from __future__ import annotations

from pathlib import Path
from typing import Optional

from fastapi.responses import FileResponse, RedirectResponse

from .config import settings


class StorageService:
    """Store files locally for development or in Aliyun OSS in production."""

    def __init__(self) -> None:
        self.enabled = settings.oss_enabled
        self.bucket = None
        self.domain = settings.oss_domain.rstrip("/") if settings.oss_domain else ""
        self.prefix = settings.oss_base_prefix.strip("/")
        if not self.enabled:
            return
        if not all((settings.oss_endpoint, settings.oss_access_key_id,
                    settings.oss_access_key_secret, settings.oss_bucket_name)):
            raise RuntimeError(
                "OSS_ENABLED=true 时必须配置 OSS_ENDPOINT、OSS_ACCESS_KEY_ID、"
                "OSS_ACCESS_KEY_SECRET 和 OSS_BUCKET_NAME"
            )
        try:
            import oss2
        except ImportError as exc:  # pragma: no cover
            raise RuntimeError("OSS_ENABLED=true 时请先安装 oss2 依赖") from exc
        endpoint = settings.oss_endpoint.replace("http://", "https://")
        self.bucket = oss2.Bucket(
            oss2.Auth(settings.oss_access_key_id, settings.oss_access_key_secret),
            endpoint,
            settings.oss_bucket_name,
        )

    def make_key(self, relative_key: str) -> str:
        relative_key = relative_key.lstrip("/")
        return f"{self.prefix}/{relative_key}" if self.prefix else relative_key

    def finalize(self, local_path: Path, relative_key: str) -> str:
        if not self.enabled:
            return str(local_path)
        key = self.make_key(relative_key)
        try:
            self.bucket.put_object_from_file(key, str(local_path))
        finally:
            local_path.unlink(missing_ok=True)
        return f"oss://{key}"

    def remove(self, storage_path: str) -> None:
        if storage_path.startswith("oss://"):
            if self.enabled:
                self.bucket.delete_object(storage_path[6:])
            return
        Path(storage_path).unlink(missing_ok=True)

    def response(self, storage_path: str, mime_type: Optional[str], filename: Optional[str]):
        if storage_path.startswith("oss://"):
            if not self.enabled:
                raise FileNotFoundError(storage_path)
            url = self.bucket.sign_url("GET", storage_path[6:], 3600)
            return RedirectResponse(url)
        path = Path(storage_path)
        if not path.is_file():
            raise FileNotFoundError(storage_path)
        return FileResponse(path, media_type=mime_type, filename=filename)

    def access_url(self, storage_path: str, fallback_url: str) -> str:
        """Return a browser-ready URL without exposing private OSS credentials.

        Production files live in a private OSS bucket, so public profile media
        uses a one-hour signed URL. Local development keeps using the API route
        supplied by the caller.
        """
        if storage_path.startswith("oss://") and self.enabled:
            return self.bucket.sign_url("GET", storage_path[6:], 3600)
        return fallback_url


storage = StorageService()