"""Obtain a Google Drive refresh token for the application.

Run this once from a development machine that has a browser. It opens a local
OAuth redirect server, asks you to log in, and prints the refresh token.

Usage:
    python app/supporting_scripts/get_refresh_token.py

Requires:
    pip install google-auth-oauthlib

Before running:
    1. Create a Google Cloud project and enable the Drive API.
    2. Create a **Desktop** OAuth 2.0 client ID.
    3. Add your email as a test user in the OAuth consent screen.
    4. Run this script and paste the values when prompted.
"""

import os
import sys


def _prompt(label, env_name, default=""):
    """Ask the user for a value, accepting an env-var fallback or a default."""
    candidate = os.getenv(env_name) or default
    hint = f" [{candidate}]" if candidate else ""
    raw = input(f"{label}{hint}: ").strip()
    if raw:
        return raw
    if candidate:
        return candidate
    return default


def _validate_client_id(client_id):
    """Warn if the client ID doesn't look like a real OAuth client ID."""
    if client_id == "YOUR_CLIENT_ID.apps.googleusercontent.com":
        print("[ERROR] You must provide a real client ID from the Google Cloud console.")
        return False
    if not client_id.endswith(".apps.googleusercontent.com"):
        print(
            f"[WARNING] Client ID should end with '.apps.googleusercontent.com'.\n"
            f"          Got: {client_id!r}\n"
            f"          If this is a placeholder, the OAuth request will fail.\n"
        )
    return True


def _validate_client_secret(secret):
    if secret == "YOUR_CLIENT_SECRET":
        print("[ERROR] You must provide a real client secret from the Google Cloud console.")
        return False
    # The GOCSPX- prefix is now used by every client type, so it no longer
    # tells us anything about whether the client was created as a Desktop app.
    return True


def main():
    print("=" * 60)
    print("Google Drive Refresh Token — Setup")
    print("=" * 60)
    print()

    # When both env vars are set, skip prompts entirely for headless runs.
    env_id = os.getenv("GOOGLE_DRIVE_CLIENT_ID")
    env_secret = os.getenv("GOOGLE_DRIVE_CLIENT_SECRET")
    if env_id and env_secret:
        client_id = env_id
        client_secret = env_secret
        print(f"Using Client ID from environment: {client_id[:30]}...")
    else:
        print("Enter your Google Cloud OAuth credentials.")
        print("You can also set GOOGLE_DRIVE_CLIENT_ID and GOOGLE_DRIVE_CLIENT_SECRET")
        print("environment variables and re-run to skip the prompts.")
        print()

        client_id = _prompt("Client ID", "GOOGLE_DRIVE_CLIENT_ID")
        client_secret = _prompt("Client Secret", "GOOGLE_DRIVE_CLIENT_SECRET")

        if not _validate_client_id(client_id) or not _validate_client_secret(client_secret):
            sys.exit(1)

    print()
    print("Opening browser to authenticate with Google...")
    print("(If it doesn't open, copy the URL below into your browser.)")
    print()

    from google_auth_oauthlib.flow import InstalledAppFlow

    SCOPE = "https://www.googleapis.com/auth/drive.file"

    client_config = {
        "installed": {
            "client_id": client_id,
            "client_secret": client_secret,
            "redirect_uris": ["http://localhost"],
            "auth_uri": "https://accounts.google.com/o/oauth2/auth",
            "token_uri": "https://oauth2.googleapis.com/token",
        }
    }

    flow = InstalledAppFlow.from_client_config(client_config, scopes=[SCOPE])
    credentials = flow.run_local_server(host="localhost", port=8080, open_browser=True)

    print()
    print("=" * 60)
    print("SUCCESS — copy these values into your .env file:")
    print("=" * 60)
    print()
    print("DOCUMENT_STORAGE_BACKEND=google_drive")
    print(f"GOOGLE_DRIVE_CLIENT_ID={credentials.client_id}")
    print(f"GOOGLE_DRIVE_CLIENT_SECRET={client_secret}")
    print(f"GOOGLE_DRIVE_REFRESH_TOKEN={credentials.refresh_token}")
    print("GOOGLE_DRIVE_FOLDER_ID=<get this from the Drive folder URL>")
    print()

    return 0


if __name__ == "__main__":
    sys.exit(main())