import base64
import logging

import requests

from infrasynth.shared.enums import ChannelType
from infrasynth.shared.results import Result
from infrasynth.shared.settings_utils import get_setting

from .base import BaseChannel

logger = logging.getLogger(__name__)


class SendGridChannel(BaseChannel):
    """Email channel that sends via the SendGrid v3 Mail Send API.

    Configuration keys (read from ``ChannelConfig.config``):
    - ``api_key`` (required)
    - ``from_email`` (falls back to DEFAULT_FROM_EMAIL)
    - ``timeout``
    """

    channel_type = ChannelType.EMAIL
    API_URL = "https://api.sendgrid.com/v3/mail/send"

    def __init__(self, api_key=None, from_email=None, timeout=30):
        self.api_key = api_key
        self.from_email = from_email or get_setting(
            "INFRASYNTH_NOTIFICATIONS", "DEFAULT_FROM_EMAIL", "noreply@example.com"
        )
        self.timeout = timeout

    @classmethod
    def from_config(cls, config: dict) -> "SendGridChannel":
        config = {str(key).lower(): value for key, value in (config or {}).items()}
        return cls(**config)

    def send(
        self,
        recipient: str,
        subject: str,
        body: str,
        is_html: bool = True,
        attachments=None,
    ) -> Result[bool, str]:
        if not self.api_key:
            return Result.err("SendGrid API key not configured")

        payload = {
            "personalizations": [{"to": [{"email": recipient}]}],
            "from": {"email": self.from_email},
            "subject": subject,
            "content": [
                {
                    "type": "text/html" if is_html else "text/plain",
                    "value": body,
                }
            ],
        }
        if attachments:
            payload["attachments"] = [
                {
                    "filename": attachment.filename,
                    "content": base64.b64encode(attachment.content).decode(),
                    "type": attachment.mime_type,
                }
                for attachment in attachments
            ]

        try:
            response = requests.post(
                self.API_URL,
                headers={
                    "Authorization": f"Bearer {self.api_key}",
                    "Content-Type": "application/json",
                },
                json=payload,
                timeout=self.timeout,
            )
        except requests.RequestException as exc:
            logger.exception("SendGrid request failed for %s", recipient)
            return Result.err(str(exc))

        if response.status_code >= 400:
            return Result.err(f"SendGrid error {response.status_code}: {response.text[:500]}")
        return Result.ok(True)

    def health_check(self) -> bool:
        return bool(self.api_key)