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

  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 <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>

#include "ProcessIO.h"

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

#define DEFAULT_CONFIG "../config/HV.conf"     // Default configuration file
#define LOCKFILE "/tmp/CTX_HV_LOCK"

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

// ================
//   Main program
// ================
//
// Several unlikely system call failures are handled via throwing an exception.

int main(int argc, char *argv[]) {

  char str[MAX_COM_SIZE];
  pthread_t thread_ConsoleCommand,thread_HVMonitor,thread_CCCommand;
  int LockDescriptor;

  // Interpret command line (do before lockfile creation in case of exit())
  if((argc==3 && strcmp(argv[1],"-c")!=0) || argc==2) {
    printf("Usage: %s [-c <ConfigFile>]    Default file is \"%s\"\n", argv[0], DEFAULT_CONFIG);
    exit(EXIT_SUCCESS);
  }

  // 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*** HV Control built %s, %s (S.Commichau, S.Stark, O.Grimm) ***\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 and create mutex for thread synchronization
  ProcessIO pio(argc==3 ? argv[2] : DEFAULT_CONFIG);
  if (pthread_mutex_init(&pio.control_mutex, NULL) != 0) {
    perror("pthread_mutex_init failed");
    throw;
  }
  
  // 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 threads
  if ((pthread_create(&thread_ConsoleCommand, NULL, (void * (*)(void *)) ConsoleCommand,(void *) &pio)) != 0) {
    perror("pthread_create failed with console thread");
    throw;
  }
  if ((pthread_create(&thread_HVMonitor, NULL, (void * (*)(void *)) HVMonitor,(void *) &pio)) != 0) {
    perror("pthread_create failed with HVMonitor thread");
    throw;
  }
  if ((pthread_create(&thread_CCCommand, NULL, (void * (*)(void *)) CCCommand,(void *) &pio)) != 0) {
    perror("pthread_create failed with socket thread");
    throw;
  }

  // Threads should be accessible for sending signals
  pio.HVMonitor = thread_HVMonitor;
  pio.SocketThread = thread_CCCommand;

  // Wait for threads to quit
  pthread_join(thread_CCCommand, NULL);
  pthread_join(thread_ConsoleCommand, NULL);
  pthread_join(thread_HVMonitor, NULL);

  // Destruct mutex and main instance
  pthread_mutex_destroy (&pio.control_mutex);
  pio.~ProcessIO();

  // Remove lockfile
  if (remove(LOCKFILE)==-1) {
    sprintf(str, "Could not remove lock file %s", LOCKFILE);
    perror(str);
    exit(EXIT_FAILURE);
  }

  exit(EXIT_SUCCESS);
}


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

  ConsoleCommand thread

  Handle console input using readline library functions to allow
  line editing and history capability

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

void ConsoleCommand(ProcessIO *m) {

  char *Command;

  while (!m->Exit) {
        
    // Assemble prompt
    snprintf(m->Prompt, sizeof(m->Prompt),"\rHV");
    if (m->NumHVBoards == 0) sprintf(m->Prompt+strlen(m->Prompt),"> "); 
    else { 
      if (m->FirstChain == m->LastChain) sprintf(m->Prompt+strlen(m->Prompt),"|C%d",m->FirstChain); 
      else sprintf(m->Prompt+strlen(m->Prompt),"|C%d-%d",m->FirstChain,m->LastChain); 

      if (m->NumHVBoards == 0) sprintf(m->Prompt+strlen(m->Prompt),"> "); 
      else if (m->FirstBoard == m->LastBoard) sprintf(m->Prompt+strlen(m->Prompt),"|B%d> ",m->FirstBoard); 
      else snprintf(m->Prompt,sizeof(m->Prompt),"\rDAQ|B%d-%d> ",m->FirstBoard,m->LastBoard); 
    }

    // Read Command
    Command = readline(m->Prompt);
    if (Command==NULL) {
      m->PrintMessage("Error reading command line input\n");
      continue;
    }
    if(strlen(Command)>0) add_history(Command);

    // Log command
    m->PrintMessage(Log, "CONSOLE> %s\n", Command);

    // Process command     
    pthread_mutex_lock(&m->control_mutex);
    m->CommandControl(Command);
    pthread_mutex_unlock(&m->control_mutex);
          
    free(Command);
  }
}


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

  CCCommand thread

  Listen to commands from socket (Central Control)
  
  This thread will block execution in the accept() and read() socket function
  while waiting for a connection or data. If the exit function is invoked through
  keyboard command, these blocking functions are interrupted by raising the signal
  SIGUSR1. Testing on errno=EINTR indicates this termination. The dummy signal
  handler below is needed to prevent the standard thread termination occurring
  when this signal is received.
  
\********************************************************************/


void CCCommand(ProcessIO *m) {

  int ServerSocket,ConnectionSocket,ReadResult;
  struct sockaddr_in SocketAddress, ClientAddress;
  struct hostent *ClientName;
  socklen_t SizeClientAddress=sizeof(ClientAddress);
  char Command[MAX_COM_SIZE];

  // Set up server socket
  if ((ServerSocket = socket(PF_INET, SOCK_STREAM, 0)) == -1) {
    m->PrintMessage(All, "Could not open server socket, no remote connection possible (%s).\n", strerror(errno));
    return;
  }

  // Allows immediate reuse of socket after closing (circumvents TIME_WAIT)
  int Value=1;
  if (setsockopt(ServerSocket, SOL_SOCKET, SO_REUSEADDR, (char *) &Value, sizeof (Value)) == -1) {
    m->PrintMessage(All, "Warning: Could not set server socket option SO_REUSEADDR (%s)\n", strerror(errno));
  }

  SocketAddress.sin_family = PF_INET;
  SocketAddress.sin_port = htons((unsigned short) m->fCCPort);
  SocketAddress.sin_addr.s_addr = INADDR_ANY;

  if (bind(ServerSocket, (struct sockaddr *) &SocketAddress, sizeof(SocketAddress)) == -1) {
    m->PrintMessage(All, "Could not bind port to socket (%s)\n", strerror(errno));
    close(ServerSocket);
    return;
  }
  if (listen(ServerSocket, 0) == -1) {
    m->PrintMessage(All, "Could not set socket to listening (%s)\n", strerror(errno));
    close(ServerSocket);
    return;
  }
  
  while (!m->Exit) { // Looping to wait for incoming connection

    if ((ConnectionSocket = accept(ServerSocket, (struct sockaddr *) &ClientAddress, &SizeClientAddress)) == -1) {
      if (errno!=EINTR) m->PrintMessage(All, "Failed to accept incoming connection (%s)\n", strerror(errno));
      close(ServerSocket);
      return;
    }

    ClientName = gethostbyaddr((char *) &ClientAddress.sin_addr ,sizeof(struct sockaddr_in),AF_INET);
    m->PrintMessage(All, "Connected to client at %s (%s).\n", inet_ntoa(ClientAddress.sin_addr), ClientName!=NULL ? ClientName->h_name:"name unknown");
    m->Socket = ConnectionSocket;

    // Looping as long as client exists and program not terminated
    while (!m->Exit) {

      // Try to read command from socket
      memset(Command, 0, sizeof(Command));
      ReadResult = read(ConnectionSocket, Command, MAX_COM_SIZE);
      if (ReadResult==0) break; // Client does not exist anymore
      if (ReadResult==-1) {
		if (errno!=EINTR) m->PrintMessage(All, "Error read from socket (%s)\n", strerror(errno));
		break;
      }
      if (Command[strlen(Command)-1]=='\n') Command[strlen(Command)-1]='\0';  // Remove trailing newline
      
      // Log command
      //m->PrintMessage(Console, "SOCKET> %s\n", Command);
      //m->PrintMessage(Log, "SOCKET> %s\n", Command);
	    
      // Process command
      pthread_mutex_lock(&m->control_mutex);
      m->CmdFromSocket = true;
      m->CommandControl(Command);
      m->CmdFromSocket = false;
      pthread_mutex_unlock(&m->control_mutex);	
    }

    m->Socket = -1;
    m->PrintMessage(All, "Disconnected from client.\n");
    close(ConnectionSocket);
  } 
  close(ServerSocket); 
}


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

  HVMonitor

  Monitor HV board status
  Sebastian Commichau, November 2008

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

void HVMonitor(ProcessIO *m) {
  
  while (!m->Exit) {
    if (m->state == active) {
      pthread_mutex_lock(&m->control_mutex);
      m->Monitor();
      pthread_mutex_unlock(&m->control_mutex);	
    }
    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() {
  remove(LOCKFILE);
  return;          
}