const fs = require("fs");
const path = require("path");
const readline = require("readline");
const { google } = require("googleapis");
require("dotenv").config();

const CREDENTIALS_PATH = process.env.GOOGLE_CREDENTIALS || "./credentials.json";
const TOKEN_PATH = process.env.GOOGLE_TOKEN || "./token.json";

function loadCredentials() {
  const raw = fs.readFileSync(CREDENTIALS_PATH, "utf8");
  const json = JSON.parse(raw);
  const cfg = json.installed || json.web;
  if (!cfg) throw new Error("Invalid credentials.json. Expected installed/web client.");
  return {
    client_id: cfg.client_id,
    client_secret: cfg.client_secret,
    redirect_uris: cfg.redirect_uris,
  };
}

async function main() {
  const { client_id, client_secret, redirect_uris } = loadCredentials();
  const oAuth2Client = new google.auth.OAuth2(client_id, client_secret, redirect_uris[0]);

  const authUrl = oAuth2Client.generateAuthUrl({
    access_type: "offline",
    scope: ["https://www.googleapis.com/auth/drive.file"],
    prompt: "consent",
  });

  console.log("Authorize this app by visiting this url:\n", authUrl, "\n");

  const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
  rl.question("Paste the code from the page here: ", async (code) => {
    rl.close();
    const { tokens } = await oAuth2Client.getToken(code.trim());
    fs.writeFileSync(TOKEN_PATH, JSON.stringify(tokens, null, 2));
    console.log("✅ Token stored at:", path.resolve(TOKEN_PATH));
  });
}

main().catch((e) => {
  console.error("Auth error:", e);
  process.exit(1);
});