import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tester to ensure forwarding wrapper works by delegating calls to the corresponding method with
 * the same parameters forwarded and return value forwarded back or exception propagated as is.
 *
 * <p>For example:
 *
 * <pre>{@code
 * new ForwardingWrapperTester().testForwarding(Foo.class, new Function<Foo, Foo>() {
 *   public Foo apply(Foo foo) {

)

var (
	// De-facto standard header keys.
	xForwardedFor    = http.CanonicalHeaderKey("X-Forwarded-For")
	xForwardedHost   = http.CanonicalHeaderKey("X-Forwarded-Host")
	xForwardedPort   = http.CanonicalHeaderKey("X-Forwarded-Port")
	xForwardedProto  = http.CanonicalHeaderKey("X-Forwarded-Proto")
	xForwardedScheme = http.CanonicalHeaderKey("X-Forwarded-Scheme")
	xRealIP          = http.CanonicalHeaderKey("X-Real-IP")
)

var (

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tester to ensure forwarding wrapper works by delegating calls to the corresponding method with
 * the same parameters forwarded and return value forwarded back or exception propagated as is.
 *
 * <p>For example:
 *
 * <pre>{@code
 * new ForwardingWrapperTester().testForwarding(Foo.class, new Function<Foo, Foo>() {
 *   public Foo apply(Foo foo) {

		{xForwardedScheme, "http", "http"},
		{xForwardedScheme, "HTTP", "http"},
		{forwarded, `For="[2001:db8:cafe::17]:4711`, ""},                    // No proto
		{forwarded, `for=192.0.2.43, for=198.51.100.17;proto=https`, ""},    // Multiple params, will be empty.
		{forwarded, `for=172.32.10.15; proto=https;by=127.0.0.1;`, "https"}, // Space before proto
		{forwarded, `for=192.0.2.60;proto=http;by=203.0.113.43`, "http"},    // Multiple params
	}

        location / {
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;

            proxy_connect_timeout 300;
            # Default is HTTP/1, keepalive is only enabled in HTTP/1.1
            proxy_http_version 1.1;

        location / {
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;

            proxy_connect_timeout 300;
            # Default is HTTP/1, keepalive is only enabled in HTTP/1.1
            proxy_http_version 1.1;

        location / {
            proxy_set_header Host $http_host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;

            proxy_connect_timeout 300;
            # Default is HTTP/1, keepalive is only enabled in HTTP/1.1
            proxy_http_version 1.1;

   * X-Forwarded-Host}</a> header field name.
   *
   * @since 20.0
   */
  public static final String X_FORWARDED_HOST = "X-Forwarded-Host";

  /**
   * The HTTP <a
   * href="https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/x-forwarded-headers.html#x-forwarded-port">{@code
   * X-Forwarded-Port}</a> header field name.
   *
   * @since 20.0
   */

		t.opts = opts
	})
}

// GetWithCtx will return a cached value or fetch a new one.
// passes a caller context, if caller context cancels nothing
// is cached.
// If the Update function returns an error the value is forwarded as is and not cached.
func (t *Cache[T]) GetWithCtx(ctx context.Context) (T, error) {
	v := t.val.Load()
	ttl := t.ttl
	vTime := t.lastUpdateMs.Load()
	tNow := time.Now().UnixMilli()

The following diagram illustrates the flow of unauthenticated traffic with a `PERMISSIVE` policy:

```mermaid
graph TD;
src[src pod]-->|plaintext port|ztunnel{"ztunnel (L4 policy applied here)"}
ztunnel{ztunnel}-->|TLS|wp{waypoint}
wp-->|mTLS|ztunnel
ztunnel-->|plaintext|dst[dst pod]
```