package netguard

import (
	"context"
	"fmt"
	"net"
	"testing"
	"time"
)

func TestIsPublic(t *testing.T) {
	public := []string{
		"8.8.8.8", "1.1.1.1", "2001:4860:4860::8888",
		// NAT64 and 6to4 wrapping a PUBLIC embedded IPv4 address a real
		// public destination on IPv6-only networks — allowed by policy.
		"64:ff9b::8.8.8.8", "2002:808:808::",
	}
	blocked := []string{
		"127.0.0.1", "::1", // loopback
		"10.1.2.3", "172.16.0.1", "192.168.1.1", "fc00::1", "fd12::1", "fec0::1", // RFC1918 + ULA + site-local
		"169.254.169.254", "fe80::1", // link-local / cloud metadata
		"100.64.0.1", "100.127.255.254", // RFC 6598 CGNAT
		"198.18.0.1", "198.19.255.255", // benchmark
		"192.0.0.1",                                                          // IETF protocol assignments
		"192.0.2.1", "198.51.100.1", "203.0.113.1", "2001:db8::1", "3fff::1", // documentation space
		"0.1.2.3", "240.0.0.1", "255.255.255.255", // this-network / reserved / broadcast
		"0.0.0.0", "::", "224.0.0.1", "ff02::1", // unspecified / multicast
		"::ffff:10.0.0.1", "::ffff:127.0.0.1", // IPv4-mapped private/loopback
		"64:ff9b::7f00:1", "64:ff9b::a00:1", "64:ff9b::a9fe:a9fe", // NAT64-embedded loopback / private / metadata
		"64:ff9b:1::8.8.8.8",                                // local-use NAT64 is never public
		"2002:7f00:1::", "2002:a00:1::", "2002:a9fe:a9fe::", // 6to4-embedded loopback / private / metadata
		"2001:0:0:0:0:0:7f00:1", "2001:0:4136:e378:8000:63bf:3fff:fdd2", // Teredo
		"::127.0.0.1", "::10.0.0.1", "::ffff:0:7f00:1", "::ffff:0:10.0.0.1", // IPv4-compatible / translated
		"100::1", "2001:2::1", "2001:10::1", "2001:20::1", "5f00::1", "3ffe::1", // discard, benchmark, ORCHID, SRv6, 6bone
	}
	for _, s := range public {
		if !IsPublic(net.ParseIP(s)) {
			t.Errorf("IsPublic(%s) = false, want true", s)
		}
	}
	for _, s := range blocked {
		if IsPublic(net.ParseIP(s)) {
			t.Errorf("IsPublic(%s) = true, want false", s)
		}
	}
}

func TestAllowPrivateEnv(t *testing.T) {
	if AllowPrivate() {
		t.Fatal("AllowPrivate must default to false")
	}
	t.Setenv("INTEGRATIONS_ALLOW_PRIVATE", "1")
	if !AllowPrivate() {
		t.Fatal("AllowPrivate must honor INTEGRATIONS_ALLOW_PRIVATE=1")
	}
}

func TestDialContextBlocksLoopbackByDefault(t *testing.T) {
	if _, e := DialContext(context.Background(), "tcp", "127.0.0.1:5432"); e == nil {
		t.Fatal("loopback destination accepted")
	}
}

func TestDialContextPortsRejectsUnusualPorts(t *testing.T) {
	// Port policy is checked before DNS, so this never dials.
	if _, e := DialContextPorts(context.Background(), "tcp", "8.8.8.8:22", 80, 443); e == nil {
		t.Fatal("SSH port accepted for a URL preview")
	}
	if _, e := DialContextPorts(context.Background(), "tcp", "8.8.8.8:not-a-port", 80, 443); e == nil {
		t.Fatal("non-numeric port accepted")
	}
}

// The NAT64 well-known prefix must not smuggle a non-public IPv4 destination
// past the guard (review follow-up: comprehensive special-range coverage).
func TestDialContextBlocksNAT64WrappedLoopback(t *testing.T) {
	if _, e := DialContext(context.Background(), "tcp", "[64:ff9b::7f00:1]:80"); e == nil {
		t.Fatal("NAT64-wrapped loopback destination accepted")
	}
	if _, e := DialContext(context.Background(), "tcp", "[64:ff9b::a9fe:a9fe]:80"); e == nil {
		t.Fatal("NAT64-wrapped metadata destination accepted")
	}
}

// Bounded fallback among already-validated addresses (review follow-up): a
// host that resolves to several addresses connects even when the first
// record is unreachable. "localhost" resolves to ::1 and/or 127.0.0.1
// depending on the resolver; the listener binds only IPv4 loopback, so on
// dual-stack machines the ::1 attempt must fail over to 127.0.0.1.
func TestDialContextFallsBackAmongValidatedAddresses(t *testing.T) {
	t.Setenv("INTEGRATIONS_ALLOW_PRIVATE", "1")
	ln, e := net.Listen("tcp4", "127.0.0.1:0")
	if e != nil {
		t.Skipf("no IPv4 loopback listener possible: %v", e)
	}
	defer ln.Close()
	go func() {
		for {
			c, e := ln.Accept()
			if e != nil {
				return
			}
			c.Close()
		}
	}()
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	conn, e := DialContext(ctx, "tcp", fmt.Sprintf("localhost:%d", ln.Addr().(*net.TCPAddr).Port))
	if e != nil {
		t.Fatalf("fallback dial to localhost failed: %v", e)
	}
	conn.Close()
}