import {
  SecretsManagerClient,
  GetSecretValueCommand,
  PutSecretValueCommand,
} from '@aws-sdk/client-secrets-manager';

const secretsClient = new SecretsManagerClient({});

const QBO_SECRET_ARN = process.env.QBO_SECRET_ARN!;
const QBO_CLIENT_ID = process.env.QBO_CLIENT_ID!;
const QBO_CLIENT_SECRET = process.env.QBO_CLIENT_SECRET!;
const REDIRECT_URI = process.env.REDIRECT_URI!; // https://bot.seahaven.com/qbo/callback

// Intuit OAuth endpoints
const AUTHORIZE_URL = 'https://appcenter.intuit.com/connect/oauth2';
const TOKEN_URL = 'https://oauth.platform.intuit.com/oauth2/v1/tokens/bearer';
const REVOKE_URL = 'https://developer.api.intuit.com/v2/oauth2/tokens/revoke';

// Scopes needed for vendor queries
const SCOPES = 'com.intuit.quickbooks.accounting';

interface APIGatewayEvent {
  requestContext: { http: { method: string; path: string } };
  queryStringParameters?: Record<string, string>;
  headers: Record<string, string>;
}

interface APIGatewayResponse {
  statusCode: number;
  headers?: Record<string, string>;
  body: string;
}

function redirect(url: string): APIGatewayResponse {
  return { statusCode: 302, headers: { Location: url }, body: '' };
}

function html(title: string, message: string): APIGatewayResponse {
  return {
    statusCode: 200,
    headers: { 'Content-Type': 'text/html' },
    body: `<!DOCTYPE html>
<html><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width,initial-scale=1">
<title>${title} — Sea Haven Industries</title>
<style>
  body { font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif; display: flex; align-items: center; justify-content: center; min-height: 100vh; margin: 0; background: #f8f8f8; color: #333; }
  .card { background: #fff; border-radius: 12px; padding: 3rem; max-width: 480px; text-align: center; box-shadow: 0 2px 12px rgba(0,0,0,.08); }
  h1 { font-size: 1.5rem; margin: 0 0 1rem; }
  p { color: #666; line-height: 1.6; margin: 0; }
</style></head>
<body><div class="card"><h1>${title}</h1><p>${message}</p></div></body></html>`,
  };
}

// ── /qbo/connect — redirect to Intuit OAuth ──────────────────────────────────

function handleConnect(): APIGatewayResponse {
  // Generate a simple state parameter for CSRF protection
  const state = crypto.randomUUID();

  const params = new URLSearchParams({
    client_id: QBO_CLIENT_ID,
    response_type: 'code',
    scope: SCOPES,
    redirect_uri: REDIRECT_URI,
    state,
  });

  return redirect(`${AUTHORIZE_URL}?${params.toString()}`);
}

// ── /qbo/callback — exchange code for tokens, store in Secrets Manager ───────

async function handleCallback(
  query: Record<string, string>,
): Promise<APIGatewayResponse> {
  const { code, realmId } = query;

  if (!code || !realmId) {
    return html('Connection Failed', 'Missing authorization code or company ID from Intuit. Please try connecting again.');
  }

  const credentials = Buffer.from(`${QBO_CLIENT_ID}:${QBO_CLIENT_SECRET}`).toString('base64');

  const tokenRes = await fetch(TOKEN_URL, {
    method: 'POST',
    headers: {
      Authorization: `Basic ${credentials}`,
      'Content-Type': 'application/x-www-form-urlencoded',
      Accept: 'application/json',
    },
    body: new URLSearchParams({
      grant_type: 'authorization_code',
      code,
      redirect_uri: REDIRECT_URI,
    }).toString(),
  });

  if (!tokenRes.ok) {
    const err = await tokenRes.text();
    console.error('Token exchange failed:', err);
    return html('Connection Failed', 'Could not exchange authorization code for tokens. Please try again.');
  }

  const tokens = (await tokenRes.json()) as {
    access_token: string;
    refresh_token: string;
    expires_in: number;
    x_refresh_token_expires_in: number;
  };

  // Store in Secrets Manager — same structure the qbo-lookup Lambda expects
  await secretsClient.send(
    new PutSecretValueCommand({
      SecretId: QBO_SECRET_ARN,
      SecretString: JSON.stringify({
        clientId: QBO_CLIENT_ID,
        clientSecret: QBO_CLIENT_SECRET,
        refreshToken: tokens.refresh_token,
        realmId,
      }),
    }),
  );

  console.log('QBO OAuth tokens stored successfully for realmId:', realmId);
  return redirect('/qbo/launch');
}

// ── /qbo/disconnect — revoke token and clear secret ──────────────────────────

async function handleDisconnect(): Promise<APIGatewayResponse> {
  let refreshToken: string | undefined;

  try {
    const res = await secretsClient.send(
      new GetSecretValueCommand({ SecretId: QBO_SECRET_ARN }),
    );
    const secret = JSON.parse(res.SecretString!);
    refreshToken = secret.refreshToken;
  } catch {
    // Secret may not exist or be empty — that's fine
  }

  // Revoke the token at Intuit if we have one
  if (refreshToken) {
    const credentials = Buffer.from(`${QBO_CLIENT_ID}:${QBO_CLIENT_SECRET}`).toString('base64');

    try {
      await fetch(REVOKE_URL, {
        method: 'POST',
        headers: {
          Authorization: `Basic ${credentials}`,
          'Content-Type': 'application/json',
          Accept: 'application/json',
        },
        body: JSON.stringify({ token: refreshToken }),
      });
    } catch (err) {
      console.error('Token revocation failed (non-fatal):', err);
    }

    // Clear the stored secret
    await secretsClient.send(
      new PutSecretValueCommand({
        SecretId: QBO_SECRET_ARN,
        SecretString: JSON.stringify({
          clientId: QBO_CLIENT_ID,
          clientSecret: QBO_CLIENT_SECRET,
          refreshToken: '',
          realmId: '',
        }),
      }),
    );
  }

  return html(
    'Disconnected',
    'Your QuickBooks account has been disconnected from Sea Haven Industries. You can reconnect at any time.',
  );
}

// ── /qbo/launch — success landing page ───────────────────────────────────────

function handleLaunch(): APIGatewayResponse {
  return html(
    'Connected',
    'Your QuickBooks account is connected to Sea Haven Industries. You can close this window.',
  );
}

// ── Router ───────────────────────────────────────────────────────────────────

export const handler = async (event: APIGatewayEvent): Promise<APIGatewayResponse> => {
  const path = event.requestContext.http.path;
  const query = event.queryStringParameters ?? {};

  switch (path) {
    case '/qbo/connect':
      return handleConnect();
    case '/qbo/callback':
      return handleCallback(query);
    case '/qbo/disconnect':
      return handleDisconnect();
    case '/qbo/launch':
      return handleLaunch();
    default:
      return { statusCode: 404, body: 'Not found' };
  }
};