/**
 * Next.js auth seam for the complete /api/0pt capability surface.
 *
 * Customer calls use verified Zitadel bearer identity and receive immutable
 * x-0pt-verified-* headers. Explicit machine routes may instead use the
 * shared X-Internal-Token convention; mutation handlers verify it again for
 * defence in depth.
 */
import { NextResponse, type NextRequest } from 'next/server';
import { assertAuthConfigSafe, resolveAuthContext } from '@/src/auth/context';
import { verifyInternalServiceToken } from '@/src/auth/internal-token';

assertAuthConfigSafe();

export const config = {
  matcher: ['/api/0pt', '/api/0pt/:path*'],
};

const EXEMPT_PATTERNS: RegExp[] = [
  /^\/api\/health(\/|$)/,
  /^\/api\/ready(\/|$)/,
  /^\/api\/admin\/metrics(\/|$)/,
];

/** Routes that may be reached with a service token instead of end-user bearer auth. */
const INTERNAL_SERVICE_ROUTES: RegExp[] = [
  /^\/api\/0pt\/quality\/bridge-run$/,
  /^\/api\/0pt\/internal\/evidence-outbox\/dispatch$/,
  /^\/api\/0pt\/internal\/er\/candidates$/,
  /^\/api\/0pt\/search\/definitions$/,
];

let _authDiagCount = 0;

export async function middleware(req: NextRequest): Promise<NextResponse> {
  const path = req.nextUrl.pathname;
  if (EXEMPT_PATTERNS.some((re) => re.test(path))) return NextResponse.next();

  if (INTERNAL_SERVICE_ROUTES.some((re) => re.test(path)) && verifyInternalServiceToken(req.headers)) {
    return NextResponse.next();
  }

  if (_authDiagCount < 5) {
    _authDiagCount += 1;
    const hasAuth = !!req.headers.get('authorization');
    console.log(
      `[0pt-auth] middleware path=${path} auth_header=${hasAuth} ` +
      `auth_enforce=${process.env.AUTH_ENFORCE ?? 'unset'} ` +
      `node_env=${process.env.NODE_ENV ?? 'unset'} request#${_authDiagCount}`,
    );
  }

  const decision = await resolveAuthContext(req.headers);
  if (!decision.ok) {
    return NextResponse.json(
      { error: decision.code, message: decision.message, ...(decision.details ? { details: decision.details } : {}) },
      { status: decision.status },
    );
  }

  const principal = decision.ctx.principal;
  if (principal) {
    const forwarded = new Headers(req.headers);
    forwarded.set('x-0pt-verified-sub', principal.sub);
    forwarded.set('x-0pt-verified-tenant', principal.tenantId);
    return NextResponse.next({ request: { headers: forwarded } });
  }

  return NextResponse.next();
}