package webhook

import (
	"context"
	"errors"
	"io"
	"net"
	"net/http"
	"net/url"
	"strings"
	"testing"
	"time"
)

type lookupIPFunc func(context.Context, string) ([]net.IPAddr, error)

func (function lookupIPFunc) LookupIPAddr(ctx context.Context, host string) ([]net.IPAddr, error) {
	return function(ctx, host)
}

type contextDialFunc func(context.Context, string, string) (net.Conn, error)

func (function contextDialFunc) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
	return function(ctx, network, address)
}

type roundTripFunc func(*http.Request) (*http.Response, error)

func (function roundTripFunc) RoundTrip(request *http.Request) (*http.Response, error) {
	return function(request)
}

func TestHTTPSenderPreservesSignedRequestAndReturnsStatus(t *testing.T) {
	client := &http.Client{Timeout: time.Second, Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
		body, _ := io.ReadAll(request.Body)
		if request.Method != http.MethodPost || request.URL.String() != "https://hooks.example.test/job" || string(body) != `{"jobId":"job"}` || request.Header.Get("X-Zhinian-Signature") != "sha256=abc" {
			t.Fatalf("request=%s %s body=%s headers=%v", request.Method, request.URL, body, request.Header)
		}
		return &http.Response{StatusCode: 204, Body: io.NopCloser(strings.NewReader("ignored")), Header: make(http.Header)}, nil
	})}
	sender, err := NewHTTPSender(client, func(context.Context, *url.URL) error { return nil })
	if err != nil {
		t.Fatal(err)
	}
	response, err := sender.Send(context.Background(), Request{URL: "https://hooks.example.test/job", Body: []byte(`{"jobId":"job"}`), Headers: map[string]string{"X-Zhinian-Signature": "sha256=abc"}})
	if err != nil || response.Status != 204 {
		t.Fatalf("Send=%#v,%v", response, err)
	}
}

func TestHTTPSenderRejectsInvalidAndPolicyDeniedDestinations(t *testing.T) {
	client := &http.Client{Timeout: time.Second, Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
		t.Fatal("transport must not run")
		return nil, nil
	})}
	sender, _ := NewHTTPSender(client, func(context.Context, *url.URL) error { return errors.New("private address") })
	for _, target := range []string{"file:///etc/passwd", "https://user:secret@example.test", "https://127.0.0.1/hook"} {
		if _, err := sender.Send(context.Background(), Request{URL: target}); err == nil || strings.Contains(err.Error(), "secret") {
			t.Fatalf("target=%q error=%v", target, err)
		}
	}
}

func TestHTTPSenderRevalidatesEveryRedirect(t *testing.T) {
	validated := make([]string, 0, 2)
	client := &http.Client{Timeout: time.Second, Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
		if request.URL.Hostname() != "public.test" {
			t.Fatal("redirect target transport must not run")
		}
		return &http.Response{StatusCode: http.StatusTemporaryRedirect, Header: http.Header{"Location": []string{"https://private.test/hook"}}, Body: io.NopCloser(strings.NewReader("")), Request: request}, nil
	})}
	sender, err := NewHTTPSender(client, func(_ context.Context, target *url.URL) error {
		validated = append(validated, target.Hostname())
		if target.Hostname() == "private.test" {
			return errors.New("private destination")
		}
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	if _, err := sender.Send(context.Background(), Request{URL: "https://public.test/hook"}); err == nil {
		t.Fatal("policy-denied redirect was accepted")
	}
	if strings.Join(validated, ",") != "public.test,private.test" {
		t.Fatalf("validated destinations = %v", validated)
	}
}

func TestNewHTTPSenderRequiresBoundedClientAndPolicy(t *testing.T) {
	if _, err := NewHTTPSender(nil, func(context.Context, *url.URL) error { return nil }); err == nil {
		t.Fatal("nil client accepted")
	}
	if _, err := NewHTTPSender(&http.Client{}, func(context.Context, *url.URL) error { return nil }); err == nil {
		t.Fatal("unbounded client accepted")
	}
	if _, err := NewHTTPSender(&http.Client{Timeout: time.Second}, nil); err == nil {
		t.Fatal("nil policy accepted")
	}
}

func TestPublicDestinationPolicyRejectsNonPublicDestinations(t *testing.T) {
	tests := []struct {
		name string
		url  string
		ips  []net.IPAddr
	}{
		{name: "userinfo", url: "https://user:secret@example.test/hook", ips: []net.IPAddr{{IP: net.ParseIP("93.184.216.34")}}},
		{name: "localhost name", url: "https://localhost/hook", ips: []net.IPAddr{{IP: net.ParseIP("93.184.216.34")}}},
		{name: "loopback", url: "https://example.test/hook", ips: []net.IPAddr{{IP: net.ParseIP("127.0.0.1")}}},
		{name: "private", url: "https://example.test/hook", ips: []net.IPAddr{{IP: net.ParseIP("10.0.0.1")}}},
		{name: "link local", url: "https://example.test/hook", ips: []net.IPAddr{{IP: net.ParseIP("169.254.169.254")}}},
		{name: "multicast", url: "https://example.test/hook", ips: []net.IPAddr{{IP: net.ParseIP("224.0.0.1")}}},
		{name: "unspecified", url: "https://example.test/hook", ips: []net.IPAddr{{IP: net.ParseIP("0.0.0.0")}}},
		{name: "mixed answers", url: "https://example.test/hook", ips: []net.IPAddr{{IP: net.ParseIP("93.184.216.34")}, {IP: net.ParseIP("192.168.1.1")}}},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			policy := NewPublicDestinationPolicy(lookupIPFunc(func(context.Context, string) ([]net.IPAddr, error) { return test.ips, nil }), nil)
			u, _ := url.Parse(test.url)
			if err := policy.Validate(context.Background(), u); err == nil || strings.Contains(err.Error(), "secret") {
				t.Fatalf("Validate(%q) = %v", test.url, err)
			}
		})
	}
}

func TestPublicDestinationPolicyRejectsSpecialUseUnicastAddresses(t *testing.T) {
	addresses := []string{
		"100.64.0.1",     // shared address space (CGNAT)
		"192.0.0.1",      // IETF protocol assignments
		"192.0.2.1",      // documentation
		"198.18.0.1",     // benchmarking
		"198.51.100.1",   // documentation
		"203.0.113.1",    // documentation
		"240.0.0.1",      // reserved
		"64:ff9b::a00:1", // IPv4/IPv6 translation can embed private IPv4
		"100::1",         // discard-only
		"2001::1",        // Teredo can embed non-public IPv4
		"2001:2::1",      // benchmarking
		"2001:db8::1",    // documentation
		"2001:10::1",     // deprecated ORCHID
		"2001:20::1",     // ORCHIDv2
	}
	for _, address := range addresses {
		t.Run(address, func(t *testing.T) {
			policy := NewPublicDestinationPolicy(nil, nil)
			target, err := url.Parse("https://[" + address + "]/hook")
			if net.ParseIP(address).To4() != nil {
				target, err = url.Parse("https://" + address + "/hook")
			}
			if err != nil {
				t.Fatal(err)
			}
			if err := policy.Validate(context.Background(), target); err == nil {
				t.Fatalf("special-use address %s was accepted", address)
			}
		})
	}
}

func TestPublicDestinationPolicyFailsClosedOnDNSFailure(t *testing.T) {
	policy := NewPublicDestinationPolicy(lookupIPFunc(func(context.Context, string) ([]net.IPAddr, error) {
		return nil, errors.New("resolver unavailable")
	}), nil)
	u, _ := url.Parse("https://hooks.example.test/job")
	if err := policy.Validate(context.Background(), u); err == nil {
		t.Fatal("DNS failure was accepted")
	}
}

func TestPublicDestinationPolicyAllowsPublicAddress(t *testing.T) {
	policy := NewPublicDestinationPolicy(lookupIPFunc(func(context.Context, string) ([]net.IPAddr, error) {
		return []net.IPAddr{{IP: net.ParseIP("93.184.216.34")}}, nil
	}), nil)
	u, _ := url.Parse("https://hooks.example.test/job")
	if err := policy.Validate(context.Background(), u); err != nil {
		t.Fatalf("public destination rejected: %v", err)
	}
}

func TestPublicDestinationPolicyDialsValidatedIPAddress(t *testing.T) {
	var dialed string
	policy := NewPublicDestinationPolicy(
		lookupIPFunc(func(context.Context, string) ([]net.IPAddr, error) {
			return []net.IPAddr{{IP: net.ParseIP("93.184.216.34")}}, nil
		}),
		contextDialFunc(func(_ context.Context, _, address string) (net.Conn, error) {
			dialed = address
			return nil, errors.New("dial stopped by test")
		}),
	)
	_, _ = policy.DialContext(context.Background(), "tcp", "hooks.example.test:443")
	if dialed != "93.184.216.34:443" {
		t.Fatalf("dialed address = %q", dialed)
	}
}