package netpol

import (
	"context"
	"io"
	"log/slog"
	"net"
	"strings"
	"sync"
	"sync/atomic"
	"testing"

	corev1 "k8s.io/api/core/v1"
	netv1 "k8s.io/api/networking/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// fakeApplier captures Apply calls for assertion. Drop-in for *Applier in
// tests because Reconciler depends only on the (Apply, Clear) pair.
type fakeApplier struct {
	mu    sync.Mutex
	calls []string
	last  string
	err   error
}

func (f *fakeApplier) Apply(_ context.Context, script string) error {
	f.mu.Lock()
	defer f.mu.Unlock()
	if f.err != nil {
		return f.err
	}
	if script == f.last {
		return nil // de-dup like the real Applier
	}
	f.last = script
	f.calls = append(f.calls, script)
	return nil
}
func (f *fakeApplier) Clear(_ context.Context) error { return nil }
func (f *fakeApplier) lastScript() string {
	f.mu.Lock()
	defer f.mu.Unlock()
	return f.last
}
func (f *fakeApplier) callCount() int {
	f.mu.Lock()
	defer f.mu.Unlock()
	return len(f.calls)
}

// applierIface is satisfied by *Applier and *fakeApplier; we narrow
// Reconciler to this in tests by adapting via a tiny wrapper.
type applierIface interface {
	Apply(context.Context, string) error
	Clear(context.Context) error
}

// reconcileOnce drives one pass synchronously without spinning a goroutine.
func reconcileOnce(t *testing.T, world *World, local LocalPodSource, app applierIface) {
	t.Helper()
	in := Inputs{
		LocalPods:  local(),
		PeerPods:   world.snapshotPeerPods(),
		Namespaces: world.snapshotNamespaces(),
		Policies:   world.snapshotPolicies(),
	}
	out, err := Translate(in, nil)
	if err != nil {
		t.Fatal(err)
	}
	if err := app.Apply(context.Background(), Render(out)); err != nil {
		t.Fatal(err)
	}
}

// silentLogger returns a slog.Logger discarding everything — keeps test
// output tidy.
func silentLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{}))
}

func TestReconciler_NoIsolatedPods_ShortScript(t *testing.T) {
	world := NewWorld(silentLogger())
	local := func() []Pod { return nil }
	app := &fakeApplier{}
	reconcileOnce(t, world, local, app)
	got := app.lastScript()
	if !strings.Contains(got, "table inet flock_netpol") {
		t.Fatalf("missing table:\n%s", got)
	}
	// Without any isolated pods the base chain has policy accept and no
	// jumps. That's the desired "open" state.
	if strings.Contains(got, "jump pod_") {
		t.Fatalf("unexpected jump in open state:\n%s", got)
	}
}

func TestReconciler_PolicyIsolatesLocalPod(t *testing.T) {
	world := NewWorld(silentLogger())

	// Seed a default-deny policy in ns1.
	world.onPolicy(&netv1.NetworkPolicy{
		ObjectMeta: metav1.ObjectMeta{Namespace: "ns1", Name: "deny-all"},
		Spec: netv1.NetworkPolicySpec{
			PodSelector: metav1.LabelSelector{},
			PolicyTypes: []netv1.PolicyType{netv1.PolicyTypeIngress},
		},
	}, false)

	local := func() []Pod {
		return []Pod{{
			Namespace: "ns1", Name: "web",
			Labels:    map[string]string{"app": "web"},
			HostIface: "flock00000001",
			IPs:       []net.IP{mustIP("2001:db8::1")},
		}}
	}
	app := &fakeApplier{}
	reconcileOnce(t, world, local, app)
	got := app.lastScript()

	if !strings.Contains(got, "_ingress {") {
		t.Fatalf("expected pod ingress chain:\n%s", got)
	}
	if !strings.Contains(got, "drop") {
		t.Fatalf("expected default-deny drop:\n%s", got)
	}
	if !strings.Contains(got, `oifname "flock00000001"`) {
		t.Fatalf("expected base-chain jump anchored on veth:\n%s", got)
	}
}

func TestReconciler_DedupesIdenticalRender(t *testing.T) {
	world := NewWorld(silentLogger())
	local := func() []Pod {
		return []Pod{{
			Namespace: "ns1", Name: "web", HostIface: "f1",
			IPs: []net.IP{mustIP("2001:db8::1")},
		}}
	}
	app := &fakeApplier{}
	reconcileOnce(t, world, local, app)
	reconcileOnce(t, world, local, app)
	reconcileOnce(t, world, local, app)
	if got := app.callCount(); got != 1 {
		t.Fatalf("expected 1 unique apply, got %d", got)
	}
}

func TestReconciler_OnChangeFiresTrigger(t *testing.T) {
	world := NewWorld(silentLogger())
	var triggered atomic.Int32
	world.OnChange(func() { triggered.Add(1) })
	world.onNamespace(&corev1.Namespace{ObjectMeta: metav1.ObjectMeta{Name: "foo"}}, false)
	world.onPolicy(&netv1.NetworkPolicy{ObjectMeta: metav1.ObjectMeta{Namespace: "foo", Name: "p"}}, false)
	if triggered.Load() != 2 {
		t.Fatalf("expected 2 OnChange calls, got %d", triggered.Load())
	}
}