# -*- coding: utf-8 -*-
"""
SyncHandler — Server-seitige Verarbeitung von Sync-Nachrichten.

Registriert sich als Message-Handler bei NetworkService.
Verarbeitet SyncPush und SyncRequest von Standalone-Clients.
"""

from __future__ import annotations

from typing import TYPE_CHECKING

from trixy_core.sync.models import SyncItem, _now_iso
from trixy_core.network.cmd.sync import SyncPush, SyncRequest, SyncResponse, SyncAck
from trixy_core.network.protocol import ProtocolMessage
from trixy_core.utils.debug import pinfo, pdebug, perror

if TYPE_CHECKING:
    from trixy_core.server import ServerApplication
    from trixy_core.satellite.satellite import Satellite


class SyncHandler:
    """
    Server-seitiger Handler fuer Sync-Nachrichten.

    Verarbeitet:
    - SyncPush: Items vom Standalone empfangen und lokal mergen
    - SyncRequest: Aenderungen seit Zeitpunkt X zuruecksenden
    """

    def __init__(self, application: ServerApplication) -> None:
        """
        Initialisiert den SyncHandler.

        Args:
            application: Die Server-Anwendung
        """
        self._app = application

    async def on_message(self, satellite: Satellite, message: ProtocolMessage) -> None:
        """
        Verarbeitet eine eingehende Sync-Nachricht.

        Wird als Message-Handler bei NetworkService registriert.

        Args:
            satellite: Der sendende Satellite
            message: Die empfangene Nachricht
        """
        class_name = message.class_name

        if class_name == "SyncPush":
            await self._handle_sync_push(satellite, message)
        elif class_name == "SyncRequest":
            await self._handle_sync_request(satellite, message)

    async def _handle_sync_push(self, satellite: Satellite, message: ProtocolMessage) -> None:
        """Verarbeitet empfangene SyncPush-Nachrichten."""
        store = self._app.sync_store
        if store is None:
            perror("SyncHandler: Kein SyncStore verfuegbar")
            return

        data = message.data
        items: list[dict] = []
        if isinstance(data, SyncPush):
            items = data.items
        elif isinstance(data, dict):
            items = data.get("items", [])
        else:
            perror(f"SyncHandler: Ungueltiges SyncPush-Format: {type(data)}")
            return

        merged_count = 0
        for item_dict in items:
            item = SyncItem.from_dict(item_dict)
            if store.merge_incoming(item):
                merged_count += 1

        # Bestaetigung senden
        ack = SyncAck(accepted_count=merged_count)
        try:
            await self._app.network.send_to_satellite(satellite.id, ack)
        except Exception as e:
            perror(f"SyncHandler: SyncAck senden fehlgeschlagen: {e}")

        if merged_count > 0:
            pdebug(f"SyncHandler: {merged_count} Items von {satellite.alias} gemerged")

            # Event emittieren (damit Server-Plugins reagieren koennen)
            await self._app.events.emit("sync_item_received", {
                "satellite_id": satellite.id,
                "merged_count": merged_count,
            })

    async def _handle_sync_request(self, satellite: Satellite, message: ProtocolMessage) -> None:
        """Verarbeitet SyncRequest-Nachrichten."""
        store = self._app.sync_store
        if store is None:
            perror("SyncHandler: Kein SyncStore verfuegbar")
            return

        data = message.data
        since = ""
        if isinstance(data, SyncRequest):
            since = data.since
        elif isinstance(data, dict):
            since = data.get("since", "")

        # Aenderungen seit 'since' sammeln
        if since:
            changes = store.get_changes_since(since)
        else:
            # Erster Sync: Alle Items senden
            changes = store.get_changes_since("")

        # Antwort senden
        server_time = _now_iso()
        response = SyncResponse(
            items=[item.to_dict() for item in changes],
            server_time=server_time,
        )

        try:
            await self._app.network.send_to_satellite(satellite.id, response)
        except Exception as e:
            perror(f"SyncHandler: SyncResponse senden fehlgeschlagen: {e}")

        pdebug(f"SyncHandler: {len(changes)} Items an {satellite.alias} gesendet (seit: {since or 'Anfang'})")