"""Factory for user-scoped cloud storage backends."""
from __future__ import annotations

from storage.cloud_base import CloudResourceAdapter, MutableCloudResourceAdapter


def build_cloud_backend(provider: str, credentials: dict):
    if provider == "google_drive":
        from storage.google_drive_backend import GoogleDriveBackend  # lazy import

        return GoogleDriveBackend(credentials)

    if provider == "onedrive":
        from storage.onedrive_backend import OneDriveBackend  # lazy import

        return OneDriveBackend(credentials)

    if provider == "nextcloud":
        from storage.nextcloud_backend import NextcloudBackend  # lazy import
        from storage.cloud_utils import normalize_nextcloud_url  # lazy import

        server_url = credentials["server_url"]
        username = credentials["username"]
        # Normalize to canonical WebDAV root idempotently; validate SSRF before construction
        try:
            server_url = normalize_nextcloud_url(server_url, username)
        except ValueError:
            # URL may already be canonical or validation rejected it — let the
            # constructor's validate_cloud_url call surface the error
            pass

        return NextcloudBackend(
            server_url,
            username,
            credentials["password"],
        )

    if provider == "webdav":
        from storage.webdav_backend import WebDAVBackend  # lazy import

        return WebDAVBackend(
            credentials["server_url"],
            credentials["username"],
            credentials["password"],
        )

    raise ValueError(f"Unknown provider: {provider}")


def build_cloud_resource_adapter(provider: str, credentials: dict) -> CloudResourceAdapter:
    """Build a CloudResourceAdapter for the given provider and credentials.

    Returns a provider instance that implements the CloudResourceAdapter read-only
    interface (list_folder, get_capabilities, merge_item_capabilities). All four
    supported providers implement CloudResourceAdapter as a mixin alongside
    their StorageBackend interface.

    Raises:
        ValueError: If provider is not one of the four supported cloud providers.
    """
    backend = build_cloud_backend(provider, credentials)
    if not isinstance(backend, CloudResourceAdapter):
        raise ValueError(
            f"Provider {provider!r} backend does not implement CloudResourceAdapter"
        )
    return backend


def build_mutable_cloud_adapter(provider: str, credentials: dict) -> MutableCloudResourceAdapter:
    """Build a MutableCloudResourceAdapter for the given provider and credentials.

    Returns a provider instance that implements the Phase 13 mutable-operation
    contract (create_folder, rename, move, delete, upload_file) in addition to
    the read-only CloudResourceAdapter interface.

    Raises:
        ValueError: If provider is not one of the four supported cloud providers,
            or if the provider backend does not implement MutableCloudResourceAdapter.
    """
    backend = build_cloud_backend(provider, credentials)
    if not isinstance(backend, MutableCloudResourceAdapter):
        raise ValueError(
            f"Provider {provider!r} backend does not implement MutableCloudResourceAdapter. "
            "All Phase 13 providers must subclass MutableCloudResourceAdapter."
        )
    return backend