import { NextRequest, NextResponse } from "next/server";
import { createClient } from "@/lib/supabase/server";

export async function GET(req: NextRequest) {
  // Make sure the user is logged in
  const supabase = await createClient();
  const { data: { user } } = await supabase.auth.getUser();
  if (!user) {
    return NextResponse.redirect(new URL("/login", req.url));
  }

  const clientId = process.env.GOOGLE_OAUTH_CLIENT_ID;
  if (!clientId) {
    return NextResponse.json(
      { error: "Google OAuth is not configured. Add GOOGLE_OAUTH_CLIENT_ID to .env.local." },
      { status: 500 }
    );
  }

  const origin = req.nextUrl.origin;
  const redirectUri = `${origin}/api/auth/google/callback`;

  const params = new URLSearchParams({
    client_id: clientId,
    redirect_uri: redirectUri,
    scope: "https://www.googleapis.com/auth/calendar.events https://www.googleapis.com/auth/userinfo.email",
    response_type: "code",
    access_type: "offline",  // gets a refresh_token
    prompt: "consent",       // force consent to always get refresh_token
    state: user.id,          // pass user id to callback for safety
  });

  return NextResponse.redirect(`https://accounts.google.com/o/oauth2/v2/auth?${params.toString()}`);
}