from __future__ import annotations

from PySide6.QtCore import QObject, Signal
from PySide6.QtMultimedia import (
    QCamera,
    QCameraDevice,
    QCameraFormat,
    QMediaCaptureSession,
    QMediaDevices,
    QVideoSink,
)
from PySide6.QtMultimediaWidgets import QVideoWidget


class CameraService(QObject):
    error_occurred = Signal(str)

    def __init__(self, parent: QObject | None = None) -> None:
        super().__init__(parent)
        self._session = QMediaCaptureSession()
        self._camera: QCamera | None = None

    @property
    def session(self) -> QMediaCaptureSession:
        return self._session

    def set_video_widget(self, widget: QVideoWidget) -> None:
        self._session.setVideoOutput(widget)

    def set_video_sink(self, sink: QVideoSink) -> None:
        self._session.setVideoSink(sink)

    @staticmethod
    def available_cameras() -> list[QCameraDevice]:
        return QMediaDevices.videoInputs()

    def is_active(self) -> bool:
        return self._camera is not None and self._camera.isActive()

    def start(self, device: QCameraDevice) -> None:
        self.stop()
        self._camera = QCamera(device, self)
        self._camera.errorOccurred.connect(self._on_error)
        self._session.setCamera(self._camera)
        self._camera.start()

    def stop(self) -> None:
        if self._camera is not None:
            self._camera.stop()
            self._session.setCamera(None)
            self._camera.deleteLater()
            self._camera = None

    def set_camera_format(self, fmt: QCameraFormat) -> None:
        if self._camera is not None:
            self._camera.setCameraFormat(fmt)

    def _on_error(self, error: QCamera.Error, error_string: str) -> None:
        self.error_occurred.emit(error_string)