"""Client helpers for posting to Mastodon."""

from __future__ import annotations

from typing import List, Sequence

import requests


class MastodonError(RuntimeError):
    """Raised when the Mastodon API indicates a failure."""


class MastodonClient:
    """Minimal Mastodon API wrapper for uploading media and posting statuses."""

    def __init__(self, base_url: str, access_token: str) -> None:
        if not base_url:
            raise ValueError("base_url is required")
        if not access_token:
            raise ValueError("access_token is required")

        self.base_url = base_url.rstrip("/")
        self.session = requests.Session()
        self.session.headers.update(
            {
                "Authorization": f"Bearer {access_token}",
                "Accept": "application/json",
                "User-Agent": "ImmichAltTextHelper/0.1 (+https://photos.4angle.com)",
            }
        )

    def _raise_for_error(self, response: requests.Response) -> None:
        try:
            payload = response.json()
        except Exception:  # pragma: no cover - fallback path
            payload = response.text
        message = f"{response.status_code} {response.reason}: {payload}"
        raise MastodonError(message)

    def upload_media(
        self, filename: str, data: bytes, mime_type: str, alt_text: str
    ) -> str:
        url = f"{self.base_url}/api/v2/media"
        files = {
            "file": (
                filename or "photo.jpg",
                data,
                mime_type or "application/octet-stream",
            )
        }
        form = {}
        if alt_text:
            form["description"] = alt_text
        try:
            response = self.session.post(url, files=files, data=form, timeout=30)
        except requests.RequestException as exc:  # pragma: no cover - network failure
            raise MastodonError(str(exc)) from exc
        if not response.ok:
            self._raise_for_error(response)
        payload = response.json()

        media_id = payload.get("id")
        if not media_id:
            raise MastodonError("Mastodon response missing media id")
        return media_id

    def create_status(self, text: str, media_ids: Sequence[str]) -> str:
        if not text.strip():
            raise MastodonError("Post text cannot be empty")
        url = f"{self.base_url}/api/v1/statuses"
        payload = {
            "status": text,
            "language": "en",
            "media_ids": list(media_ids),
        }
        try:
            response = self.session.post(url, json=payload, timeout=30)
        except requests.RequestException as exc:  # pragma: no cover
            raise MastodonError(str(exc)) from exc
        if not response.ok:
            self._raise_for_error(response)
        data = response.json()

        status_id = data.get("id")
        if not status_id:
            raise MastodonError("Mastodon response missing status id")
        return status_id