/* Copyright (c) 2023, 2024, Oracle and/or its affiliates.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.

This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation.  The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License, version 2.0, for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include "mysql_service_implementation.h"
#include "registry_no_lock_imp.h"

#include <mysql/components/my_service.h>
#include <mysql/components/service_implementation.h>
#include <mysql/components/services/registry.h>
#include <map>
#include <memory>

typedef std::map<const char *, mysql_service_implementation *, c_string_less>
    my_service_registry;

/**
  De-initializes registry, other structures.
*/
void mysql_registry_no_lock_imp::deinit() {
  mysql_registry_no_lock_imp::service_registry.clear();
  mysql_registry_no_lock_imp::interface_mapping.clear();
}

/**
  Finds a Service Implementation data structure based on the pointer to
  interface struct supplied. Assumes caller has at least a read lock on the
  Registry.

  @param interface A pointer to the interface structure of the Service
    Implementation to look for.
  @return A pointer to respective Service Implementation data structure, or
    NULL if no such interface pointer is registered within the Registry.
*/
mysql_service_implementation *
mysql_registry_no_lock_imp::get_service_implementation_by_interface(
    my_h_service interface) {
  my_interface_mapping::const_iterator iter =
      mysql_registry_no_lock_imp::interface_mapping.find(interface);
  if (iter == mysql_registry_no_lock_imp::interface_mapping.cend()) {
    return nullptr;
  }

  return iter->second;
}

/**
  Gets current reference count for a Service Implementation related to the
  specified pointer to the interface structure. Assumes caller has at least
  a read lock on the Registry.

  @param interface A pointer to the interface structure of the Service
    Implementation to get reference count of.
  @return A current reference count for specified Service Implementation.
    Returns 0 in case there is no such interface or it is not referenced.
*/
uint64_t mysql_registry_no_lock_imp::get_service_implementation_reference_count(
    my_h_service interface) {
  my_interface_mapping::const_iterator iter =
      mysql_registry_no_lock_imp::interface_mapping.find(interface);
  if (iter == mysql_registry_no_lock_imp::interface_mapping.cend()) {
    return -1;
  }

  return iter->second->get_reference_count();
}

/**
  Finds and acquires a Service by name. A name of the Service or the Service
  Implementation can be specified. In case of the Service name, the default
  Service Implementation for Service specified will be returned. Assumes
  caller has at least a read lock on the Registry.

  @param service_name Name of Service or Service Implementation to acquire.
  @param [out] out_service Pointer to Service handle to set acquired Service.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
bool mysql_registry_no_lock_imp::acquire_nolock(const char *service_name,
                                                my_h_service *out_service) {
  try {
    if (out_service == nullptr) {
      return true;
    }
    my_service_registry::const_iterator iter;

    iter = mysql_registry_no_lock_imp::service_registry.find(service_name);

    if (iter == mysql_registry_no_lock_imp::service_registry.cend())
      return true;

    mysql_service_implementation *imp = iter->second;
    imp->add_reference();
    *out_service = imp->interface();
    return false;
  } catch (...) {
  }
  return true;
}

/**
  Releases the Service Implementation previously acquired. After the call to
  this method the usage of the Service Implementation handle will lead to
  unpredicted results. Assumes caller has at least a read lock on the
  Registry.

  @param service Service Implementation handle of already acquired Service.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
bool mysql_registry_no_lock_imp::release_nolock(my_h_service service) {
  try {
    if (service == nullptr) {
      return true;
    }

    mysql_service_implementation *service_implementation =
        mysql_registry_no_lock_imp::get_service_implementation_by_interface(
            service);
    if (service_implementation == nullptr) {
      return true;
    }
    return service_implementation->release_reference();
  } catch (...) {
  }
  return true;
}

/**
  Registers a new Service Implementation. If it is the first Service
  Implementation for the specified Service then it is made a default one.
  Assumes caller has a write lock on the Registry.

  @param service_implementation_name Name of the Service Implementation to
    register.
  @param ptr Pointer to the Service Implementation structure.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
bool mysql_registry_no_lock_imp::register_service_nolock(
    const char *service_implementation_name, my_h_service ptr) {
  try {
    std::unique_ptr<mysql_service_implementation> imp =
        std::unique_ptr<mysql_service_implementation>(
            new mysql_service_implementation(ptr, service_implementation_name));

    if (imp->interface() == nullptr) {
      return true;
    }

    /* Register the implementation name. */
    std::pair<my_service_registry::iterator, bool> addition_result =
        mysql_registry_no_lock_imp::service_registry.emplace(imp->name_c_str(),
                                                             imp.get());

    /* Fail if it was present already. */
    if (!addition_result.second) {
      return true;
    } else {
      try {
        /* Register interface in mapping */
        mysql_registry_no_lock_imp::interface_mapping.emplace(imp->interface(),
                                                              imp.get());

        /* Register the Service Implementation as default for Service name in
          case none were registered before. */
        mysql_registry_no_lock_imp::service_registry.emplace_hint(
            addition_result.first, imp->service_name_c_str(), imp.get());
      } catch (...) {
        mysql_registry_no_lock_imp::service_registry.erase(
            addition_result.first);
        /* unique_ptr still has ownership over implementation object, we
          don't have to delete it explicitly. */
        return true;
      }
    }

    /* Pointer is stored in registry, thous we release ownership. */
    imp.release();

    return false;
  } catch (...) {
  }
  return true;
}

/**
  Removes previously registered Service Implementation from registry. If it is
  the default one for specified Service then any one still registered is made
  default. If there is no other, the default entry is removed from the
  Registry too. Assumes caller has a write lock on the Registry.

  @param service_implementation_name Name of the Service Implementation to
    unregister.
  @return Status of performed operation
  @retval false success
  @retval true Failure. May happen when Service is still being referenced.
*/
bool mysql_registry_no_lock_imp::unregister_nolock(
    const char *service_implementation_name) {
  try {
    std::unique_ptr<mysql_service_implementation> imp;

    {
      /* Find the implementation and check if it is not being referenced. */
      my_service_registry::iterator imp_iter =
          mysql_registry_no_lock_imp::service_registry.find(
              service_implementation_name);
      if (imp_iter == mysql_registry_no_lock_imp::service_registry.end() ||
          imp_iter->second->get_reference_count() > 0) {
        return true;
      }

      /* First remove specified implementation, to not include it in search
        for new default one. Take ownership on implementation object. */
      imp.reset(imp_iter->second);
      mysql_registry_no_lock_imp::service_registry.erase(imp_iter);
      /* After deletion, implementation iterator is not valid, we go out of
        scope to prevent it from being reused. */
    }

    /* Remove interface mapping. */
    mysql_registry_no_lock_imp::interface_mapping.erase(
        mysql_registry_no_lock_imp::interface_mapping.find(imp->interface()));

    /* Look if it is the default implementation. */
    my_service_registry::iterator default_iter =
        mysql_registry_no_lock_imp::service_registry.find(
            imp->service_name_c_str());
    if (default_iter == mysql_registry_no_lock_imp::service_registry.end()) {
      /* A Service Implementation and no default present. The state is not
        consistent. */
      return true;
    }

    if (default_iter->second == imp.get()) {
      /* Remove the default implementation too. */
      my_service_registry::iterator new_default_iter =
          mysql_registry_no_lock_imp::service_registry.erase(default_iter);

      /* Search for a new default implementation. */
      if (new_default_iter !=
              mysql_registry_no_lock_imp::service_registry.end() &&
          !strcmp(imp->service_name_c_str(),
                  new_default_iter->second->service_name_c_str())) {
        /* Set as default implementation. */
        mysql_service_implementation *new_default = new_default_iter->second;
        mysql_registry_no_lock_imp::service_registry.emplace_hint(
            new_default_iter, new_default->service_name_c_str(), new_default);
      }
    }

    return false;
  } catch (...) {
  }
  return true;
}

/**
  Finds and acquires a Service by name. A name of the Service or the Service
  Implementation can be specified. In case of the Service name, the default
  Service Implementation for Service specified will be returned.

  This does not take any lock on the registry. It must not be used unless
  absolutely necessary. Use the mysql_registry_imp version instead.

  @param service_name Name of Service or Service Implementation to acquire.
  @param [out] out_service Pointer to Service handle to set acquired Service.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
DEFINE_BOOL_METHOD(mysql_registry_no_lock_imp::acquire,
                   (const char *service_name, my_h_service *out_service)) {
  return mysql_registry_no_lock_imp::acquire_nolock(service_name, out_service);
}

/**
  Finds a Service by name. If there is a Service Implementation with the same
  Component part of name as the input Service then the found Service is
  returned.

  This does not take any lock on the registry. It must not be used unless
  absolutely necessary. Use the mysql_registry_imp version instead.

  @param service_name Name of Service or Service Implementation to acquire.
  @param service Service handle already acquired Service Implementation.
  @param [out] out_service Pointer to Service Implementation handle to set
    acquired Service Implementation.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
DEFINE_BOOL_METHOD(mysql_registry_no_lock_imp::acquire_related,
                   (const char *service_name, my_h_service service,
                    my_h_service *out_service)) {
  try {
    mysql_service_implementation *service_implementation =
        mysql_registry_no_lock_imp::get_service_implementation_by_interface(
            service);
    if (service_implementation == nullptr) {
      return true;
    }
    /* Find dot, the component name is right after the dot. */
    const char *component_part =
        strchr(service_implementation->name_c_str(), '.');
    if (component_part == nullptr) {
      return true;
    }
    /* Assure given service_name is not fully qualified. */
    if (strchr(service_name, '.') != nullptr) {
      return true;
    }
    my_string service_implementation_name =
        my_string(service_name) + component_part;
    /* Try to acquire such Service. */
    if (mysql_registry_no_lock_imp::acquire_nolock(
            service_implementation_name.c_str(), out_service)) {
      /* service is not found */
      return true;
    }
    return false;
  } catch (...) {
  }
  return true;
}

/**
  Releases the Service Implementation previously acquired. After the call to
  this method the usage of the Service Implementation handle will lead to
  unpredicted results.

  This does not take any lock on the registry. It must not be used unless
  absolutely necessary. Use the mysql_registry_imp version instead.

  @param service Service Implementation handle of already acquired Service.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
DEFINE_BOOL_METHOD(mysql_registry_no_lock_imp::release,
                   (my_h_service service)) {
  return mysql_registry_no_lock_imp::release_nolock(service);
}

/**
  Registers a new Service Implementation. If it is the first Service
  Implementation for the specified Service then it is made a default one.

  This does not take any lock on the registry. It must not be used unless
  absolutely necessary. Use the mysql_registry_imp version instead.

  @param service_implementation_name Name of the Service Implementation to
    register.
  @param ptr Pointer to the Service Implementation structure.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
DEFINE_BOOL_METHOD(mysql_registry_no_lock_imp::register_service,
                   (const char *service_implementation_name,
                    my_h_service ptr)) {
  return mysql_registry_no_lock_imp::register_service_nolock(
      service_implementation_name, ptr);
}

/**
  Removes previously registered Service Implementation from registry. If it is
  the default one for specified Service then any one still registered is made
  default. If there is no other, the default entry is removed from the
  Registry too.

  This does not take any lock on the registry. It must not be used unless
  absolutely necessary. Use the mysql_registry_imp version instead.

  @param service_implementation_name Name of the Service Implementation to
    unregister.
  @return Status of performed operation
  @retval false success
  @retval true Failure. May happen when Service is still being referenced.
*/
DEFINE_BOOL_METHOD(mysql_registry_no_lock_imp::unregister,
                   (const char *service_implementation_name)) {
  return mysql_registry_no_lock_imp::unregister_nolock(
      service_implementation_name);
}

/**
  Sets new default Service Implementation for corresponding Service name.

  This does not take any lock on the registry. It must not be used unless
  absolutely necessary. Use the mysql_registry_imp version instead.

  @param service_implementation_name Name of the Service Implementation to
    set as default one.
  @return Status of performed operation
  @retval false success
  @retval true failure
*/
DEFINE_BOOL_METHOD(mysql_registry_no_lock_imp::set_default,
                   (const char *service_implementation_name)) {
  try {
    my_service_registry::const_iterator iter;

    /* register the implementation name */
    iter = mysql_registry_no_lock_imp::service_registry.find(
        service_implementation_name);

    if (iter == mysql_registry_no_lock_imp::service_registry.cend()) {
      return true;
    }
    mysql_service_implementation *imp = iter->second;
    /* We have to remove and reinsert value as key, the string pointer will
      not be valid if we unregister previous default implementation. */
    iter = mysql_registry_no_lock_imp::service_registry.erase(
        mysql_registry_no_lock_imp::service_registry.find(
            imp->service_name_c_str()));
    mysql_registry_no_lock_imp::service_registry.emplace_hint(
        iter, imp->service_name_c_str(), imp);

    return false;
  } catch (...) {
  }
  return true;
}

/* This includes metadata-related method implementations that are shared
  by registry and dynamic_loader, so we don't duplicate the code. Following
  defines set up all required symbols. Unfortunately they are not only the
  types, but also static members with different name, so usage of templates
  is not enough to reuse that part of code. */
#define REGISTRY_IMP mysql_registry_no_lock_imp
#define REGISTRY mysql_registry_no_lock_imp::service_registry
#define REGISTRY_TYPE my_service_registry

/* static members for mysql_registry_no_lock_imp */
my_service_registry mysql_registry_no_lock_imp::service_registry;
mysql_registry_no_lock_imp::my_interface_mapping
    mysql_registry_no_lock_imp::interface_mapping;