import io
import json
from typing import Optional, List, Dict

from google.oauth2.credentials import Credentials
from googleapiclient.discovery import build
from googleapiclient.http import MediaIoBaseUpload

# Scope is enough to create/update files your app creates/has access to in Drive
DRIVE_SCOPES = ["https://www.googleapis.com/auth/drive.file"]


def build_drive_service(token_json_str: str):
    """
    token_json_str = HF secret GOOGLE_TOKEN_JSON (contents of token.json)
    """
    info = json.loads(token_json_str)
    creds = Credentials.from_authorized_user_info(info, scopes=DRIVE_SCOPES)
    return build("drive", "v3", credentials=creds, cache_discovery=False)


def list_children(service, parent_folder_id: str, page_size: int = 20) -> List[Dict]:
    """
    List immediate children in a folder (files + folders).
    """
    q = f"'{parent_folder_id}' in parents and trashed = false"
    resp = (
        service.files()
        .list(
            q=q,
            pageSize=page_size,
            fields="files(id,name,modifiedTime,mimeType)",
        )
        .execute()
    )
    return resp.get("files", [])


def find_file_by_name(service, parent_folder_id: str, filename: str) -> Optional[str]:
    """
    Returns the fileId if a file exists with this exact name in the folder.
    """
    # IMPORTANT: sanitize BEFORE f-string (no backslashes inside f-string expressions)
    safe_name = filename.replace("'", "\\'")

    q = (
        f"'{parent_folder_id}' in parents "
        f"and trashed = false "
        f"and name = '{safe_name}'"
    )

    resp = (
        service.files()
        .list(
            q=q,
            pageSize=1,
            fields="files(id,name)",
        )
        .execute()
    )

    files = resp.get("files", [])
    return files[0]["id"] if files else None


def upsert_json_file(service, parent_folder_id: str, filename: str, payload: dict) -> str:
    """
    Create the JSON file if missing, otherwise update it.
    Returns the Drive fileId.
    """
    data = json.dumps(payload, indent=2).encode("utf-8")
    media = MediaIoBaseUpload(io.BytesIO(data), mimetype="application/json", resumable=False)

    existing_id = find_file_by_name(service, parent_folder_id, filename)

    if existing_id:
        updated = (
            service.files()
            .update(
                fileId=existing_id,
                media_body=media,
                fields="id,modifiedTime,name",
            )
            .execute()
        )
        return updated["id"]

    created = (
        service.files()
        .create(
            body={"name": filename, "parents": [parent_folder_id]},
            media_body=media,
            fields="id,modifiedTime,name",
        )
        .execute()
    )
    return created["id"]