/**
 *******************************************************************************
 * Copyright (C) 2001-2004, International Business Machines Corporation.       *
 * All Rights Reserved.                                                        *
 *******************************************************************************
 */

#include "unicode/utypes.h"

#if !UCONFIG_NO_SERVICE

#include "icuserv.h"
#include "umutex.h"

#undef SERVICE_REFCOUNT

// in case we use the refcount stuff

U_NAMESPACE_BEGIN

/*
 ******************************************************************
 */

const UChar ICUServiceKey::PREFIX_DELIMITER = 0x002F;   /* '/' */

ICUServiceKey::ICUServiceKey(const UnicodeString& id) 
  : _id(id) {
}

ICUServiceKey::~ICUServiceKey() 
{
}

const UnicodeString& 
ICUServiceKey::getID() const 
{
  return _id;
}

UnicodeString& 
ICUServiceKey::canonicalID(UnicodeString& result) const 
{
  return result.append(_id);
}

UnicodeString& 
ICUServiceKey::currentID(UnicodeString& result) const 
{
  return canonicalID(result);
}

UnicodeString& 
ICUServiceKey::currentDescriptor(UnicodeString& result) const 
{
  prefix(result);
  result.append(PREFIX_DELIMITER);
  return currentID(result);
}

UBool 
ICUServiceKey::fallback() 
{
  return FALSE;
}

UBool 
ICUServiceKey::isFallbackOf(const UnicodeString& id) const 
{
  return id == _id;
}

UnicodeString& 
ICUServiceKey::prefix(UnicodeString& result) const 
{
  return result;
}

UnicodeString& 
ICUServiceKey::parsePrefix(UnicodeString& result) 
{
  int32_t n = result.indexOf(PREFIX_DELIMITER);
  if (n < 0) {
    n = 0;
  }
  result.remove(n);
  return result;
}

UnicodeString& 
ICUServiceKey::parseSuffix(UnicodeString& result) 
{
  int32_t n = result.indexOf(PREFIX_DELIMITER);
  if (n >= 0) {
    result.remove(0, n+1);
  }
  return result;
}

#ifdef SERVICE_DEBUG
UnicodeString& 
ICUServiceKey::debug(UnicodeString& result) const 
{
  debugClass(result);
  result.append(" id: ");
  result.append(_id);
  return result;
}

UnicodeString& 
ICUServiceKey::debugClass(UnicodeString& result) const 
{
  return result.append("ICUServiceKey");
}
#endif

UOBJECT_DEFINE_RTTI_IMPLEMENTATION(ICUServiceKey)

/*
 ******************************************************************
 */

SimpleFactory::SimpleFactory(UObject* instanceToAdopt, const UnicodeString& id, UBool visible) 
  : _instance(instanceToAdopt), _id(id), _visible(visible)
{
}

SimpleFactory::~SimpleFactory() 
{
  delete _instance;
}

UObject* 
SimpleFactory::create(const ICUServiceKey& key, const ICUService* service, UErrorCode& status) const 
{
  if (U_SUCCESS(status)) {
    UnicodeString temp;
    if (_id == key.currentID(temp)) {
      return service->cloneInstance(_instance); 
    }
  }
  return NULL;
}

void 
SimpleFactory::updateVisibleIDs(Hashtable& result, UErrorCode& status) const 
{
  if (_visible) {
    result.put(_id, (void*)this, status); // cast away const
  } else {
    result.remove(_id);
  }
}

UnicodeString& 
SimpleFactory::getDisplayName(const UnicodeString& id, const Locale& /* locale */, UnicodeString& result) const 
{
  if (_visible && _id == id) {
    result = _id;
  } else {
    result.setToBogus();
  }
  return result;
}

#ifdef SERVICE_DEBUG
UnicodeString& 
SimpleFactory::debug(UnicodeString& toAppendTo) const 
{
  debugClass(toAppendTo);
  toAppendTo.append(" id: ");
  toAppendTo.append(_id);
  toAppendTo.append(", visible: ");
  toAppendTo.append(_visible ? "T" : "F");
  return toAppendTo;
}

UnicodeString& 
SimpleFactory::debugClass(UnicodeString& toAppendTo) const 
{
  return toAppendTo.append("SimpleFactory");
}
#endif

UOBJECT_DEFINE_RTTI_IMPLEMENTATION(SimpleFactory)

/*
 ******************************************************************
 */

UOBJECT_DEFINE_RTTI_IMPLEMENTATION(ServiceListener)

/*
 ******************************************************************
 */

 // Record the actual id for this service in the cache, so we can return it
 // even if we succeed later with a different id.
class CacheEntry : public UMemory {
private:
  int32_t refcount;

public:
  UnicodeString actualDescriptor;
  UObject* service;

  /**
   * Releases a reference to the shared resource.
   */
  ~CacheEntry() {
    delete service;
  }

  CacheEntry(const UnicodeString& _actualDescriptor, UObject* _service) 
    : refcount(1), actualDescriptor(_actualDescriptor), service(_service) {
  }

  /**
   * Instantiation creates an initial reference, so don't call this
   * unless you're creating a new pointer to this.  Management of
   * that pointer will have to know how to deal with refcounts.  
   * Return true if the resource has not already been released.
   */
  CacheEntry* ref() {
    ++refcount;
    return this;
  }

  /**
   * Destructions removes a reference, so don't call this unless
   * you're removing pointer to this somewhere.  Management of that
   * pointer will have to know how to deal with refcounts.  Once
   * the refcount drops to zero, the resource is released.  Return
   * false if the resouce has been released.
   */
  CacheEntry* unref() {
    if ((--refcount) == 0) {
      delete this;
      return NULL;
    }
    return this;
  }

  /**
   * Return TRUE if there is at least one reference to this and the
   * resource has not been released.
   */
  UBool isShared() const {
    return refcount > 1;
  }
};

// UObjectDeleter for serviceCache
U_CDECL_BEGIN
static void U_CALLCONV
cacheDeleter(void* obj) {
  U_NAMESPACE_USE
    ((CacheEntry*)obj)->unref();
}

/**
 * Deleter for UObjects
 */
static void U_CALLCONV
deleteUObject(void *obj) {
  U_NAMESPACE_USE
    delete (UObject*) obj;
}
U_CDECL_END

/*
 ******************************************************************
 */

class DNCache : public UMemory {
public:
  Hashtable cache;
  const Locale locale;

  DNCache(const Locale& _locale) 
    : cache(FALSE), locale(_locale) 
  {
    // cache.setKeyDeleter(uhash_deleteUnicodeString);
  }
};


/*
 ******************************************************************
 */

StringPair* 
StringPair::create(const UnicodeString& displayName, 
                   const UnicodeString& id,
                   UErrorCode& status)
{
  if (U_SUCCESS(status)) {
    StringPair* sp = new StringPair(displayName, id);
    if (sp == NULL || sp->isBogus()) {
      status = U_MEMORY_ALLOCATION_ERROR;
      delete sp;
      return NULL;
    }
    return sp;
  }
  return NULL;
}

UBool 
StringPair::isBogus() const {
  return displayName.isBogus() || id.isBogus();
}

StringPair::StringPair(const UnicodeString& _displayName, 
                       const UnicodeString& _id)
  : displayName(_displayName)
  , id(_id)
{
}

U_CAPI void U_EXPORT2
userv_deleteStringPair(void *obj) {
  U_NAMESPACE_USE
    delete (StringPair*) obj;
}

/*
 ******************************************************************
 */

ICUService::ICUService()
  : name()
  , lock(0)
  , timestamp(0)
  , factories(NULL)
  , serviceCache(NULL)
  , idCache(NULL)
  , dnCache(NULL)
{
  umtx_init(&lock);
}

ICUService::ICUService(const UnicodeString& newName) 
  : name(newName)
  , lock(0)
  , timestamp(0)
  , factories(NULL)
  , serviceCache(NULL)
  , idCache(NULL)
  , dnCache(NULL) {
  umtx_init(&lock);
}

ICUService::~ICUService()
 {
   {
     Mutex mutex(&lock);
     clearCaches();
     delete factories;
     factories = NULL;
   }
   umtx_destroy(&lock);
}

UObject* 
ICUService::get(const UnicodeString& descriptor, UErrorCode& status) const 
{
  return get(descriptor, NULL, status);
}

UObject* 
ICUService::get(const UnicodeString& descriptor, UnicodeString* actualReturn, UErrorCode& status) const 
{
  UObject* result = NULL;
    ICUServiceKey* key = createKey(&descriptor, status);
    if (key) {
      result = getKey(*key, actualReturn, status);
      delete key;
    }
  return result;
}

UObject* 
ICUService::getKey(ICUServiceKey& key, UErrorCode& status) const 
{
  return getKey(key, NULL, status);
}

// this is a vector that subclasses of ICUService can override to further customize the result object
// before returning it.  All other public get functions should call this one.

UObject* 
ICUService::getKey(ICUServiceKey& key, UnicodeString* actualReturn, UErrorCode& status) const 
{
  return getKey(key, actualReturn, NULL, status);
}

// make it possible to call reentrantly on systems that don't have reentrant mutexes.
// we can use this simple approach since we know the situation where we're calling
// reentrantly even without knowing the thread.
class XMutex : public UMemory {
public:
  inline XMutex(UMTX *mutex, UBool reentering) 
    : fMutex(mutex)
    , fActive(!reentering) 
  {
    if (fActive) umtx_lock(fMutex);
  }
  inline ~XMutex() {
    if (fActive) umtx_unlock(fMutex);
  }

private:
  UMTX  *fMutex;
  UBool fActive;
};

struct UVectorDeleter {
  UVector* _obj;
  UVectorDeleter() : _obj(NULL) {}
  ~UVectorDeleter() { delete _obj; }
};

// called only by factories, treat as private
UObject* 
ICUService::getKey(ICUServiceKey& key, UnicodeString* actualReturn, const ICUServiceFactory* factory, UErrorCode& status) const 
{
  if (U_FAILURE(status)) {
    return NULL;
  }

  if (isDefault()) {
    return handleDefault(key, actualReturn, status);
  }

  ICUService* ncthis = (ICUService*)this; // cast away semantic const

  CacheEntry* result = NULL;
  {
    // The factory list can't be modified until we're done, 
    // otherwise we might update the cache with an invalid result.
    // The cache has to stay in synch with the factory list.
    // ICU doesn't have monitors so we can't use rw locks, so 
    // we single-thread everything using this service, for now.
	
    // if factory is not null, we're calling from within the mutex,
    // and since some unix machines don't have reentrant mutexes we
    // need to make sure not to try to lock it again.
    XMutex(&ncthis->lock, factory != NULL);

    if (serviceCache == NULL) {
      ncthis->serviceCache = new Hashtable(FALSE, status);
      if (U_FAILURE(status)) {
        delete serviceCache;
        return NULL;
      }
      serviceCache->setValueDeleter(cacheDeleter);
    }

    UnicodeString currentDescriptor;
    UVectorDeleter cacheDescriptorList;
    UBool putInCache = FALSE;

    int32_t startIndex = 0;
    int32_t limit = factories->size();
    UBool cacheResult = TRUE;

    if (factory != NULL) {
      for (int32_t i = 0; i < limit; ++i) {
        if (factory == (const ICUServiceFactory*)factories->elementAt(i)) {
          startIndex = i + 1;
          break;
        }
      }
      if (startIndex == 0) {
        // throw new InternalError("Factory " + factory + "not registered with service: " + this);
        status = U_ILLEGAL_ARGUMENT_ERROR;
        return NULL;
      }
      cacheResult = FALSE;
    }

    do {
      currentDescriptor.remove();
      key.currentDescriptor(currentDescriptor);
      result = (CacheEntry*)serviceCache->get(currentDescriptor);
      if (result != NULL) {
        break;
      }

      // first test of cache failed, so we'll have to update
      // the cache if we eventually succeed-- that is, if we're 
      // going to update the cache at all.
      putInCache = TRUE;

      int32_t index = startIndex;
      while (index < limit) {
        ICUServiceFactory* f = (ICUServiceFactory*)factories->elementAt(index++);
        UObject* service = f->create(key, this, status);
        if (U_FAILURE(status)) {
          delete service;
          return NULL;
        }
        if (service != NULL) {
          result = new CacheEntry(currentDescriptor, service);
          if (result == NULL) {
            delete service;
            status = U_MEMORY_ALLOCATION_ERROR;
            return NULL;
          }

          goto outerEnd;
        }
      }

      // prepare to load the cache with all additional ids that 
      // will resolve to result, assuming we'll succeed.  We
      // don't want to keep querying on an id that's going to
      // fallback to the one that succeeded, we want to hit the
      // cache the first time next goaround.
      if (cacheDescriptorList._obj == NULL) {
        cacheDescriptorList._obj = new UVector(uhash_deleteUnicodeString, NULL, 5, status);
        if (U_FAILURE(status)) {
          return NULL;
        }
      }
      UnicodeString* idToCache = new UnicodeString(currentDescriptor);
      if (idToCache == NULL || idToCache->isBogus()) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return NULL;
      }

      cacheDescriptorList._obj->addElement(idToCache, status);
      if (U_FAILURE(status)) {
        return NULL;
      }
    } while (key.fallback());
  outerEnd:

    if (result != NULL) {
      if (putInCache && cacheResult) {
        serviceCache->put(result->actualDescriptor, result, status);
        if (U_FAILURE(status)) {
          delete result;
          return NULL;
        }

        if (cacheDescriptorList._obj != NULL) {
          for (int32_t i = cacheDescriptorList._obj->size(); --i >= 0;) {
            UnicodeString* desc = (UnicodeString*)cacheDescriptorList._obj->elementAt(i);
            serviceCache->put(*desc, result, status);
            if (U_FAILURE(status)) {
              delete result;
              return NULL;
            }

            result->ref();
            cacheDescriptorList._obj->removeElementAt(i);
          }
        }
      }

      if (actualReturn != NULL) {
        // strip null prefix
        if (result->actualDescriptor.indexOf("/") == 0) {
          actualReturn->remove();
          actualReturn->append(result->actualDescriptor, 
                               1, 
                               result->actualDescriptor.length() - 1);
        } else {
          *actualReturn = result->actualDescriptor;
        }

        if (actualReturn->isBogus()) {
          status = U_MEMORY_ALLOCATION_ERROR;
	  delete result;
          return NULL;
        }
      }

      UObject* service = cloneInstance(result->service);
      if (putInCache && !cacheResult) {
	delete result;
      }
      return service;
    }
  }

  return handleDefault(key, actualReturn, status);
}

UObject* 
ICUService::handleDefault(const ICUServiceKey& /* key */, UnicodeString* /* actualIDReturn */, UErrorCode& /* status */) const 
{
  return NULL;
}
  
UVector& 
ICUService::getVisibleIDs(UVector& result, UErrorCode& status) const {
  return getVisibleIDs(result, NULL, status);
}

UVector& 
ICUService::getVisibleIDs(UVector& result, const UnicodeString* matchID, UErrorCode& status) const 
{
  result.removeAllElements();

  if (U_FAILURE(status)) {
    return result;
  }

  ICUService * ncthis = (ICUService*)this; // cast away semantic const
  {
    Mutex mutex(&ncthis->lock);
    const Hashtable* map = getVisibleIDMap(status);
    if (map != NULL) {
      ICUServiceKey* fallbackKey = createKey(matchID, status);

      for (int32_t pos = 0;;) {
        const UHashElement* e = map->nextElement(pos);
        if (e == NULL) {
          break;
        }

        const UnicodeString* id = (const UnicodeString*)e->key.pointer;
        if (fallbackKey != NULL) {
          if (!fallbackKey->isFallbackOf(*id)) {
            continue;
          }
        }

        UnicodeString* idClone = new UnicodeString(*id);
        if (idClone == NULL || idClone->isBogus()) {
          delete idClone;
          status = U_MEMORY_ALLOCATION_ERROR;
          break;
        }
        result.addElement(idClone, status);
        if (U_FAILURE(status)) {
          delete idClone;
          break;
        }
      }
      delete fallbackKey;
    }
  }
  if (U_FAILURE(status)) {
    result.removeAllElements();
  }
  return result;
}

const Hashtable* 
ICUService::getVisibleIDMap(UErrorCode& status) const {
  if (U_FAILURE(status)) return NULL;

  // must only be called when lock is already held

  ICUService* ncthis = (ICUService*)this; // cast away semantic const
  if (idCache == NULL) {
    ncthis->idCache = new Hashtable();
    if (idCache == NULL) {
      status = U_MEMORY_ALLOCATION_ERROR;
    } else if (factories != NULL) {
      for (int32_t pos = factories->size(); --pos >= 0;) {
        ICUServiceFactory* f = (ICUServiceFactory*)factories->elementAt(pos);
        f->updateVisibleIDs(*idCache, status);
      }
      if (U_FAILURE(status)) {
        delete idCache;
        ncthis->idCache = NULL;
      }
    }
  }

  return idCache;
}

 
UnicodeString& 
ICUService::getDisplayName(const UnicodeString& id, UnicodeString& result) const 
{
  return getDisplayName(id, result, Locale::getDefault());
}

UnicodeString& 
ICUService::getDisplayName(const UnicodeString& id, UnicodeString& result, const Locale& locale) const 
{
  {
    ICUService* ncthis = (ICUService*)this; // cast away semantic const
    UErrorCode status = U_ZERO_ERROR;
    Mutex mutex(&ncthis->lock);
    const Hashtable* map = getVisibleIDMap(status);
    if (map != NULL) {
      ICUServiceFactory* f = (ICUServiceFactory*)map->get(id);
      if (f != NULL) {
        f->getDisplayName(id, locale, result);
		return result;
      }

      // fallback
      UErrorCode status = U_ZERO_ERROR;
      ICUServiceKey* fallbackKey = createKey(&id, status);
      while (fallbackKey->fallback()) {
          UnicodeString us;
          fallbackKey->currentID(us);
          f = (ICUServiceFactory*)map->get(us);
          if (f != NULL) {
              f->getDisplayName(id, locale, result);
              delete fallbackKey;
              return result;
          }
      }
      delete fallbackKey;
    }
  }
  result.setToBogus();
  return result;
}

UVector& 
ICUService::getDisplayNames(UVector& result, UErrorCode& status) const 
{
  return getDisplayNames(result, Locale::getDefault(), NULL, status);
}


UVector& 
ICUService::getDisplayNames(UVector& result, const Locale& locale, UErrorCode& status) const 
{
  return getDisplayNames(result, locale, NULL, status);
}

UVector& 
ICUService::getDisplayNames(UVector& result, 
                            const Locale& locale, 
                            const UnicodeString* matchID, 
                            UErrorCode& status) const 
{
  result.removeAllElements();
  if (U_SUCCESS(status)) {
    ICUService* ncthis = (ICUService*)this; // cast away semantic const
    Mutex mutex(&ncthis->lock);

    if (dnCache != NULL && dnCache->locale != locale) {
      delete dnCache;
      ncthis->dnCache = NULL;
    }

    if (dnCache == NULL) {
      const Hashtable* m = getVisibleIDMap(status);
      if (m != NULL) {
        ncthis->dnCache = new DNCache(locale); 
        if (dnCache == NULL) {
          status = U_MEMORY_ALLOCATION_ERROR;
          return result;
        }

        int32_t pos = 0;
        const UHashElement* entry = NULL;
        while ((entry = m->nextElement(pos)) != NULL) {
          const UnicodeString* id = (const UnicodeString*)entry->key.pointer;
          ICUServiceFactory* f = (ICUServiceFactory*)entry->value.pointer;
          UnicodeString dname;
          f->getDisplayName(*id, locale, dname);
          if (dname.isBogus()) {
            status = U_MEMORY_ALLOCATION_ERROR;
          } else {
            dnCache->cache.put(dname, (void*)id, status); // share pointer with visibleIDMap
            if (U_SUCCESS(status)) {
              continue;
            }
          }
          delete dnCache;
          ncthis->dnCache = NULL;
          return result;
        }
      }
    }
  }

  ICUServiceKey* matchKey = createKey(matchID, status);
  int32_t pos = 0;
  const UHashElement *entry = NULL;
  while ((entry = dnCache->cache.nextElement(pos)) != NULL) {
    const UnicodeString* id = (const UnicodeString*)entry->value.pointer;
    if (matchKey != NULL && !matchKey->isFallbackOf(*id)) {
      continue;
    }
    const UnicodeString* dn = (const UnicodeString*)entry->key.pointer;
    StringPair* sp = StringPair::create(*id, *dn, status);
    result.addElement(sp, status);
    if (U_FAILURE(status)) {
      result.removeAllElements();
      break;
    }
  }
  delete matchKey;

  return result;
}

URegistryKey
ICUService::registerInstance(UObject* objToAdopt, const UnicodeString& id, UErrorCode& status) 
{
  return registerInstance(objToAdopt, id, TRUE, status);
}

URegistryKey
ICUService::registerInstance(UObject* objToAdopt, const UnicodeString& id, UBool visible, UErrorCode& status) 
{
  ICUServiceKey* key = createKey(&id, status);
  if (key != NULL) {
    UnicodeString canonicalID;
    key->canonicalID(canonicalID);
    delete key;

    ICUServiceFactory* f = createSimpleFactory(objToAdopt, canonicalID, visible, status);
    if (f != NULL) {
      return registerFactory(f, status);
    }
  }
  delete objToAdopt;
  return NULL;
}

ICUServiceFactory* 
ICUService::createSimpleFactory(UObject* objToAdopt, const UnicodeString& id, UBool visible, UErrorCode& status)
{
  if (U_SUCCESS(status)) {
    if ((objToAdopt != NULL) && (!id.isBogus())) {
      return new SimpleFactory(objToAdopt, id, visible);
    }
    status = U_ILLEGAL_ARGUMENT_ERROR;
  }
  return NULL;
}

URegistryKey
ICUService::registerFactory(ICUServiceFactory* factoryToAdopt, UErrorCode& status) 
{
  if (U_SUCCESS(status) && factoryToAdopt != NULL) {
    Mutex mutex(&lock);

    if (factories == NULL) {
      factories = new UVector(deleteUObject, NULL, status);
      if (U_FAILURE(status)) {
        delete factories;
        return NULL;
      }
    }
    factories->insertElementAt(factoryToAdopt, 0, status);
    if (U_SUCCESS(status)) {
      clearCaches();
    } else {
      delete factoryToAdopt;
      factoryToAdopt = NULL;
    }
  }

  if (factoryToAdopt != NULL) {
      notifyChanged();
  }

  return (URegistryKey)factoryToAdopt;
}

UBool 
ICUService::unregister(URegistryKey rkey, UErrorCode& status) 
{
  ICUServiceFactory *factory = (ICUServiceFactory*)rkey;
  UBool result = FALSE;
  if (factory != NULL && factories != NULL) {
    Mutex mutex(&lock);

    if (factories->removeElement(factory)) {
      clearCaches();
      result = TRUE;
    } else {
      status = U_ILLEGAL_ARGUMENT_ERROR;
      delete factory;
    }
  }
  if (result) {
    notifyChanged();
  }
  return result;
}

void 
ICUService::reset() 
{
  {
    Mutex mutex(&lock);
    reInitializeFactories();
    clearCaches();
  }
  notifyChanged();
}

void 
ICUService::reInitializeFactories() 
{
  if (factories != NULL) {
    factories->removeAllElements();
  }
}

UBool 
ICUService::isDefault() const 
{
  return countFactories() == 0;
}

ICUServiceKey* 
ICUService::createKey(const UnicodeString* id, UErrorCode& status) const 
{
  return (U_FAILURE(status) || id == NULL) ? NULL : new ICUServiceKey(*id);
}

void 
ICUService::clearCaches() 
{
  // callers synchronize before use
  ++timestamp;
  delete dnCache; dnCache = NULL;
  delete idCache; idCache = NULL;
  delete serviceCache; serviceCache = NULL;
}

void 
ICUService::clearServiceCache() 
{
  // callers synchronize before use
  delete serviceCache; serviceCache = NULL;
}

UBool 
ICUService::acceptsListener(const EventListener& l) const 
{
  return l.getDynamicClassID() == ServiceListener::getStaticClassID();
}

void 
ICUService::notifyListener(EventListener& l) const 
{
  ((ServiceListener&)l).serviceChanged(*this);
}

UnicodeString&
ICUService::getName(UnicodeString& result) const 
{
  return result.append(name);
}

int32_t 
ICUService::countFactories() const 
{
  return factories == NULL ? 0 : factories->size();
}

int32_t
ICUService::getTimestamp() const
{
  return timestamp;
}

U_NAMESPACE_END

/* UCONFIG_NO_SERVICE */
#endif