"""Network-Watchdog: überwacht WLAN-Verbindung und startet Recovery-AP bei Ausfall.

Strategie:
  1. Default-Gateway-Ping alle CHECK_INTERVAL_S
  2. failed_pings zählt; bei FAIL_THRESHOLD sofortiger Reconnect-Versuch
  3. Nach REASSURE_TIMEOUT_S erfolglos: AP-Modus starten
  4. Im AP-Modus: alle AP_RECHECK_S prüfen ob echtes WLAN zurück ist, dann AP aus
"""
from __future__ import annotations
import subprocess, time, threading, logging, os
from pathlib import Path
from dataclasses import dataclass, field

# Defaults
WLAN_IFACE = "wlan0"  # Pi 4 builtin
CLIENT_CON_NAME = "dashboard-wifi"  # NetworkManager connection profile name
AP_SSID = "epaper-recovery"
AP_PASSWORD = "recovery1234"

CHECK_INTERVAL_S = 30       # alle 30s pingen
FAIL_THRESHOLD = 2          # 2 misses hintereinander → reconnect versuchen
RECONNECT_COOLDOWN_S = 90   # zwischen zwei Reconnect-Versuchen mind. 90s warten
AP_RECHECK_S = 60           # im AP-Modus: alle 60s versuchen zurück zu wechseln
AP_ENABLE_TIMEOUT_S = 30    # warten bis AP steht, dann gilt: "AP ist aktiv"
PING_TIMEOUT_S = 3
PING_TARGETS = ["1.1.1.1", "8.8.8.8"]  # wenn eins antwortet → online


@dataclass
class NetState:
    mode: str = "unknown"          # "client" | "ap" | "connecting" | "offline" | "unknown"
    ssid: str = ""
    ip: str = ""
    signal: int = 0               # 0..100
    gateway_ping_ms: float = 0.0
    failed_pings: int = 0
    last_state_change: float = field(default_factory=time.time)
    last_reconnect_attempt: float = 0.0
    error: str = ""


def _nm(args: list[str], timeout: int = 15) -> tuple[int, str, str]:
    """Run nmcli with timeout, return (rc, stdout, stderr)."""
    try:
        r = subprocess.run(["nmcli", *args], capture_output=True, text=True, timeout=timeout)
        return r.returncode, r.stdout, r.stderr
    except subprocess.TimeoutExpired:
        return -1, "", "timeout"
    except Exception as e:
        return -1, "", str(e)


def ping(target: str) -> float | None:
    try:
        r = subprocess.run(
            ["ping", "-c", "1", "-W", str(PING_TIMEOUT_S), target],
            capture_output=True, text=True, timeout=PING_TIMEOUT_S + 2,
        )
        if r.returncode != 0:
            return None
        for line in r.stdout.splitlines():
            if "time=" in line:
                return float(line.split("time=")[1].split()[0])
    except Exception:
        return None
    return None


def get_active_wifi_info() -> dict:
    """Liest aktuelle WLAN-Informationen aus NetworkManager."""
    rc, out, err = _nm(["-t", "-f", "ACTIVE,SSID,SIGNAL,FREQ,CHAN,RATE,BARS", "device", "wifi"])
    info = {"ssid": "", "signal": 0, "bars": "", "active": False}
    if rc != 0:
        return info
    for line in out.splitlines():
        parts = line.split(":")
        if len(parts) < 6:
            continue
        # Format: yes:ssid:signal:...
        if parts[0] == "yes":
            info["active"] = True
            info["ssid"] = parts[1] if len(parts) > 1 else ""
            try:
                info["signal"] = int(parts[2]) if len(parts) > 2 and parts[2] else 0
            except ValueError:
                pass
            info["bars"] = parts[6] if len(parts) > 6 else ""
            break
    return info


def get_wifi_ip() -> str:
    """Hole IPv4-Adresse von WLAN-Interface."""
    try:
        r = subprocess.run(
            ["ip", "-4", "-o", "addr", "show", "dev", WLAN_IFACE],
            capture_output=True, text=True, timeout=5,
        )
        for line in r.stdout.splitlines():
            if "inet " in line:
                return line.split("inet ")[1].split("/")[0]
    except Exception:
        pass
    return ""


def list_wifi_networks() -> list[dict]:
    """Scannt verfügbare WLANs."""
    rc, out, err = _nm(["-t", "-f", "SSID,SIGNAL,SECURITY,FREQ,CHAN", "device", "wifi",
                        "list", "--rescan", "yes"])
    if rc != 0:
        # zweiter versuch ohne rescan
        rc, out, err = _nm(["-t", "-f", "SSID,SIGNAL,SECURITY,FREQ,CHAN", "device", "wifi", "list"])
    seen = set()
    result = []
    for line in out.splitlines():
        parts = line.split(":")
        if len(parts) < 3: continue
        ssid = parts[0]
        if not ssid or ssid in seen: continue
        seen.add(ssid)
        try:
            sig = int(parts[1]) if parts[1] else 0
        except ValueError:
            sig = 0
        result.append({"ssid": ssid, "signal": sig, "security": parts[2] if len(parts) > 2 else "",
                       "freq": parts[3] if len(parts) > 3 else "",
                       "chan": parts[4] if len(parts) > 4 else ""})
    result.sort(key=lambda w: w["signal"], reverse=True)
    return result


def list_saved_connections() -> list[dict]:
    """Liste alle gespeicherten WLAN-Profile."""
    rc, out, err = _nm(["-t", "-f", "NAME,TYPE,UUID", "connection", "show"])
    result = []
    for line in out.splitlines():
        parts = line.split(":")
        if len(parts) < 3: continue
        if parts[1] != "802-11-wireless": continue
        if parts[0] in (AP_SSID, "Hotspot"): continue  # skip AP profile
        result.append({"name": parts[0], "uuid": parts[2]})
    return result


def save_wifi(ssid: str, password: str, security: str = "wpa-psk") -> tuple[bool, str]:
    """Speichere (oder update) ein WLAN-Profil mit gegebenen Credentials.

    Wenn schon ein Profil mit gleicher SSID existiert, wird es aktualisiert;
    sonst wird ein neues angelegt.
    """
    # Existierendes Profil finden
    saved = list_saved_connections()
    target_name = None
    for c in saved:
        if c["name"].startswith(ssid):
            target_name = c["name"]
            break
    if target_name is None:
        target_name = CLIENT_CON_NAME + "-" + ssid.replace(" ", "_")

    args = ["connection", "modify" if target_name in [c["name"] for c in saved] else "add",
            "type", "wifi",
            "con-name", target_name,
            "ifname", WLAN_IFACE,
            "ssid", ssid]
    if security and security != "" and password:
        if "WPA" in security.upper() or "WPA2" in security.upper() or "WPA3" in security.upper():
            args += ["wifi-sec.key-mgmt", "wpa-psk", "wifi-sec.psk", password]
        elif "WEP" in security.upper():
            args += ["wifi-sec.key-mgmt", "none", "wifi-sec.wep-key-type", "1",
                     "wifi-sec.wep-key0", password]
        else:
            args += ["wifi-sec.key-mgmt", "wpa-psk", "wifi-sec.psk", password]
    else:
        args += ["wifi-sec.key-mgmt", "none"]
    rc, out, err = _nm(args, timeout=20)
    if rc != 0:
        return False, err or out or "unknown error"
    return True, target_name


def connect_wifi(connection_name: str) -> tuple[bool, str]:
    rc, out, err = _nm(["connection", "up", connection_name], timeout=30)
    if rc != 0:
        return False, err or out or "unknown error"
    return True, "connected"


def disconnect_wifi() -> tuple[bool, str]:
    rc, out, err = _nm(["device", "disconnect", WLAN_IFACE], timeout=10)
    return rc == 0, err if rc != 0 else "ok"


def start_ap() -> tuple[bool, str]:
    """Startet einen Hotspot auf wlan0 mit fester SSID/PW."""
    # Alten Hotspot ggf. löschen (idempotent)
    _nm(["connection", "delete", AP_SSID], timeout=10)
    rc, out, err = _nm([
        "device", "wifi", "hotspot",
        "ifname", WLAN_IFACE,
        "ssid", AP_SSID,
        "password", AP_PASSWORD,
    ], timeout=30)
    if rc != 0:
        return False, err or out
    return True, "hotspot up"


def stop_ap() -> tuple[bool, str]:
    rc, out, err = _nm(["connection", "down", AP_SSID], timeout=15)
    if rc != 0:
        return False, err or out
    _nm(["connection", "delete", AP_SSID], timeout=10)
    return True, "ap stopped"


def is_ap_active() -> bool:
    rc, out, _ = _nm(["-t", "-f", "NAME", "connection", "show", "--active"])
    if rc != 0:
        return False
    return AP_SSID in out.splitlines()


def is_wifi_connected() -> bool:
    rc, out, _ = _nm(["-t", "-f", "STATE", "device", "show", WLAN_IFACE])
    if rc != 0:
        return False
    return "connected" in out.lower()


# ============================================================================
# Recovery threshold helper (used by admin.py)
# ============================================================================
def get_recovery_threshold() -> int:
    """Liest recovery_threshold_s aus config.json (default 60s)."""
    try:
        from pathlib import Path as _P
        cfg_path = _P("/home/koptikp/epaper-dashboard/port/config.json")
        if cfg_path.exists():
            import json as _json
            cfg = _json.loads(cfg_path.read_text())
            return int(cfg.get("recovery_threshold_s", 60))
    except Exception:
        pass
    return 60


# ============================================================================
# Watchdog
# ============================================================================
def _check_recovery_needed(state: dict, threshold_s: int) -> dict:
    """Entscheidet, ob die Recovery-Info UI angezeigt werden soll.

    Returns dict mit:
      show: bool
      reason: 'offline' | 'ap_active' | 'connecting_timeout' | 'no_ip'
      duration_s: Sekunden im aktuellen (nicht-client) Zustand
    """
    mode = state.get("mode", "unknown")
    if mode == "client":
        return {"show": False, "reason": "client", "duration_s": 0}
    # Im AP-Modus: immer anzeigen
    if mode == "ap":
        return {"show": True, "reason": "ap_active", "duration_s": state.get("since_change_s", 0)}
    if mode == "offline":
        return {"show": True, "reason": "offline", "duration_s": state.get("since_change_s", 0)}
    if mode == "connecting":
        # Connecting dauert zu lange? Zeige info.
        return {"show": state.get("since_change_s", 0) > threshold_s,
                "reason": "connecting_timeout",
                "duration_s": state.get("since_change_s", 0)}
    return {"show": False, "reason": "unknown", "duration_s": state.get("since_change_s", 0)}


class Watchdog:
    def __init__(self):
        self.state = NetState()
        self._lock = threading.Lock()
        self._stop = threading.Event()

    def get_state(self) -> dict:
        with self._lock:
            return {
                "mode": self.state.mode,
                "ssid": self.state.ssid,
                "ip": self.state.ip,
                "signal": self.state.signal,
                "gateway_ping_ms": round(self.state.gateway_ping_ms, 1),
                "failed_pings": self.state.failed_pings,
                "since_change_s": int(time.time() - self.state.last_state_change),
                "error": self.state.error,
            }

    def _set_mode(self, new_mode: str):
        with self._lock:
            if self.state.mode != new_mode:
                logging.info(f"network mode: {self.state.mode} → {new_mode}")
                self.state.mode = new_mode
                self.state.last_state_change = time.time()
                self.state.error = ""

    def run_once(self) -> dict:
        """Führt einen Check durch und triggert ggf. State-Übergänge."""
        with self._lock:
            cur_mode = self.state.mode

        ping_ms = None
        for tgt in PING_TARGETS:
            r = ping(tgt)
            if r is not None:
                ping_ms = r
                break

        wifi_info = get_active_wifi_info()
        ip = get_wifi_ip()

        if wifi_info["active"] and ip and ping_ms is not None:
            # ONLINE
            with self._lock:
                self.state.ssid = wifi_info["ssid"]
                self.state.signal = wifi_info["signal"]
                self.state.ip = ip
                self.state.gateway_ping_ms = ping_ms
                self.state.failed_pings = 0
            # Falls im AP-Modus → AP aus
            if cur_mode == "ap":
                logging.info("client wifi back, stopping AP")
                stop_ap()
            self._set_mode("client")
            return self.get_state()

        # OFFLINE PATH
        with self._lock:
            if ping_ms is None:
                self.state.failed_pings += 1
            self.state.gateway_ping_ms = ping_ms or 0.0
            self.state.ip = ip
            self.state.ssid = wifi_info["ssid"]
            self.state.signal = wifi_info["signal"]
            failed = self.state.failed_pings
            last_recon = self.state.last_reconnect_attempt

        if cur_mode == "ap":
            # Bereits im AP — nur gelegentlich versuchen zurück zu wechseln
            # (durch den regulären 60s-Loop in self._loop)
            return self.get_state()

        if failed >= FAIL_THRESHOLD:
            now = time.time()
            if now - last_recon < RECONNECT_COOLDOWN_S:
                return self.get_state()
            # Reconnect versuchen
            with self._lock:
                self.state.last_reconnect_attempt = now
            saved = list_saved_connections()
            if saved:
                logging.info(f"wifi lost ({failed} failed pings), reconnecting to {saved[0]['name']}")
                self._set_mode("connecting")
                ok, msg = connect_wifi(saved[0]["name"])
                if ok:
                    time.sleep(AP_ENABLE_TIMEOUT_S)
                    # Nach reconnect: wenn immer noch offline → AP
                    return self.run_once()
                else:
                    logging.error(f"reconnect failed: {msg}")
                    with self._lock:
                        self.state.error = msg
            else:
                # Kein Profil → direkt in AP
                self._set_mode("connecting")
                return self._enter_ap()
        return self.get_state()

    def _enter_ap(self) -> dict:
        logging.warning(f"entering AP mode ({AP_SSID})")
        ok, msg = start_ap()
        if ok:
            self._set_mode("ap")
            with self._lock:
                self.state.ip = "10.42.0.1"
                self.state.error = ""
        else:
            logging.error(f"failed to start AP: {msg}")
            self._set_mode("offline")
            with self._lock:
                self.state.error = msg
        return self.get_state()

    def _try_exit_ap(self) -> dict:
        """Versuch, aus dem AP zurück in Client-Modus zu wechseln."""
        if not is_ap_active():
            self._set_mode("client")
            return self.get_state()
        saved = list_saved_connections()
        if not saved:
            return self.get_state()
        logging.info("trying to exit AP back to client")
        ok, msg = connect_wifi(saved[0]["name"])
        if ok:
            time.sleep(AP_ENABLE_TIMEOUT_S)
            wifi_info = get_active_wifi_info()
            ip = get_wifi_ip()
            if wifi_info["active"] and ip and ping(PING_TARGETS[0]) is not None:
                logging.info("back online, stopping AP")
                stop_ap()
                self._set_mode("client")
                with self._lock:
                    self.state.failed_pings = 0
            else:
                # Immer noch kein echtes WLAN → AP wieder hoch
                start_ap()
                self._set_mode("ap")
        return self.get_state()

    def _loop(self):
        # Initial: state aus NM ableiten
        wifi_info = get_active_wifi_info()
        ip = get_wifi_ip()
        if is_ap_active():
            self._set_mode("ap")
            with self._lock:
                self.state.ssid = AP_SSID
                self.state.ip = "10.42.0.1"
        elif wifi_info["active"] and ip:
            self._set_mode("client")
            with self._lock:
                self.state.ssid = wifi_info["ssid"]
                self.state.signal = wifi_info["signal"]
                self.state.ip = ip
        else:
            self._set_mode("offline")

        while not self._stop.is_set():
            try:
                if self.state.mode == "ap":
                    # im AP-Modus: alle AP_RECHECK_S versuchen zurück zu wechseln
                    if self._stop.wait(timeout=AP_RECHECK_S):
                        break
                    self._try_exit_ap()
                else:
                    if self._stop.wait(timeout=CHECK_INTERVAL_S):
                        break
                    self.run_once()
            except Exception as e:
                logging.error(f"watchdog error: {e}")
                time.sleep(5)

    def start(self):
        t = threading.Thread(target=self._loop, name="network-watchdog", daemon=True)
        t.start()

    def stop(self):
        self._stop.set()


# ============================================================================
# Singleton für Web-UI
# ============================================================================
_watchdog: Watchdog | None = None


def get_watchdog() -> Watchdog:
    global _watchdog
    if _watchdog is None:
        _watchdog = Watchdog()
        _watchdog.start()
    return _watchdog