package surf

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

func TestClientIPEmptyTrustedUsesRemoteAddr(t *testing.T) {
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.RemoteAddr = "203.0.113.9:1234"
	req.Header.Set("X-Forwarded-For", "198.51.100.1")
	got := ClientIP(req, nil)
	if got != "203.0.113.9" {
		t.Fatalf("got %q", got)
	}
}

func TestClientIPRejectsSpoofedXFF(t *testing.T) {
	trusted := []netip.Prefix{mustPrefix("10.0.0.0/8")}
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.RemoteAddr = "203.0.113.9:1234"
	req.Header.Set("X-Forwarded-For", "198.51.100.1")
	got := ClientIP(req, trusted)
	if got != "203.0.113.9" {
		t.Fatalf("untrusted RemoteAddr must ignore X-Forwarded-For, got %q", got)
	}
}

func TestClientIPRightmostUntrustedHop(t *testing.T) {
	trusted := []netip.Prefix{mustPrefix("10.0.0.0/8")}
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.RemoteAddr = "10.0.0.1:443"
	req.Header.Set("X-Forwarded-For", "198.51.100.7, 203.0.113.10, 10.0.0.2")
	got := ClientIP(req, trusted)
	if got != "203.0.113.10" {
		t.Fatalf("rightmost untrusted hop = %q", got)
	}
}

func TestClientIPAllHopsTrustedFallsBack(t *testing.T) {
	trusted := []netip.Prefix{mustPrefix("10.0.0.0/8")}
	req := httptest.NewRequest(http.MethodGet, "/", nil)
	req.RemoteAddr = "10.0.0.1:443"
	req.Header.Set("X-Forwarded-For", "10.0.0.8, 10.0.0.9")
	got := ClientIP(req, trusted)
	if got != "10.0.0.1" {
		t.Fatalf("fallback RemoteAddr = %q", got)
	}
}

func mustPrefix(s string) netip.Prefix {
	p, err := netip.ParsePrefix(s)
	if err != nil {
		panic(err)
	}
	return p
}