import asyncio
from typing import Any

from googleapiclient.discovery import build

from app.google.auth import GoogleAuthError, GoogleAuthManager
from app.tools.base import Tool


class GmailTool(Tool):
    name = "gmail"
    description = "List and search Gmail messages for the connected Google account."

    def __init__(self, auth_manager: GoogleAuthManager) -> None:
        self.auth_manager = auth_manager

    def parameters_schema(self) -> dict[str, Any]:
        return {
            "type": "object",
            "properties": {
                "query": {
                    "type": "string",
                    "description": "Optional Gmail search query such as from:someone newer_than:7d.",
                },
                "max_results": {
                    "type": "integer",
                    "description": "Maximum number of messages to return, from 1 to 20.",
                    "minimum": 1,
                    "maximum": 20,
                },
                "label_ids": {
                    "type": "array",
                    "items": {"type": "string"},
                    "description": "Optional Gmail label filters. Defaults to INBOX.",
                },
            },
            "additionalProperties": False,
        }

    async def run(self, payload: dict[str, Any]) -> dict[str, Any]:
        query = str(payload.get("query", "")).strip()
        max_results = max(1, min(20, int(payload.get("max_results", 10) or 10)))
        label_ids = payload.get("label_ids")
        if not isinstance(label_ids, list) or not label_ids:
            label_ids = ["INBOX"]

        try:
            creds = await self.auth_manager.get_credentials()
        except GoogleAuthError as exc:
            return {"tool": self.name, "status": "error", "message": str(exc)}

        return await asyncio.to_thread(
            self._list_messages,
            creds,
            query,
            max_results,
            [str(label) for label in label_ids],
        )

    def _list_messages(
        self,
        credentials: Any,
        query: str,
        max_results: int,
        label_ids: list[str],
    ) -> dict[str, Any]:
        service = build("gmail", "v1", credentials=credentials, cache_discovery=False)
        response = (
            service.users()
            .messages()
            .list(userId="me", q=query or None, labelIds=label_ids, maxResults=max_results)
            .execute()
        )
        message_refs = response.get("messages", [])
        messages = []
        for item in message_refs:
            detail = (
                service.users()
                .messages()
                .get(
                    userId="me",
                    id=item["id"],
                    format="metadata",
                    metadataHeaders=["From", "Subject", "Date"],
                )
                .execute()
            )
            headers = {
                header.get("name", "").lower(): header.get("value", "")
                for header in detail.get("payload", {}).get("headers", [])
            }
            messages.append(
                {
                    "id": detail.get("id", ""),
                    "thread_id": detail.get("threadId", ""),
                    "from": headers.get("from", ""),
                    "subject": headers.get("subject", "(no subject)"),
                    "date": headers.get("date", ""),
                    "snippet": detail.get("snippet", ""),
                    "label_ids": detail.get("labelIds", []),
                }
            )

        return {
            "tool": self.name,
            "status": "ok",
            "query": query,
            "count": len(messages),
            "messages": messages,
        }