import json
from pathlib import Path
from filelock import FileLock


class ContactStore:
    """联系人关系和 chat_id 存储。

    存储格式 (data/contacts.json):
    {
        "alice": {
            "contacts": ["bob", "charlie"],
            "chats": {
                "bob": ["chat_001", "chat_002"],
                "charlie": ["chat_003"]
            }
        }
    }
    """

    def __init__(self, data_dir: str = "data"):
        self.data_dir = Path(data_dir)
        self.data_dir.mkdir(parents=True, exist_ok=True)
        self.contacts_path = self.data_dir / "contacts.json"
        self._lock = FileLock(str(self.data_dir / ".contacts.lock"))

        if not self.contacts_path.exists():
            self.contacts_path.write_text("{}")

    def add_contact(self, user_id: str, contact_id: str):
        """添加联系人（单向）。"""
        with self._lock:
            data = self._load()
            if user_id not in data:
                data[user_id] = {"contacts": [], "chats": {}}
            if contact_id not in data[user_id]["contacts"]:
                data[user_id]["contacts"].append(contact_id)
            if contact_id not in data[user_id]["chats"]:
                data[user_id]["chats"][contact_id] = []
            self._save(data)

    def add_chat(self, user_id: str, contact_id: str, chat_id: str):
        """为某个联系人添加新的 chat_id。"""
        with self._lock:
            data = self._load()
            if user_id not in data:
                data[user_id] = {"contacts": [], "chats": {}}
            if contact_id not in data[user_id]["chats"]:
                data[user_id]["chats"][contact_id] = []
            if chat_id not in data[user_id]["chats"][contact_id]:
                data[user_id]["chats"][contact_id].append(chat_id)
            self._save(data)

    def get_contacts(self, user_id: str) -> list[str]:
        """获取某用户的联系人列表。"""
        with self._lock:
            data = self._load()
            if user_id not in data:
                return []
            return data[user_id].get("contacts", [])

    def get_chats(self, user_id: str, contact_id: str) -> list[str]:
        """获取与某联系人的所有 chat_id。"""
        with self._lock:
            data = self._load()
            if user_id not in data:
                return []
            return data[user_id].get("chats", {}).get(contact_id, [])

    def _load(self) -> dict:
        text = self.contacts_path.read_text(encoding="utf-8")
        return json.loads(text) if text.strip() else {}

    def _save(self, data: dict):
        self.contacts_path.write_text(json.dumps(data, ensure_ascii=False, indent=2), encoding="utf-8")