go-bbs/main.go

package main

import (
	"bufio"
	"context"
	"flag"
	"log"
	"net"
	"os/exec"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/xtaci/gaio"
	"versestudios.com/go-telnet-asyncio-test/openconn"
)

type InChanKey string
type OutChanKey string

func ioHandler(w *gaio.Watcher, WatcherControl *chan string) {
	for {
		select {
		case msg := <-*WatcherControl:
			switch msg {
			case "":
				log.Println("empty WatcherControl command")
			case "stop":
				log.Println("stopping ioHandler via WatcherControl stop command")
				return
			default:
				log.Println("unknown WatcherControl command:", msg)
			}
		default:
			// loop wait for any IO events
			results, err := w.WaitIO()
			if err != nil {
				log.Println(err)
				return
			}

		IOLoop:
			for _, res := range results {
				if res.Context != nil && nil != res.Context.(context.Context) {
					if inChan, _, ok := openconn.FromContext(res.Context.(context.Context)); ok {
						switch res.Operation {
						case gaio.OpRead: // read completion event
							inChan <- res
							// queue next read
							w.Read(res.Context, res.Conn, nil)
						default: // anything else (meaning write completions)
							continue IOLoop
						}
					} else {
						log.Printf("error getting inChan and outChan from context: %v\n", res.Context)
					}
				} else {
					log.Printf("nil context! res: %v\n", res)
				}
			}
		}
		time.Sleep(time.Millisecond)
	}
}

func main() {
	port := flag.Int("port", 3333, "Port to accept connections on.")
	host := flag.String("host", "127.0.0.1", "Host or IP to bind to")
	flag.Parse()

	w, err := gaio.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}
	defer w.Close()

	l, err := net.Listen("tcp", *host+":"+strconv.Itoa(*port))
	if err != nil {
		log.Panicln(err)
	}
	log.Println("Listening to connections at '"+*host+"' on port", strconv.Itoa(*port))
	defer l.Close()

	for {
		conn, err := l.Accept()
		if err != nil {
			log.Panicln(err)
		}

		log.Println("new client: ", conn.RemoteAddr())
		// chan to terminate ioHandler when neccessary
		WatcherControl := make(chan string)

		// get new context with inChan and outChan for this client connection
		ctx := openconn.NewContext(context.Background())
		log.Printf("new context for client %v: %v\n", conn.RemoteAddr(), ctx)

		// submit the first async write IO request
		err = w.Write(ctx, conn, welcomeHandler())
		if err != nil {
			log.Printf("err sending welcomeHandler: %v\n", err)
			return
		}
		// now that a prompt is (or will be) displayed, go ahead and listen for input
		err = w.Read(ctx, conn, nil)
		if err != nil {
			log.Printf("err queueing w.Read: %v\n", err)
			return
		}

		time.Sleep(time.Millisecond)

		// menu handler for this connection
		go menuHandler(ctx, conn, w)
		// io handler for this connection
		go ioHandler(w, &WatcherControl)

		log.Println("main thread looping")
		//		wg.Wait()
		//		log.Printf("Goodbye %s!", conn.RemoteAddr())
	}
}

func menuHandler(ctx context.Context, conn net.Conn, w *gaio.Watcher) {
	var wg sync.WaitGroup

	MenuControl := make(chan string)

	var inChan, outChan chan gaio.OpResult
	var ok bool

	if inChan, outChan, ok = openconn.FromContext(ctx); !ok {
		log.Println("Could not get inChan/outChan from context!", ok, ctx)
	}

	wg.Add(1)
	go func(inChan, outChan chan gaio.OpResult, MenuControl chan string) {
		defer wg.Done()
		log.Println("starting menu loop")
		paused := false
	ControlLoop:
		for {
			//				log.Println("checking watcher waitio")
			select {
			case msg := <-MenuControl:
				log.Println("msg on MenuControl:", msg)
				switch string(msg) {

				case "stop":
					log.Println("closing menu loop")
					paused = true
					break ControlLoop

				case "pause":
					log.Println("pausing menu loop via menucontrol")
					paused = true

				case "unpause":
					log.Println("unpausing menu loop via menucontrol")
					paused = false

				default:
					log.Println("menu received unknown command: ", msg)
				}

			default:
				//					log.Println("no msg on MenuControl, continuing")
				if !paused {
					//						log.Println("menu watchercontrol waiting for IO")
					select {
					case res := <-inChan:
						if res.Error != nil {
							log.Println("error on inChan: ", res.Error)
						}
						if res.Operation == gaio.OpRead && res.Size > 0 && res.Conn == conn {
							log.Printf("received on inChan: conn: %v, buffer size: %v\n", res.Conn.RemoteAddr(), res.Size)
							log.Println("menu receive: ", strings.TrimSpace(string(res.Buffer[:res.Size-2])))
							switch string(strings.TrimSpace(string(res.Buffer[:res.Size-2]))) {

							case "welcome":
								if err := w.Write(ctx, conn, welcomeHandler()); err != nil {
									log.Printf("error sending welcomeHandler from cmd `welcome`: %v", err)
								}

							case "adventure":
								// start the door and wait
								log.Println("starting door handler...")

								var wg sync.WaitGroup
								wg.Add(1)
								go doorHandler(ctx, conn, w, &wg)
								log.Println("menu handler waiting for wg to return from door")
								wg.Wait()
								log.Println("returning from door")
								//MenuControl <- "unpause"
								err := w.Write(ctx, conn, []byte("\n\n> "))
								if err != nil {
									log.Printf("error writing to connection: %v", err)
								}

							case "exit":
								if err := w.Write(ctx, conn, exitHandler()); err != nil {
									log.Printf("error sending exitHandler from cmd `exit`: %v\n", err)
								} else {
									// let's wait before we actually close the connection to try and ensure the write gets through
									time.Sleep(time.Second)
									log.Println("exiting...")
									log.Printf("Goodbye %s!\n", conn.RemoteAddr())
									err := w.Free(conn)
									if err != nil {
										log.Printf("err closing connection: %v\n", err)
									}
									MenuControl <- "stop"
									break ControlLoop
								}
							default:

								err := w.Write(ctx, conn, []byte("huh?\n\n> "))
								if err != nil {
									log.Printf("error writing to connection: %v", err)
								}
							}

						} else {
							// noop
							log.Printf("received on inChan: conn: %v, buffer: %v\n", res.Conn.RemoteAddr(), string(res.Buffer))
						}
						/*
							case res := <-outChan:
								//							log.Println("OpResult on outChan:", res)
								if res.Error != nil {
									log.Println("error on outChan: ", res.Error)
								}
								if res.Operation == gaio.OpWrite && res.Size > 0 && res.Conn == conn {
									// write confirmation received
									//log.Printf("received on outChan: conn: %v, buffer: %v\n", res.Conn.RemoteAddr(), string(res.Buffer))
								} else {
									// noop
									log.Printf("watcher sent unknown on outChan: %v\n", res)
								}
						*/
					default:
						// noop - wait a lil bit
						time.Sleep(time.Millisecond)
					}
					if conn == nil {
						log.Println("conn is nil!")
					}
				}
			}
			time.Sleep(time.Millisecond)
		}
		log.Println("menu controlloop closed!")
	}(inChan, outChan, MenuControl)

	log.Println("menu waiting on waitgroup")
	wg.Wait()
	log.Println("terminating menucontrol for client")
}

func welcomeHandler() []byte {
	const bannerText = "\x1b[2J\x1b[H\x1b[31m\x1b[J\r\n" + `

    _       __     _ ` + "" + `
   | |     / /__  / /________  ____ ___  ___` + "" + `
   | | /| / / _ \/ / ___/ __ \/ __ '__ \/ _ \` + "" + `
   | |/ |/ /  __/ / /__/ /_/ / / / / / /  __/` + "" + `
   |__/|__/\___/_/\___/\____/_/ /_/ /_/\___/` + "\r\n\x1b[33m" + `
                __` + "" + `
               / /_____ ` + "" + `
              / __/ __ \` + "" + `
             / /_/ /_/ /` + "" + `
             \__/\____/` + "\x1b[35m\r\n" + `
                    _    __` + "" + `
                   | |  / /__  _____________` + "" + `
                   | | / / _ \/ ___/ ___/ _ \` + "" + `
                   | |/ /  __/ /  (__  )  __/` + "" + `
                   |___/\___/_/  /____/\___/` + "\x1b[37m\r\n" + `
                          _____ __            ___` + "" + `
                         / ___// /___  ______/ (_)___  _____` + "" + `
                         \__ \/ __/ / / / __  / / __ \/ ___/` + "" + `
                        ___/ / /_/ /_/ / /_/ / / /_/ (__  ) ` + "" + `
                       /____/\__/\__,_/\__,_/_/\____/____/  ` + "\x1b[32m\r\n\r\n\r\n" + `
   Help is available: type help` + "\r\n\r\n> "

	return []byte(bannerText)
}

func exitHandler() []byte {
	const exitMessage = "\x1b[2J\x1b[H\x1b[31m\x1b[J\r\n" + `

      ___|                                                                                  |                 |
    \___ \   _ \  _ \  |   |  _ \  |   |     __| __ \   _' |  __|  _ \   __|  _ \\ \  \   / __ \   _ \  |   | |
          |  __/  __/  |   | (   | |   |   \__ \ |   | (   | (     __/  (    (   |\ \  \ /  |   | (   | |   |_|
    _____/ \___|\___| \__, |\___/ \__,_| ) ____/ .__/ \__,_|\___|\___| \___|\___/  \_/\_/  _.__/ \___/ \__, |_)
                      ____/             /       _|                                                     ____/


`

	return []byte(exitMessage)
}

func doorHandler(ctx context.Context, c net.Conn, w *gaio.Watcher, menuwg *sync.WaitGroup) error {
	defer menuwg.Done()

	const bannerText = "\r\nCOLOSSAL CAVE\r\n\r\n"
	err := w.Write(ctx, c, []byte(bannerText))
	if err != nil {
		log.Printf("error writing to connection: %v\n", err)
	}

	var inChan, _ chan gaio.OpResult
	var ok bool

	if inChan, _, ok = openconn.FromContext(ctx); !ok {
		log.Println("Could not get inChan/outChan from context!", ok, ctx)
	}

	cmd := exec.Command("/usr/games/adventure")

	stdout, _ := cmd.StdoutPipe()
	stdin, _ := cmd.StdinPipe()

	cmd.Start()

	var wg sync.WaitGroup
	wg.Add(1)
	Terminator := make(chan bool)
	go func(Terminator *chan bool, wg *sync.WaitGroup) {
		log.Println("starting stdin reader goroutine")
		defer wg.Done()
	Check:
		for {
			select {
			case <-*Terminator:
				break Check
			case result, ok := <-inChan:
				if ok {
					if result.Operation == gaio.OpRead {
						// we asked for a read - send it to stdin
						stdin.Write(result.Buffer[:result.Size])
					}
				} else {
					log.Println("yikes, problem getting a result from inChan in doorHandler!")
				}
			default:
				time.Sleep(time.Millisecond)
			}
		}
		log.Println("exiting stdin reader goroutine")
	}(&Terminator, &wg)

	log.Println("starting stdout reader goroutine")
	scanner := bufio.NewScanner(stdout)
	scanner.Split(bufio.ScanLines)

	for scanner.Scan() {
		m := scanner.Bytes()
		m = append(m, '\n')
		w.Write(ctx, c, m)
		log.Printf("wrote %d bytes to watcher from door stdout: %v\n", len(m)+1, string(m))
	}
	log.Println("exiting stdout reader goroutine")
	Terminator <- true

	log.Println("waiting for wg")
	wg.Wait()
	log.Println("waiting for cmd")
	exitErr := cmd.Wait()
	if exitErr != nil {
		log.Printf("cmd exited with err: %v\n", exitErr)
	}
	log.Println("leaving door handler")
	return nil
}