"""Common utilities for device traits.

This module provides shared infrastructure for mapping Roborock Data Points (DPS) to
Python dataclass fields and handling the lifecycle of data updates from the device.

### DPS Metadata Annotation

Classes extending `RoborockBase` can annotate their fields with DPS IDs using
the `field(metadata={"dps": ...})` convention. This creates a declarative
mapping that `DpsDataConverter` uses to automatically route incoming device
data to the correct attribute.

Example:

```python
@dataclass
class MyStatus(RoborockBase):
    battery: int = field(metadata={"dps": B01_Q10_DP.BATTERY})
```

### Update Lifecycle
1. **Raw Data**: The device sends encoded DPS updates over MQTT.
2. **Decoding**: The transport layer decodes these into a dictionary (e.g., {"101": 80}).
3. **Conversion**: `DpsDataConverter` uses `RoborockBase.convert_dict` to transform
   raw values into appropriate Python types (e.g., Enums, ints) based on the
   dataclass field types.
4. **Update**: `update_from_dps` maps these converted values to field names and
   updates the target object using `setattr`.

### Usage

Typically, a trait will instantiate a single `DpsDataConverter` for its status class
and call `update_from_dps` whenever new data is received from the device stream.
"""

import dataclasses
import logging
from collections.abc import Callable
from typing import Any, Generic, TypeVar

from roborock.callbacks import CallbackList
from roborock.data.containers import RoborockBase

TDps = TypeVar("TDps", bound=int)


class TraitUpdateListener:
    """Trait update listener.

    This is a base class for traits to support notifying listeners when they
    have been updated. Clients may register callbacks to be notified when the
    trait has been updated. When the listener callback is invoked, the client
    should read the trait's properties to get the updated values.
    """

    def __init__(self, logger: logging.Logger) -> None:
        """Initialize the trait update listener."""
        self._update_callbacks: CallbackList[None] = CallbackList(logger=logger)

    def add_update_listener(self, callback: Callable[[], None]) -> Callable[[], None]:
        """Register a callback when the trait has been updated.

        Returns a callable to remove the listener.
        """
        # We wrap the callback to ignore the value passed to it.
        return self._update_callbacks.add_callback(lambda _: callback())

    def _notify_update(self) -> None:
        """Notify all update listeners."""
        self._update_callbacks(None)


class DpsDataConverter(Generic[TDps]):
    """Utility to handle the transformation and merging of DPS data into models.

    This class pre-calculates the mapping between Data Point IDs and dataclass fields
    to optimize repeated updates from device streams.
    """

    def __init__(self, dps_type_map: dict[TDps, type], dps_field_map: dict[TDps, str]):
        """Initialize the converter for a specific RoborockBase-derived class."""
        self._dps_type_map = dps_type_map
        self._dps_field_map = dps_field_map

    @classmethod
    def from_dataclass(cls, dataclass_type: type[RoborockBase]):
        """Initialize the converter for a specific RoborockBase-derived class."""
        dps_type_map: dict[TDps, type] = {}
        dps_field_map: dict[TDps, str] = {}
        for field_obj in dataclasses.fields(dataclass_type):
            if field_obj.metadata and "dps" in field_obj.metadata:
                dps_id = field_obj.metadata["dps"]
                dps_type_map[dps_id] = field_obj.type
                dps_field_map[dps_id] = field_obj.name
        return cls(dps_type_map, dps_field_map)

    def update_from_dps(self, target: RoborockBase, decoded_dps: dict[TDps, Any]) -> bool:
        """Convert and merge raw DPS data into the target object.

        Uses the pre-calculated type mapping to ensure values are converted to the
        correct Python types before being updated on the target.

        Args:
            target: The target object to update.
            decoded_dps: The decoded DPS data to convert.

        Returns:
            True if any values were updated, False otherwise.
        """
        conversions = RoborockBase.convert_dict(self._dps_type_map, decoded_dps)
        for dps_id, value in conversions.items():
            field_name = self._dps_field_map[dps_id]
            setattr(target, field_name, value)
        return bool(conversions)
