// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT

//go:build !wasm
// +build !wasm

package vnet

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"net"
	"os"
	"sync"
	"testing"
	"time"

	"github.com/pion/logging"
	"github.com/stretchr/testify/assert"
)

type MockUDPEchoServer struct {
	realServerAddr        *net.UDPAddr
	realServerReady       context.Context //nolint:containedctx // this is a test context...
	realServerReadyCancel context.CancelFunc
}

func NewMockUDPEchoServer() *MockUDPEchoServer {
	v := &MockUDPEchoServer{}
	v.realServerReady, v.realServerReadyCancel = context.WithCancel(context.Background())

	return v
}

func (v *MockUDPEchoServer) doMockUDPServer(ctx context.Context) error { //nolint:cyclop
	// Listen to a random port.
	laddr, err := net.ResolveUDPAddr("udp4", "127.0.0.1:0")
	if err != nil {
		return err
	}

	conn, err := net.ListenUDP("udp4", laddr)
	if err != nil {
		return err
	}

	v.realServerAddr = conn.LocalAddr().(*net.UDPAddr) //nolint:forcetypeassert
	v.realServerReadyCancel()

	// When system quit, interrupt client.
	selfKill, selfKillCancel := context.WithCancel(context.Background())
	go func() {
		<-ctx.Done()
		selfKillCancel()
		_ = conn.Close()
	}()

	// Note that if they has the same ID, the address should not changed.
	addrs := make(map[string]net.Addr)

	// Start an echo UDP server.
	buf := make([]byte, 1500)
	for ctx.Err() == nil {
		n, addr, err := conn.ReadFrom(buf)
		if err != nil {
			if errors.Is(selfKill.Err(), context.Canceled) {
				return nil
			}

			return err
		} else if n == 0 || addr == nil {
			return fmt.Errorf("n=%v, addr=%v", n, addr) // nolint:err113
		} else if nn, err := conn.WriteTo(buf[:n], addr); err != nil {
			return err
		} else if nn != n {
			return fmt.Errorf("nn=%v, n=%v", nn, n) // nolint:err113
		}

		// Check the address, should not change, use content as ID.
		clientID := string(buf[:n])
		if oldAddr, ok := addrs[clientID]; ok && oldAddr.String() != addr.String() {
			return fmt.Errorf("address change %v to %v", oldAddr.String(), addr.String()) // nolint:err113
		}
		addrs[clientID] = addr
	}

	return nil
}

var testTimeout = flag.Int("timeout", 5000, "For each case, the timeout in ms") // nolint:gochecknoglobals

func TestMain(m *testing.M) {
	flag.Parse()
	os.Exit(m.Run()) //nolint:forbidigo
}

// vnet client:
//
//	10.0.0.11:5787
//
// proxy to real server:
//
//	192.168.1.10:8000
//
// .
func TestUDPProxyOne2One(t *testing.T) { //nolint:gocyclo,cyclop
	ctx, cancel := context.WithCancel(context.Background())

	var r0, r1, r2 error
	defer func() {
		assert.NoErrorf(t, r0, "fail for ctx=%v, r0=%v", ctx.Err(), r0)
		assert.NoErrorf(t, r1, "fail for ctx=%v, r1=%v", ctx.Err(), r1)
		assert.NoErrorf(t, r2, "fail for ctx=%v, r2=%v", ctx.Err(), r2)
	}()

	var wg sync.WaitGroup
	defer wg.Wait()

	// Timeout, fail
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()

		select {
		case <-ctx.Done():
		case <-time.After(time.Duration(*testTimeout) * time.Millisecond):
			r2 = fmt.Errorf("timeout") // nolint:err113
		}
	}()

	// For utest, we always proxy vnet packets to the random port we listen to.
	mockServer := NewMockUDPEchoServer()
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()
		if err := mockServer.doMockUDPServer(ctx); err != nil {
			r0 = err
		}
	}()

	// Create a vent and proxy.
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()

		// When real server is ready, start the vnet test.
		select {
		case <-ctx.Done():
			return
		case <-mockServer.realServerReady.Done():
		}

		doVnetProxy := func() error {
			router, err := NewRouter(&RouterConfig{
				CIDR:          "0.0.0.0/0",
				LoggerFactory: logging.NewDefaultLoggerFactory(),
			})
			if err != nil {
				return err
			}

			clientNetwork, err := NewNet(&NetConfig{
				StaticIP: "10.0.0.11",
			})
			if err != nil {
				return err
			}

			if err = router.AddNet(clientNetwork); err != nil {
				return err
			}

			if err = router.Start(); err != nil {
				return err
			}
			defer router.Stop() // nolint:errcheck

			proxy, err := NewProxy(router)
			if err != nil {
				return err
			}
			defer proxy.Close() // nolint:errcheck

			// For utest, mock the target real server.
			proxy.mockRealServerAddr = mockServer.realServerAddr

			// The real server address to proxy to.
			// Note that for utest, we will proxy to a local address.
			serverAddr, err := net.ResolveUDPAddr("udp4", "192.168.1.10:8000")
			if err != nil {
				return err
			}

			if err = proxy.Proxy(clientNetwork, serverAddr); err != nil { //nolint:contextcheck
				return err
			}

			// Now, all packets from client, will be proxy to real server, vice versa.
			client, err := clientNetwork.ListenPacket("udp4", "10.0.0.11:5787")
			if err != nil {
				return err
			}

			// When system quit, interrupt client.
			selfKill, selfKillCancel := context.WithCancel(context.Background())
			go func() {
				<-ctx.Done()
				selfKillCancel()
				_ = client.Close() // nolint:errcheck
			}()

			for i := 0; i < 10; i++ {
				if _, err = client.WriteTo([]byte("Hello"), serverAddr); err != nil {
					return err
				}

				var n int
				var addr net.Addr
				buf := make([]byte, 1500)
				if n, addr, err = client.ReadFrom(buf); err != nil { // nolint:gocritic
					if errors.Is(selfKill.Err(), context.Canceled) {
						return nil
					}

					return err
				} else if n != 5 || addr == nil {
					return fmt.Errorf("n=%v, addr=%v", n, addr) // nolint:err113
				} else if string(buf[:n]) != "Hello" {
					return fmt.Errorf("data %v", buf[:n]) // nolint:err113
				}

				// Wait for awhile for each UDP packet, to simulate real network.
				select {
				case <-ctx.Done():
					return nil
				case <-time.After(30 * time.Millisecond):
				}
			}

			return err
		}

		if err := doVnetProxy(); err != nil {
			r1 = err
		}
	}()
}

// vnet client:
//
//	10.0.0.11:5787
//	10.0.0.11:5788
//
// proxy to real server:
//
//	192.168.1.10:8000
func TestUDPProxyTwo2One(t *testing.T) { //nolint:gocyclo,cyclop
	ctx, cancel := context.WithCancel(context.Background())

	var r0, r1, r2, r3 error
	defer func() {
		assert.NoErrorf(t, r0, "fail for ctx=%v, r0=%v", ctx.Err(), r0)
		assert.NoErrorf(t, r1, "fail for ctx=%v, r1=%v", ctx.Err(), r1)
		assert.NoErrorf(t, r2, "fail for ctx=%v, r2=%v", ctx.Err(), r2)
		assert.NoErrorf(t, r3, "fail for ctx=%v, r3=%v", ctx.Err(), r3)
	}()

	var wg sync.WaitGroup
	defer wg.Wait()

	// Timeout, fail
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()

		select {
		case <-ctx.Done():
		case <-time.After(time.Duration(*testTimeout) * time.Millisecond):
			r2 = fmt.Errorf("timeout") // nolint:err113
		}
	}()

	// For utest, we always proxy vnet packets to the random port we listen to.
	mockServer := NewMockUDPEchoServer()
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()
		if err := mockServer.doMockUDPServer(ctx); err != nil {
			r0 = err
		}
	}()

	// Create a vent and proxy.
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()

		// When real server is ready, start the vnet test.
		select {
		case <-ctx.Done():
			return
		case <-mockServer.realServerReady.Done():
		}

		doVnetProxy := func() error {
			router, err := NewRouter(&RouterConfig{
				CIDR:          "0.0.0.0/0",
				LoggerFactory: logging.NewDefaultLoggerFactory(),
			})
			if err != nil {
				return err
			}

			clientNetwork, err := NewNet(&NetConfig{
				StaticIP: "10.0.0.11",
			})
			if err != nil {
				return err
			}

			if err = router.AddNet(clientNetwork); err != nil {
				return err
			}

			if err = router.Start(); err != nil {
				return err
			}
			defer router.Stop() // nolint:errcheck

			proxy, err := NewProxy(router)
			if err != nil {
				return err
			}
			defer proxy.Close() // nolint:errcheck

			// For utest, mock the target real server.
			proxy.mockRealServerAddr = mockServer.realServerAddr

			// The real server address to proxy to.
			// Note that for utest, we will proxy to a local address.
			serverAddr, err := net.ResolveUDPAddr("udp4", "192.168.1.10:8000")
			if err != nil {
				return err
			}

			if err = proxy.Proxy(clientNetwork, serverAddr); err != nil { //nolint:contextcheck
				return err
			}

			handClient := func(address, echoData string) error {
				// Now, all packets from client, will be proxy to real server, vice versa.
				client, err := clientNetwork.ListenPacket("udp4", address) // nolint:govet
				if err != nil {
					return err
				}

				// When system quit, interrupt client.
				selfKill, selfKillCancel := context.WithCancel(context.Background())
				go func() {
					<-ctx.Done()
					selfKillCancel()
					_ = client.Close()
				}()

				for i := 0; i < 10; i++ {
					if _, err := client.WriteTo([]byte(echoData), serverAddr); err != nil { // nolint:govet
						return err
					}

					var n int
					var addr net.Addr
					buf := make([]byte, 1400)
					if n, addr, err = client.ReadFrom(buf); err != nil { // nolint:gocritic
						if errors.Is(selfKill.Err(), context.Canceled) {
							return nil
						}

						return err
					} else if n != len(echoData) || addr == nil {
						return fmt.Errorf("n=%v, addr=%v", n, addr) // nolint:err113
					} else if string(buf[:n]) != echoData {
						return fmt.Errorf("check data %v", buf[:n]) // nolint:err113
					}

					// Wait for awhile for each UDP packet, to simulate real network.
					select {
					case <-ctx.Done():
						return nil
					case <-time.After(30 * time.Millisecond):
					}
				}

				return nil
			}

			client0, client0Cancel := context.WithCancel(context.Background())
			go func() {
				defer client0Cancel()
				address := "10.0.0.11:5787"
				if handClientErr := handClient(address, "Hello"); handClientErr != nil {
					r3 = fmt.Errorf("client %v err %w", address, handClientErr)
				}
			}()

			client1, client1Cancel := context.WithCancel(context.Background())
			go func() {
				defer client1Cancel()
				address := "10.0.0.11:5788"
				if handClientErr := handClient(address, "World"); handClientErr != nil {
					r3 = fmt.Errorf("client %v err %w", address, handClientErr)
				}
			}()

			select {
			case <-ctx.Done():
			case <-client0.Done():
			case <-client1.Done():
			}

			return err
		}

		if err := doVnetProxy(); err != nil {
			r1 = err
		}
	}()
}

// vnet client:
//
//	10.0.0.11:5787
//
// proxy to real server:
//
//	192.168.1.10:8000
//
// vnet client:
//
//	10.0.0.11:5788
//
// proxy to real server:
//
//	192.168.1.10:8000
func TestUDPProxyProxyTwice(t *testing.T) { //nolint:gocyclo,cyclop
	ctx, cancel := context.WithCancel(context.Background())

	var r0, r1, r2, r3 error
	defer func() {
		assert.NoErrorf(t, r0, "fail for ctx=%v, r0=%v", ctx.Err(), r0)
		assert.NoErrorf(t, r1, "fail for ctx=%v, r1=%v", ctx.Err(), r1)
		assert.NoErrorf(t, r2, "fail for ctx=%v, r2=%v", ctx.Err(), r2)
		assert.NoErrorf(t, r3, "fail for ctx=%v, r3=%v", ctx.Err(), r3)
	}()

	var wg sync.WaitGroup
	defer wg.Wait()

	// Timeout, fail
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()

		select {
		case <-ctx.Done():
		case <-time.After(time.Duration(*testTimeout) * time.Millisecond):
			r2 = fmt.Errorf("timeout") // nolint:err113
		}
	}()

	// For utest, we always proxy vnet packets to the random port we listen to.
	mockServer := NewMockUDPEchoServer()
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()
		if err := mockServer.doMockUDPServer(ctx); err != nil {
			r0 = err
		}
	}()

	// Create a vent and proxy.
	wg.Add(1)
	go func() {
		defer wg.Done()
		defer cancel()

		// When real server is ready, start the vnet test.
		select {
		case <-ctx.Done():
			return
		case <-mockServer.realServerReady.Done():
		}

		doVnetProxy := func() error {
			router, err := NewRouter(&RouterConfig{
				CIDR:          "0.0.0.0/0",
				LoggerFactory: logging.NewDefaultLoggerFactory(),
			})
			if err != nil {
				return err
			}

			clientNetwork, err := NewNet(&NetConfig{
				StaticIP: "10.0.0.11",
			})
			if err != nil {
				return err
			}

			if err = router.AddNet(clientNetwork); err != nil {
				return err
			}

			if err = router.Start(); err != nil {
				return err
			}
			defer router.Stop() // nolint:errcheck

			proxy, err := NewProxy(router)
			if err != nil {
				return err
			}
			defer proxy.Close() // nolint:errcheck

			// For utest, mock the target real server.
			proxy.mockRealServerAddr = mockServer.realServerAddr

			// The real server address to proxy to.
			// Note that for utest, we will proxy to a local address.
			serverAddr, err := net.ResolveUDPAddr("udp4", "192.168.1.10:8000")
			if err != nil {
				return err
			}

			handClient := func(address, echoData string) error {
				// We proxy multiple times, for example, in publisher and player, both call
				// the proxy when got answer.
				if handClientErr := proxy.Proxy(clientNetwork, serverAddr); handClientErr != nil { //nolint:contextcheck
					return handClientErr
				}

				// Now, all packets from client, will be proxy to real server, vice versa.
				client, handClientErr := clientNetwork.ListenPacket("udp4", address) // nolint:govet
				if handClientErr != nil {
					return handClientErr
				}

				// When system quit, interrupt client.
				selfKill, selfKillCancel := context.WithCancel(context.Background())
				go func() {
					<-ctx.Done()
					selfKillCancel()
					_ = client.Close() // nolint:errcheck
				}()

				for i := 0; i < 10; i++ {
					if _, handClientErr = client.WriteTo([]byte(echoData), serverAddr); handClientErr != nil {
						return handClientErr
					}

					buf := make([]byte, 1500)
					if n, addr, handClientErr := client.ReadFrom(buf); handClientErr != nil { // nolint:gocritic,govet
						if errors.Is(selfKill.Err(), context.Canceled) {
							return nil
						}

						return handClientErr
					} else if n != len(echoData) || addr == nil {
						return fmt.Errorf("n=%v, addr=%v", n, addr) // nolint:err113
					} else if string(buf[:n]) != echoData {
						return fmt.Errorf("verify data %v", buf[:n]) // nolint:err113
					}

					// Wait for awhile for each UDP packet, to simulate real network.
					select {
					case <-ctx.Done():
						return nil
					case <-time.After(30 * time.Millisecond):
					}
				}

				return nil
			}

			client0, client0Cancel := context.WithCancel(context.Background())
			go func() {
				defer client0Cancel()
				address := "10.0.0.11:5787"
				if err = handClient(address, "Hello"); err != nil {
					r3 = fmt.Errorf("client %v err %w", address, err)
				}
			}()

			client1, client1Cancel := context.WithCancel(context.Background())
			go func() {
				defer client1Cancel()

				// Slower than client0, 60ms.
				// To simulate the real player or publisher, might not start at the same time.
				select {
				case <-ctx.Done():
					return
				case <-time.After(150 * time.Millisecond):
				}

				address := "10.0.0.11:5788"
				if err = handClient(address, "World"); err != nil {
					r3 = fmt.Errorf("client %v err %w", address, err) // nolint:err113
				}
			}()

			select {
			case <-ctx.Done():
			case <-client0.Done():
			case <-client1.Done():
			}

			return err
		}

		if err := doVnetProxy(); err != nil {
			r1 = err
		}
	}()
}