#include <errno.h>
#include <tcl.h>
#include <json-c/json.h>
#include "uselect.h"
#include "ascon.h"
#include "ascon.i"
#include "script.h"

/*
 * protocol for SECoP 
 *
 * Markus Zolliker Feb 2019
 */

/* the first item in this linked list contains a partial or empty buffer.
   all the following are the messages in the queue */
   
typedef struct secop_msg {
  struct secop_msg *next;
  char *message;
} SecopMsg;

typedef struct secop_buf {
  SecopMsg *queue;
  pDynString buffer;
} SecopBuf;

/*----------------------------------------------------------------------------*/
void SecopKillPrivate(void *private) {
  SecopBuf *msgbuf = private;
  SecopMsg *msg, *next;

  for (msg = msgbuf->queue; msg != NULL; msg = next) {
    next = msg->next;
    if (msg->message) {
      free(msg->message);
    }
    free(msg);
  }
  DeleteDynString(msgbuf->buffer);
  free(msgbuf);
}
/*----------------------------------------------------------------------------*/
int Secop3ReadChars(int fd, char *bytes, int maxbytes)
{
  fd_set rmask;
  struct timeval tmo = { 0, 0 };
  int ret;

  FD_ZERO(&rmask);
  FD_SET(fd, &rmask);
  ret = uselect(fd + 1, &rmask, NULL, NULL, &tmo);
  if (ret <= 0)
    return ret;
  ret = recv(fd, bytes, maxbytes, 0);
  /* PrintChar(*chr); fflush(stdout); */
  if (ret > 0)
    return ret;
  if (ret == 0) {
    errno = ECONNRESET;
    return ASCON_DISCONNECTED;
  }
  return ASCON_RECV_ERROR;
}

/*----------------------------------------------------------------------------*/
int Secop3ProtHandler(Ascon *a) {
  int ret;
  char *result;
  char *space;
  char *json;
  char *specifier;
  Tcl_Obj *tcllist[3], *tclobj;
  int l, l1, l2;
  struct json_object *jobj;
  char buffer[1024];
  char *bytes;
  char *str;
  SecopBuf *msgbuf;
  SecopMsg *msg, **msgp;
  
  if (a->state <= AsconConnectDone) {
    /* handle connect states */
    return AsconStdHandler(a);
  }
  /* treat incoming messages always */
  msgbuf = a->private;
  if (msgbuf == NULL) {
    msgbuf = calloc(1, sizeof *msgbuf);
    a->private = msgbuf;
    a->killPrivate = SecopKillPrivate;
    msgbuf->buffer = CreateDynString(60, 65536);
  }
  ret = Secop3ReadChars(a->fd, buffer, sizeof buffer - 1);
  while (ret > 0) {
    assert(ret < sizeof buffer);
    buffer[ret] = '\0';
    bytes = buffer;
    str = strchr(bytes, '\n');
    while (str) {
      l = str - bytes;
      DynStringConcatBytes(msgbuf->buffer, bytes, l);
      /* append at end of queue */
      for (msgp = &msgbuf->queue; *msgp != NULL; msgp = &(*msgp)->next);
      msg = calloc(1, sizeof *msg);
      *msgp = msg;
      msg->message = strdup(GetCharArray(msgbuf->buffer));
      DynStringClear(msgbuf->buffer);
      bytes += l + 1;
      str = strchr(bytes, '\n');
    }
    DynStringConcat(msgbuf->buffer, bytes);
    ret = Secop3ReadChars(a->fd, buffer, sizeof buffer - 1);
  }  
  if (ret < 0) {
    AsconError(a, "SECoP.rd", errno);
  }
  switch (a->state) {
  case AsconWriting:
    /* do not skip garbage */
    l = GetDynStringLength(a->wrBuffer) - a->wrPos;
    ret = AsconWriteChars(a->fd, GetCharArray(a->wrBuffer) + a->wrPos, l);
    if (ret < 0) {
      AsconError(a, "SECoP.wr", errno); /* sets state to AsconFailed */
    } else {
      a->wrPos += ret;
      if (a->wrPos >= GetDynStringLength(a->wrBuffer)) {
        a->state = AsconWriteDone;
      }
    }
    return 1;
  case AsconWriteStart:
    if (GetDynStringLength(a->wrBuffer) == 0) {
      /* do not send empty message */
      a->state = AsconWriteDone;
      return 1;
    }
    if (a->sendTerminator) {
      DynStringConcat(a->wrBuffer, a->sendTerminator);
    }
    a->wrPos = 0;
    a->state = AsconWriting;
    break;
  case AsconReadStart:
    a->state = AsconReadDone;
    msgbuf = a->private;
    if (msgbuf->queue == NULL) {
      DynStringClear(a->rdBuffer);
      return 1;
    }
    msg = msgbuf->queue;
    msgbuf->queue = msg->next;
    space = strchr(msg->message, ' ');
    jobj = NULL;
    specifier = "";
    if (space) {
      l1 = space - msg->message;
      specifier = space + 1;
      json = strchr(specifier, ' ');
      if (json) {
        l2 = json - specifier;
        json++;
        jobj = json_tokener_parse(json);
      } else {
        l2 = strlen(specifier);
      }
    } else {
      l1 = strlen(msg->message);
      l2 = 0;
    }
    tcllist[0] = Tcl_NewStringObj(msg->message, l1);
    tcllist[1] = Tcl_NewStringObj(specifier, l2);
    if (jobj) {
      tcllist[2] = json2tcl(jobj);
      tclobj = Tcl_NewListObj(3, tcllist);
    } else {
      tclobj = Tcl_NewListObj(2, tcllist);
    }
    DynStringCopy(a->rdBuffer, Tcl_GetString(tclobj));
    Tcl_DecrRefCount(tclobj); /* this line avoids a big memory leak! */
    a->responseValid = 1;
    json_object_put(jobj); /* free jobj */
    free(msg->message);
    free(msg);
    break;
  }
  return 1;
}

/*----------------------------------------------------------------------------*/
void AddSecop3Protocol() {
  static AsconProtocol secopprot;
  secopprot.name = "SECoP3";
  secopprot.handler = Secop3ProtHandler;
  secopprot.init = AsconStdInit;
  AsconInsertProtocol(&secopprot);
}