# -*- coding: utf-8 -*-
"""
Online-Service — Konnektivitaets-Ueberwachung.

Prueft periodisch ob das System online ist:
- Online: alle 5 Minuten pruefen
- Offline: jede Minute pruefen

Stellt einen HttpClient mit integriertem Offline-Cache bereit.

Events:
- online_status_changed: {"online": bool, "since": datetime}
"""

from __future__ import annotations

import asyncio
import socket
import time
from dataclasses import dataclass
from datetime import datetime
from typing import TYPE_CHECKING

from trixy_core.online.cache import ResponseCache
from trixy_core.online.client import HttpClient
from trixy_core.service import IService, ServicePriority, ServiceGroup
from trixy_core.utils.debug import pinfo, pdebug, perror

if TYPE_CHECKING:
    from trixy_core.application import BaseApplication


@dataclass
class OnlineServiceConfig:
    """Konfiguration fuer den Online-Service."""
    # Pruef-Intervalle (Sekunden)
    check_interval_online: float = 300.0    # 5 Minuten
    check_interval_offline: float = 60.0    # 1 Minute

    # Pruef-Methode: DNS-Lookup auf bekannte Hosts
    check_hosts: list[str] | None = None    # Default: Google DNS + Cloudflare

    # Timeout fuer einzelne Pruefung
    check_timeout: float = 5.0

    # HTTP-Client Defaults
    http_timeout: float = 30.0

    # Cache-Verzeichnis (relativ zum Source-Dir)
    cache_dir: str = "cache"


class OnlineService(IService):
    """
    Konnektivitaets-Service.

    Ueberwacht die Internet-Verbindung und stellt einen
    HTTP-Client mit Offline-Cache bereit.

    Beispiel:
        ```python
        online = app.services.get("online")

        # Status pruefen
        if online.is_online:
            resp = await online.http.get("https://api.example.com")

        # Request mit Cache (funktioniert auch offline)
        resp = await online.http.get(
            "https://api.weather.com/forecast",
            cache_ttl=3600,
        )
        if resp.from_cache:
            print("Offline — verwende gecachte Daten")
        ```
    """

    PRIORITY = ServicePriority.CORE
    GROUP = ServiceGroup.NETWORK
    DEPENDENCIES = []

    def __init__(
        self,
        application: "BaseApplication",
        config: OnlineServiceConfig | None = None,
    ) -> None:
        super().__init__(application)
        self._config = config or OnlineServiceConfig()

        # Status
        self._online = False
        self._online_since: datetime | None = None
        self._offline_since: datetime | None = datetime.now()
        self._last_check: float = 0.0
        self._check_count = 0

        # Check-Hosts
        self._check_hosts = self._config.check_hosts or [
            "8.8.8.8",          # Google DNS
            "1.1.1.1",          # Cloudflare DNS
            "9.9.9.9",          # Quad9 DNS
        ]

        # Cache + HTTP-Client
        source_path = ""
        if hasattr(application, "config_manager"):
            source_path = getattr(application.config_manager, "base_path", "")
        if not source_path:
            source_path = "."

        cache_path = f"{source_path}/{self._config.cache_dir}"
        self._cache = ResponseCache(cache_path)
        self._http = HttpClient(
            cache=self._cache,
            is_online_fn=lambda: self._online,
            timeout=self._config.http_timeout,
        )

        # Task
        self._check_task: asyncio.Task | None = None

    # === Properties ===

    @property
    def is_online(self) -> bool:
        """True wenn Internet-Verbindung besteht."""
        return self._online

    @property
    def is_offline(self) -> bool:
        """True wenn keine Internet-Verbindung besteht."""
        return not self._online

    @property
    def online_since(self) -> datetime | None:
        """Zeitpunkt seit dem online. None wenn offline."""
        return self._online_since

    @property
    def offline_since(self) -> datetime | None:
        """Zeitpunkt seit dem offline. None wenn online."""
        return self._offline_since

    @property
    def online_duration_seconds(self) -> float:
        """Wie lange online in Sekunden. 0 wenn offline."""
        if self._online and self._online_since:
            return (datetime.now() - self._online_since).total_seconds()
        return 0.0

    @property
    def offline_duration_seconds(self) -> float:
        """Wie lange offline in Sekunden. 0 wenn online."""
        if not self._online and self._offline_since:
            return (datetime.now() - self._offline_since).total_seconds()
        return 0.0

    @property
    def http(self) -> HttpClient:
        """HTTP/HTTPS-Client mit Offline-Cache."""
        return self._http

    def ftp(self, config: "FTPConfig") -> "FTPClient":
        """
        Erstellt einen FTP/SFTP-Client.

        Nutzung als Context-Manager:
            ```python
            async with online.ftp(FTPConfig(host="...")) as ftp:
                await ftp.download("/remote/file", "/local/file")
            ```
        """
        from trixy_core.online.ftp import FTPClient
        return FTPClient(config)

    @property
    def cache(self) -> ResponseCache:
        """Zugriff auf den Response-Cache."""
        return self._cache

    # === Service Lifecycle ===

    async def start(self) -> None:
        """Startet den Online-Service."""
        # Initialen Check durchfuehren
        online = await self._check_connectivity()
        self._set_status(online, emit_event=False)

        status = "online" if self._online else "offline"
        pinfo(f"Online-Service gestartet (Status: {status})")

        # Periodischen Check starten
        self._check_task = asyncio.create_task(self._check_loop())

    async def stop(self) -> None:
        """Stoppt den Online-Service."""
        if self._check_task:
            self._check_task.cancel()
            try:
                await self._check_task
            except asyncio.CancelledError:
                pass
            self._check_task = None

        await self._http.close()
        pinfo("Online-Service gestoppt")

    # === Konnektivitaets-Pruefung ===

    async def _check_loop(self) -> None:
        """Periodischer Konnektivitaets-Check."""
        try:
            while True:
                # Intervall: 5 Min online, 1 Min offline
                if self._online:
                    interval = self._config.check_interval_online
                else:
                    interval = self._config.check_interval_offline

                await asyncio.sleep(interval)

                online = await self._check_connectivity()
                self._set_status(online)

        except asyncio.CancelledError:
            pass

    async def _check_connectivity(self) -> bool:
        """
        Prueft die Internet-Verbindung.

        Versucht einen TCP-Connect zu bekannten DNS-Servern (Port 53).
        Schneller und zuverlaessiger als HTTP oder ICMP.
        """
        self._last_check = time.time()
        self._check_count += 1

        for host in self._check_hosts:
            try:
                # TCP-Connect zu DNS-Port (schnell, kein Payload)
                _, writer = await asyncio.wait_for(
                    asyncio.open_connection(host, 53),
                    timeout=self._config.check_timeout,
                )
                writer.close()
                await writer.wait_closed()
                return True
            except (OSError, asyncio.TimeoutError):
                continue

        return False

    def _set_status(self, online: bool, emit_event: bool = True) -> None:
        """
        Setzt den Online-Status und loest Events aus.

        Events:
        - online_status_changed: Immer bei Statuswechsel (online/offline)
        - connection_online: Wenn Verbindung wiederhergestellt (war offline)
        - connection_offline: Wenn Verbindung verloren (war online)
        """
        if online == self._online:
            return  # Keine Aenderung

        was_online = self._online
        self._online = online
        now = datetime.now()

        # Offline-Dauer berechnen (fuer Event-Daten)
        offline_duration = 0.0
        online_duration = 0.0

        if online:
            # Wechsel: offline → online
            if self._offline_since:
                offline_duration = (now - self._offline_since).total_seconds()
            self._online_since = now
            self._offline_since = None
            pinfo(f"Verbindung hergestellt — ONLINE (war {offline_duration:.0f}s offline)")
        else:
            # Wechsel: online → offline
            if self._online_since:
                online_duration = (now - self._online_since).total_seconds()
            self._online_since = None
            self._offline_since = now
            pinfo(f"Verbindung verloren — OFFLINE (war {online_duration:.0f}s online)")

        if not emit_event:
            return

        events = getattr(self._application, "events", None)
        if not events:
            return

        event_data = {
            "online": online,
            "since": now.isoformat(),
            "previous": "online" if was_online else "offline",
        }

        # 1. Allgemeines Status-Change Event (immer)
        asyncio.create_task(events.emit("online_status_changed", event_data))

        # 2. Spezifisches Event (zusaetzlich)
        if online:
            asyncio.create_task(events.emit("connection_online", {
                **event_data,
                "offline_duration_seconds": offline_duration,
            }))
        else:
            asyncio.create_task(events.emit("connection_offline", {
                **event_data,
                "online_duration_seconds": online_duration,
            }))

    # === Manuelle Pruefung ===

    async def check_now(self) -> bool:
        """Fuehrt sofort einen Konnektivitaets-Check durch."""
        online = await self._check_connectivity()
        self._set_status(online)
        return online

    def get_status(self) -> dict:
        """Gibt den aktuellen Status als Dictionary zurueck."""
        return {
            "online": self._online,
            "online_since": self._online_since.isoformat() if self._online_since else None,
            "offline_since": self._offline_since.isoformat() if self._offline_since else None,
            "online_duration_seconds": self.online_duration_seconds,
            "offline_duration_seconds": self.offline_duration_seconds,
            "last_check": self._last_check,
            "check_count": self._check_count,
            "cache_entries": self._cache.size,
        }