package cluster

import (
	"context"
	"testing"
	"time"
)

func TestVPNPacketHubPopBatchAndStatsKeys(t *testing.T) {
	hub := newVPNPacketHub()
	key := vpnPacketKey{
		ClusterID:       "cluster-1",
		VPNConnectionID: "vpn-1",
		Direction:       vpnDirectionClientToGateway,
	}

	packetA := []byte{
		0x45, 0x00, 0x00, 20,
		0x00, 0x01, 0x00, 0x00,
		64, 17, 0, 0,
		192, 168, 0, 1,
		192, 168, 0, 2,
		0x00, 0x50, 0x01, 0xBB,
	}

	packetB := make([]byte, len(packetA))
	copy(packetB, packetA)
	packetB[19] = 0xBA

	hub.Push(key, packetA)
	hub.Push(key, packetB)

	packets := hub.PopBatch(context.Background(), key, 0, vpnPacketBatchMaxPackets, vpnPacketBatchMaxBytes)
	if len(packets) != 2 {
		t.Fatalf("expected 2 packets in batch, got %d", len(packets))
	}

	statsAny := hub.Snapshot("cluster-1", "vpn-1")[vpnDirectionClientToGateway]
	stats, ok := statsAny.(map[string]any)
	if !ok {
		t.Fatalf("unexpected stats payload type: %T", statsAny)
	}

	for _, keyName := range []string{
		"pushed",
		"pushed_bytes",
		"popped",
		"popped_bytes",
		"window_push_rate_pps",
		"window_pop_rate_pps",
		"window_push_rate_mbps",
		"window_pop_rate_mbps",
		"window_push_packets",
		"window_pop_packets",
		"queue_depth",
		"queue_depths",
		"queue_depth_max",
		"queue_depth_high_watermark",
		"queue_depth_high_at",
		"shard_depth_high_watermark",
		"shard_depth_high_at",
		"queue_capacity",
		"queue_shard_capacity",
		"queue_full_drops",
		"requeue_drops",
		"cleared_stale_packets",
		"flow_shard_count",
		"flow_isolation",
	} {
		if _, found := stats[keyName]; !found {
			t.Fatalf("missing vpn packet stat key %s", keyName)
		}
	}

	if got, ok := stats["popped"].(uint64); !ok || got != 2 {
		t.Fatalf("expected popped=2, got %v (ok=%v)", stats["popped"], ok)
	}
	if got, ok := stats["pushed"].(uint64); !ok || got != 2 {
		t.Fatalf("expected pushed=2, got %v (ok=%v)", stats["pushed"], ok)
	}
	if got, ok := stats["queue_depth_high_watermark"].(int); !ok || got < 1 {
		t.Fatalf("expected queue depth high watermark, got %v (ok=%v)", stats["queue_depth_high_watermark"], ok)
	}
}

func TestVPNPacketHubGatherBehavior(t *testing.T) {
	hub := newVPNPacketHub()
	key := vpnPacketKey{
		ClusterID:       "cluster-1",
		VPNConnectionID: "vpn-1",
		Direction:       vpnDirectionGatewayToClient,
	}
	packet := []byte{
		0x45, 0x00, 0x00, 20,
		0x00, 0x01, 0x00, 0x00,
		64, 6, 0, 0,
		10, 0, 0, 1,
		10, 0, 0, 2,
		0x12, 0x34, 0x56, 0x78,
	}

	hub.Push(key, packet)
	hub.Push(key, packet)
	hub.Push(key, packet)

	first, ok := hub.Pop(context.Background(), key, 0)
	if !ok {
		t.Fatal("expected packet from queue")
	}
	batch := hub.PopBatch(context.Background(), key, 0, 1, 1024)
	if len(batch) != 1 {
		t.Fatalf("expected 1 packet because batch limit 1, got %d", len(batch))
	}

	_ = first
}

func TestVPNPacketHubFlowShardsReportDepths(t *testing.T) {
	hub := newVPNPacketHub()
	key := vpnPacketKey{
		ClusterID:       "cluster-1",
		VPNConnectionID: "vpn-1",
		Direction:       vpnDirectionGatewayToClient,
	}

	for i := byte(1); i <= 8; i++ {
		packet := []byte{
			0x45, 0x00, 0x00, 24,
			0x00, i, 0x00, 0x00,
			64, 6, 0, 0,
			10, 0, 0, i,
			192, 168, 200, i,
			0x12, i, 0x56, i,
		}
		if err := hub.Push(key, packet); err != nil {
			t.Fatalf("push packet %d: %v", i, err)
		}
	}

	statsAny := hub.Snapshot("cluster-1", "vpn-1")[vpnDirectionGatewayToClient]
	stats, ok := statsAny.(map[string]any)
	if !ok {
		t.Fatalf("unexpected stats payload type: %T", statsAny)
	}
	if got, ok := stats["queue_depth"].(int); !ok || got != 8 {
		t.Fatalf("expected queue_depth=8, got %v (ok=%v)", stats["queue_depth"], ok)
	}
	depths, ok := stats["queue_depths"].([]int)
	if !ok {
		t.Fatalf("unexpected queue_depths payload type: %T", stats["queue_depths"])
	}
	if len(depths) != vpnPacketFlowShardCount {
		t.Fatalf("expected %d queue shards, got %d", vpnPacketFlowShardCount, len(depths))
	}
	nonEmpty := 0
	for _, depth := range depths {
		if depth > 0 {
			nonEmpty++
		}
	}
	if nonEmpty < 2 {
		t.Fatalf("expected packets to be distributed across at least 2 shards, got depths=%v", depths)
	}
}

func TestVPNPacketHubClearDoesNotCountAsDrop(t *testing.T) {
	hub := newVPNPacketHub()
	key := vpnPacketKey{
		ClusterID:       "cluster-1",
		VPNConnectionID: "vpn-1",
		Direction:       vpnDirectionClientToGateway,
	}
	packet := []byte{
		0x45, 0x00, 0x00, 20,
		0x00, 0x01, 0x00, 0x00,
		64, 6, 0, 0,
		10, 0, 0, 1,
		10, 0, 0, 2,
		0x12, 0x34, 0x56, 0x78,
	}
	if err := hub.Push(key, packet); err != nil {
		t.Fatalf("push packet: %v", err)
	}
	if cleared := hub.Clear(key); cleared != 1 {
		t.Fatalf("expected cleared=1, got %d", cleared)
	}
	statsAny := hub.Snapshot("cluster-1", "vpn-1")[vpnDirectionClientToGateway]
	stats, ok := statsAny.(map[string]any)
	if !ok {
		t.Fatalf("unexpected stats payload type: %T", statsAny)
	}
	if got, ok := stats["dropped"].(uint64); !ok || got != 0 {
		t.Fatalf("expected dropped=0 for stale clear, got %v (ok=%v)", stats["dropped"], ok)
	}
	if got, ok := stats["cleared_stale_packets"].(uint64); !ok || got != 1 {
		t.Fatalf("expected cleared_stale_packets=1, got %v (ok=%v)", stats["cleared_stale_packets"], ok)
	}
}

func TestVPNClientDiagnosticStopCommandDrainsPendingWork(t *testing.T) {
	hub := newVPNClientDiagnosticHub()
	hub.Enqueue("cluster-1", "device-1", map[string]any{"type": "vpn_page_probe", "url": "https://speedtest.rt.ru/"})
	hub.Enqueue("cluster-1", "device-1", map[string]any{"type": "vpn_tcp_connect", "host": "192.168.200.95"})
	hub.Enqueue("cluster-1", "device-1", map[string]any{"type": "stop_vpn"})

	item, ok := hub.Pop(context.Background(), "cluster-1", "device-1", time.Millisecond)
	if !ok {
		t.Fatal("expected priority stop command")
	}
	if got, _ := item.Payload["type"].(string); got != "stop_vpn" {
		t.Fatalf("first command = %q, want stop_vpn", got)
	}
	if item, ok := hub.Pop(context.Background(), "cluster-1", "device-1", 0); ok {
		t.Fatalf("expected old commands to be drained, got %#v", item.Payload)
	}
}