// Copyright Epic Games, Inc. All Rights Reserved.

/*=============================================================================
ScriptStackTracker.h: Script Stack Tracking within Unreal Engine.
=============================================================================*/
#pragma once

#include "CoreMinimal.h"

struct FFrame;

struct FScriptStackTracker
{
private:
    /** Maximum number of backtrace depth. */
    static const int32 MAX_BACKTRACE_DEPTH = 50;

    /** Helper structure to capture callstack addresses and stack count. */
    struct FCallStack
    {
        /** Stack count, aka the number of calls to CalculateStack */
        int64 StackCount;
        /** String representation of script callstack. */
        FString StackTrace;
    };

    /** Array of unique callstacks. */
    TArray<FCallStack> CallStacks;
    /** Mapping from callstack CRC to index in callstack array. */
    TMap<uint32, int32> CRCToCallStackIndexMap;
    /** Whether we are currently capturing or not, used to avoid re-entrancy. */
    bool bAvoidCapturing;
    /** Whether stack tracking is enabled. */
    bool bIsEnabled;
    /** Frame counter at the time tracking was enabled. */
    uint64 StartFrameCounter;
    /** Frame counter at the time tracking was disabled. */
    uint64 StopFrameCounter;

public:
    /** Constructor, initializing all member variables */
    FScriptStackTracker(bool bInIsEnabled = false)
        : bAvoidCapturing(false), bIsEnabled(bInIsEnabled), StartFrameCounter(0), StopFrameCounter(0)
    {}

    /**
     * Captures the current stack and updates stack tracking information.
     */
    COREUOBJECT_API void CaptureStackTrace(const FFrame* StackFrame, int32 EntriesToIgnore = 0);

    /**
     * Dumps capture stack trace summary to the passed in log.
     */
    COREUOBJECT_API void DumpStackTraces(int32 StackThreshold, FOutputDevice& Ar);

    /** Resets stack tracking. */
    COREUOBJECT_API void ResetTracking();

    /** Toggles tracking. */
    COREUOBJECT_API void ToggleTracking();
};