/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2020 - Raw Material Software Limited

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

//==============================================================================
/**
    This class is a useful way of tracking down hard to find memory leaks when the
    regular LeakedObjectDetector isn't enough.

    As well as firing when any instances of the OwnerClass type are leaked, it will
    print out a stack trace showing where the leaked object was created. This is obviously
    quite a heavyweight task so, unlike the LeakedObjectDetector which should be always
    be added to your classes, you should only use this object temporarily when you are
    debugging and remove it when finished.

    To use it, use the JUCE_HEAVYWEIGHT_LEAK_DETECTOR macro as a simple way to put
    one in your class declaration.

    @tags{Core}
*/
template <class OwnerClass>
class HeavyweightLeakedObjectDetector
{
public:
    //==============================================================================
    HeavyweightLeakedObjectDetector() noexcept                                           { getBacktraceMap()[this] = SystemStats::getStackBacktrace(); }
    HeavyweightLeakedObjectDetector (const HeavyweightLeakedObjectDetector&) noexcept    { getBacktraceMap()[this] = SystemStats::getStackBacktrace(); }

    ~HeavyweightLeakedObjectDetector()                                                   { getBacktraceMap().erase (this); }

private:
    //==============================================================================
    typedef std::map<HeavyweightLeakedObjectDetector<OwnerClass>*, String> BacktraceMap;

    //==============================================================================
    struct BacktraceMapHolder
    {
        BacktraceMapHolder() = default;

        ~BacktraceMapHolder()
        {
            if (map.size() > 0)
            {
                DBG ("*** Leaked objects detected: " << map.size() << " instance(s) of class " << getLeakedObjectClassName());
                DBG (getFormattedBacktracesString());

                /** If you hit this, then you've leaked one or more objects of the type specified by
                    the 'OwnerClass' template parameter - the name and stack trace of its creation should
                    have been printed by the lines above.

                    If you're leaking, it's probably because you're using old-fashioned, non-RAII techniques for
                    your object management. Tut, tut. Always, always use std::unique_ptrs, OwnedArrays,
                    ReferenceCountedObjects, etc, and avoid the 'delete' operator at all costs!
                */
                jassertfalse;
            }
        }

        String getFormattedBacktracesString() const
        {
            String str;

            int counter = 1;
            for (auto& bt : map)
            {
                str << "\nBacktrace " << String (counter++)                                << "\n"
                    << "-----------------------------------------------------------------" << "\n"
                    << bt.second;
            }

            return str;
        }

        BacktraceMap map;
    };

    static BacktraceMap& getBacktraceMap()
    {
        static BacktraceMapHolder holder;
        return holder.map;
    }

    static const char* getLeakedObjectClassName()
    {
        return OwnerClass::getLeakedObjectClassName();
    }
};

//==============================================================================
#if DOXYGEN || ! defined (JUCE_HEAVYWEIGHT_LEAK_DETECTOR)
 #if (DOXYGEN || JUCE_CHECK_MEMORY_LEAKS)
  /** This macro lets you embed a heavyweight leak-detecting object inside a class.

      To use it, simply declare a JUCE_HEAVYWEIGHT_LEAK_DETECTOR (YourClassName) inside a private section
      of the class declaration. E.g.

      @code
      class MyClass
      {
      public:
          MyClass();
          void blahBlah();

      private:
          JUCE_HEAVYWEIGHT_LEAK_DETECTOR (MyClass)
      };
      @endcode

      NB: you should only use this when you really need to track down a tricky memory leak, and
      should never leave one of these inside a class!

      @see HeavyweightLeakedObjectDetector, JUCE_LEAK_DETECTOR, LeakedObjectDetector
  */
  #define JUCE_HEAVYWEIGHT_LEAK_DETECTOR(OwnerClass) \
        friend class juce::HeavyweightLeakedObjectDetector<OwnerClass>; \
        static const char* getLeakedObjectClassName() noexcept { return #OwnerClass; } \
        juce::HeavyweightLeakedObjectDetector<OwnerClass> JUCE_JOIN_MACRO (leakDetector, __LINE__);
 #else
  #define JUCE_HEAVYWEIGHT_LEAK_DETECTOR(OwnerClass)
 #endif
#endif

} // namespace juce
