package server

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"net/netip"
	"testing"
)

func TestClientIPResolverOnlyTrustsForwardedChainFromTrustedPeer(t *testing.T) {
	t.Parallel()

	resolver, err := NewClientIPResolver([]string{"10.0.0.0/8", "192.0.2.0/24"})
	if err != nil {
		t.Fatalf("NewClientIPResolver() error = %v", err)
	}
	request := httptest.NewRequest(http.MethodGet, "http://example.test", nil)
	request.RemoteAddr = "10.0.0.9:1234"
	request.Header.Set("X-Forwarded-For", "198.51.100.7, 192.0.2.5")
	address, err := resolver.Resolve(request)
	if err != nil {
		t.Fatalf("Resolve(trusted) error = %v", err)
	}
	if address != netip.MustParseAddr("198.51.100.7") {
		t.Fatalf("trusted forwarded address = %s", address)
	}

	request.RemoteAddr = "203.0.113.9:1234"
	address, err = resolver.Resolve(request)
	if err != nil {
		t.Fatalf("Resolve(untrusted) error = %v", err)
	}
	if address != netip.MustParseAddr("203.0.113.9") {
		t.Fatalf("untrusted forwarded address = %s", address)
	}
}

func TestClientIPResolverSupportsRFCForwardedIPv4AndIPv6(t *testing.T) {
	t.Parallel()

	resolver, err := NewClientIPResolver([]string{"10.0.0.0/8", "192.0.2.0/24"})
	if err != nil {
		t.Fatalf("NewClientIPResolver() error = %v", err)
	}
	request := httptest.NewRequest(http.MethodGet, "http://example.test", nil)
	request.RemoteAddr = "10.0.0.9:1234"
	request.Header.Set("Forwarded", `for="[2001:db8::7]:4711";proto=https, for=192.0.2.5`)

	address, err := resolver.Resolve(request)
	if err != nil {
		t.Fatalf("Resolve() error = %v", err)
	}
	if address != netip.MustParseAddr("2001:db8::7") {
		t.Fatalf("Forwarded address = %s", address)
	}
}

func TestAccessAndAdmissionGuardsShareResolvedClientIdentity(t *testing.T) {
	t.Parallel()

	resolver, err := NewClientIPResolver(nil)
	if err != nil {
		t.Fatalf("NewClientIPResolver() error = %v", err)
	}
	access, err := NewAccessGuard(resolver, []string{"198.51.100.0/24"})
	if err != nil {
		t.Fatalf("NewAccessGuard() error = %v", err)
	}
	admitter := &recordingAdmitter{}
	admission := NewAdmissionGuard(resolver, admitter)
	request := httptest.NewRequest(http.MethodGet, "http://example.test", nil)
	request.RemoteAddr = "198.51.100.8:1234"

	if err := access.Check(context.Background(), request); err != nil {
		t.Fatalf("access.Check() error = %v", err)
	}
	if err := admission.Check(context.Background(), request); err != nil {
		t.Fatalf("admission.Check() error = %v", err)
	}
	if admitter.key != "198.51.100.8" {
		t.Fatalf("admission key = %q", admitter.key)
	}
}

func TestAdmissionGuardMapsLimiterRejectionTo429(t *testing.T) {
	t.Parallel()

	resolver, _ := NewClientIPResolver(nil)
	guard := NewAdmissionGuard(resolver, rejectingAdmitter{})
	request := httptest.NewRequest(http.MethodGet, "http://example.test", nil)
	request.RemoteAddr = "198.51.100.8:1234"

	err := guard.Check(context.Background(), request)
	var httpError *HTTPError
	if !errors.As(err, &httpError) || httpError.StatusCode != http.StatusTooManyRequests {
		t.Fatalf("Check() error = %T %v, want HTTP 429", err, err)
	}
}

type recordingAdmitter struct{ key string }

func (admitter *recordingAdmitter) Admit(_ context.Context, key string) error {
	admitter.key = key
	return nil
}

type rejectingAdmitter struct{}

func (rejectingAdmitter) Admit(context.Context, string) error {
	return errors.New("rate limited")
}