package main

import (
  "flag"
  "fmt"
  "io"
  "net"
  "os"
  "strconv"
)

func usage() {
  fmt.Fprintf(os.Stderr, "\nusage: go run chatserver.go\n")
  flag.PrintDefaults();
  fmt.Println()

  os.Exit(1)
}

func handleConnection(conn net.Conn) {
  // Why don't these work?
  //buf := make([]byte, 0, 1024)
  //buf := []byte{}
  // But this does
  buf := make([]byte, 1024)
  for {
    count, err := conn.Read(buf)
    if nil != err {
      if io.EOF != err {
        fmt.Fprintf(os.Stderr, "Non-EOF socket error: %s\n", err)
      }
      fmt.Fprintf(os.Stdout, "Ending socket\n")
      break
    }
    // not so sure about why this case exists
    // we'll just ignore it for now...
    if 0 == count {
      // fmt.Fprintf(os.Stdout, "Weird")
      continue
    }
    fmt.Fprintf(os.Stdout, "Message:\n%s\n", buf[0:count])
  }
}

func main() {
  flag.Usage = usage
  port:= flag.Uint("telnet-port", 4080, "tcp telnet chat port")
  flag.Parse()
  addr := ":" + strconv.Itoa(int(*port))


  // https://golang.org/pkg/net/
  sock, err := net.Listen("tcp", addr)
  if nil != err {
		fmt.Fprintf(os.Stderr, "Couldn't bind to TCP socket %q: %s\n", addr, err)
		os.Exit(2)
  }
  fmt.Println("Listening on", addr);

  for {
    conn, err := sock.Accept()
    if err != nil {
      // Not sure what kind of error this could be or how it could happen.
      // Could a connection abort or end before it's handled?
      fmt.Fprintf(os.Stderr, "Error accepting connection:\n%s\n", err)
    }
    fmt.Fprintf(os.Stdout, "Accepting socket\n")
    go handleConnection(conn)
  }
}