import { type Router as ExpressRouter, Router, Request, Response } from 'express';
import { nanoid } from 'nanoid';
import { db } from '../db/index.js';
import { integrationTokens } from '../db/schema.js';
import { eq, and } from 'drizzle-orm';
import { config } from '../config.js';
import { requireAuth, AuthenticatedRequest } from '../middleware/session.js';

const router: ExpressRouter = Router();

const TODOIST_OAUTH_URL = 'https://todoist.com/oauth/authorize';
const TODOIST_TOKEN_URL = 'https://todoist.com/oauth/access_token';
const TODOIST_SCOPES = 'data:read_write';

// In-memory CSRF state store
const pendingStates = new Map<string, { userId: string; redirectTo: string }>();

/** GET /api/integrations — list connected integrations */
router.get('/', requireAuth, async (req: AuthenticatedRequest, res: Response) => {
  const tokens = await db
    .select()
    .from(integrationTokens)
    .where(eq(integrationTokens.userId, req.userId!));

  const integrations = tokens.map((t) => ({
    provider: t.provider,
    status: t.tokenStatus === 'needs_reconnect' ? 'needs_reconnect' : 'connected',
    connectedAt: t.connectedAt,
  }));

  res.json({ integrations });
});

/** GET /api/integrations/todoist/connect — start OAuth */
router.get('/todoist/connect', requireAuth, (req: AuthenticatedRequest, res: Response) => {
  const state = nanoid();
  pendingStates.set(state, {
    userId: req.userId!,
    redirectTo: (req.query.redirectTo as string) ?? '/connect',
  });
  setTimeout(() => pendingStates.delete(state), 10 * 60 * 1000);

  const url = new URL(TODOIST_OAUTH_URL);
  url.searchParams.set('client_id', config.TODOIST_CLIENT_ID);
  url.searchParams.set('scope', TODOIST_SCOPES);
  url.searchParams.set('state', state);
  url.searchParams.set('redirect_uri', `${config.API_BASE_URL}/api/integrations/todoist/callback`);

  res.redirect(url.toString());
});

/** GET /api/integrations/todoist/callback — Todoist returns here */
router.get('/todoist/callback', async (req: Request, res: Response) => {
  const state = req.query.state as string;
  const code = req.query.code as string;
  const pending = pendingStates.get(state);
  if (!pending) {
    res.status(400).json({ error: 'Invalid or expired state' });
    return;
  }
  pendingStates.delete(state);

  // Exchange code for token
  const body = new URLSearchParams({
    client_id: config.TODOIST_CLIENT_ID,
    client_secret: config.TODOIST_CLIENT_SECRET,
    code,
    redirect_uri: `${config.API_BASE_URL}/api/integrations/todoist/callback`,
  });

  const tokenRes = await fetch(TODOIST_TOKEN_URL, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded', Accept: 'application/json' },
    body: body.toString(),
  });

  if (!tokenRes.ok) {
    res.status(502).json({ error: 'Failed to exchange Todoist token' });
    return;
  }

  const { access_token } = (await tokenRes.json()) as { access_token: string };
  const now = new Date().toISOString();
  const id = nanoid();

  // Delete existing token (if any) then insert fresh
  await db
    .delete(integrationTokens)
    .where(
      and(
        eq(integrationTokens.userId, pending.userId),
        eq(integrationTokens.provider, 'todoist'),
      ),
    );
  await db.insert(integrationTokens).values({
    id,
    userId: pending.userId,
    provider: 'todoist',
    accessToken: access_token,
    tokenStatus: 'active',
    connectedAt: now,
  });

  res.redirect(`${config.WEB_BASE_URL}${pending.redirectTo}?connected=todoist`);
});

/** DELETE /api/integrations/:provider — revoke token */
router.delete('/:provider', requireAuth, async (req: AuthenticatedRequest, res: Response) => {
  const provider = String(req.params.provider);

  const [token] = await db
    .select()
    .from(integrationTokens)
    .where(
      and(
        eq(integrationTokens.userId, req.userId!),
        eq(integrationTokens.provider, provider),
      ),
    )
    .limit(1);

  if (token?.provider === 'todoist') {
    // Best-effort revocation
    await fetch('https://api.todoist.com/sync/v9/access_tokens/revoke', {
      method: 'POST',
      headers: { Authorization: `Bearer ${token.accessToken}` },
    }).catch(() => {});
  }

  await db
    .delete(integrationTokens)
    .where(
      and(
        eq(integrationTokens.userId, req.userId!),
        eq(integrationTokens.provider, provider),
      ),
    );

  res.json({ ok: true });
});

export { router as integrationsRouter };