import { isValidHostLabel } from "@/worker/auth/host-labels";
import type { HostInfo } from "@/worker/types";

function stripPort(host: string): string {
  if (host.startsWith("[")) {
    const end = host.indexOf("]");
    return end === -1 ? host : host.slice(0, end + 1);
  }

  const colon = host.lastIndexOf(":");
  if (colon === -1) return host;
  return host.slice(0, colon);
}

export function normalizeHostHeader(hostHeader: string | null): string {
  if (!hostHeader) return "";
  const withoutPort = stripPort(hostHeader.trim());
  const withoutTrailingDot = withoutPort.endsWith(".") ? withoutPort.slice(0, -1) : withoutPort;
  return withoutTrailingDot.toLowerCase();
}

export function classifyHost(request: Request, env: Env): HostInfo {
  const controlPlaneHost = env.CONTROL_PLANE_HOST.toLowerCase();
  const subjectHostSuffix = env.SUBJECT_HOST_SUFFIX.toLowerCase();
  const originalHost = request.headers.get("host") ?? new URL(request.url).host;
  const normalizedHost = normalizeHostHeader(originalHost);

  if (normalizedHost === controlPlaneHost) {
    return {
      kind: "control",
      originalHost,
      normalizedHost,
      controlPlaneHost,
      subjectHostSuffix,
    };
  }

  if (normalizedHost.endsWith(subjectHostSuffix)) {
    const hostLabel = normalizedHost.slice(0, -subjectHostSuffix.length);
    if (isValidHostLabel(hostLabel)) {
      return {
        kind: "subject",
        originalHost,
        normalizedHost,
        controlPlaneHost,
        subjectHostSuffix,
        hostLabel,
      };
    }
  }

  return {
    kind: "unknown",
    originalHost,
    normalizedHost,
    controlPlaneHost,
    subjectHostSuffix,
  };
}