/**************************************************************\

  Main program for the CTX G-APD HV supply, sends commands, 
  reads and monitors status of the G-APD HV supply

  Sebastian Commichau, Sabrina Stark, Oliver Grimm
  
\**************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <signal.h>

#include "ProcessIO.h"

#include <readline/readline.h>
#include <readline/history.h>

#define LOCKFILE "/tmp/CTX_HV_LOCK"

// Function prototypes
void HVMonitor(ProcessIO *);
void DummyHandler(int);
void CrashHandler(int);
void ExitFunction();

// ================
//   Main program
// ================

int main() {

  char str[MAX_COM_SIZE], *Command;
  pthread_t thread_HVMonitor;
  int LockDescriptor;

  // Assure only one instance of the HV control program runs
  // The flag O_EXCL together with O_CREAT assure that the lock 
  // file cannot be opened by another instance, i.e. there are no parallel write accesses
  if((LockDescriptor = open(LOCKFILE,O_WRONLY|O_CREAT|O_EXCL,S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH)) == -1) {
    if(errno==EEXIST) {
      printf("Error: Lock file already existing\n");
      sprintf(str,"paste %s -s -d ' '",LOCKFILE);
      system(str);
    }
    else printf("Could not create lock file %s (%s)\n", LOCKFILE, strerror(errno));
    exit(EXIT_FAILURE);
  }
  close(LockDescriptor);
  sprintf(str,"echo Created >%s; date >>%s; echo by $USER@$HOSTNAME>>%s",LOCKFILE,LOCKFILE,LOCKFILE);
  system(str);
  
  system("clear");                   
  printf("\n*** Bias control (%s, %s, O. Grimm, S.Commichau, S.Stark) ***\n\n",__DATE__,__TIME__);
 
  // Install signal handler and set signal SIGUSR1 to interrupt blocking system calls
  signal(SIGUSR1, &DummyHandler);
  siginterrupt (SIGUSR1, true);

  // Assure lock file is deleted in case of a program crash or call to exit()
  signal(SIGILL, &CrashHandler);
  signal(SIGABRT, &CrashHandler);
  signal(SIGFPE, &CrashHandler);
  signal(SIGSEGV, &CrashHandler);
  signal(SIGBUS, &CrashHandler);
  atexit(&ExitFunction);
  
  // Construct main instance
  static ProcessIO M;
  
  // These signals were set during construction of EvidenceServer
  signal(SIGQUIT, &CrashHandler);  // CTRL-Backspace
  signal(SIGINT, &CrashHandler);   // CTRL-C
  signal(SIGHUP, &CrashHandler);   // Terminal closed
  signal(SIGTERM, &CrashHandler);

  // Create monitor thread and make accessible for sending signal
  if ((pthread_create(&thread_HVMonitor, NULL, (void * (*)(void *)) HVMonitor,(void *) &M)) != 0) {
    M.Message(M.FATAL, "pthread_create failed with HVMonitor thread");
  }
  M.HVMonitor = thread_HVMonitor;

  while (!M.ExitRequest) {        
    // Assemble prompt
    if (M.NumHVBoards == 0) snprintf(M.Prompt, sizeof(M.Prompt), "\rBias> "); 
    else { 
      if (M.FirstBoard == M.LastBoard) snprintf(M.Prompt, sizeof(M.Prompt), "\rBias|B%d> ",M.FirstBoard); 
      else snprintf(M.Prompt, sizeof(M.Prompt),"\rBias|B%d-%d> ",M.FirstBoard, M.LastBoard); 
    }

    // Read Command
    Command = readline(M.Prompt);
    if (Command == NULL) continue;
    if(strlen(Command)>0) add_history(Command);

    // Process command (via DIM gives automatic thread serialisation)
	DimClient::sendCommand("Bias/Command", Command);
    free(Command);
  }

  // Wait for thread to quit
  if (pthread_join(thread_HVMonitor, NULL) != 0) {
    M.PrintMessage("pthread_join() failed in main()");
  }
}


/********************************************************************\

  Monitor HV board status

\********************************************************************/

void HVMonitor(ProcessIO *m) {

  while (!m->ExitRequest) {
    if (m->state == active) m->Monitor();
    usleep((unsigned long)floor(1000000./(m->NumHVBoards*m->fStatusRefreshRate)));
  }
}


/********************************************************************\

  Signal handlers

\********************************************************************/

// Remove lock file before running default signal code
void CrashHandler(int Signal) {

  remove(LOCKFILE);
  printf("Caught signal number %d. Removing lockfile and performing standard signal action. Good luck.\n",Signal);
  signal(Signal, SIG_DFL);
  raise(Signal);
}

// Dummy signal handler to return from blocking syscalls
void DummyHandler(int Signal) {
  return;          
}

// This function will be implicitly called by exit()
void ExitFunction() {

  if (remove(LOCKFILE) == -1) {
    printf("Could not remove lock file %s (%s)\n", LOCKFILE, strerror(errno));
  }
}