"""Serve firmware images to lamps under one-time URLs."""

from __future__ import annotations

from collections.abc import Mapping
from pathlib import Path
import secrets
from typing import Any

from aiohttp import web
from homeassistant.components.http import HomeAssistantView
from homeassistant.core import HomeAssistant
from homeassistant.exceptions import HomeAssistantError
from homeassistant.helpers.network import NoURLAvailableError, get_url

from .const import CONF_LAMP_BASE_URL, DOMAIN, FIRMWARE_URL_PREFIX


class OtaRegistry:
    """Random keys, each bound to exactly one file, valid only while its update runs."""

    def __init__(self) -> None:
        self._paths: dict[str, Path] = {}

    def create(self, path: Path) -> str:
        key = secrets.token_urlsafe(32)
        self._paths[key] = path
        return key

    def revoke(self, key: str) -> None:
        self._paths.pop(key, None)

    def get(self, key: str) -> Path | None:
        return self._paths.get(key)

    def __len__(self) -> int:
        return len(self._paths)


class NinlightFirmwareView(HomeAssistantView):
    """No HA login: the lamp cannot authenticate. The unguessable key is the protection."""

    url = FIRMWARE_URL_PREFIX + "{key}"
    name = "api:ninlight:firmware"
    requires_auth = False

    def __init__(self, hass: HomeAssistant, registry: OtaRegistry) -> None:
        self._hass = hass
        self._registry = registry

    async def get(self, request: web.Request, key: str) -> web.Response:
        path = self._registry.get(key)
        if path is None:
            return web.Response(status=404)
        try:
            body = await self._hass.async_add_executor_job(path.read_bytes)
        except OSError:
            return web.Response(status=404)
        return web.Response(body=body, content_type="application/octet-stream")


def lamp_base_url(hass: HomeAssistant, options: Mapping[str, Any]) -> str:
    """The http:// address lamps use to reach Home Assistant."""
    base = options.get(CONF_LAMP_BASE_URL)
    if not base:
        try:
            base = get_url(hass, allow_external=False, allow_cloud=False, prefer_external=False)
        except NoURLAvailableError as err:
            raise HomeAssistantError(
                translation_domain=DOMAIN, translation_key="no_http_url"
            ) from err
    if not str(base).startswith("http://"):
        raise HomeAssistantError(translation_domain=DOMAIN, translation_key="no_http_url")
    return str(base)