package middleware_test

import (
	"net/http"
	"net/http/httptest"
	"net/netip"
	"testing"
	"time"

	"go4.org/netipx"
	"sneak.berlin/go/neoirc/internal/config"
	"sneak.berlin/go/neoirc/internal/globals"
	"sneak.berlin/go/neoirc/internal/logger"
	"sneak.berlin/go/neoirc/internal/middleware"
)

// The tests trust 10.0.0.0/8. Clients use the documentation ranges
// 192.0.2.0/24, 198.51.100.0/24 and 203.0.113.0/24.
const (
	trustedNetwork = "10.0.0.0/8"
	proxyPeer      = "10.0.0.1:4000"
	directPeer     = "192.0.2.1:4000"
	client         = "203.0.113.7"
	clientWithPort = "203.0.113.7:4000"
	realIPClient   = "203.0.113.8"
)

type clientIPTest struct {
	name       string
	remoteAddr string
	forwarded  []string
	realIP     string
	want       string
}

func clientIPTests() []clientIPTest {
	return []clientIPTest{
		{
			name:       "untrusted peer ignores forged headers",
			remoteAddr: directPeer,
			forwarded:  []string{client},
			realIP:     realIPClient,
			want:       directPeer,
		},
		{name: "trusted peer without headers", remoteAddr: proxyPeer, want: proxyPeer},
		{
			name:       "trusted peer gives rightmost untrusted entry",
			remoteAddr: proxyPeer,
			forwarded:  []string{"198.51.100.9, 203.0.113.7, 10.0.0.2"},
			want:       clientWithPort,
		},
		{
			name:       "entries split over several headers",
			remoteAddr: proxyPeer,
			forwarded:  []string{"198.51.100.9", client, "10.0.0.2"},
			want:       clientWithPort,
		},
		{
			name:       "all-trusted chain gives leftmost entry",
			remoteAddr: proxyPeer,
			forwarded:  []string{"10.0.0.3, 10.0.0.2"},
			want:       "10.0.0.3:4000",
		},
		{
			name:       "X-Real-IP without X-Forwarded-For",
			remoteAddr: proxyPeer,
			realIP:     realIPClient,
			want:       "203.0.113.8:4000",
		},
		{
			name:       "X-Forwarded-For wins over X-Real-IP",
			remoteAddr: proxyPeer,
			forwarded:  []string{client},
			realIP:     realIPClient,
			want:       clientWithPort,
		},
		{
			name:       "unparseable X-Forwarded-For entry gives peer",
			remoteAddr: proxyPeer,
			forwarded:  []string{"203.0.113.7, not-an-ip, 10.0.0.2"},
			want:       proxyPeer,
		},
		{
			name:       "unparseable entry past the client is not read",
			remoteAddr: proxyPeer,
			forwarded:  []string{"not-an-ip, 203.0.113.7"},
			want:       clientWithPort,
		},
		{
			name:       "unparseable X-Real-IP gives peer",
			remoteAddr: proxyPeer,
			realIP:     "not-an-ip",
			want:       proxyPeer,
		},
		{
			name:       "mapped IPv6 peer is unmapped and trusted",
			remoteAddr: "[::ffff:10.0.0.1]:4000",
			forwarded:  []string{client},
			want:       clientWithPort,
		},
		{
			name:       "mapped IPv6 peer outside the set",
			remoteAddr: "[::ffff:192.0.2.1]:4000",
			forwarded:  []string{client},
			want:       directPeer,
		},
		{
			name:       "IPv6 client",
			remoteAddr: proxyPeer,
			forwarded:  []string{"2001:db8::1"},
			want:       "[2001:db8::1]:4000",
		},
	}
}

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

	mware := newMiddleware(t, trustedNetwork)

	for _, test := range clientIPTests() {
		t.Run(test.name, func(t *testing.T) {
			t.Parallel()

			var got string

			handler := mware.ClientIP()(http.HandlerFunc(func(
				_ http.ResponseWriter, request *http.Request,
			) {
				got = request.RemoteAddr
			}))

			request := httptest.NewRequestWithContext(
				t.Context(), http.MethodGet, "/", nil,
			)
			request.RemoteAddr = test.remoteAddr

			for _, value := range test.forwarded {
				request.Header.Add("X-Forwarded-For", value)
			}

			if test.realIP != "" {
				request.Header.Set("X-Real-IP", test.realIP)
			}

			handler.ServeHTTP(httptest.NewRecorder(), request)

			if got != test.want {
				t.Errorf("RemoteAddr = %q, want %q", got, test.want)
			}
		})
	}
}

// newMiddleware returns a Middleware that trusts the network trusted.
func newMiddleware(t *testing.T, trusted string) *middleware.Middleware {
	t.Helper()

	var builder netipx.IPSetBuilder

	builder.AddPrefix(netip.MustParsePrefix(trusted))

	trustedSet, err := builder.IPSet()
	if err != nil {
		t.Fatal(err)
	}

	globs := &globals.Globals{
		Appname:   "neoirc-test",
		Version:   "test",
		StartTime: time.Now(),
	}

	log, err := logger.New(nil, logger.Params{Globals: globs})
	if err != nil {
		t.Fatal(err)
	}

	mware, err := middleware.New(nil, middleware.Params{
		Logger:  log,
		Globals: globs,
		Config:  &config.Config{TrustedProxies: trustedSet},
	})
	if err != nil {
		t.Fatal(err)
	}

	return mware
}