package toki_socket

import (
	"context"
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/tls"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/binary"
	"encoding/pem"
	"io"
	"math/big"
	"net"
	"testing"
	"time"

	"google.golang.org/protobuf/proto"
	"nhooyr.io/websocket"

	"toki-labs.com/toki_socket/go/packets"
)

func TestTcpRequestResponse(t *testing.T) {
	port := freePort(t)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	server := NewTcpServer("127.0.0.1", port, func(conn net.Conn) *TcpClient {
		return NewTcpClient(conn, 0, 0, testParserMap())
	})
	server.OnClientConnected = func(client *TcpClient) {
		AddRequestListenerTyped[*packets.TestData, *packets.TestData](&client.Communicator, func(req *packets.TestData) (*packets.TestData, error) {
			return &packets.TestData{
				Index:   req.GetIndex() * 2,
				Message: "echo: " + req.GetMessage(),
			}, nil
		})
	}
	if err := server.Start(ctx); err != nil {
		t.Fatal(err)
	}
	defer server.Stop()

	client, err := DialTcp(ctx, "127.0.0.1", port, 0, 0, testParserMap())
	if err != nil {
		t.Fatal(err)
	}
	defer client.Close()

	res, err := SendRequestTyped[*packets.TestData, *packets.TestData](
		&client.Communicator,
		&packets.TestData{Index: 21, Message: "hello"},
		2*time.Second,
	)
	if err != nil {
		t.Fatal(err)
	}
	if res.GetIndex() != 42 || res.GetMessage() != "echo: hello" {
		t.Fatalf("unexpected response: %v", res)
	}
}

func TestTcpBroadcast(t *testing.T) {
	port := freePort(t)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	server := NewTcpServer("127.0.0.1", port, func(conn net.Conn) *TcpClient {
		return NewTcpClient(conn, 0, 0, testParserMap())
	})
	if err := server.Start(ctx); err != nil {
		t.Fatal(err)
	}
	defer server.Stop()

	client, err := DialTcp(ctx, "127.0.0.1", port, 0, 0, testParserMap())
	if err != nil {
		t.Fatal(err)
	}
	defer client.Close()

	received := make(chan *packets.TestData, 1)
	AddListenerTyped[*packets.TestData](&client.Communicator, func(m *packets.TestData) {
		received <- m
	})

	for deadline := time.Now().Add(time.Second); time.Now().Before(deadline) && len(server.Clients()) == 0; {
		time.Sleep(time.Millisecond)
	}
	if err := server.Broadcast(&packets.TestData{Index: 9, Message: "broadcast"}); err != nil {
		t.Fatal(err)
	}

	select {
	case msg := <-received:
		if msg.GetMessage() != "broadcast" {
			t.Fatalf("unexpected broadcast: %v", msg)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("broadcast timed out")
	}
}

func TestTcpBroadcastAttemptsAllClients(t *testing.T) {
	badConn, badPeer := net.Pipe()
	badClient := NewTcpClient(badConn, 0, 0, testParserMap())
	_ = badClient.Close()
	_ = badPeer.Close()

	goodConn, goodPeer := net.Pipe()
	defer goodPeer.Close()
	goodClient := NewTcpClient(goodConn, 0, 0, testParserMap())
	defer goodClient.Close()

	received := make(chan *packets.PacketBase, 1)
	go func() {
		base, err := readTCPPacket(goodPeer)
		if err == nil {
			received <- base
		}
	}()

	server := &TcpServer{clients: []*TcpClient{badClient, goodClient}}
	err := server.Broadcast(&packets.TestData{Index: 9, Message: "best effort"})
	if err == nil {
		t.Fatal("expected broadcast to report the failed client")
	}

	select {
	case base := <-received:
		if base.GetTypeName() != TypeNameOf(&packets.TestData{}) {
			t.Fatalf("unexpected packet type: %s", base.GetTypeName())
		}
	case <-time.After(2 * time.Second):
		t.Fatal("broadcast did not attempt the healthy client")
	}
}

func TestWsRequestResponse(t *testing.T) {
	port := freePort(t)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	server := NewWsServer("127.0.0.1", port, "/", func(conn *websocket.Conn) *WsClient {
		return NewWsClient(conn, 0, 0, testParserMap())
	})
	server.OnClientConnected = func(client *WsClient) {
		AddRequestListenerTyped[*packets.TestData, *packets.TestData](&client.Communicator, func(req *packets.TestData) (*packets.TestData, error) {
			return &packets.TestData{
				Index:   req.GetIndex() * 2,
				Message: "echo: " + req.GetMessage(),
			}, nil
		})
	}
	if err := server.Start(ctx); err != nil {
		t.Fatal(err)
	}
	defer server.Stop()

	client, err := DialWsWithHeartbeat(ctx, "127.0.0.1", port, "/", 0, 0, testParserMap())
	if err != nil {
		t.Fatal(err)
	}
	defer client.Close()

	res, err := SendRequestTyped[*packets.TestData, *packets.TestData](
		&client.Communicator,
		&packets.TestData{Index: 21, Message: "hello ws"},
		2*time.Second,
	)
	if err != nil {
		t.Fatal(err)
	}
	if res.GetIndex() != 42 || res.GetMessage() != "echo: hello ws" {
		t.Fatalf("unexpected response: %v", res)
	}
}

func TestTcpSendReceive(t *testing.T) {
	port := freePort(t)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	received := make(chan *packets.TestData, 1)
	server := NewTcpServer("127.0.0.1", port, func(conn net.Conn) *TcpClient {
		return NewTcpClient(conn, 0, 0, testParserMap())
	})
	server.OnClientConnected = func(client *TcpClient) {
		AddListenerTyped[*packets.TestData](&client.Communicator, func(m *packets.TestData) {
			received <- m
		})
	}
	if err := server.Start(ctx); err != nil {
		t.Fatal(err)
	}
	defer server.Stop()

	client, err := DialTcp(ctx, "127.0.0.1", port, 0, 0, testParserMap())
	if err != nil {
		t.Fatal(err)
	}
	defer client.Close()

	if err := client.Send(&packets.TestData{Index: 42, Message: "hello toki-socket"}); err != nil {
		t.Fatal(err)
	}

	select {
	case msg := <-received:
		if msg.GetIndex() != 42 {
			t.Fatalf("unexpected message: %v", msg)
		}
	case <-time.After(2 * time.Second):
		t.Fatal("receive timed out")
	}
}

func TestHeartbeatDisconnectsWithoutResponse(t *testing.T) {
	clientConn, peerConn := net.Pipe()
	defer peerConn.Close()

	go func() {
		_, _ = io.Copy(io.Discard, peerConn)
	}()

	client := NewTcpClient(clientConn, 1, 1, testParserMap())
	defer client.Close()

	disconnected := make(chan struct{}, 1)
	client.AddDisconnectListener(func(*TcpClient) {
		disconnected <- struct{}{}
	})

	select {
	case <-disconnected:
	case <-time.After(3500 * time.Millisecond):
		t.Fatal("heartbeat timeout did not disconnect client")
	}
	if client.IsAlive() {
		t.Fatal("client is still marked alive after heartbeat timeout")
	}
}

func TestTypeNameMatchesDartConvention(t *testing.T) {
	if got := TypeNameOf(&packets.TestData{}); got != "TestData" {
		t.Fatalf("type name = %q, want TestData", got)
	}
}

func freePort(t *testing.T) int {
	t.Helper()
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()
	return ln.Addr().(*net.TCPAddr).Port
}

func readTCPPacket(conn net.Conn) (*packets.PacketBase, error) {
	header := make([]byte, 4)
	if _, err := io.ReadFull(conn, header); err != nil {
		return nil, err
	}
	length := binary.BigEndian.Uint32(header)
	packetBytes := make([]byte, int(length))
	if _, err := io.ReadFull(conn, packetBytes); err != nil {
		return nil, err
	}
	base := &packets.PacketBase{}
	if err := proto.Unmarshal(packetBytes, base); err != nil {
		return nil, err
	}
	return base, nil
}

// generateSelfSignedCert creates an in-memory self-signed certificate valid
// for 127.0.0.1. Returns the server tls.Config and a client tls.Config that
// trusts the generated certificate.
func generateSelfSignedCert(t *testing.T) (serverCfg, clientCfg *tls.Config) {
	t.Helper()

	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	if err != nil {
		t.Fatal(err)
	}

	tmpl := &x509.Certificate{
		SerialNumber: big.NewInt(1),
		Subject:      pkix.Name{CommonName: "toki-socket-test"},
		NotBefore:    time.Now().Add(-time.Hour),
		NotAfter:     time.Now().Add(time.Hour),
		IPAddresses:  []net.IP{net.ParseIP("127.0.0.1")},
	}

	certDER, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &priv.PublicKey, priv)
	if err != nil {
		t.Fatal(err)
	}
	privDER, err := x509.MarshalECPrivateKey(priv)
	if err != nil {
		t.Fatal(err)
	}

	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER})
	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: privDER})

	cert, err := tls.X509KeyPair(certPEM, keyPEM)
	if err != nil {
		t.Fatal(err)
	}

	serverCfg = &tls.Config{Certificates: []tls.Certificate{cert}}

	pool := x509.NewCertPool()
	parsed, err := x509.ParseCertificate(certDER)
	if err != nil {
		t.Fatal(err)
	}
	pool.AddCert(parsed)
	clientCfg = &tls.Config{RootCAs: pool, ServerName: "127.0.0.1"}

	return serverCfg, clientCfg
}

func TestTLSTcp(t *testing.T) {
	port := freePort(t)
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	serverTLS, clientTLS := generateSelfSignedCert(t)

	server := NewTcpServerTLS("127.0.0.1", port, serverTLS, func(conn net.Conn) *TcpClient {
		return NewTcpClient(conn, 0, 0, testParserMap())
	})
	server.OnClientConnected = func(client *TcpClient) {
		AddRequestListenerTyped[*packets.TestData, *packets.TestData](&client.Communicator, func(req *packets.TestData) (*packets.TestData, error) {
			return &packets.TestData{
				Index:   req.GetIndex() * 2,
				Message: "tls-echo: " + req.GetMessage(),
			}, nil
		})
	}
	if err := server.Start(ctx); err != nil {
		t.Fatal(err)
	}
	defer server.Stop()

	client, err := DialTcpTLS(ctx, "127.0.0.1", port, clientTLS, 0, 0, testParserMap())
	if err != nil {
		t.Fatal(err)
	}
	defer client.Close()

	res, err := SendRequestTyped[*packets.TestData, *packets.TestData](
		&client.Communicator,
		&packets.TestData{Index: 7, Message: "hello tls"},
		2*time.Second,
	)
	if err != nil {
		t.Fatal(err)
	}
	if res.GetIndex() != 14 || res.GetMessage() != "tls-echo: hello tls" {
		t.Fatalf("unexpected response: %v", res)
	}
}