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

  General code to start a server of the Evidence Control System
  
  - The server is started with the given name.
  - DIM exit and error handlers are implemented.
  - A Message service is published with severity encoding. It can be updated
    with the Message() method. The text will also be logged.
  - If the severity of a Message() call is FATAL, exit() will be called (with
    this severity, the call to Message() is guranteed not to return).
  - Configuration data can be requested by GetConfig() and non-blocking by GetConfigNB().
  - If the configuration file changes a signal can be emitted which is caught by the standard
    signal handler. The handler invokes ConfigChanged() which can be redefined by the user application.
	The signal is delivered only to the main thread (where the constructor is executed) and thus
	blocking rpc can be made from it. The signal is set using ActivateSignal().
  - Signal handlers to ignore common signals are installed.
    These signals will then cause pause() to return which can be used
	by the application to terminate gracefully.
  - The static method ToString() converts the contents of a DIM service into text
  - A terminate-handler is installed for catching unhandled C++ exceptions.

  Oliver Grimm
 
\********************************************************************/

#include "Evidence.h"
using namespace std;

//
// Internal configuration class of EvidenceServer
//

// Constructor: Subscribe to be informed on configuration file change
EvidenceServer::Config::Config():	DimCommand((This->Name+"/ResetMessage").c_str(), (char *) ""),
									DimRpcInfo("ConfigRequest", NO_LINK) {

  CurrentItem = string();
  ConfigTimeStamp = 0;
  Service = new DimInfo("Config/ModifyTime", NO_LINK, this);
}

// Destructor
EvidenceServer::Config::~Config() {
  
  delete Service;
}

// Reset message and severity
void EvidenceServer::Config::commandHandler() {

  This->Message(INFO, "Message reset by %s (ID %d)", getClientName(), getClientId());
}

// Track last modification time of configuration file
void EvidenceServer::Config::infoHandler() {

  pthread_t Thread;
  int Ret;

  if (!ServiceOK(DimInfo::getInfo())) return;

  This->Lock();
  ConfigTimeStamp = getInfo()->getInt();
  This->Unlock();

  // Launch ConfigChanged() as detached thread
  if ((Ret = pthread_create(&Thread, NULL, (void * (*)(void *)) EvidenceServer::CallConfigChanged, (void *) NULL)) != 0) {
    This->Message(ERROR, "pthread_create() failed in EvidenceServer::Config::infoHandler() (%s)\n", strerror(Ret));
  }
  else if ((Ret = pthread_detach(Thread)) != 0) {
	This->Message(ERROR, "pthread_detach() failed in EvidenceServer::Config::infoHandler() (%s)\n", strerror(Ret));
  }  
}

// Answer to remote procedure call: Update map
void EvidenceServer::Config::rpcInfoHandler(){

  This->Lock();
  This->List[CurrentItem].Value = string(DimRpcInfo::getString(), DimRpcInfo::getSize()-1);
  This->List[CurrentItem].Time = ConfigTimeStamp;

  // Clear to allow new rpc call
  CurrentItem.clear(); 
  This->Unlock();
}


//////////////////////////
// EvidenceServer Class //
//////////////////////////

// Initialise
EvidenceServer *EvidenceServer::This = NULL;
pthread_mutex_t EvidenceServer::Mutex;

// Constructor
EvidenceServer::EvidenceServer(string ServerName): Name(ServerName) {

  // Initialize
  MessageService = NULL;
  MessageData = NULL;
  ExitRequest = false;
  This = this;
  LocalMode = false;

  dis_disable_padding();
  dic_disable_padding();
  
  // Initialise mutex
  int Ret;
  pthread_mutexattr_t Attr;

  if ((Ret = pthread_mutexattr_init(&Attr)) != 0) {
    Message(FATAL, "pthread_mutex_init() failed in Evidence constructor (%s)", strerror(Ret));
  }
  if ((Ret = pthread_mutexattr_settype(&Attr, PTHREAD_MUTEX_ERRORCHECK)) != 0) {
    Message(FATAL, "pthread_mutex_settype() failed in Evidence constructor (%s)", strerror(Ret));
  }
  if ((Ret = pthread_mutex_init(&Mutex, &Attr)) != 0) {
    Message(FATAL, "pthread_mutex_init() failed in Evidence constructor (%s)", strerror(Ret));
  }

  // Catch some signals
  signal(SIGQUIT, &SignalHandler);  // CTRL-Backspace
  signal(SIGTERM, &SignalHandler);  // Termination signal
  signal(SIGINT, &SignalHandler);   // CTRL-C
  signal(SIGHUP, &SignalHandler);   // Terminal closed
  
  // Catch C++ unhandled exceptions
  set_terminate(Terminate);

  // If name server node not set, use localhost and launch dns
  if (getenv("DIM_DNS_NODE") == NULL) {
	printf("Environment variable DIM_DNS_NODE not set, will run in local mode. One moment please...\n");

	if (setenv("DIM_DNS_NODE", "localhost", 0) == -1) {
	  printf("setenv() failed in EvidenceServer::EvidenceServer (%s)\n", strerror(errno));
	}
	else LocalMode = true;
	
	// Launch dns in a separate process (currently no further checks to avoid zombie generation)
	if ((ChildPID = fork()) == 0) {
	  if (execlp("dns", "dns", (char *) NULL) == -1) {
		printf("execlp() failed in child process forked in EvidenceServer::EvidenceServer() (%s)\n", strerror(errno));
		exit(EXIT_FAILURE);
	  }
	}
	if (ChildPID == -1) printf("fork() failed in EvidenceServer::EvidenceServer() (%s)\n", strerror(errno));

	// Wait for dns to become active
	sleep(3);
  }

  // Message service and initial message
  MessageService = new DimService((Name+"/Message").c_str(), (char *) "I:1;C", NULL, 0);

  string Rev(EVIDENCE_REVISION); 
  Message(INFO, "Server started (%s, compiled %s %s)", (Rev.substr(1, Rev.size()-3)).c_str(),__DATE__, __TIME__);

  // Configuration class
  ConfClass = new class Config();

  // Start server
  start(ServerName.c_str());
  addExitHandler(this);
}


// Destructor: Free memory
EvidenceServer::~EvidenceServer() {

  Message(INFO, "Server stopped");

  delete ConfClass;

  int Ret;
  if ((Ret = pthread_mutex_destroy(&Mutex)) != 0) {
	Message(ERROR, "pthread_mutex_destroy() failed (%s)", strerror(Ret));
  }

  delete MessageService;
  delete[] MessageData;
}


// DIM exit handler
// Note handler runs in DIM thread, thus exit() will call destructors of static objects in this thread
void EvidenceServer::exitHandler(int Code) {

  Message(INFO, "Exit handler called (DIM exit code %d)", Code);
  exit(EXIT_SUCCESS);
}

// DIM error handler
void EvidenceServer::errorHandler(int Severity, int Code, char *Text) {

  Message(ERROR, "%s (DIM error code %d, DIM severity %d)\n", Text, Code, Severity);
}


// Set server message (if Severity is FATAL, exit() will be invoked)
void EvidenceServer::Message(int Severity, const char *Format, ...) {

  static char ErrorString[] = "vasprintf() failed in Message()";
  char Buffer[10];
  char *Text;
  
  // Assemble message from application
  va_list ArgumentPointer;
  va_start(ArgumentPointer, Format);
  if (vasprintf(&Text, Format, ArgumentPointer) == -1) {
	Text = ErrorString;
	Severity = ERROR;
  }
  va_end(ArgumentPointer);

  // Generate new Message structure and free text
  struct Message *NewMsg = (struct Message *) new char [sizeof(struct Message)+strlen(Text)+1];
  NewMsg->Severity = Severity;
  strcpy(NewMsg->Text, Text);
  if (Text != ErrorString) free(Text);
  
  // Send message to console and log file
  const char *Desc;
  switch (Severity) {
	case INFO:	Desc = "Info"; break;
	case WARN:	Desc = "Warn"; break;
	case ERROR:	Desc = "Error"; break;
	case FATAL:	Desc = "Fatal"; break;
	default:	snprintf(Buffer, sizeof(Buffer),  "%d", Severity);
				Desc = Buffer;
  }
  
  printf("%s (%s): %s\n", MessageService->getName(), Desc, NewMsg->Text);
  SendToLog("%s (%s): %s", MessageService->getName(), Desc, NewMsg->Text);

  // Update DIM message service
  if (MessageService != NULL) {
	MessageService->updateService(NewMsg, sizeof(struct Message)+strlen(NewMsg->Text)+1);
  }

  // Delete old message
  Lock();
  delete[] MessageData;
  MessageData = NewMsg;
  Unlock();  

  // Terminate if severity if FATAL  
  if (Severity == FATAL) exit(EXIT_FAILURE);
}


// Send to central logging server with non-blocking command
void EvidenceServer::SendToLog(const char *Format, ...) {

  static char ErrorString[] = "vasprintf() failed in SendToLog()";
  char *Buffer;
  int Ret;

  // Evaluate variable argument list
  va_list ArgumentPointer;
  va_start(ArgumentPointer, Format);
  Ret = vasprintf(&Buffer, Format, ArgumentPointer);
  va_end(ArgumentPointer);

  // Send to logger
  if (Ret != -1) {
	DimClient::sendCommandNB("DColl/Log", Buffer);
	free (Buffer);
  }
  else DimClient::sendCommandNB("DColl/Log", ErrorString);
}


// Get configuration data
//
// Program terminates if data is missing and no default given. Actual configuration
// request will be made only if config file has modification since last request.
// If called from infoHandler(), a non-blocking request will be made
string EvidenceServer::GetConfig(string Item, string Default) {

  string Result;
  
  // If up-to-date data in configuration list available, return this
  Lock();
  if ((List.count(Item) > 0) && (List[Item].Time >= ConfClass->ConfigTimeStamp)) Result = List[Item].Value;
  Unlock();
  if (!Result.empty()) return Result;

  if (inCallback() == 0) {
	// Blocking configuration request
	DimRpcInfo Config((char *) "ConfigRequest", NO_LINK);
	Config.setData((char *) (Name + " " + Item).c_str());

	// Check if successful
	if (!EvidenceServer::ServiceOK(&Config)) {
      if (Default.empty() && !LocalMode) {
		Message(FATAL, "Configuration server unreachable, can't retrieve '%s'", Item.c_str());
	  }
	  else Result = Default;
	}
	else {
	  if (Config.getSize() <= 1) Result = Default;
	  else Result = string(Config.getString(), Config.getSize()-1); // Retrieve string safely
    }

	// Update configuration map	
	if (!Result.empty()) {
	  Lock();
	  List[Item].Value = Result;
	  List[Item].Time = ConfClass->ConfigTimeStamp;
	  Unlock();
	}	
  }
  else {
	// Non-blocking configuration request
 	Lock();

	// Make request if currently non is processed
	if (ConfClass->CurrentItem.empty()) {
	  ConfClass->CurrentItem = Item;
	  ConfClass->setData(((char *) (Name + " " + Item).c_str()));
	}

	if (List.count(Item) > 0) Result = List[Item].Value;
	else Result = Default;
	Unlock();
  }

  // Terminate if no configuration information found
  if (Result.empty() && !LocalMode) Message(FATAL, "Missing configuration data '%s'", Item.c_str());

  return Result;
}


// Locking and unlocking functions.
// Message() is not used to avoid infinite recursion
void EvidenceServer::Lock() {

  int Ret;

  if ((Ret = pthread_mutex_lock(&EvidenceServer::Mutex)) != 0) {
	printf("pthread_mutex_lock() failed in Lock() (%s)", strerror(Ret));
	SendToLog("pthread_mutex_lock() failed in Lock() (%s)", strerror(Ret));
	exit(EXIT_FAILURE);
  }
}

void EvidenceServer::Unlock() {

  int Ret;

  if ((Ret = pthread_mutex_unlock(&EvidenceServer::Mutex)) != 0) {
	printf("pthread_mutex_unlock() failed in Unlock() (%s)", strerror(Ret));
	SendToLog("pthread_mutex_unlock() failed in Unlock() (%s)", strerror(Ret));
	exit(EXIT_FAILURE);
  }  
}


// ====== Static methods ======

// Stub to call ConfigChanged() method of class as separate thread
// Thread set is used to determine if blocking or non-blocking rpc is to be used
void EvidenceServer::CallConfigChanged() {

  This->ConfigChanged();
}


// Signal handler (causes pause() and other syscalls to return)
void EvidenceServer::SignalHandler(int Signal) {

  static int Count = 0;

  // At first invocation just request exit
  if (++Count == 1) {
	This->ExitRequest = true;
	return;
  }

  // If invoked twice, call exit()
  if (Count == 2) {
	This->Message(WARN, "Signal handler called twice, invoking exit(). Will abort() on next signal without message. (signal %d)", Signal);
	exit(EXIT_FAILURE);
  }

  // If invoked more than twice, call abort()
  // Does not use Message() again, as this might be blocked
  abort();
}


// C++ exception handler (derived from gcc __verbose_terminate_handler())
void EvidenceServer::Terminate() {

  ostringstream Msg;
  static bool Terminating = false;

  if (Terminating) {
	Msg << This->Name << ": Terminate() called recursively, calling abort()";
	printf("%s\n", Msg.str().c_str());
	This->SendToLog(Msg.str().c_str());
	abort();
  }

  Terminating = true;

  // Make sure there was an exception; terminate is also called for an
  // attempt to rethrow when there is no suitable exception.
  type_info *Type = abi::__cxa_current_exception_type();
  if (Type != NULL) {
	int Status = -1;
	char *Demangled = NULL;

	Demangled = abi::__cxa_demangle(Type->name(), 0, 0, &Status);
	Msg << "Terminate() called after throwing an instance of '" << (Status==0 ? Demangled : Type->name()) << "'";
	free(Demangled);

	// If exception derived from std::exception, more information.
	try { __throw_exception_again; }
	catch (exception &E) {
	  Msg << " (what(): " << E.what() << ")";	  
	}
	catch (...) { }
  }
  else Msg << "Terminate() called without an active exception";

  This->Message(FATAL, Msg.str().c_str());
}


// Translates DIM data safely to string (assures no invalid memory accesses are made)
// Structure evaluation requires that no padding is used
string EvidenceServer::ToString(char *Format, const void *Data, int Size) {

  ostringstream Text;
  vector<string> Components;
  int ElementSize, N, Byte = 0;

  // Find component types
  Components = Tokenize(Format, ";");
  
  for (unsigned int n=0; n<Components.size(); n++) {
    // If empty, format error
  	if (Components[n].empty()) return string();

	// Determine maximum number of elements 
	if (Components[n].size() > 2) N = atoi(Components[n].c_str()+2); 
	else N = numeric_limits<int>::max();

	// Determine length in bytes of elements
	switch (toupper(Components[n][0])) {
	  case 'B':
	  case 'V':
	  case 'C': ElementSize = sizeof(char);			break;
	  case 'I':
	  case 'L': ElementSize = sizeof(int);			break;
	  case 'S': ElementSize = sizeof(short);		break;
	  case 'F': ElementSize = sizeof(float);		break;
	  case 'D': ElementSize = sizeof(double);		break;
	  case 'X': ElementSize = sizeof(long long);	break;
	  default: return string();
	}

	// Covert elements
	for (int i=0; i<N; i++) {	
	  // Check that not overrunning memory
	  if (Byte + ElementSize > Size) return Text.str();
	  
	  // Translate elements into text (handle string specially when format is 'C')
	  switch (toupper(Components[n][0])) {
    	case 'C': if (Components[n].size() == 1) {
					string String((char *) Data, Size-Byte);
					
					// Remove trailing '\0'
					if (!String.empty() && String[String.size()-1] == '\0') String.resize(String.size()-1);
					
					Text << String;
					return Text.str();
				  }
				  Text << *((char *) Data);
				  break;
		case 'B':
		case 'V': Text << *((char *) Data);
				  break;
    	case 'I':
    	case 'L': Text << *((int *) Data);
				  break;
    	case 'S': Text << *((short *) Data);
				  break;
    	case 'F': Text << *((float *) Data);
				  break;
    	case 'D': Text << *((double *) Data);
				  break;
    	case 'X': Text << *((long long *) Data);
			      break;
	  }

	  Byte += ElementSize;
	  Data = (void *) ((char *) Data + ElementSize);

	  // Space between entries
	  Text << " ";
	}
  }
  return Text.str();
}


// Checks if service contents indicates not available
bool EvidenceServer::ServiceOK(DimInfo *Item) {

  return !((Item->getSize() == strlen(NO_LINK)+1) &&  
	  (memcmp(Item->getData(), NO_LINK, Item->getSize()) == 0));
}

bool EvidenceServer::ServiceOK(DimRpcInfo *Item) {

  return !((Item->getSize() == strlen(NO_LINK)+1) &&  
	  (memcmp(Item->getData(), NO_LINK, Item->getSize()) == 0));
}

bool EvidenceServer::ServiceOK(DimCurrentInfo *Item) {

  return !((Item->getSize() == strlen(NO_LINK)+1) &&  
	  (memcmp(Item->getData(), NO_LINK, Item->getSize()) == 0));
}


// Tokenize std::string using given delimeter list
vector<string> EvidenceServer::Tokenize(const string &String, const string &Delimiters) {

  vector<string> Tokens;
  string::size_type Next, EndNext=0;
    
  while (EndNext != string::npos) {
    // Find next token
    Next = String.find_first_not_of(Delimiters, EndNext);
    EndNext = String.find_first_of(Delimiters, Next);

	// Stop if end of string reached
	if (Next == string::npos) break;

    // Add token to vector.
    Tokens.push_back(String.substr(Next, EndNext - Next));
  }
  
  return Tokens;
}


///////////////////////////
// EvidenceHistory Class //
///////////////////////////

// Organisaztion of history buffer
// F | T S D | T S D | 0 0 ......  | T S D | T S D | 0 -1
//
// F: Offset of oldest entry  T: Time  S: Size  D: Data
// F, T, S: int

// Marker for history buffer
const struct EvidenceHistory::Item EvidenceHistory::WrapMark = {0, -1, {}};
const struct EvidenceHistory::Item EvidenceHistory::EndMark = {0, 0, {}};

// Constructor
EvidenceHistory::EvidenceHistory(std::string Name):	Name(Name) {

  Buffer = NULL;
}

// Destructor
EvidenceHistory::~EvidenceHistory() {

  delete[] Buffer;
}

// Requests service history (returns true if data received OK)
bool EvidenceHistory::GetHistory() {

  DimRpcInfo R((char *) "ServiceHistory", NO_LINK);
  R.setData((char *) Name.c_str());

  // Check if data OK
  if (!EvidenceServer::ServiceOK(&R)) return false;
  if (R.getSize() == 0) return false;
  
  // Copy data to buffer
  delete[] Buffer;
  BufferSize = R.getSize();
  Buffer = new char [BufferSize];

  memcpy(Buffer, R.getData(), BufferSize);
  DataStart = Buffer + strlen(Buffer) + 1;
  Rewind();
  
  return true;
}

// Returns next item in history buffer
const struct EvidenceHistory::Item *EvidenceHistory::Next() {

  if (Buffer == NULL) return NULL;

  // Check for wrap around
  if (memcmp(Pointer, &WrapMark, sizeof(WrapMark)) == 0) Pointer = (struct Item *) (DataStart + sizeof(int));
  // Check if at end of ring buffer
  if (memcmp(Pointer, &EndMark, sizeof(EndMark)) == 0) return NULL;

  const struct Item *Ret = Pointer;
  Pointer = (struct Item *) ((char *) (Ret + 1) + Ret->Size);

  return Ret;
}

// Reset to start of buffer
void EvidenceHistory::Rewind() {

  if (Buffer != NULL) Pointer = (struct Item *) (DataStart + (*(int *) DataStart));
}

// Return DIM format string of service (NULL if no data)
char *EvidenceHistory::GetFormat() {

  return Buffer;
}