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

#pragma once

#include "CoreMinimal.h"
#include "UObject/UnrealType.h"
#include "Templates/UniquePtr.h"
#include "Misc/EnumClassFlags.h"

class UObject;
class UStruct;
class FProperty;

/**
 * Result flags from property access.
 */
enum class EPropertyAccessResultFlags : uint8
{
    /** The property was accessed successfully */
    Success = 0,

    /** The property could not be accessed due to a permission error (the permission flags can give more detail of the error) */
    PermissionDenied = 1 << 0,
    /** The property could not be read or written due to a failure converting from the source or to the destination */
    ConversionFailed = 1 << 1,

    /** Permission flag added when the property cannot be accessed due to being protected (is not marked for editor or Blueprint access) */
    AccessProtected = 1 << 4,
    /** Permission flag added when attempting to edit a property on a template that cannot be edited on templates */
    CannotEditTemplate = 1 << 5,
    /** Permission flag added when attempting to edit a property on an instance that cannot be edited on instances */
    CannotEditInstance = 1 << 6,
    /** Permission flag added when attempting to edit a property that is read-only (based on the given read-only flags) */
    ReadOnly = 1 << 7,
};
ENUM_CLASS_FLAGS(EPropertyAccessResultFlags);

/**
 * Enum controlling when to emit property change notifications when setting a property value.
 * @note Mirrored in NoExportTypes.h for UHT.
 */
enum class EPropertyAccessChangeNotifyMode : uint8
{
    /** Notify only when a value change has actually occurred */
    Default,
    /** Never notify that a value change has occurred */
    Never,
    /** Always notify that a value change has occurred, even if the value is unchanged */
    Always,
};

/**
 * Information needed to emit property change notifications when setting a property value.
 */
struct FPropertyAccessChangeNotify
{
    /** The kind of change that occurred */
    EPropertyChangeType::Type ChangeType = EPropertyChangeType::Unspecified;
    /** The object that is being changed */
    UObject* ChangedObject = nullptr;
    /** The chain of properties that are being changed */
    FEditPropertyChain ChangedPropertyChain;
    /** When to emit property change notifications */
    EPropertyAccessChangeNotifyMode NotifyMode = EPropertyAccessChangeNotifyMode::Default;
};

/**
 * Callback used to get the value of a property.
 */
using FPropertyAccessGetFunc = TFunctionRef<bool()>;

/**
 * Callback used to set the value of a property.
 */
using FPropertyAccessSetFunc = TFunctionRef<bool(const FPropertyAccessChangeNotify*)>;

/**
 * Callback used to build the information needed to emit property change notifications when setting a property value.
 */
using FPropertyAccessBuildChangeNotifyFunc = TFunctionRef<TUniquePtr<FPropertyAccessChangeNotify>()>;

namespace PropertyAccessUtil
{
/** Flags that make a property read-only when settings its value at runtime */
static const uint64 RuntimeReadOnlyFlags = CPF_EditConst | CPF_BlueprintReadOnly;

/** Flags that make a property read-only when settings its value in the editor */
static const uint64 EditorReadOnlyFlags = CPF_EditConst;

/**
 * High-level function for getting the value of a property from an object.
 * @note This function calls CanGetPropertyValue internally.
 *
 * @param InObjectProp Property to get the value of.
 * @param InObject Object containing the property.
 * @param InDestProp Property of the value to set (must be compatible with the source property).
 * @param InDestValue Instance to fill with the property value (must be a valid and constructed block of memory that is compatible with the property).
 * @param InArrayIndex For fixed-size array properties denotes which index of the array to get, or INDEX_NONE to get the entire property.
 *
 * @return Flags describing whether the get was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags GetPropertyValue_Object(const FProperty* InObjectProp, const UObject* InObject, const FProperty* InDestProp, void* InDestValue, const int32 InArrayIndex);

/**
 * High-level function for getting the value of a property from a property container (object or struct).
 * @note This function calls CanGetPropertyValue internally.
 *
 * @param InContainerProp Property to get the value of.
 * @param InContainerData The instance data containing the property.
 * @param InDestProp Property of the value to set (must be compatible with the source property).
 * @param InDestValue Instance to fill with the property value (must be a valid and constructed block of memory that is compatible with the property).
 * @param InArrayIndex For fixed-size array properties denotes which index of the array to get, or INDEX_NONE to get the entire property.
 *
 * @return Flags describing whether the get was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags GetPropertyValue_InContainer(const FProperty* InContainerProp, const void* InContainerData, const FProperty* InDestProp, void* InDestValue, const int32 InArrayIndex);

/**
 * High-level function for getting the single-element value of a property from memory.
 * @note This function calls CanGetPropertyValue internally.
 *
 * @param InSrcProp Property to get the value of.
 * @param InSrcValue The property value to copy.
 * @param InDestProp Property of the value to set (must be compatible with the source property).
 * @param InDestValue Instance to fill with the property value (must be a valid and constructed block of memory that is compatible with the property).
 *
 * @return Flags describing whether the get was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags GetPropertyValue_DirectSingle(const FProperty* InSrcProp, const void* InSrcValue, const FProperty* InDestProp, void* InDestValue);

/**
 * High-level function for getting the multi-element value of a property from memory.
 * @note This function calls CanGetPropertyValue internally.
 *
 * @param InSrcProp Property to get the value of.
 * @param InSrcValue The property value to copy.
 * @param InDestProp Property of the value to set (must be compatible with the source property).
 * @param InDestValue Instance to fill with the property value (must be a valid and constructed block of memory that is compatible with the property).
 *
 * @return Flags describing whether the get was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags GetPropertyValue_DirectComplete(const FProperty* InSrcProp, const void* InSrcValue, const FProperty* InDestProp, void* InDestValue);

/**
 * Low-level function for getting the value of a property.
 * @note This function does *not* CanGetPropertyValue internally, you must call it yourself to validate the get.
 *
 * @param InGetFunc Logic for getting the value of the property.
 *
 * @return Flags describing whether the get was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags GetPropertyValue(const FPropertyAccessGetFunc& InGetFunc);

/**
 * Low-level function for checking whether it's valid to get the value of a property.
 *
 * @param InProp Property to query.
 *
 * @return Flags describing whether it's valid to get the value of the property.
 */
COREUOBJECT_API EPropertyAccessResultFlags CanGetPropertyValue(const FProperty* InProp);

/**
 * High-level function for setting the value of a property on an object.
 * @note This function calls CanSetPropertyValue internally, and will emit property change notifications for the object.
 *
 * @param InObjectProp Property to set the value of.
 * @param InObject Object containing the property.
 * @param InSrcProp Property of the value to set (must be compatible with the dest property).
 * @param InSrcValue The value to set on the property.
 * @param InArrayIndex For fixed-size array properties denotes which index of the array to set, or INDEX_NONE to set the entire property.
 * @param InReadOnlyFlags Flags controlling which properties are considered read-only.
 * @param InNotifyMode When to emit property change notifications.
 *
 * @return Flags describing whether the set was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags SetPropertyValue_Object(const FProperty* InObjectProp, UObject* InObject, const FProperty* InSrcProp, const void* InSrcValue, const int32 InArrayIndex, const uint64 InReadOnlyFlags, const EPropertyAccessChangeNotifyMode InNotifyMode);

/**
 * High-level function for setting the value of a property on a property container (object or struct).
 * @note This function calls CanSetPropertyValue internally.
 *
 * @param InContainerProp Property to set the value of.
 * @param InContainerData The instance data containing the property.
 * @param InSrcProp Property of the value to set (must be compatible with the dest property).
 * @param InSrcValue The value to set on the property.
 * @param InArrayIndex For fixed-size array properties denotes which index of the array to set, or INDEX_NONE to set the entire property.
 * @param InReadOnlyFlags Flags controlling which properties are considered read-only.
 * @param InOwnerIsTemplate True if the owner object is considered a template (see IsObjectTemplate).
 * @param InBuildChangeNotifyFunc Logic for building the information needed to emit property change notifications when setting a property value (can return nullptr if no notifications are needed or possible).
 *
 * @return Flags describing whether the set was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags SetPropertyValue_InContainer(const FProperty* InContainerProp, void* InContainerData, const FProperty* InSrcProp, const void* InSrcValue, const int32 InArrayIndex, const uint64 InReadOnlyFlags, const bool InOwnerIsTemplate, const FPropertyAccessBuildChangeNotifyFunc& InBuildChangeNotifyFunc);

/**
 * High-level function for setting the single-element value of a property in memory.
 * @note This function calls CanSetPropertyValue internally.
 *
 * @param InSrcProp Property to set the value of.
 * @param InSrcValue The value to set on the property.
 * @param InDestProp Property to get the value from (must be compatible with the source property).
 * @param InDestValue Instance to fill with the property value (must be a valid and constructed block of memory that is compatible with the property).
 * @param InReadOnlyFlags Flags controlling which properties are considered read-only.
 * @param InOwnerIsTemplate True if the owner object is considered a template (see IsObjectTemplate).
 * @param InBuildChangeNotifyFunc Logic for building the information needed to emit property change notifications when setting a property value (can return nullptr if no notifications are needed or possible).
 *
 * @return Flags describing whether the set was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags SetPropertyValue_DirectSingle(const FProperty* InSrcProp, const void* InSrcValue, const FProperty* InDestProp, void* InDestValue, const uint64 InReadOnlyFlags, const bool InOwnerIsTemplate, const FPropertyAccessBuildChangeNotifyFunc& InBuildChangeNotifyFunc);

/**
 * High-level function for setting the multi-element value of a property in memory.
 * @note This function calls CanSetPropertyValue internally.
 *
 * @param InSrcProp Property to set the value of.
 * @param InSrcValue The value to set on the property.
 * @param InDestProp Property to get the value from (must be compatible with the source property).
 * @param InDestValue Instance to fill with the property value (must be a valid and constructed block of memory that is compatible with the property).
 * @param InReadOnlyFlags Flags controlling which properties are considered read-only.
 * @param InOwnerIsTemplate True if the owner object is considered a template (see IsObjectTemplate).
 * @param InBuildChangeNotifyFunc Logic for building the information needed to emit property change notifications when setting a property value (can return nullptr if no notifications are needed or possible).
 *
 * @return Flags describing whether the set was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags SetPropertyValue_DirectComplete(const FProperty* InSrcProp, const void* InSrcValue, const FProperty* InDestProp, void* InDestValue, const uint64 InReadOnlyFlags, const bool InOwnerIsTemplate, const FPropertyAccessBuildChangeNotifyFunc& InBuildChangeNotifyFunc);

/**
 * Low-level function for setting the value of a property.
 * @note This function does *not* CanSetPropertyValue internally, you must call it yourself to validate the set.
 *
 * @param InSetFunc Logic for setting the value of the property (should call EmitPreChangeNotify and EmitPostChangeNotify using the given FPropertyAccessChangeNotify instance).
 * @param InBuildChangeNotifyFunc Logic for building the information needed to emit property change notifications when setting a property value (can return nullptr if no notifications are needed or possible).
 *
 * @return Flags describing whether the get was successful.
 */
COREUOBJECT_API EPropertyAccessResultFlags SetPropertyValue(const FPropertyAccessSetFunc& InSetFunc, const FPropertyAccessBuildChangeNotifyFunc& InBuildChangeNotifyFunc);

/**
 * Low-level function for checking whether it's valid to set the value of a property.
 *
 * @param InProp Property to query.
 *
 * @return Flags describing whether it's valid to set the value of the property.
 */
COREUOBJECT_API EPropertyAccessResultFlags CanSetPropertyValue(const FProperty* InProp, const uint64 InReadOnlyFlags, const bool InOwnerIsTemplate);

/**
 * Low-level function called before modifying an object to notify that its value is about to change.
 *
 * @param InChangeNotify Information needed to emit property change notifications, or nullptr if no notifications are needed or possible.
 * @param InIdenticalValue True if the value being set was identical to the current value, false otherwise.
 */
COREUOBJECT_API void EmitPreChangeNotify(const FPropertyAccessChangeNotify* InChangeNotify, const bool InIdenticalValue);

/**
 * Low-level function called after modifying an object to notify that its value has changed.
 *
 * @param InChangeNotify Information needed to emit property change notifications, or nullptr if no notifications are needed or possible.
 * @param InIdenticalValue True if the value being set was identical to the current value, false otherwise.
 */
COREUOBJECT_API void EmitPostChangeNotify(const FPropertyAccessChangeNotify* InChangeNotify, const bool InIdenticalValue);

/**
 * Low-level function to build the basic information needed to emit property change notifications.
 * @note This function can only build the notification for a property directly on the object instance, as more complex cases require external management as the reflection data doesn't let you backtrack over different types.
 *
 * @param InProp Property being modified.
 * @param InObject Object being modified.
 * @param InNotifyMode When to emit property change notifications.
 *
 * @return The information needed to emit property change notifications.
 */
COREUOBJECT_API TUniquePtr<FPropertyAccessChangeNotify> BuildBasicChangeNotify(const FProperty* InProp, const UObject* InObject, const EPropertyAccessChangeNotifyMode InNotifyMode);

/**
 * Low-level function for checking whether the given object instance is considered a template for property access.
 *
 * @param InObject Object to query.
 *
 * @return True if the object instance is considered a template.
 */
COREUOBJECT_API bool IsObjectTemplate(const UObject* InObject);

/**
 * Low-level function to find a property by its name, following redirectors if it cannot be found.
 *
 * @param InPropName The name of the property to find.
 * @param InStruct The struct that should contain the property.
 *
 * @return The found property, or null if the property cannot be found.
 */
COREUOBJECT_API FProperty* FindPropertyByName(const FName InPropName, const UStruct* InStruct);
}  // namespace PropertyAccessUtil