
	if err != nil {
		log.Printf("Error reading rx_bytes for %s: %v", interfaceName, err)
	} else {
		rxBytes, _ = strconv.ParseInt(strings.TrimSpace(string(rxData)), 10, 64)
	}

	// Read TX bytes
	txData, err := os.ReadFile(txPath)
	if err != nil {
		log.Printf("Error reading tx_bytes for %s: %v", interfaceName, err)
	} else {
		txBytes, _ = strconv.ParseInt(strings.TrimSpace(string(txData)), 10, 64)
	}

	return rxBytes, txBytes
}

// periodicStatusUpdate updates WiFi connection status periodically
func (a *App) periodicStatusUpdate() {
	defer a.wg.Done()
	ticker := time.NewTicker(5 * time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-a.stopCh:
			return
		case <-ticker.C:
		}

		var eth *models.EthernetStatus
		if a.Config != nil {
			if e, err := probeEthernet(a.Config.EthernetInterface); err == nil {
				eth = e
			}
		}

		a.StatusMutex.Lock()
		if eth != nil {
			a.Status.EthernetStatus = eth
		}

		// Skip every wifi.* call when the Ethernet uplink is the chosen
		// path: the WiFi backend isn't initialized in that mode and the
		// wrappers would otherwise return zero values; either way we don't
		// want to risk dbus-activating wpa_supplicant from this hot loop.
		ethActive := a.Status.EthernetStatus != nil && a.Status.EthernetStatus.Active
		if !ethActive {
			a.Status.Connected = wifi.IsConnected()
			a.Status.ConnectionState = wifi.GetConnectionState()
			a.Status.ConnectedSSID = wifi.GetConnectedSSID()
		} else {
			a.Status.Connected = false
			a.Status.ConnectionState = "disabled"
			a.Status.ConnectedSSID = ""
		}
		a.Status.Uptime = getSystemUptime()

		// Get detailed hotspot status
		a.Status.HotspotStatus = hotspot.GetDetailedStatus()

		// Get network data usage for WiFi interface
		if a.Config != nil {
			rxBytes, txBytes := getInterfaceBytes(a.Config.WifiInterface)
			// Convert to MB and sum rx + tx
			a.Status.DataUsage = float64(rxBytes+txBytes) / (1024 * 1024)
		}

		a.StatusMutex.Unlock()
	}
}

// periodicDeviceUpdate updates connected devices list periodically
func (a *App) periodicDeviceUpdate() {
	defer a.wg.Done()
	ticker := time.NewTicker(10 * time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-a.stopCh:
			return
		case <-ticker.C:
		}

		devices, err := station.GetStations()
		if err != nil {
			log.Printf("Error getting connected devices: %v", err)
		}

		a.StatusMutex.Lock()
		// Preserve ConnectedAt across refreshes so the UI's "connected since"
		// timestamp doesn't reset every poll. Backends that don't track a
		// real connection time return time.Now() each call.
		previous := make(map[string]time.Time, len(a.Status.ConnectedDevices))
		for _, d := range a.Status.ConnectedDevices {
			if !d.ConnectedAt.IsZero() {
				previous[d.MAC] = d.ConnectedAt
			}
		}
		for i := range devices {
			if t, ok := previous[devices[i].MAC]; ok {
				devices[i].ConnectedAt = t
			}
		}
		a.Status.ConnectedDevices = devices
		a.Status.ConnectedCount = len(devices)
		a.StatusMutex.Unlock()
	}
}

// handleStationConnected handles station connection events
func (a *App) handleStationConnected(st backend.Station) {
	a.StatusMutex.Lock()
	defer a.StatusMutex.Unlock()

	device := station.ToConnectedDevice(st)

	// Check if device already exists
	found := false
	for i, d := range a.Status.ConnectedDevices {
		if d.MAC == device.MAC {
			a.Status.ConnectedDevices[i] = device
			found = true
			break
		}
	}

	// Add new device if not found
	if !found {
		a.Status.ConnectedDevices = append(a.Status.ConnectedDevices, device)
		a.Status.ConnectedCount = len(a.Status.ConnectedDevices)
		logging.AddLog("Stations", "Device connected: "+device.MAC+" ("+device.IP+")")
	}
}

// handleStationDisconnected handles station disconnection events
func (a *App) handleStationDisconnected(mac string) {
	a.StatusMutex.Lock()
	defer a.StatusMutex.Unlock()

	// Remove device from list
	for i, d := range a.Status.ConnectedDevices {
		if d.MAC == mac {
			a.Status.ConnectedDevices = append(a.Status.ConnectedDevices[:i], a.Status.ConnectedDevices[i+1:]...)
			a.Status.ConnectedCount = len(a.Status.ConnectedDevices)
			logging.AddLog("Stations", "Device disconnected: "+mac)
			break
		}
	}
}

// handleStationUpdated handles station update events
func (a *App) handleStationUpdated(st backend.Station) {
	a.StatusMutex.Lock()
	defer a.StatusMutex.Unlock()

	// Update existing device. Preserve the original ConnectedAt so the
	// device card doesn't reset its "connected since" badge each time the
	// IP or signal updates.
	for i, d := range a.Status.ConnectedDevices {
		if d.MAC == st.MAC {
			updated := station.ToConnectedDevice(st)
			if !d.ConnectedAt.IsZero() {
				updated.ConnectedAt = d.ConnectedAt
			}
			a.Status.ConnectedDevices[i] = updated
			break
		}
	}
}