import json
import uuid
from datetime import datetime
from pathlib import Path
from typing import Dict, List, Optional

from .config import DATA_DIR, CONVERSATIONS_DIR


def _path(cid: str) -> Path:
    return CONVERSATIONS_DIR / f"{cid}.json"


def make_conversation(title: str = "新对话") -> Dict:
    cid = str(uuid.uuid4())
    convo = {
        "id": cid,
        "title": (title or "新对话").strip()[:40],
        "messages": [],
        "updated_at": datetime.utcnow().isoformat(),
    }
    save(convo)
    return convo


def save(convo: Dict) -> None:
    _path(convo["id"]).write_text(json.dumps(convo, ensure_ascii=False), encoding="utf-8")


def load(cid: str) -> Optional[Dict]:
    path = _path(cid)
    legacy = DATA_DIR / f"{cid}.json"
    if not path.exists() and legacy.exists():
        path = legacy
    if not path.exists():
        return None
    try:
        return json.loads(path.read_text(encoding="utf-8"))
    except Exception:
        return None


def list_conversations() -> List[Dict]:
    items = []
    for root in (CONVERSATIONS_DIR, DATA_DIR):
        for path in root.glob("*.json"):
            try:
                convo = json.loads(path.read_text(encoding="utf-8"))
                if isinstance(convo, dict) and convo.get("id") and isinstance(convo.get("messages"), list):
                    items.append(convo)
            except Exception:
                continue
    return sorted(items, key=lambda x: x.get("updated_at", ""), reverse=True)