import { Request, Response, NextFunction } from 'express';
import jwt from 'jsonwebtoken';
import type { AuthPayload, AccessRule } from '../shared/types';

export type { AuthPayload, AccessRule };

// Extend Express Request so TypeScript knows about req.auth in every route file.
declare global
{
  namespace Express
  {
    interface Request { auth?: AuthPayload; rawToken?: string; }
  }
}

// ── Config (all from environment) ──────────────────────────────────────────────

const JWT_SECRET         = process.env.JWT_SECRET         ?? '';
const AUTH_HOST          = process.env.AUTH_HOST          ?? 'https://account.rokojori.com';
const AUTH_INTERNAL_HOST = process.env.AUTH_INTERNAL_HOST ?? AUTH_HOST;
const COOKIE_DOMAIN      = process.env.COOKIE_DOMAIN      ?? '.rokojori.com';
const CLOCK_TOLERANCE    = parseInt( process.env.JWT_CLOCK_TOLERANCE ?? '0', 10 );

// How long before actual expiry a still-valid access token gets refreshed anyway.
// Must comfortably exceed the browser Token Updater's check interval (5 min) so a
// session kept alive by that updater never actually reaches expiry in normal use.
const PROACTIVE_REFRESH_MARGIN_SEC = parseInt( process.env.PROACTIVE_REFRESH_MARGIN_SEC ?? '900', 10 );

// ── Internal helpers ───────────────────────────────────────────────────────────

function extractToken( req: Request ): string | undefined
{
  const header = req.headers.authorization;
  if ( header?.startsWith( 'Bearer ' ) ) return header.slice( 7 );
  const cookie = req.cookies?.accessToken as string | undefined;
  if ( cookie ) return cookie;
  return undefined;
}

function cookieOpts( maxAge: number )
{
  return {
    domain:   COOKIE_DOMAIN,
    httpOnly: true,
    secure:   process.env.NODE_ENV === 'production',
    sameSite: 'lax' as const,
    path:     '/',
    maxAge,
  };
}

interface RefreshResult { accessToken: string; refreshToken: string; }

async function tryRefresh( refreshToken: string ): Promise<RefreshResult | null>
{
  const url = `${ AUTH_INTERNAL_HOST }/api/auth/refresh`;
  console.log( '[auth] tryRefresh →', url );
  try
  {
    const r = await fetch( url,
    {
      method:  'POST',
      headers: { 'Content-Type': 'application/json' },
      body:    JSON.stringify( { refreshToken } ),
    } );

    console.log( '[auth] tryRefresh status:', r.status );
    if ( !r.ok )
    {
      console.log( '[auth] tryRefresh error body:', await r.text() );
      return null;
    }

    const data = await r.json() as Partial<RefreshResult>;
    if ( !data.accessToken || !data.refreshToken )
    {
      console.log( '[auth] tryRefresh: missing tokens in response' );
      return null;
    }

    console.log( '[auth] tryRefresh: succeeded' );
    return { accessToken: data.accessToken, refreshToken: data.refreshToken };
  }
  catch ( err )
  {
    console.log( '[auth] tryRefresh: fetch error:', err );
    return null;
  }
}

// ── jwtMiddleware ──────────────────────────────────────────────────────────────
//
// Register globally before all routes and express.static.
// Sets req.auth when a valid (or silently refreshed) token is present.
// Never redirects — redirection is the responsibility of requireAuth / requireAccess.
//
// Requires in index.ts:
//   app.set('trust proxy', 1)
//   app.use(cookieParser())
//   app.use(jwtMiddleware)

export function jwtMiddleware( req: Request, res: Response, next: NextFunction ): void
{
  const token = extractToken( req );
  if ( !token ) { next(); return; }

  let verified: AuthPayload | null = null;

  try
  {
    verified = jwt.verify( token, JWT_SECRET, CLOCK_TOLERANCE ? { clockTolerance: CLOCK_TOLERANCE } : {} ) as AuthPayload;
  }
  catch ( err: unknown )
  {
    if ( !( err instanceof jwt.TokenExpiredError ) ) { next(); return; }
  }

  // Proactively refresh a still-valid token once it's within the margin of expiring,
  // not just a fully expired one — this is what lets the browser Token Updater keep a
  // session alive indefinitely just by pinging a cheap endpoint on its interval, instead
  // of every request needing to race a reactive refresh right at the expiry boundary.
  const closeToExpiry = !!verified?.exp && ( verified.exp - Date.now() / 1000 ) < PROACTIVE_REFRESH_MARGIN_SEC;

  if ( verified && !closeToExpiry )
  {
    req.auth     = verified;
    req.rawToken = token;
    next();
    return;
  }

  // Fall back to the still-valid token if refreshing (for any reason) doesn't pan out —
  // only relevant for the proactive case; when verified is null (actually expired) there's
  // nothing to fall back to and the request proceeds unauthenticated, same as before.
  const useVerifiedAsFallback = () => { if ( verified ) { req.auth = verified; req.rawToken = token; } };

  // Bearer-only clients (Electron) handle their own refresh in the Electron main process
  // via the 401-retry pattern; they do not send a refreshToken cookie.
  console.log( verified ? '[auth] proactively refreshing token on:' : '[auth] expired token on:', req.method, req.path );

  const refreshToken = req.cookies?.refreshToken as string | undefined;
  if ( !refreshToken )
  {
    console.log( '[auth] no refreshToken cookie — cannot refresh' );
    useVerifiedAsFallback();
    next();
    return;
  }

  tryRefresh( refreshToken ).then( result =>
  {
    if ( !result )
    {
      console.log( '[auth] refresh failed for:', req.method, req.path );
      useVerifiedAsFallback();
      next();
      return;
    }

    res.cookie( 'accessToken',  result.accessToken,  cookieOpts( 60 * 60 * 1000 ) );
    res.cookie( 'refreshToken', result.refreshToken, cookieOpts( 30 * 24 * 60 * 60 * 1000 ) );

    try
    {
      req.auth     = jwt.verify( result.accessToken, JWT_SECRET ) as AuthPayload;
      req.rawToken = result.accessToken;
    }
    catch
    {
      console.log( '[auth] unexpected: new access token failed verification' );
      useVerifiedAsFallback();
    }

    next();
  } ).catch( () =>
  {
    useVerifiedAsFallback();
    next();
  } );
}

// ── requireAuth ────────────────────────────────────────────────────────────────
//
// Guards API routes. Always returns 401 JSON — never redirects.
// Place after jwtMiddleware on the route or router.

export function requireAuth( req: Request, res: Response, next: NextFunction ): void
{
  if ( !req.auth )
  {
    res.status( 401 ).json( { error: 'Not authenticated' } );
    return;
  }
  next();
}

// ── requireAuthPage ────────────────────────────────────────────────────────────
//
// Guards server-rendered HTML pages. Redirects to login when not authenticated.
// Never use on API routes.

export function requireAuthPage( req: Request, res: Response, next: NextFunction ): void
{
  if ( !req.auth )
  {
    const here = encodeURIComponent( req.protocol + '://' + req.get( 'host' ) + req.originalUrl );
    res.redirect( `${ AUTH_HOST }/login.html?redirect=${ here }` );
    return;
  }
  next();
}

// ── requireAccess ──────────────────────────────────────────────────────────────
//
// Optional role/product gate. Use after requireAuth on routes that need
// more than "any authenticated user".
//
// Rules are OR-combined: access is granted if any rule matches.
// Within a rule, role and product are AND-combined.
// superadmin always passes regardless of rules.
//
// Example:
//   const RULES: AccessRule[] = [
//     { role: 'admin' },
//     { role: 'user', product: 'pro' },
//   ];
//   app.get('/dashboard', jwtMiddleware, requireAccess(RULES), handler);

export function requireAccess( rules: AccessRule[] )
{
  return ( req: Request, res: Response, next: NextFunction ): void =>
  {
    const auth = req.auth;

    if ( !auth )
    {
      if ( req.accepts( 'html' ) )
      {
        const here = encodeURIComponent( req.protocol + '://' + req.get( 'host' ) + req.originalUrl );
        res.redirect( `${ AUTH_HOST }/login.html?redirect=${ here }` );
      }
      else
      {
        res.status( 401 ).json( { error: 'Not authenticated' } );
      }
      return;
    }

    if ( auth.roles.includes( 'superadmin' ) ) { next(); return; }

    const allowed = rules.some( rule =>
      auth.roles.includes( rule.role ) &&
      ( !rule.product || auth.products.includes( rule.product ) )
    );

    if ( allowed ) { next(); return; }

    if ( req.accepts( 'html' ) )
    {
      res.redirect( '/' );
    }
    else
    {
      res.status( 403 ).json( { error: 'Forbidden' } );
    }
  };
}