import httpx

from .config import settings


class WhatsAppGraphError(Exception):
    def __init__(self, detail: str, status_code: int = 502) -> None:
        super().__init__(detail)
        self.detail = detail
        self.status_code = status_code


class WhatsAppGraphClient:
    def __init__(
        self,
        *,
        access_token: str | None = None,
        phone_number_id: str | None = None,
        api_version: str | None = None,
    ) -> None:
        self.access_token = access_token or settings.whatsapp_access_token
        self.phone_number_id = phone_number_id or settings.whatsapp_phone_number_id
        self.api_version = api_version or settings.whatsapp_api_version

    @property
    def configured(self) -> bool:
        return bool(self.access_token and self.phone_number_id)

    def _messages_url(self) -> str:
        return (
            f"https://graph.facebook.com/{self.api_version}/"
            f"{self.phone_number_id}/messages"
        )

    async def send_text(self, to: str, body: str) -> dict:
        if not self.configured:
            raise WhatsAppGraphError("WhatsApp Graph API is not configured", status_code=503)

        payload = {
            "messaging_product": "whatsapp",
            "recipient_type": "individual",
            "to": to,
            "type": "text",
            "text": {"preview_url": False, "body": body},
        }
        headers = {"Authorization": f"Bearer {self.access_token}"}
        async with httpx.AsyncClient(timeout=30.0) as client:
            response = await client.post(self._messages_url(), json=payload, headers=headers)
        try:
            data = response.json()
        except ValueError:
            data = {"raw": response.text}
        if response.status_code >= 400:
            detail = data.get("error", {}).get("message") if isinstance(data, dict) else response.text
            raise WhatsAppGraphError(detail or "WhatsApp Graph API request failed", status_code=response.status_code)
        return data