"""Cloud provider integration utilities.

Adapted for Batch Agent Service: import from shared.config instead of app.config.

Provides:
  * Shared message dataclasses (EmailMessage, ChatMessage)
  * get_provider() — factory for Gmail/MS Graph clients
  * encrypt_token() / decrypt_token() — Fernet-based OAuth token encryption
"""

from __future__ import annotations

import json
import logging
from dataclasses import dataclass, field
from datetime import datetime
from typing import TYPE_CHECKING

from cryptography.fernet import Fernet, InvalidToken

from shared.config import settings

if TYPE_CHECKING:
    from app.integrations.gmail import GmailClient
    from app.integrations.ms_graph import MSGraphClient

logger = logging.getLogger(__name__)


@dataclass
class EmailMessage:
    id: str
    subject: str
    sender: str
    body_text: str
    date: datetime
    labels: list[str] = field(default_factory=list)

    @property
    def as_text(self) -> str:
        date_str = self.date.strftime("%Y-%m-%d %H:%M")
        labels_str = f" [{', '.join(self.labels)}]" if self.labels else ""
        return (
            f"From: {self.sender}\n"
            f"Date: {date_str}{labels_str}\n"
            f"Subject: {self.subject}\n\n"
            f"{self.body_text}"
        )


@dataclass
class ChatMessage:
    id: str
    content: str
    sender: str
    channel: str | None
    date: datetime

    @property
    def as_text(self) -> str:
        date_str = self.date.strftime("%Y-%m-%d %H:%M")
        channel_str = f" [channel: {self.channel}]" if self.channel else ""
        return (
            f"From: {self.sender}\n"
            f"Date: {date_str}{channel_str}\n\n"
            f"{self.content}"
        )


def _get_fernet() -> Fernet:
    key = settings.OAUTH_ENCRYPTION_KEY
    if not key:
        raise RuntimeError(
            "OAUTH_ENCRYPTION_KEY is not set. "
            "Generate one with: python -c \"from cryptography.fernet import Fernet; print(Fernet.generate_key().decode())\""
        )
    return Fernet(key.encode() if isinstance(key, str) else key)


def encrypt_token(token_info: dict) -> str:
    if not isinstance(token_info, dict) or not token_info:
        raise ValueError("token_info must be a non-empty dict")
    plaintext = json.dumps(token_info).encode("utf-8")
    return _get_fernet().encrypt(plaintext).decode("utf-8")


def decrypt_token(encrypted: str) -> dict:
    try:
        plaintext = _get_fernet().decrypt(encrypted.encode("utf-8"))
        return json.loads(plaintext)
    except (InvalidToken, json.JSONDecodeError) as exc:
        raise ValueError(f"Failed to decrypt OAuth token: {exc}") from exc


def get_provider(
    provider: str,
    credentials_info: dict,
) -> "GmailClient | MSGraphClient":
    if provider == "gmail":
        from app.integrations.gmail import GmailClient
        return GmailClient(credentials_info)
    if provider in {"outlook", "teams"}:
        from app.integrations.ms_graph import MSGraphClient
        return MSGraphClient(credentials_info)
    raise ValueError(
        f"Unknown cloud provider {provider!r}. "
        "Supported: 'gmail', 'outlook', 'teams'."
    )