"""
Conversation-State — ein einziger Rolling-Window-State fuer ARIAs
laufendes Gespraech mit Stefan.

Stefan-Entscheidung: KEINE Sessions, KEIN Multi-Thread. EIN Strang,
intern rollend. Was rausfaellt, wird ggf. destilliert und landet
als type=fact Memory in der Vector-DB.

Persistenz: append-only JSONL unter /data/conversation.jsonl.
Bei Restart wird die letzte N gelesen (komplett vermeidet Memory-
Overhead bei sehr langen Verlaeufen).
"""

from __future__ import annotations

import json
import logging
import os
from dataclasses import dataclass, field, asdict
from datetime import datetime, timezone
from pathlib import Path
from typing import List, Optional

logger = logging.getLogger(__name__)

CONVERSATION_FILE = Path(os.environ.get("CONVERSATION_FILE", "/data/conversation.jsonl"))


@dataclass
class Turn:
    role: str         # "user" | "assistant"
    content: str
    ts: str = field(default_factory=lambda: datetime.now(timezone.utc).isoformat())
    source: str = ""  # "app" / "diagnostic" / "stt" — optional


class Conversation:
    """In-Memory Rolling Window, mit JSONL-Persistenz."""

    def __init__(self, max_window: int = 50, distill_threshold: int = 60,
                 distill_count: int = 30):
        self.max_window = max_window
        self.distill_threshold = distill_threshold
        self.distill_count = distill_count
        self.turns: List[Turn] = []
        self._load()

    def _load(self):
        if not CONVERSATION_FILE.exists():
            return
        try:
            lines = CONVERSATION_FILE.read_text(encoding="utf-8").splitlines()
        except Exception as exc:
            logger.warning("Konversation laden fehlgeschlagen: %s", exc)
            return
        loaded: List[Turn] = []
        for line in lines:
            line = line.strip()
            if not line:
                continue
            try:
                obj = json.loads(line)
            except Exception:
                continue
            if obj.get("op") == "distill":
                # Marker: bis hierhin wurde alles destilliert
                drop_until_ts = obj.get("ts", "")
                if drop_until_ts:
                    loaded = [t for t in loaded if t.ts > drop_until_ts]
                continue
            role = obj.get("role")
            content = obj.get("content")
            if role in ("user", "assistant") and isinstance(content, str):
                loaded.append(Turn(role=role, content=content,
                                   ts=obj.get("ts", ""),
                                   source=obj.get("source", "")))
        self.turns = loaded
        logger.info("Konversation geladen: %d Turns aus %s", len(self.turns), CONVERSATION_FILE)

    def _append_to_file(self, record: dict):
        try:
            CONVERSATION_FILE.parent.mkdir(parents=True, exist_ok=True)
            with CONVERSATION_FILE.open("a", encoding="utf-8") as f:
                f.write(json.dumps(record, ensure_ascii=False) + "\n")
        except Exception as exc:
            logger.warning("Konversation persist fehlgeschlagen: %s", exc)

    def add(self, role: str, content: str, source: str = "") -> Turn:
        t = Turn(role=role, content=content, source=source)
        self.turns.append(t)
        self._append_to_file({
            "ts": t.ts, "role": t.role, "content": t.content, "source": t.source,
        })
        return t

    def window(self) -> List[Turn]:
        """Die letzten max_window Turns — gehen in den LLM-Prompt."""
        return self.turns[-self.max_window:]

    def needs_distill(self) -> bool:
        return len(self.turns) > self.distill_threshold

    def take_oldest_for_distill(self) -> List[Turn]:
        """Gibt die N aeltesten Turns zurueck — fuer den Destillat-Call.
        Entfernt sie NICHT — das macht commit_distill nach erfolgreichem Call."""
        return self.turns[: self.distill_count]

    def commit_distill(self, last_distilled_ts: str):
        """Schreibt einen Distill-Marker, entfernt aus dem In-Memory-Window."""
        self._append_to_file({"op": "distill", "ts": last_distilled_ts})
        self.turns = [t for t in self.turns if t.ts > last_distilled_ts]
        logger.info("Distill commit bei ts=%s — Window jetzt %d Turns", last_distilled_ts, len(self.turns))

    def reset(self):
        """Hardes Reset — verwende vorsichtig (Diagnostic-Button)."""
        try:
            if CONVERSATION_FILE.exists():
                CONVERSATION_FILE.unlink()
        except Exception:
            pass
        self.turns = []
        logger.warning("Konversation komplett zurueckgesetzt")

    def stats(self) -> dict:
        return {
            "turns": len(self.turns),
            "max_window": self.max_window,
            "distill_threshold": self.distill_threshold,
            "needs_distill": self.needs_distill(),
        }