/**
 * Simple bsdsocket.library server for AmigaOS
 * Copyright 2022 John Bintz
 * Released under the MIT License
 * Visit theindustriousrabbit.com for more fun!
 *
 * You would not believe how sparse the documentation for
 * bsdsocket.library is on the Amiga. All this required
 * digging through documentation on multiple sites, in
 * multiple forum threads to describe the Amiga quirks
 * (Amiga code has quirks? who knew!), and required a bunch of
 * experimentation and resetting the Minimig MiSTer core
 * and PPP connection to get this working. I tested it
 * with CodeWatcher and nothing is leaking, so this should
 * be a (hopefully) good bsdsocket example in C for the Amiga.
 *
 * This code is built for SAS/C. Be sure to disable ChkAbort
 * in the Linker options, otherwise the SAS/C Ctrl-c
 * handler will take over and screw up server teardown.
 *
 * You can use netcat/ncat on another machine to send data
 * to the running server:
 *
 * echo "whoa computers" | netcat 192.168.50.100 8090
 *
 */

#include <stdio.h>
#include <strings.h>

#include <proto/exec.h>
#include <dos/dos.h>

#include <proto/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>

// socket stuff
struct Library *SocketBase;
int serverSocket = -1;
struct sockaddr_in serverAddress;

#define PORT (8090)
#define MAX_CONNECTIONS (2)

// data handling
#define BUFFER_LENGTH (256)
char buffer [BUFFER_LENGTH];
int msgSize;

// set up all the global stuff we need, allowing for early exits
// on failures.
int setup(void) {
  const int enable = 1;

  // this works with the most modern MiamiDX
  if (!(SocketBase = OpenLibrary("bsdsocket.library", 4))) {
    printf("Can't open socket library\n");
    return 1;
  }

  serverSocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (serverSocket < 0) {
    printf("can't get a socket\n");
    return 1;
  }

  // AmiTCP 4.3 SDK does not have SO_REUSEPORT, this is all you get
  if (setsockopt(
    serverSocket,
    SOL_SOCKET,
    SO_REUSEADDR,
    // oh c...
    &enable,
    sizeof(int)
   ) < 0) {
    printf("can't set socket options\n");
    return 1;
  }

  return 0;
}

void teardown(void) {
  if (serverSocket != -1) {

    shutdown(
      serverSocket,
      // SHUT_RDWR, stop all communication both ways
      2
    );
    CloseSocket(serverSocket);
  }

  if (SocketBase) {
    CloseLibrary(SocketBase);
  }
}

int startServer(void) {
  // bind to all addresses on our defined port
  memset(&serverAddress, 0, sizeof(serverAddress));
  serverAddress.sin_family = AF_INET;
  serverAddress.sin_port = htons(PORT);
  serverAddress.sin_addr.s_addr = htonl(INADDR_ANY);

  if (bind(
    serverSocket,
    (struct sockaddr *) &serverAddress,
    sizeof(serverAddress)
  ) < 0) {
    printf("can't bind\n");
    return 1;
  }

  if (listen(serverSocket, MAX_CONNECTIONS) < 0) {
    printf("can't listen\n");
    return 1;
  }

  return 0;
}

void readData(int clientSocket) {
  do {
    // keep stomping over the same buffer
    // ideally we'd take the data out of the buffer and
    // do something with it.
    msgSize = recv(clientSocket, buffer, BUFFER_LENGTH, 0);

    if (msgSize <= 0) {
      printf("End of data\n");
    } else {
      printf("Got stuff: %i\n", msgSize);
      printf("%s\n", buffer);
    }
  } while (msgSize == 256);
  printf("Data received: %s\n", buffer);
}

int main(void) {
  // The incoming netcat client
  int clientSocket;
  struct sockaddr_in clientAddress;
  LONG clientLength = sizeof(clientAddress);

  // be able to use WaitSelect
  int waitSelectResult;
  fd_set readFDs;

  if (setup() != 0) {
    teardown();
    return 1;
  }

  printf("got socket number %d\n", serverSocket);

  if (startServer() != 0) {
    teardown();
    return 1;
  }

  printf("listening on port %d\n", PORT);

  // just enough to get WaitSelect working
  // this macro also wants strings.h included
  FD_ZERO(&readFDs);
  FD_SET(serverSocket, &readFDs);
  waitSelectResult = WaitSelect(
    serverSocket + 1,
    &readFDs,
    NULL, NULL, NULL,
    // other Exec Signals would go here as ORed mp_SigBits
    NULL
  );

  // WaitSelect will trap on Ctrl-C for us, and returns -1 if that happens
  if (waitSelectResult == -1) {
    printf("ctrl-c\n");
    teardown();
    return 1;
  }

  if (
    (
      clientSocket = accept(
        serverSocket,
        (struct sockaddr *) &clientAddress,
        &clientLength
      )
    ) < 0
  ) {
    printf("can't accept\n");
    return 1;
  }

  // note the capitalization difference on Inet_NtoA. the Amiga does
  // that a lot...
  printf("connection from %s\n", Inet_NtoA(clientAddress.sin_addr.s_addr));

  readData(clientSocket);

  printf("all done\n");

  teardown();

  return 0;
}