////////////////////////////////////////////////////////////////////////////////
/// @brief error handling
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2011-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#include "Basics/Common.h"

#include "Basics/tri-strings.h"
#include "Basics/vector.h"
#include "Basics/associative.h"

// -----------------------------------------------------------------------------
// --SECTION--                                                     private types
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief error number and system error
////////////////////////////////////////////////////////////////////////////////

typedef struct tri_error_s {
  int _number;
  int _sys;
}
tri_error_t;

// -----------------------------------------------------------------------------
// --SECTION--                                                 private variables
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief already initialized
////////////////////////////////////////////////////////////////////////////////

static bool Initialized = false;

////////////////////////////////////////////////////////////////////////////////
/// @brief holds the last error
////////////////////////////////////////////////////////////////////////////////

#ifdef TRI_GCC_THREAD_LOCAL_STORAGE
static __thread tri_error_t ErrorNumber;
#elif defined(TRI_WIN32_THREAD_LOCAL_STORAGE)
static __declspec(thread) tri_error_t ErrorNumber;
#elif defined(TRI_HAVE_POSIX_THREADS)
static pthread_key_t ErrorKey;
#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief the error messages
////////////////////////////////////////////////////////////////////////////////

static TRI_associative_pointer_t ErrorMessages;

// -----------------------------------------------------------------------------
// --SECTION--                                                 private functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief cleanup
////////////////////////////////////////////////////////////////////////////////

#ifndef TRI_GCC_THREAD_LOCAL_STORAGE
#ifdef TRI_HAVE_POSIX_THREADS

static void CleanupError (void* ptr) {
  TRI_Free(TRI_CORE_MEM_ZONE, ptr);
}

#endif
#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief Hash function used to hash error codes (no real hash, uses the error
/// code only)
////////////////////////////////////////////////////////////////////////////////

static uint64_t HashErrorCode (TRI_associative_pointer_t* array,
                               void const* key) {
  return (uint64_t) *((int*) key);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Hash function used to hash errors messages (not used)
////////////////////////////////////////////////////////////////////////////////

static uint64_t HashError (TRI_associative_pointer_t* array,
                           void const* element) {

  TRI_error_t* entry = (TRI_error_t*) element;
  return (uint64_t) entry->_code;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief Comparison function used to determine error equality
////////////////////////////////////////////////////////////////////////////////

static bool EqualError (TRI_associative_pointer_t* array,
                        void const* key,
                        void const* element) {
  TRI_error_t* entry = (TRI_error_t*) element;

  return *((int*) key) == entry->_code;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the last error
////////////////////////////////////////////////////////////////////////////////

#if defined(TRI_GCC_THREAD_LOCAL_STORAGE) || defined(TRI_WIN32_THREAD_LOCAL_STORAGE)

int TRI_errno () {
  return ErrorNumber._number;
}

#elif defined(TRI_HAVE_POSIX_THREADS)

int TRI_errno () {
  tri_error_t* eptr;

  eptr = static_cast<decltype(eptr)>(pthread_getspecific(ErrorKey));

  if (eptr == nullptr) {
    return 0;
  }
  else {
    return eptr->_number;
  }
}

#else
#error no TLS
#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief returns the last error as string
////////////////////////////////////////////////////////////////////////////////

char const* TRI_last_error () {
  int err;
  int sys;
  TRI_error_t* entry;

#if defined(TRI_GCC_THREAD_LOCAL_STORAGE) || defined(TRI_WIN32_THREAD_LOCAL_STORAGE)

  err = ErrorNumber._number;
  sys = ErrorNumber._sys;

#elif defined(TRI_HAVE_POSIX_THREADS)

  tri_error_t* eptr;

  eptr = static_cast<decltype(eptr)>(pthread_getspecific(ErrorKey));

  if (eptr == nullptr) {
    err = 0;
    sys = 0;
  }
  else {
    err = eptr->_number;
    sys = eptr->_sys;
  }

#else
#error no TLS
#endif

  if (err == TRI_ERROR_SYS_ERROR) {
    return strerror(sys);
  }

  entry = (TRI_error_t*)
    TRI_LookupByKeyAssociativePointer(&ErrorMessages, (void const*) &err);

  if (entry == nullptr) {
    return "general error";
  }

  return entry->_message;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief sets the last error
////////////////////////////////////////////////////////////////////////////////

int TRI_set_errno (int error) {
#if defined(TRI_GCC_THREAD_LOCAL_STORAGE) || defined(TRI_WIN32_THREAD_LOCAL_STORAGE)

  ErrorNumber._number = error;

  if (error == TRI_ERROR_SYS_ERROR) {
    ErrorNumber._sys = errno;
  }
  else {
    ErrorNumber._sys = 0;
  }

#elif defined(TRI_HAVE_POSIX_THREADS)

  tri_error_t* eptr;
  int copyErrno = errno;

  eptr = static_cast<decltype(eptr)>(pthread_getspecific(ErrorKey));

  if (eptr == nullptr) {
    eptr = static_cast<decltype(eptr)>(TRI_Allocate(TRI_CORE_MEM_ZONE, sizeof(tri_error_t), false));
    pthread_setspecific(ErrorKey, eptr);
  }

  eptr->_number = error;

  if (error == TRI_ERROR_SYS_ERROR) {
    eptr->_sys = copyErrno;
  }
  else {
    eptr->_sys = 0;
  }

#else
#error no TLS
#endif

  return error;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief defines an error string
////////////////////////////////////////////////////////////////////////////////

void TRI_set_errno_string (int error, char const* msg) {
  TRI_error_t* entry;

  if (TRI_LookupByKeyAssociativePointer(&ErrorMessages, (void const*) &error)) {

    // logic error, error number is redeclared
    printf("Error: duplicate declaration of error code %i in %s:%i\n",
           error, __FILE__, __LINE__);
    TRI_EXIT_FUNCTION(EXIT_FAILURE, nullptr);
  }

  entry = (TRI_error_t*) TRI_Allocate(TRI_CORE_MEM_ZONE, sizeof(TRI_error_t), false);

  entry->_code = error;
  entry->_message = TRI_DuplicateString(msg);

  TRI_InsertKeyAssociativePointer(&ErrorMessages,
                                  &error,
                                  entry,
                                  false);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief return an error message for an error code
////////////////////////////////////////////////////////////////////////////////

char const* TRI_errno_string (int error) {
  TRI_error_t* entry;

  entry = (TRI_error_t*) TRI_LookupByKeyAssociativePointer(&ErrorMessages, (void const*) &error);

  if (entry == nullptr) {
    // return a hard-coded string as not all callers check for nullptr
    return "unknown error";
  }

  TRI_ASSERT(entry->_message != nullptr);

  return entry->_message;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                            MODULE
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                                  public functions
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @brief initializes the error messages
////////////////////////////////////////////////////////////////////////////////

void TRI_InitializeError () {
  if (Initialized) {
    return;
  }

  TRI_InitAssociativePointer(&ErrorMessages,
                             TRI_CORE_MEM_ZONE,
                             HashErrorCode,
                             HashError,
                             EqualError,
                             0);

  TRI_InitializeErrorMessages();

#if defined(TRI_GCC_THREAD_LOCAL_STORAGE) || defined(TRI_WIN32_THREAD_LOCAL_STORAGE)
  ErrorNumber._number = 0;
  ErrorNumber._sys = 0;
#elif defined(TRI_HAVE_POSIX_THREADS)
  pthread_key_create(&ErrorKey, CleanupError);
#else
#error no TLS
#endif

  Initialized = true;
}

////////////////////////////////////////////////////////////////////////////////
/// @brief shuts down the error messages
////////////////////////////////////////////////////////////////////////////////

void TRI_ShutdownError () {
  size_t i;

  if (! Initialized) {
    return;
  }

  for (i = 0; i < ErrorMessages._nrAlloc; i++) {
    TRI_error_t* entry = static_cast<TRI_error_t*>(ErrorMessages._table[i]);

    if (entry != nullptr) {
      TRI_Free(TRI_CORE_MEM_ZONE, entry->_message);
      TRI_Free(TRI_CORE_MEM_ZONE, entry);
    }
  }

  TRI_DestroyAssociativePointer(&ErrorMessages);

  Initialized = false;
}

// -----------------------------------------------------------------------------
// --SECTION--                                                       END-OF-FILE
// -----------------------------------------------------------------------------

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