/* @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 or if the driver fails to find a line that
 * contains the "Power:" field then it returns the unprocessed reply
 * characters in the data buffer.
 *
 * The reply is expected to have a form similar to the following,
 *   HTTP/1.1 200 OK
 *   Date: Thu, 26 Feb 2015 01:27:30 GMT
 *   Server: Oracle-Application-Server-10g/10.1.3.5.0 Oracle-HTTP-Server
 *   Content-Location: /reactor.jsp
 *   Content-Type: text/plain; charset=UTF-8
 *   Set-Cookie: JSESSIONID=74646fa7cf3cdf53a371694a33ab760cd649631d758f416d916c6d1b496a477b.e34Pc3qNbh4RaO0Ma3yMbxaRaN0Ke0; path=/Bragg
 *   Connection: close
 *   Transfer-Encoding: chunked
 *   
 *   4f
 *   Power: 19.381588; CNS Out: 25.76; TG123: 1; CG123: 1; TG4: Open; HB1: 0; HB2: 1
 *   
 *   0
 *
 * It should have no more than 512 characters excluding the HTTP OK status.
 * Each line is expected to be terminated with a \r\n.
 * The reply is expected to begin with "HTTP/1.1 200 OK"
 * A line is identified as the status message if and only if it includes
 * "Power:" regardless of case.
 * The reply is expected to end with 0\r\n\r\n
 *
 * Processing lines is simplified by discarding \r characters and then just
 * checking for \n.
 * NOTE: This implies that \n should not be used in the status line as a
 * delimiter.
 */
#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"
/* Assume that the first field in the reactor status starts with "Power" */
#define PWR_FLD "Power"
#define PWR_FLD_LEN 5

enum replystates {START, CHK_PWR_FLD, MSG, END_MSG, DRAIN_REPLY};
static pAsyncProtocol OPAL_Protocol = NULL;

/* The message is assumed to start with "Power:" and terminated with crlf.
 * by two more crlf pairs of characters
 * Processing of line terminators is simplified by discarding cr chars */
static int OPAL_Rx(pAsyncProtocol p, pAsyncTxn txn, int ch) {
  char *fldptr;
  int ret = 1;
  static int char_ctr = 0, newline_ctr = 0;
  static enum replystates state = START;

  if (char_ctr++ >= txn->inp_len) {
    char_ctr = 0;
    newline_ctr = 0;
    state = START;
    return AQU_POP_CMD;
  }
  if (ch == '\r') {
    return ret;
  }
  switch (state) {
    case START:
      if (ch == '\n') {
        /* check HTTP status is OK before proceeding */
        if ( strncmp(txn->inp_buf, HTTP_OK, strlen(HTTP_OK) ) == 0 ) {
          txn->inp_idx = 0;
          state = CHK_PWR_FLD;
        } else
          ret = AQU_POP_CMD;
      } else
        txn->inp_buf[txn->inp_idx++] = ch;
      break;
    case CHK_PWR_FLD:
      if (ch == '\n') {
        txn->inp_idx = 0;
      } else if (ch == ':') {
        if ( txn->inp_idx >= PWR_FLD_LEN ) {
          /* Check for "Power" field anywhere in status line */
          fldptr = &txn->inp_buf[txn->inp_idx - PWR_FLD_LEN];
          if ( strncasecmp(fldptr, PWR_FLD, PWR_FLD_LEN) == 0 ) {
            state = MSG;
          }
        }
      }
      txn->inp_buf[txn->inp_idx++] = ch;
      break;
    case MSG:
      if (ch == '\n') {
        state = END_MSG;
      } else {
        txn->inp_buf[txn->inp_idx++] = ch;
      }
      break;
    case END_MSG:
      if (ch == '0') {
        state = DRAIN_REPLY;
      }
      break;
    case DRAIN_REPLY:
      newline_ctr++;
      if (newline_ctr >= 2)
        ret = AQU_POP_CMD;
      break;
  }
  if (ret == AQU_POP_CMD) {
    char_ctr = 0;
    newline_ctr = 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 = 512;
  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 = NULL;
    OPAL_Protocol->handleInput = OPAL_Rx;
    OPAL_Protocol->killPrivate = NULL;
    OPAL_Protocol->handleEvent = OPAL_Ev;
    OPAL_Protocol->prepareTxn = OPAL_PrepareTxn;
  }
}