import json
from pathlib import Path
from core.user import User
from core.item import Item
from core.transaction import Transaction


class DataManager:
    def __init__(self, data_dir) -> None:
        self.data_dir = Path(data_dir)
        self.data_dir.mkdir(exist_ok=True)

        self.users_file = self.data_dir / "users.json"
        self.items_file = self.data_dir / "items.json"
        self.debts_file = self.data_dir / "debts.json"
        self.transactions_file = self.data_dir / "transactions.json"

        self._init_files()

    def _init_files(self):
        if not self.users_file.exists():
            self._save_json(self.users_file, {})
        if not self.items_file.exists():
            self._save_json(self.items_file, {})
        if not self.debts_file.exists():
            self._save_json(self.debts_file, {})
        if not self.transactions_file.exists():
            self._save_json(self.transactions_file, [])

    def load_users(self):
        data = self._load_json(self.users_file)
        return {
            user_id: User.from_json(user_data) for user_id, user_data in data.items()
        }

    def load_items(self):
        data = self._load_json(self.items_file)
        return {
            item_id: Item.from_json(item_data) for item_id, item_data in data.items()
        }

    def load_debts(self):
        return self._load_json(self.debts_file)

    def load_transactions(self):
        data = self._load_json(self.transactions_file)
        return [Transaction.from_json(t) for t in data]

    def save_users(self, users):
        data = {user_id: user.to_json() for user_id, user in users.items()}
        self._save_json(self.users_file, data)

    def save_items(self, items):
        data = {item_id: item.to_json() for item_id, item in items.items()}
        self._save_json(self.items_file, data)

    def save_debts(self, debts):
        self._save_json(self.debts_file, debts)

    def save_transactions(self, transactions):
        data = [t.to_json() for t in transactions]
        self._save_json(self.transactions_file, data)

    def _load_json(self, filepath):
        try:
            with open(filepath, "r") as f:
                return json.load(f)

        except (FileNotFoundError, json.JSONDecodeError):
            return (
                {}
                if filepath.name.endswith(".json")
                and "transaction" not in filepath.name
                else []
            )

    def _save_json(self, filepath, data):
        with open(filepath, "w") as f:
            json.dump(data, f, indent=2)