import json
import threading
import shutil
import os
from typing import Callable, Any

class DataManager:
    def __init__(self, json_path: str):
        self.json_path = json_path
        self.lock = threading.Lock()
        self._data = self._load()

    def _load(self):
        try:
            with open(self.json_path, 'r') as f:
                return json.load(f)
        except FileNotFoundError:
            default = {
                'agreed_rules': [],
                'agreed_engagement': [],
                'agreed_nickname': [],
                'nick_same_confirmed': [],
                'nick_nudged': [],
                'nick_dm_map': [],
                'pirates': [],
                'modlog': [],
                'reports': [],
                'encounters': [],
                'vc_channels': [],
                'user_cards': [],
                'pirates_list_posts': [],
                'spicepay_prefs': [],
            }
            self._save(default)
            return default

    def _safe_write(self, data: dict):
        tmp = self.json_path + ".tmp"
        with open(tmp, 'w') as f:
            json.dump(data, f, indent=4)
        # backup current file (best-effort)
        if os.path.exists(self.json_path):
            try:
                shutil.copy2(self.json_path, self.json_path + ".bak")
            except Exception:
                pass
        os.replace(tmp, self.json_path)

    def _save(self, data: dict):
        # single place to write (atomic replace + rolling .bak)
        self._safe_write(data)

    def get(self, category: str):
        with self.lock:
            return list(self._data.get(category, []))

    def add(self, category: str, item: Any):
        with self.lock:
            self._data.setdefault(category, []).append(item)
            self._save(self._data)

    def remove(self, category: str, predicate: Callable[[Any], bool]):
        with self.lock:
            arr = self._data.get(category, [])
            self._data[category] = [i for i in arr if not predicate(i)]
            self._save(self._data)

    def update(self, category: str, predicate: Callable[[Any], bool], updater: Callable[[dict], dict]) -> bool:
        """
        Atomically find one item in `category` matching predicate and update it with `updater`.
        Returns True if an item was updated, else False.
        """
        with self.lock:
            arr = self._data.get(category, [])
            for idx, item in enumerate(arr):
                if predicate(item):
                    # Copy → mutate → save back
                    new_item = dict(item)
                    new_item = updater(new_item) or new_item
                    arr[idx] = new_item
                    self._data[category] = arr
                    self._save(self._data)
                    return True
            return False