"""Dependency injection for FastAPI.

Provides access to service-specific Jellyfin/Jellyseerr clients and
remote-machine SSH clients via FastAPI's request context.

- Jellyfin/Jellyseerr are selected with a ``jellyfin_service_id`` query
  parameter (resolved against the service registry); the backend falls back to
  the first enabled ``jellyfin``/``jellyseerr`` service instance.
- SSH/Files transport is selected with an enabled ``remote_machine`` ``service_id``.
"""

from __future__ import annotations

import logging
from functools import lru_cache
from typing import Any

from fastapi import HTTPException, Request

from media_library_viewer_api.clients.jellyfin import JellyfinClient
from media_library_viewer_api.clients.ssh import RemoteSSHClient
from media_library_viewer_api.services.mail_queue import MailQueue
from media_library_viewer_api.services.mail_queue import get_mail_queue as _get_mail_queue
from media_library_viewer_api.services.settings_store import SettingsStore
from media_library_viewer_api.services.settings_store import get_settings_store as _get_settings_store

logger = logging.getLogger(__name__)


def _request_remote_machine_service_id(request: Request | None) -> str | None:
    if request is None:
        return None
    service_id = request.query_params.get("service_id")
    return service_id or None


def _request_jellyfin_service_id(request: Request | None) -> str | None:
    if request is None:
        return None
    service_id = request.query_params.get("jellyfin_service_id")
    return service_id or None


def _service_record(store: SettingsStore, service_type: str, service_id: str | None) -> dict[str, Any] | None:
    """Return a service row for a type, preferring the requested id.

    The row carries an in-memory decrypted ``secrets`` dict. Returns None if no
    enabled instance of the type exists.
    """
    from media_library_viewer_api.services.secrets import decrypt_secrets

    row = None
    if service_id:
        candidate = store.get_service(service_id)
        if candidate and candidate.get("service_type") == service_type and candidate.get("enabled", True):
            row = candidate
    if row is None:
        instances = [s for s in store.list_services(service_type) if s.get("enabled", True)]
        row = instances[0] if instances else None
    if row is None:
        return None
    decrypted = {}
    blob = row.get("secrets") or {}
    if blob:
        try:
            decrypted = decrypt_secrets(blob)
        except Exception:
            logger.exception("Failed to decrypt service secrets service_id=%s", row.get("id"))
    return {**row, "secrets": decrypted}


@lru_cache(maxsize=32)
def _jellyfin_client_for(cache_key: tuple[str, str, str]) -> JellyfinClient:
    machine_id, url, api_key = cache_key
    logger.info(
        "Creating Jellyfin client machine_id=%s url=%s", machine_id or "<default>", url.rstrip("/") or "<unset>"
    )
    return JellyfinClient(url, api_key)


def get_jellyfin_client(request: Request) -> JellyfinClient:
    """Return a Jellyfin client for the selected enabled service instance."""
    store = get_settings_store()
    service = _service_record(store, "jellyfin", _request_jellyfin_service_id(request))
    if service is None:
        raise HTTPException(
            status_code=503,
            detail="No Jellyfin service is configured. Add a Jellyfin service on the Services page.",
        )
    base_url = str(service.get("config", {}).get("base_url") or "")
    api_key = str(service.get("secrets", {}).get("api_key") or "")
    if not base_url or not api_key:
        raise HTTPException(
            status_code=503,
            detail="Jellyfin service is missing base_url or api_key. Edit it on the Services page.",
        )
    return _jellyfin_client_for((service["id"], base_url, api_key))


def get_ssh_client(request: Request) -> RemoteSSHClient:
    """Return SSH transport for the requested enabled remote-machine service."""
    from media_library_viewer_api.services.task_runner import build_ssh_client
    from media_library_viewer_api.widgets.sources import build_service_record

    store = get_settings_store()
    service_id = _request_remote_machine_service_id(request)
    if not service_id:
        raise HTTPException(status_code=400, detail="service_id is required for remote file and job operations")
    row = store.get_service(service_id)
    if not row or row.get("service_type") != "remote_machine" or not row.get("enabled", True):
        raise HTTPException(status_code=404, detail="Enabled remote machine service not found")
    try:
        return build_ssh_client(store, build_service_record(store, row))
    except ValueError as exc:
        raise HTTPException(status_code=400, detail=str(exc)) from exc


def get_mail_queue() -> MailQueue:
    """Return the singleton background email queue."""
    return _get_mail_queue()


def get_settings_store() -> SettingsStore:
    """Return the singleton persistent settings store."""
    return _get_settings_store()


def get_user_id(request: Request) -> str:
    """Return the Jellyfin user Id, resolving a configured username if needed.

    The service ``user_id`` config field accepts either the internal Jellyfin Id
    or a username (e.g. ``'admin'``). Jellyfin's ``/Users/{id}/...`` endpoints
    reject usernames with HTTP 400 (``"The value 'admin' is not valid."``), so
    always resolve to the internal Id before use. Resolution is cached per
    (service, base_url, api_key, configured) so repeated dashboard/media requests
    don't re-list users on every call.
    """
    store = get_settings_store()
    service_id = _request_jellyfin_service_id(request)
    service = _service_record(store, "jellyfin", service_id)
    if service is None:
        raise HTTPException(
            status_code=503,
            detail="No Jellyfin service is configured. Add a Jellyfin service on the Services page.",
        )
    configured = str(service.get("config", {}).get("user_id") or "").strip()
    base_url = str(service.get("config", {}).get("base_url") or "")
    api_key = str(service.get("secrets", {}).get("api_key") or "")
    if not base_url or not api_key:
        raise HTTPException(
            status_code=503,
            detail="Jellyfin service is missing base_url or api_key. Edit it on the Services page.",
        )
    return _resolved_user_id((service["id"], base_url, api_key, configured))


@lru_cache(maxsize=64)
def _resolved_user_id(cache_key: tuple[str, str, str, str]) -> str:
    """Resolve a configured Jellyfin identifier (Id or username) to the internal Id.

    Keyed by (service_id, base_url, api_key, configured) so a credentials change
    or a different configured user busts the cache automatically.
    """
    service_id, base_url, api_key, configured = cache_key
    client = _jellyfin_client_for((service_id, base_url, api_key))
    return client.resolve_user_id(configured or None)