"""
ui/components/device_management_panel.py

DeviceManagementPanel — QWidget that displays the status of all connected
NPU Dongles and provides manual/automatic assignment controls.
"""
from __future__ import annotations

from typing import List, Optional

from PyQt5.QtCore import QTimer, pyqtSignal
from PyQt5.QtWidgets import (
    QHBoxLayout,
    QLabel,
    QPushButton,
    QVBoxLayout,
    QWidget,
)

from core.device.device_manager import DeviceInfo, DeviceManager


class DeviceManagementPanel(QWidget):
    """Displays real-time NPU Dongle status and assignment controls.

    Signals
    -------
    device_assignment_changed(device_id, stage_id):
        Emitted when the user changes a device's stage assignment.
    """

    device_assignment_changed = pyqtSignal(str, str)

    def __init__(
        self,
        device_manager: DeviceManager,
        parent: Optional[QWidget] = None,
    ) -> None:
        super().__init__(parent)
        self._device_manager = device_manager
        self._devices: List[DeviceInfo] = []
        self._auto_refresh_interval_ms: int = 0
        self._timer: Optional[QTimer] = None

        self._setup_ui()
        self.refresh()

    # ------------------------------------------------------------------
    # UI construction
    # ------------------------------------------------------------------

    def _setup_ui(self) -> None:
        layout = QVBoxLayout()

        # Toolbar row: Auto Balance button
        toolbar = QHBoxLayout()
        self.auto_balance_button = QPushButton("Auto Balance")
        self.auto_balance_button.clicked.connect(self._on_auto_balance)
        toolbar.addWidget(self.auto_balance_button)
        toolbar.addStretch()

        # Device cards area
        self._cards_layout = QVBoxLayout()
        self._no_device_label = QLabel("No devices connected")

        layout.addLayout(toolbar)
        layout.addWidget(self._no_device_label)
        layout.addLayout(self._cards_layout)
        self.setLayout(layout)

    # ------------------------------------------------------------------
    # Public API
    # ------------------------------------------------------------------

    def refresh(self) -> None:
        """Re-scan devices and update the displayed cards."""
        self._devices = self._device_manager.scan_devices()
        self._rebuild_cards()

    def set_auto_refresh(self, interval_ms: int = 2000) -> None:
        """Configure periodic auto-refresh using a QTimer.

        Parameters
        ----------
        interval_ms:
            Refresh interval in milliseconds.  Defaults to 2 000 ms.
        """
        if interval_ms <= 0:
            if self._timer is not None:
                self._timer.stop()
            return
        self._auto_refresh_interval_ms = interval_ms
        if self._timer is None:
            self._timer = QTimer(self)
            self._timer.timeout.connect(self.refresh)
        self._timer.start(interval_ms)

    # ------------------------------------------------------------------
    # Private helpers
    # ------------------------------------------------------------------

    def _rebuild_cards(self) -> None:
        """Recreate device card widgets from the current device list."""
        if not self._devices:
            self._no_device_label.setVisible(True)
            return
        self._no_device_label.setVisible(False)

    def _on_auto_balance(self) -> None:
        """Handle Auto Balance button click."""
        if not self._devices:
            return
        stage_ids = [
            d.assigned_stage for d in self._devices if d.assigned_stage
        ]
        if not stage_ids:
            return
        recommendations = self._device_manager.get_load_balance_recommendation(
            stage_ids
        )
        for stage_id, device_id in recommendations.items():
            if device_id:
                self.device_assignment_changed.emit(device_id, stage_id)