// Copyright 2024 Kelvin Clement Mwinuka
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package pubsub_test

import (
	"context"
	"github.com/echovault/echovault/echovault"
	"github.com/echovault/echovault/internal"
	"github.com/echovault/echovault/internal/config"
	"github.com/echovault/echovault/internal/constants"
	"github.com/echovault/echovault/internal/modules/pubsub"
	"github.com/tidwall/resp"
	"net"
	"reflect"
	"slices"
	"strings"
	"sync"
	"testing"
	"unsafe"
)

var ps *pubsub.PubSub
var mockServer *echovault.EchoVault

var bindAddr = "localhost"
var port uint16

func init() {
	p, _ := internal.GetFreePort()
	port = uint16(p)

	mockServer = setUpServer(bindAddr, port)

	getPubSub := getUnexportedField(reflect.ValueOf(mockServer).Elem().FieldByName("getPubSub")).(func() interface{})
	ps = getPubSub().(*pubsub.PubSub)

	wg := sync.WaitGroup{}
	wg.Add(1)
	go func() {
		wg.Done()
		mockServer.Start()
	}()
	wg.Wait()
}

func setUpServer(bindAddr string, port uint16) *echovault.EchoVault {
	server, _ := echovault.NewEchoVault(
		echovault.WithConfig(config.Config{
			BindAddr:       bindAddr,
			Port:           port,
			DataDir:        "",
			EvictionPolicy: constants.NoEviction,
		}),
	)
	return server
}

func getUnexportedField(field reflect.Value) interface{} {
	return reflect.NewAt(field.Type(), unsafe.Pointer(field.UnsafeAddr())).Elem().Interface()
}

func getHandler(commands ...string) internal.HandlerFunc {
	if len(commands) == 0 {
		return nil
	}
	getCommands :=
		getUnexportedField(reflect.ValueOf(mockServer).Elem().FieldByName("getCommands")).(func() []internal.Command)
	for _, c := range getCommands() {
		if strings.EqualFold(commands[0], c.Command) && len(commands) == 1 {
			// Get command handler
			return c.HandlerFunc
		}
		if strings.EqualFold(commands[0], c.Command) {
			// Get sub-command handler
			for _, sc := range c.SubCommands {
				if strings.EqualFold(commands[1], sc.Command) {
					return sc.HandlerFunc
				}
			}
		}
	}
	return nil
}

func getHandlerFuncParams(ctx context.Context, cmd []string, conn *net.Conn, mockServer *echovault.EchoVault) internal.HandlerFuncParams {
	getPubSub :=
		getUnexportedField(reflect.ValueOf(mockServer).Elem().FieldByName("getPubSub")).(func() interface{})
	return internal.HandlerFuncParams{
		Context:    ctx,
		Command:    cmd,
		Connection: conn,
		GetPubSub:  getPubSub,
	}
}

// func Test_HandleSubscribe(t *testing.T) {
// 	ctx := context.WithValue(context.Background(), "test_name", "SUBSCRIBE/PSUBSCRIBE")
//
// 	numOfConnection := 20
// 	connections := make([]*net.Conn, numOfConnection)
//
// 	for i := 0; i < numOfConnection; i++ {
// 		conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", bindAddr, port))
// 		if err != nil {
// 			t.Error(err)
// 		}
// 		connections[i] = &conn
// 	}
// 	defer func() {
// 		for _, conn := range connections {
// 			if err := (*conn).Close(); err != nil {
// 				t.Error(err)
// 			}
// 		}
// 	}()
//
// 	// Test subscribe to channels
// 	channels := []string{"sub_channel1", "sub_channel2", "sub_channel3"}
// 	for _, conn := range connections {
// 		_, err := getHandler("SUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"SUBSCRIBE"}, channels...), conn, mockServer))
// 		if err != nil {
// 			t.Error(err)
// 		}
// 	}
// 	for _, channel := range channels {
// 		// Check if the channel exists in the pubsub module
// 		if !slices.ContainsFunc(ps.GetAllChannels(), func(c *pubsub.Channel) bool {
// 			return c.Name() == channel
// 		}) {
// 			t.Errorf("expected pubsub to contain channel \"%s\" but it was not found", channel)
// 		}
// 		for _, c := range ps.GetAllChannels() {
// 			if c.Name() == channel {
// 				// Check if channel has nil pattern
// 				if c.Pattern() != nil {
// 					t.Errorf("expected channel \"%s\" to have nil pattern, found pattern \"%s\"", channel, c.Name())
// 				}
// 				// Check if the channel has all the connections from above
// 				for _, conn := range connections {
// 					if _, ok := c.Subscribers()[conn]; !ok {
// 						t.Errorf("could not find all expected connection in the \"%s\"", channel)
// 					}
// 				}
// 			}
// 		}
// 	}
//
// 	// Test subscribe to patterns
// 	patterns := []string{"psub_channel*"}
// 	for _, conn := range connections {
// 		_, err := getHandler("PSUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"PSUBSCRIBE"}, patterns...), conn, mockServer))
// 		if err != nil {
// 			t.Error(err)
// 		}
// 	}
// 	for _, pattern := range patterns {
// 		// Check if pattern channel exists in pubsub module
// 		if !slices.ContainsFunc(ps.GetAllChannels(), func(c *pubsub.Channel) bool {
// 			return c.Name() == pattern
// 		}) {
// 			t.Errorf("expected pubsub to contain pattern channel \"%s\" but it was not found", pattern)
// 		}
// 		for _, c := range ps.GetAllChannels() {
// 			if c.Name() == pattern {
// 				// Check if channel has non-nil pattern
// 				if c.Pattern() == nil {
// 					t.Errorf("expected channel \"%s\" to have pattern \"%s\", found nil pattern", pattern, c.Name())
// 				}
// 				// Check if the channel has all the connections from above
// 				for _, conn := range connections {
// 					if _, ok := c.Subscribers()[conn]; !ok {
// 						t.Errorf("could not find all expected connection in the \"%s\"", pattern)
// 					}
// 				}
// 			}
// 		}
// 	}
// }

// func Test_HandleUnsubscribe(t *testing.T) {
// 	generateConnections := func(noOfConnections int) []*net.Conn {
// 		connections := make([]*net.Conn, noOfConnections)
// 		for i := 0; i < noOfConnections; i++ {
// 			conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", bindAddr, port))
// 			if err != nil {
// 				t.Error(err)
// 			}
// 			connections[i] = &conn
// 		}
// 		return connections
// 	}
//
// 	closeConnections := func(conns []*net.Conn) {
// 		for _, conn := range conns {
// 			if err := (*conn).Close(); err != nil {
// 				t.Error(err)
// 			}
// 		}
// 	}
//
// 	verifyResponse := func(res []byte, expectedResponse [][]string) {
// 		rd := resp.NewReader(bytes.NewReader(res))
// 		rv, _, err := rd.ReadValue()
// 		if err != nil {
// 			t.Error(err)
// 		}
// 		v := rv.Array()
// 		if len(v) != len(expectedResponse) {
// 			t.Errorf("expected subscribe response of length %d, but got %d", len(expectedResponse), len(v))
// 		}
// 		for _, item := range v {
// 			arr := item.Array()
// 			if len(arr) != 3 {
// 				t.Errorf("expected subscribe response item to be length %d, but got %d", 3, len(arr))
// 			}
// 			if !slices.ContainsFunc(expectedResponse, func(strings []string) bool {
// 				return strings[0] == arr[0].String() && strings[1] == arr[1].String() && strings[2] == arr[2].String()
// 			}) {
// 				t.Errorf("expected to find item \"%s\" in response, did not find it.", arr[1].String())
// 			}
// 		}
// 	}
//
// 	tests := []struct {
// 		subChannels       []string              // All channels to subscribe to
// 		subPatterns       []string              // All patterns to subscribe to
// 		unSubChannels     []string              // Channels to unsubscribe from
// 		unSubPatterns     []string              // Patterns to unsubscribe from
// 		remainChannels    []string              // Channels to remain subscribed to
// 		remainPatterns    []string              // Patterns to remain subscribed to
// 		targetConn        *net.Conn             // Connection used to test unsubscribe functionality
// 		otherConnections  []*net.Conn           // Connections to fill the subscribers list for channels and patterns
// 		expectedResponses map[string][][]string // The expected response from the handler
// 	}{
// 		{ // 1. Unsubscribe from channels and patterns
// 			subChannels:      []string{"xx_channel_one", "xx_channel_two", "xx_channel_three", "xx_channel_four"},
// 			subPatterns:      []string{"xx_pattern_[ab]", "xx_pattern_[cd]", "xx_pattern_[ef]", "xx_pattern_[gh]"},
// 			unSubChannels:    []string{"xx_channel_one", "xx_channel_two"},
// 			unSubPatterns:    []string{"xx_pattern_[ab]"},
// 			remainChannels:   []string{"xx_channel_three", "xx_channel_four"},
// 			remainPatterns:   []string{"xx_pattern_[cd]", "xx_pattern_[ef]", "xx_pattern_[gh]"},
// 			targetConn:       generateConnections(1)[0],
// 			otherConnections: generateConnections(20),
// 			expectedResponses: map[string][][]string{
// 				"channel": {
// 					{"unsubscribe", "xx_channel_one", "1"},
// 					{"unsubscribe", "xx_channel_two", "2"},
// 				},
// 				"pattern": {
// 					{"punsubscribe", "xx_pattern_[ab]", "1"},
// 				},
// 			},
// 		},
// 		{ // 2. Unsubscribe from all channels no channel or pattern is passed to command
// 			subChannels:      []string{"xx_channel_one", "xx_channel_two", "xx_channel_three", "xx_channel_four"},
// 			subPatterns:      []string{"xx_pattern_[ab]", "xx_pattern_[cd]", "xx_pattern_[ef]", "xx_pattern_[gh]"},
// 			unSubChannels:    []string{},
// 			unSubPatterns:    []string{},
// 			remainChannels:   []string{},
// 			remainPatterns:   []string{},
// 			targetConn:       generateConnections(1)[0],
// 			otherConnections: generateConnections(20),
// 			expectedResponses: map[string][][]string{
// 				"channel": {
// 					{"unsubscribe", "xx_channel_one", "1"},
// 					{"unsubscribe", "xx_channel_two", "2"},
// 					{"unsubscribe", "xx_channel_three", "3"},
// 					{"unsubscribe", "xx_channel_four", "4"},
// 				},
// 				"pattern": {
// 					{"punsubscribe", "xx_pattern_[ab]", "1"},
// 					{"punsubscribe", "xx_pattern_[cd]", "2"},
// 					{"punsubscribe", "xx_pattern_[ef]", "3"},
// 					{"punsubscribe", "xx_pattern_[gh]", "4"},
// 				},
// 			},
// 		},
// 		{ // 3. Don't unsubscribe from any channels or patterns if the provided ones are non-existent
// 			subChannels:      []string{"xx_channel_one", "xx_channel_two", "xx_channel_three", "xx_channel_four"},
// 			subPatterns:      []string{"xx_pattern_[ab]", "xx_pattern_[cd]", "xx_pattern_[ef]", "xx_pattern_[gh]"},
// 			unSubChannels:    []string{"xx_channel_non_existent_channel"},
// 			unSubPatterns:    []string{"xx_channel_non_existent_pattern_[ae]"},
// 			remainChannels:   []string{"xx_channel_one", "xx_channel_two", "xx_channel_three", "xx_channel_four"},
// 			remainPatterns:   []string{"xx_pattern_[ab]", "xx_pattern_[cd]", "xx_pattern_[ef]", "xx_pattern_[gh]"},
// 			targetConn:       generateConnections(1)[0],
// 			otherConnections: generateConnections(20),
// 			expectedResponses: map[string][][]string{
// 				"channel": {},
// 				"pattern": {},
// 			},
// 		},
// 	}
//
// 	for i, test := range tests {
// 		ctx := context.WithValue(context.Background(), "test_name", fmt.Sprintf("UNSUBSCRIBE/PUNSUBSCRIBE, %d", i))
//
// 		// Subscribe all the connections to the channels and patterns
// 		for _, conn := range append(test.otherConnections, test.targetConn) {
// 			_, err := getHandler("SUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"SUBSCRIBE"}, test.subChannels...), conn, mockServer))
// 			if err != nil {
// 				t.Error(err)
// 			}
// 			_, err = getHandler("PSUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"PSUBSCRIBE"}, test.subPatterns...), conn, mockServer))
// 			if err != nil {
// 				t.Error(err)
// 			}
// 		}
//
// 		// Unsubscribe the target connection from the unsub channels and patterns
// 		res, err := getHandler("UNSUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"UNSUBSCRIBE"}, test.unSubChannels...), test.targetConn, mockServer))
// 		if err != nil {
// 			t.Error(err)
// 		}
// 		verifyResponse(res, test.expectedResponses["channel"])
//
// 		res, err = getHandler("PUNSUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"PUNSUBSCRIBE"}, test.unSubPatterns...), test.targetConn, mockServer))
// 		if err != nil {
// 			t.Error(err)
// 		}
// 		verifyResponse(res, test.expectedResponses["pattern"])
//
// 		for _, channel := range append(test.unSubChannels, test.unSubPatterns...) {
// 			for _, pubsubChannel := range ps.GetAllChannels() {
// 				if pubsubChannel.Name() == channel {
// 					// Assert that target connection is no longer in the unsub channels and patterns
// 					if _, ok := pubsubChannel.Subscribers()[test.targetConn]; ok {
// 						t.Errorf("found unexpected target connection after unsubscrining in channel \"%s\"", channel)
// 					}
// 					for _, conn := range test.otherConnections {
// 						if _, ok := pubsubChannel.Subscribers()[conn]; !ok {
// 							t.Errorf("did not find expected other connection in channel \"%s\"", channel)
// 						}
// 					}
// 				}
// 			}
// 		}
//
// 		// Assert that the target connection is still in the remain channels and patterns
// 		for _, channel := range append(test.remainChannels, test.remainPatterns...) {
// 			for _, pubsubChannel := range ps.GetAllChannels() {
// 				if pubsubChannel.Name() == channel {
// 					if _, ok := pubsubChannel.Subscribers()[test.targetConn]; !ok {
// 						t.Errorf("could not find expected target connection in channel \"%s\"", channel)
// 					}
// 				}
// 			}
// 		}
// 	}
//
// 	for _, test := range tests {
// 		// Close all the connections
// 		closeConnections(append(test.otherConnections, test.targetConn))
// 	}
// }

// func Test_HandlePublish(t *testing.T) {
// 	ctx := context.WithValue(context.Background(), "test_name", "PUBLISH")
//
// 	// verifyChannelMessage reads the message from the connection and asserts whether
// 	// it's the message we expect to read as a subscriber of a channel or pattern.
// 	verifyEvent := func(c *net.Conn, r *resp.Conn, expected []string) {
// 		if err := (*c).SetReadDeadline(time.Now().Add(100 * time.Millisecond)); err != nil {
// 			t.Error(err)
// 		}
// 		rv, _, err := r.ReadValue()
// 		if err != nil {
// 			t.Error(err)
// 		}
// 		v := rv.Array()
// 		for i := 0; i < len(v); i++ {
// 			if v[i].String() != expected[i] {
// 				t.Errorf("expected item at index %d to be \"%s\", got \"%s\"", i, expected[i], v[i].String())
// 			}
// 		}
// 	}
//
// 	// The subscribe function handles subscribing the connection to the given
// 	// channels and patterns and reading/verifying the message sent by the echovault after
// 	// subscription.
// 	subscribe := func(ctx context.Context, channels []string, patterns []string, c *net.Conn, r *resp.Conn) {
// 		// Subscribe to channels
// 		go func() {
// 			_, _ = getHandler("SUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"SUBSCRIBE"}, channels...), c, mockServer))
// 		}()
// 		// Verify all the responses for each channel subscription
// 		for i := 0; i < len(channels); i++ {
// 			verifyEvent(c, r, []string{"subscribe", channels[i], fmt.Sprintf("%d", i+1)})
// 		}
// 		// Subscribe to all the patterns
// 		go func() {
// 			_, _ = getHandler("PSUBSCRIBE")(getHandlerFuncParams(ctx, append([]string{"PSUBSCRIBE"}, patterns...), c, mockServer))
// 		}()
// 		// Verify all the responses for each pattern subscription
// 		for i := 0; i < len(patterns); i++ {
// 			verifyEvent(c, r, []string{"psubscribe", patterns[i], fmt.Sprintf("%d", i+1)})
// 		}
// 	}
//
// 	subscriptions := map[string]map[string][]string{
// 		"subscriber1": {
// 			"channels": {"pub_channel_1", "pub_channel_2", "pub_channel_3"}, // Channels to subscribe to
// 			"patterns": {"pub_channel_[456]"},                               // Patterns to subscribe to
// 		},
// 		"subscriber2": {
// 			"channels": {"pub_channel_6", "pub_channel_7"}, // Channels to subscribe to
// 			"patterns": {"pub_channel_[891]"},              // Patterns to subscribe to
// 		},
// 	}
//
// 	// Create subscriber one and subscribe to channels and patterns
// 	r1, w1 := net.Pipe()
// 	rc1 := resp.NewConn(r1)
// 	subscribe(ctx, subscriptions["subscriber1"]["channels"], subscriptions["subscriber1"]["patterns"], &w1, rc1)
//
// 	// Create subscriber two and subscribe to channels and patterns
// 	r2, w2 := net.Pipe()
// 	rc2 := resp.NewConn(r2)
// 	subscribe(ctx, subscriptions["subscriber2"]["channels"], subscriptions["subscriber2"]["patterns"], &w2, rc2)
//
// 	type SubscriberType struct {
// 		c *net.Conn
// 		r *resp.Conn
// 		l string
// 	}
//
// 	tests := []struct {
// 		channel     string
// 		message     string
// 		subscribers []SubscriberType
// 	}{
// 		{
// 			channel: "pub_channel_1",
// 			message: "Test both subscribers 1",
// 			subscribers: []SubscriberType{
// 				{c: &r1, r: rc1, l: "pub_channel_1"},
// 				{c: &r2, r: rc2, l: "pub_channel_[891]"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_6",
// 			message: "Test both subscribers 2",
// 			subscribers: []SubscriberType{
// 				{c: &r1, r: rc1, l: "pub_channel_[456]"},
// 				{c: &r2, r: rc2, l: "pub_channel_6"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_2",
// 			message: "Test subscriber 1 1",
// 			subscribers: []SubscriberType{
// 				{c: &r1, r: rc1, l: "pub_channel_2"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_3",
// 			message: "Test subscriber 1 2",
// 			subscribers: []SubscriberType{
// 				{c: &r1, r: rc1, l: "pub_channel_3"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_4",
// 			message: "Test both subscribers 2",
// 			subscribers: []SubscriberType{
// 				{c: &r1, r: rc1, l: "pub_channel_[456]"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_5",
// 			message: "Test subscriber 1 3",
// 			subscribers: []SubscriberType{
// 				{c: &r1, r: rc1, l: "pub_channel_[456]"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_7",
// 			message: "Test subscriber 2 1",
// 			subscribers: []SubscriberType{
// 				{c: &r2, r: rc2, l: "pub_channel_7"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_8",
// 			message: "Test subscriber 2 2",
// 			subscribers: []SubscriberType{
// 				{c: &r1, r: rc2, l: "pub_channel_[891]"},
// 			},
// 		},
// 		{
// 			channel: "pub_channel_9",
// 			message: "Test subscriber 2 3",
// 			subscribers: []SubscriberType{
// 				{c: &r2, r: rc2, l: "pub_channel_[891]"},
// 			},
// 		},
// 	}
//
// 	// Dial echovault to make publisher connection
// 	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", bindAddr, port))
// 	if err != nil {
// 		t.Error(err)
// 	}
// 	defer func() {
// 		if err = conn.Close(); err != nil {
// 			t.Error(err)
// 		}
// 	}()
// 	w := resp.NewConn(conn)
//
// 	for _, test := range tests {
// 		err = w.WriteArray([]resp.Value{
// 			resp.StringValue("PUBLISH"),
// 			resp.StringValue(test.channel),
// 			resp.StringValue(test.message),
// 		})
// 		if err != nil {
// 			t.Error(err)
// 		}
//
// 		rv, _, err := w.ReadValue()
// 		if err != nil {
// 			t.Error(err)
// 		}
// 		if rv.String() != "OK" {
// 			t.Errorf("Expected publish response to be \"OK\", got \"%s\"", rv.String())
// 		}
//
// 		for _, sub := range test.subscribers {
// 			verifyEvent(sub.c, sub.r, []string{"message", sub.l, test.message})
// 		}
// 	}
// }

func Test_HandlePubSubChannels(t *testing.T) {
	verifyExpectedResponse := func(res resp.Value, expected []string) {
		if len(res.Array()) != len(expected) {
			t.Errorf("expected response array of length %d, got %d", len(expected), len(res.Array()))
		}
		for _, e := range expected {
			if !slices.ContainsFunc(res.Array(), func(v resp.Value) bool {
				return e == v.String()
			}) {
				t.Errorf("expected to find element \"%s\" in response array, could not find it", e)
			}
		}
	}

	port, _ := internal.GetFreePort()
	mockServer := setUpServer(bindAddr, uint16(port))

	wg := sync.WaitGroup{}
	wg.Add(1)
	go func() {
		wg.Done()
		mockServer.Start()
	}()
	wg.Wait()

	subscribers := make([]*resp.Conn, 2)
	for i := 0; i < len(subscribers); i++ {
		conn, err := internal.GetConnection(bindAddr, port)
		if err != nil {
			t.Error(err)
		}
		subscribers[i] = resp.NewConn(conn)
	}

	channels := []string{"channel_1", "channel_2", "channel_3"}
	patterns := []string{"channel_[123]", "channel_[456]"}

	subscriptions := []struct {
		client   *resp.Conn
		action   string
		channels []string
		patterns []string
	}{
		{
			client:   subscribers[0],
			action:   "SUBSCRIBE",
			channels: channels,
			patterns: make([]string, 0),
		},
		{
			client:   subscribers[1],
			action:   "PSUBSCRIBE",
			channels: make([]string, 0),
			patterns: patterns,
		},
	}
	for _, subscription := range subscriptions {
		command := []resp.Value{resp.StringValue(subscription.action)}
		if len(subscription.channels) > 0 {
			for _, channel := range subscription.channels {
				command = append(command, resp.StringValue(channel))
			}
		} else if len(subscription.patterns) > 0 {
			for _, pattern := range subscription.patterns {
				command = append(command, resp.StringValue(pattern))
			}
		}
		if err := subscription.client.WriteArray(command); err != nil {
			t.Error(err)
		}
		if len(subscription.channels) > 0 {
			for i := 0; i < len(subscription.channels); i++ {
				_, _, _ = subscription.client.ReadValue()
			}
			return
		}
		for i := 0; i < len(subscription.patterns); i++ {
			_, _, _ = subscription.client.ReadValue()
		}
	}

	// Get fresh connection for the next phase.
	conn, err := internal.GetConnection(bindAddr, port)
	if err != nil {
		t.Error(err)
	}
	client := resp.NewConn(conn)

	// Check if all subscriptions are returned.
	if err = client.WriteArray([]resp.Value{resp.StringValue("PUBSUB"), resp.StringValue("CHANNELS")}); err != nil {
		t.Error(err)
	}
	res, _, err := client.ReadValue()
	if err != nil {
		t.Error(err)
	}
	verifyExpectedResponse(res, append(channels, patterns...))

	// Unsubscribe from one pattern and one channel before checking against a new slice of
	// expected channels/patterns in the response of the "PUBSUB CHANNELS" command.
	for _, unsubscribe := range []struct {
		client  *resp.Conn
		command []resp.Value
	}{
		{
			client:  subscribers[0],
			command: []resp.Value{resp.StringValue("UNSUBSCRIBE"), resp.StringValue("channel_2"), resp.StringValue("channel_3")},
		},
		{
			client:  subscribers[1],
			command: []resp.Value{resp.StringValue("UNSUBSCRIBE"), resp.StringValue("channel_[456]")},
		},
	} {
		if err = unsubscribe.client.WriteArray(unsubscribe.command); err != nil {
			t.Error(err)
		}
		for i := 0; i < len(unsubscribe.command[1:]); i++ {
			_, _, err = unsubscribe.client.ReadValue()
			if err != nil {
				t.Error(err)
			}
		}
	}

	// Return all the remaining channels.
	if err = client.WriteArray([]resp.Value{resp.StringValue("PUBSUB"), resp.StringValue("CHANNELS")}); err != nil {
		t.Error(err)
	}
	res, _, err = client.ReadValue()
	if err != nil {
		t.Error(err)
	}
	verifyExpectedResponse(res, []string{"channel_1", "channel_[123]"})

	// Return only one of the remaining channels when passed a pattern that matches it.
	if err = client.WriteArray([]resp.Value{
		resp.StringValue("PUBSUB"),
		resp.StringValue("CHANNELS"),
		resp.StringValue("channel_[189]"),
	}); err != nil {
		t.Error(err)
	}
	verifyExpectedResponse(res, []string{"channel_1"})

	// Return both remaining channels when passed a pattern that matches them.
	if err := client.WriteArray([]resp.Value{
		resp.StringValue("PUBSUB"),
		resp.StringValue("CHANNELS"),
		resp.StringValue("channel_[123]"),
	}); err != nil {
		t.Error(err)
	}
	res, _, err = client.ReadValue()
	if err != nil {
		t.Error(err)
	}
	verifyExpectedResponse(res, []string{"channel_1", "channel_[123]"})

	// Return no channels when passed a pattern that does not match either channel.
	if err = client.WriteArray([]resp.Value{
		resp.StringValue("PUBSUB"),
		resp.StringValue("CHANNELS"),
		resp.StringValue("channel_[456]"),
	}); err != nil {
		t.Error(err)
	}
	res, _, err = client.ReadValue()
	if err != nil {
		t.Error(err)
	}
	verifyExpectedResponse(res, []string{})
}

func Test_HandleNumPat(t *testing.T) {
	port, _ := internal.GetFreePort()
	mockServer := setUpServer(bindAddr, uint16(port))

	wg := sync.WaitGroup{}
	wg.Add(1)
	go func() {
		wg.Done()
		mockServer.Start()
	}()
	wg.Wait()

	// Create subscribers.
	subscribers := make([]*resp.Conn, 3)
	for i := 0; i < len(subscribers); i++ {
		conn, err := internal.GetConnection(bindAddr, port)
		if err != nil {
			t.Error(err)
		}
		subscribers[i] = resp.NewConn(conn)
	}

	patterns := []string{"pattern_[123]", "pattern_[456]", "pattern_[789]"}

	// Subscribe to all patterns
	for _, client := range subscribers {
		command := []resp.Value{resp.StringValue("PSUBSCRIBE")}
		for _, pattern := range patterns {
			command = append(command, resp.StringValue(pattern))
		}
		if err := client.WriteArray(command); err != nil {
			t.Error(err)
		}
		// Read subscription responses to make sure we've subscribed to all the channels.
		for i := 0; i < len(patterns); i++ {
			res, _, err := client.ReadValue()
			if err != nil {
				t.Error(err)
			}
			if len(res.Array()) != 3 {
				t.Errorf("expected array response of length %d, got %d", 3, len(res.Array()))
			}
			if !strings.EqualFold(res.Array()[0].String(), "psubscribe") {
				t.Errorf("expected the first array item to be \"psubscribe\", got \"%s\"", res.Array()[0].String())
			}
			if !slices.Contains(patterns, res.Array()[1].String()) {
				t.Errorf("unexpected channel name \"%s\", expected %v", res.Array()[1].String(), patterns)
			}
		}
	}

	// Get fresh connection for the next phase.
	conn, err := internal.GetConnection(bindAddr, port)
	if err != nil {
		t.Error(err)
	}
	client := resp.NewConn(conn)

	// Check that we receive all the patterns with NUMPAT commands.
	if err = client.WriteArray([]resp.Value{resp.StringValue("PUBSUB"), resp.StringValue("NUMPAT")}); err != nil {
		t.Error(err)
	}
	res, _, err := client.ReadValue()
	if res.Integer() != len(patterns) {
		t.Errorf("expected response \"%d\", got \"%d\"", len(patterns), res.Integer())
	}

	// Unsubscribe all subscribers from one pattern and check if the response is updated.
	for _, subscriber := range subscribers {
		if err = subscriber.WriteArray([]resp.Value{
			resp.StringValue("PUNSUBSCRIBE"),
			resp.StringValue(patterns[0]),
		}); err != nil {
			t.Error(err)
		}
		res, _, err = subscriber.ReadValue()
		if err != nil {
			t.Error(err)
		}
		if len(res.Array()[0].Array()) != 3 {
			t.Errorf("expected array response of length %d, got %d", 3, len(res.Array()[0].Array()))
		}
		if !strings.EqualFold(res.Array()[0].Array()[0].String(), "punsubscribe") {
			t.Errorf("expected the first array item to be \"punsubscribe\", got \"%s\"", res.Array()[0].Array()[0].String())
		}
		if res.Array()[0].Array()[1].String() != patterns[0] {
			t.Errorf("unexpected channel name \"%s\", expected %s", res.Array()[0].Array()[1].String(), patterns[0])
		}
	}
	if err = client.WriteArray([]resp.Value{resp.StringValue("PUBSUB"), resp.StringValue("NUMPAT")}); err != nil {
		t.Error(err)
	}
	res, _, err = client.ReadValue()
	if res.Integer() != len(patterns)-1 {
		t.Errorf("expected response \"%d\", got \"%d\"", len(patterns)-1, res.Integer())
	}

	// Unsubscribe from all the channels and check if we get a 0 response
	for _, subscriber := range subscribers {
		for _, pattern := range patterns[1:] {
			if err = subscriber.WriteArray([]resp.Value{
				resp.StringValue("PUNSUBSCRIBE"),
				resp.StringValue(pattern),
			}); err != nil {
				t.Error(err)
			}
			res, _, err = subscriber.ReadValue()
			if err != nil {
				t.Error(err)
			}
			if len(res.Array()[0].Array()) != 3 {
				t.Errorf("expected array response of length %d, got %d", 3,
					len(res.Array()[0].Array()))
			}
			if !strings.EqualFold(res.Array()[0].Array()[0].String(), "punsubscribe") {
				t.Errorf("expected the first array item to be \"punsubscribe\", got \"%s\"",
					res.Array()[0].Array()[0].String())
			}
			if res.Array()[0].Array()[1].String() != pattern {
				t.Errorf("unexpected channel name \"%s\", expected %s",
					res.Array()[0].Array()[1].String(), pattern)
			}
		}
	}
	if err = client.WriteArray([]resp.Value{resp.StringValue("PUBSUB"), resp.StringValue("NUMPAT")}); err != nil {
		t.Error(err)
	}
	res, _, err = client.ReadValue()
	if res.Integer() != 0 {
		t.Errorf("expected response \"%d\", got \"%d\"", 0, res.Integer())
	}
}

func Test_HandleNumSub(t *testing.T) {
	port, _ := internal.GetFreePort()
	mockServer := setUpServer(bindAddr, uint16(port))

	wg := sync.WaitGroup{}
	wg.Add(1)
	go func() {
		wg.Done()
		mockServer.Start()
	}()
	wg.Wait()

	channels := []string{"channel_1", "channel_2", "channel_3"}

	for i := 0; i < 3; i++ {
		conn, err := internal.GetConnection(bindAddr, port)
		if err != nil {
			t.Error(err)
		}
		client := resp.NewConn(conn)
		command := []resp.Value{
			resp.StringValue("SUBSCRIBE"),
		}
		for _, channel := range channels {
			command = append(command, resp.StringValue(channel))
		}
		err = client.WriteArray(command)
		if err != nil {
			t.Error(err)
		}

		// Read subscription responses to make sure we've subscribed to all the channels.
		for i := 0; i < len(channels); i++ {
			res, _, err := client.ReadValue()
			if err != nil {
				t.Error(err)
			}
			if len(res.Array()) != 3 {
				t.Errorf("expected array response of length %d, got %d", 3, len(res.Array()))
			}
			if !strings.EqualFold(res.Array()[0].String(), "subscribe") {
				t.Errorf("expected the first array item to be \"subscribe\", got \"%s\"", res.Array()[0].String())
			}
			if !slices.Contains(channels, res.Array()[1].String()) {
				t.Errorf("unexpected channel name \"%s\", expected %v", res.Array()[1].String(), channels)
			}
		}
	}

	// Get fresh connection for the next phase.
	conn, err := internal.GetConnection(bindAddr, port)
	if err != nil {
		t.Error(err)
	}
	client := resp.NewConn(conn)

	tests := []struct {
		name             string
		cmd              []string
		expectedResponse [][]string
	}{
		{
			name:             "1. Get all subscriptions on existing channels",
			cmd:              append([]string{"PUBSUB", "NUMSUB"}, channels...),
			expectedResponse: [][]string{{"channel_1", "3"}, {"channel_2", "3"}, {"channel_3", "3"}},
		},
		{
			name: "2. Get all the subscriptions of on existing channels and a few non-existent ones",
			cmd:  append([]string{"PUBSUB", "NUMSUB", "non_existent_channel_1", "non_existent_channel_2"}, channels...),
			expectedResponse: [][]string{
				{"non_existent_channel_1", "0"},
				{"non_existent_channel_2", "0"},
				{"channel_1", "3"},
				{"channel_2", "3"},
				{"channel_3", "3"},
			},
		},
		{
			name:             "3. Get an empty array when channels are not provided in the command",
			cmd:              []string{"PUBSUB", "NUMSUB"},
			expectedResponse: make([][]string, 0),
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			var command []resp.Value
			for _, token := range test.cmd {
				command = append(command, resp.StringValue(token))
			}

			if err = client.WriteArray(command); err != nil {
				t.Error(err)
			}

			res, _, err := client.ReadValue()
			if err != nil {
				t.Error(err)
			}

			arr := res.Array()
			if len(arr) != len(test.expectedResponse) {
				t.Errorf("expected response array of length %d, got %d", len(test.expectedResponse), len(arr))
			}

			for _, item := range arr {
				itemArr := item.Array()
				if len(itemArr) != 2 {
					t.Errorf("expected each response item to be of length 2, got %d", len(itemArr))
				}
				if !slices.ContainsFunc(test.expectedResponse, func(expected []string) bool {
					return expected[0] == itemArr[0].String() && expected[1] == itemArr[1].String()
				}) {
					t.Errorf("could not find entry with channel \"%s\", with %d subscribers in expected response",
						itemArr[0].String(), itemArr[1].Integer())
				}
			}
		})
	}
}