from __future__ import annotations
import json
import pathlib
from dataclasses import dataclass, field

_SAVE_FILE = pathlib.Path(__file__).parent.parent / "saved_state.json"


@dataclass
class GameState:
    timer_state: dict = field(default_factory=lambda: {
        "running": False,
        "mode": "pomodoro",
        "duration_minutes": 25,
        "phase": "work",
    })
    todos: list[dict] = field(default_factory=list)
    xp: int = 0
    coins: int = 0
    _next_id: int = field(default=0, repr=False)

    XP_PER_TODO    = 10
    COINS_PER_TODO = 5
    XP_PER_LEVEL   = 100

    @property
    def level(self) -> int:
        return self.xp // self.XP_PER_LEVEL + 1

    @property
    def xp_in_level(self) -> int:
        return self.xp % self.XP_PER_LEVEL

    def add_xp(self, amount: int) -> int:
        self.xp += amount
        _save(self)
        return self.xp

    def add_coins(self, amount: int) -> int:
        self.coins += amount
        _save(self)
        return self.coins

    def add_todo(self, task: str) -> dict:
        self._next_id += 1
        todo = {"id": self._next_id, "task": task, "done": False}
        self.todos.append(todo)
        _save(self)
        return todo

    def complete_todo(self, todo_id: int) -> bool:
        """Toggle a todo's done state. Awards XP on the False→True transition."""
        for t in self.todos:
            if t["id"] == todo_id:
                was_done = t["done"]
                t["done"] = not t["done"]
                if t["done"] and not was_done:
                    self.xp   += self.XP_PER_TODO
                    self.coins += self.COINS_PER_TODO
                _save(self)
                return True
        return False

    def mark_done(self, todo_id: int) -> bool:
        """Force a todo to done (idempotent). Awards XP only on the first completion."""
        for t in self.todos:
            if t["id"] == todo_id:
                if not t["done"]:
                    t["done"]   = True
                    self.xp    += self.XP_PER_TODO
                    self.coins += self.COINS_PER_TODO
                    _save(self)
                return True
        return False

    def remove_todo(self, todo_id: int) -> bool:
        before = len(self.todos)
        self.todos = [t for t in self.todos if t["id"] != todo_id]
        if len(self.todos) < before:
            _save(self)
            return True
        return False


def _save(state: GameState) -> None:
    try:
        _SAVE_FILE.write_text(
            json.dumps(
                {"todos": state.todos, "next_id": state._next_id, "xp": state.xp, "coins": state.coins},
                indent=2,
            ),
            encoding="utf-8",
        )
    except OSError:
        pass


def _load() -> GameState:
    try:
        data = json.loads(_SAVE_FILE.read_text(encoding="utf-8"))
        s = GameState(todos=data.get("todos", []), xp=data.get("xp", 0), coins=data.get("coins", 0))
        s._next_id = data.get("next_id", 0)
        return s
    except (OSError, json.JSONDecodeError, KeyError):
        return GameState()


_state = _load()


def get_state() -> GameState:
    return _state