/* @file aqp_opalstatus.c
 * @brief
 * Implements a simple protocol to GET reactor status using an HTTP/1.1 GET.
 * It sets the UserAgent as SICS to avoid re-directs because we don't handle them.
 * If the HTTP status is not OK then it returns the status in the data buffer.
 */
#include "../made_config.h"
#include <sics.h>
#include <asyncqueue.h>

#define HTTP_OK "HTTP/1.1 200 OK"
#define HTTP11 " HTTP/1.1\r\n"
#if defined SICS_VERSION && defined SICS_REVISION
#define USERAGENT "User-Agent: SICS Version = " SICS_VERSION " Revision = " SICS_REVISION "\r\n"
#else
#define USERAGENT "User-Agent: SICS\r\n"
#endif
#define HOST "Host: neutron.ansto.gov.au\r\n"

enum replystates {START, HEADER, CHKHEADEREND, MSG};
static pAsyncProtocol OPAL_Protocol = NULL;

static int OPAL_Tx(pAsyncProtocol p, pAsyncTxn txn) {
  if (txn == NULL) {
    return 0;
  }
  txn->txn_status = ATX_ACTIVE;
  if (AsyncUnitWrite(txn->unit, txn->out_buf, txn->out_len) < 0) {
    return 0;
  }
  return 1;
}

/* The header and message are followed by the character sequences given below,
 * HEADER cr lf cr lf <msg len> cr lf
 * MESSAGE cr lf 0x30 cr lf cr lf
 * So we assume that the header is terminated by two consecutive crlf char
 * pairs which are eventually followed by another crlf
 * The message is assumed to be terminated by a crlf pair eventually followed
 * by two more crlf pairs of characters
 * Processing is simplified by discarding cr chars and counting lf chars */
static int OPAL_Rx(pAsyncProtocol p, pAsyncTxn txn, int ch) {
  int ret = 1;
  static int nlctr = 0;
  static enum replystates state = START;

  if (ch == '\r') {
    return ret;
  }
  switch (state) {
    case START:
      if (ch == '\n') {
        /* check HTTP status */
        if ( strncmp(txn->inp_buf, HTTP_OK, strlen(HTTP_OK) ) == 0 ) {
          txn->inp_idx = 0;
          nlctr = 0;
          state = HEADER;
        } else
          ret = AQU_POP_CMD;
      } else if (txn->inp_idx < txn->inp_len)
        txn->inp_buf[txn->inp_idx++] = ch;
      else
        ret = AQU_POP_CMD;
      break;
    case HEADER:
      if (ch == '\n') {
        nlctr++;
        state = CHKHEADEREND;
      }
      break;
    case CHKHEADEREND:
      if (nlctr == 1 && ch == '\n')
        nlctr++;
      else if (nlctr == 1 && ch != '\n') {
        txn->inp_idx = 0;
        nlctr = 0;
        state = HEADER;
      } else if (nlctr == 2 && ch == '\n') {
        txn->inp_idx = 0;
        nlctr = 0;
        state = MSG;
      }
      break;
    case MSG:
      if (txn->inp_idx >= txn->inp_len)
        ret = AQU_POP_CMD;
      if (nlctr == 0 && ch != '\n')
        txn->inp_buf[txn->inp_idx++] = ch;
      else if (nlctr == 2 && ch == '\n')
        ret = AQU_POP_CMD;
      else
        nlctr++;
      break;
  }
  if (ret == AQU_POP_CMD) {
    nlctr = 0;
    state = START;
  }
  return ret;
}

static int OPAL_Ev(pAsyncProtocol p, pAsyncTxn pTxn, int event) {
  if (event == AQU_TIMEOUT) {
    pTxn->txn_status = ATX_TIMEOUT;
    return AQU_POP_CMD;
  }
  return AQU_POP_CMD;
}

/* Append HTTP/1.1 and Host: line to message */
static int OPAL_PrepareTxn(pAsyncProtocol p, pAsyncTxn txn, const char* cmd, int cmd_len, int rsp_len) {
  int msglen;

  msglen = cmd_len + strlen(HTTP11) + strlen(USERAGENT) + strlen(HOST) + 3;
  txn->out_buf = (char*) malloc(msglen);
  if (txn->out_buf == NULL) {
    SICSLogWrite("ERROR: Out of memory in OPAL_PrepareTxn", eError);
    return 0;
  }
  strcpy(txn->out_buf, cmd);
  strcat(txn->out_buf, HTTP11);
  strcat(txn->out_buf, USERAGENT);
  strcat(txn->out_buf, HOST);
  strcat(txn->out_buf, "\r\n");
  txn->out_len = msglen;
  txn->out_idx = 0;
  if (txn->inp_buf != NULL) {
    free(txn->inp_buf);
  }
  txn->inp_len = rsp_len;
  txn->inp_idx = 0;
  txn->txn_state = 0;
  txn->txn_status = 0;
  return 1;
}

void OpalStatusInitProtocol(SicsInterp *pSics) {
  if (OPAL_Protocol == NULL) {
    OPAL_Protocol = AsyncProtocolCreate(pSics, "OPALSTAT", NULL, NULL);
    OPAL_Protocol->sendCommand = OPAL_Tx;
    OPAL_Protocol->handleInput = OPAL_Rx;
    OPAL_Protocol->killPrivate = NULL;
    OPAL_Protocol->handleEvent = OPAL_Ev;
    OPAL_Protocol->prepareTxn = OPAL_PrepareTxn;
  }
}