"""Nest Media Source implementation.

The Nest MediaSource implementation provides a directory tree of devices and
events and associated media (e.g. an image or clip). Camera device events
publish an event message, received by the subscriber library. Media for an
event, such as camera image or clip, may be fetched from the cloud during a
short time window after the event happens.

The actual management of associating events to devices, fetching media for
events, caching, and the overall lifetime of recent events are managed outside
of the Nest MediaSource.

Users may also record clips to local storage, unrelated to this MediaSource.

For additional background on Nest Camera events see:
https://developers.google.com/nest/device-access/api/camera#handle_camera_events
"""

from __future__ import annotations

from collections.abc import Mapping
from dataclasses import dataclass
import logging
import os

from google_nest_sdm.camera_traits import CameraClipPreviewTrait, CameraEventImageTrait
from google_nest_sdm.device import Device
from google_nest_sdm.event import EventImageType, ImageEventBase
from google_nest_sdm.event_media import EventMediaStore
from google_nest_sdm.google_nest_subscriber import GoogleNestSubscriber

from homeassistant.components.media_player.const import (
    MEDIA_CLASS_DIRECTORY,
    MEDIA_CLASS_IMAGE,
    MEDIA_CLASS_VIDEO,
    MEDIA_TYPE_IMAGE,
    MEDIA_TYPE_VIDEO,
)
from homeassistant.components.media_player.errors import BrowseError
from homeassistant.components.media_source.error import Unresolvable
from homeassistant.components.media_source.models import (
    BrowseMediaSource,
    MediaSource,
    MediaSourceItem,
    PlayMedia,
)
from homeassistant.core import HomeAssistant
from homeassistant.helpers import device_registry as dr
from homeassistant.helpers.storage import Store
from homeassistant.helpers.template import DATE_STR_FORMAT
from homeassistant.util import dt as dt_util, raise_if_invalid_filename

from .const import DATA_SUBSCRIBER, DOMAIN
from .device_info import NestDeviceInfo
from .events import EVENT_NAME_MAP, MEDIA_SOURCE_EVENT_TITLE_MAP

_LOGGER = logging.getLogger(__name__)

MEDIA_SOURCE_TITLE = "Nest"
DEVICE_TITLE_FORMAT = "{device_name}: Recent Events"
CLIP_TITLE_FORMAT = "{event_name} @ {event_time}"
EVENT_MEDIA_API_URL_FORMAT = "/api/nest/event_media/{device_id}/{event_id}"

STORAGE_KEY = "nest.event_media"
STORAGE_VERSION = 1
# Buffer writes every few minutes (plus guaranteed to be written at shutdown)
STORAGE_SAVE_DELAY_SECONDS = 120
# Path under config directory
MEDIA_PATH = f"{DOMAIN}/event_media"

# Size of small in-memory disk cache to avoid excessive disk reads
DISK_READ_LRU_MAX_SIZE = 32


async def async_get_media_event_store(
    hass: HomeAssistant, subscriber: GoogleNestSubscriber
) -> EventMediaStore:
    """Create the disk backed EventMediaStore."""
    media_path = hass.config.path(MEDIA_PATH)

    def mkdir() -> None:
        os.makedirs(media_path, exist_ok=True)

    await hass.async_add_executor_job(mkdir)
    store = Store(hass, STORAGE_VERSION, STORAGE_KEY, private=True)
    return NestEventMediaStore(hass, subscriber, store, media_path)


class NestEventMediaStore(EventMediaStore):
    """Storage hook to locally persist nest media for events.

    This interface is meant to provide two storage features:
    - media storage of events (jpgs, mp4s)
    - metadata about events (e.g. motion, person), filename of the media, etc.

    The default implementation in nest is in memory, and this allows the data
    to be backed by disk.

    The nest event media manager internal to the subscriber manages the lifetime
    of individual objects stored here (e.g. purging when going over storage
    limits). This store manages the addition/deletion once instructed.
    """

    def __init__(
        self,
        hass: HomeAssistant,
        subscriber: GoogleNestSubscriber,
        store: Store,
        media_path: str,
    ) -> None:
        """Initialize NestEventMediaStore."""
        self._hass = hass
        self._subscriber = subscriber
        self._store = store
        self._media_path = media_path
        self._data: dict | None = None
        self._devices: Mapping[str, str] | None = {}

    async def async_load(self) -> dict | None:
        """Load data."""
        if self._data is None:
            self._devices = await self._get_devices()
            data = await self._store.async_load()
            if data is None:
                _LOGGER.debug("Loaded empty event store")
                self._data = {}
            elif isinstance(data, dict):
                _LOGGER.debug("Loaded event store with %d records", len(data))
                self._data = data
            else:
                raise ValueError(
                    "Unexpected data in storage version={}, key={}".format(
                        STORAGE_VERSION, STORAGE_KEY
                    )
                )
        return self._data

    async def async_save(self, data: dict) -> None:
        """Save data."""
        self._data = data

        def provide_data() -> dict:
            return data

        self._store.async_delay_save(provide_data, STORAGE_SAVE_DELAY_SECONDS)

    def get_media_key(self, device_id: str, event: ImageEventBase) -> str:
        """Return the filename to use for a new event."""
        # Convert a nest device id to a home assistant device id
        device_id_str = (
            self._devices.get(device_id, f"{device_id}-unknown_device")
            if self._devices
            else "unknown_device"
        )
        event_id_str = event.event_session_id
        try:
            raise_if_invalid_filename(event_id_str)
        except ValueError:
            event_id_str = ""
        time_str = str(int(event.timestamp.timestamp()))
        event_type_str = EVENT_NAME_MAP.get(event.event_type, "event")
        suffix = "jpg" if event.event_image_type == EventImageType.IMAGE else "mp4"
        return f"{device_id_str}/{time_str}-{event_id_str}-{event_type_str}.{suffix}"

    def get_media_filename(self, media_key: str) -> str:
        """Return the filename in storage for a media key."""
        return f"{self._media_path}/{media_key}"

    async def async_load_media(self, media_key: str) -> bytes | None:
        """Load media content."""
        filename = self.get_media_filename(media_key)

        def load_media(filename: str) -> bytes | None:
            if not os.path.exists(filename):
                return None
            _LOGGER.debug("Reading event media from disk store: %s", filename)
            with open(filename, "rb") as media:
                return media.read()

        try:
            return await self._hass.async_add_executor_job(load_media, filename)
        except OSError as err:
            _LOGGER.error("Unable to read media file: %s %s", filename, err)
            return None

    async def async_save_media(self, media_key: str, content: bytes) -> None:
        """Write media content."""
        filename = self.get_media_filename(media_key)

        def save_media(filename: str, content: bytes) -> None:
            os.makedirs(os.path.dirname(filename), exist_ok=True)
            if os.path.exists(filename):
                _LOGGER.debug(
                    "Event media already exists, not overwriting: %s", filename
                )
                return
            _LOGGER.debug("Saving event media to disk store: %s", filename)
            with open(filename, "wb") as media:
                media.write(content)

        try:
            await self._hass.async_add_executor_job(save_media, filename, content)