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

#include "SequencerCustomizationManager.h"
#include "MovieSceneSequence.h"
#include "Containers/UnrealString.h"

FSequencerCustomizationManager::FSequencerCustomizationManager()
{
}

void FSequencerCustomizationManager::RegisterInstancedSequencerCustomization(const UClass* SequenceClass, FOnGetSequencerCustomizationInstance GetCustomizationDelegate)
{
    if (!ensure(SequenceClass != nullptr))
    {
        return;
    }

    const bool bFound = CustomizationRegistryEntries.ContainsByPredicate([=](const FCustomizationRegistryEntry& Entry) { return Entry.SequenceClass == SequenceClass; });
    ensureMsgf(!bFound, TEXT("Customization already registered for sequence class: %s"), *SequenceClass->GetName());
    if (bFound)
    {
        return;
    }

    FCustomizationRegistryEntry Entry;
    Entry.SequenceClass = SequenceClass;
    Entry.Factory = GetCustomizationDelegate;
    CustomizationRegistryEntries.Add(Entry);
}

void FSequencerCustomizationManager::UnregisterInstancedSequencerCustomization(const UClass* SequenceClass)
{
    if (!ensure(SequenceClass != nullptr))
    {
        return;
    }

    for (TArray<FCustomizationRegistryEntry>::SizeType Idx = 0; Idx < CustomizationRegistryEntries.Num(); ++Idx)
    {
        const FCustomizationRegistryEntry& Entry = CustomizationRegistryEntries[Idx];
        if (Entry.SequenceClass == SequenceClass)
        {
            CustomizationRegistryEntries.RemoveAt(Idx);
            return;
        }
    }
    ensureMsgf(false, TEXT("No customization found for sequence class: %s"), *SequenceClass->GetName());
}

void FSequencerCustomizationManager::GetSequencerCustomizations(UMovieSceneSequence* FocusedSequence, TArray<TUniquePtr<ISequencerCustomization>>& OutCustomizations)
{
	if (UNLIKELY(!FocusedSequence))
	{
		return;
	}

    const UClass* SequenceClass = FocusedSequence->GetClass();

    const FCustomizationRegistryEntry* FoundEntry = CustomizationRegistryEntries.FindByPredicate(
            [=](const FCustomizationRegistryEntry& Entry)
            {
                return Entry.SequenceClass == SequenceClass;
            });
    if (FoundEntry != nullptr)
    {
        TUniquePtr<ISequencerCustomization> Instance(FoundEntry->Factory.Execute());
        OutCustomizations.Add(MoveTemp(Instance));
    }
}

bool FSequencerCustomizationManager::NeedsCustomizationChange(const UMovieSceneSequence* OldFocusedSequence, const UMovieSceneSequence* NewFocusedSequence) const
{
	if (OldFocusedSequence == nullptr || NewFocusedSequence == nullptr)
	{
		return true;
	}

	// For now, we only map customizations to the sequence's class, so we only need to rebuild customizations
	// if the class has changed between the old and new sequence.
    const UClass* OldSequenceClass = OldFocusedSequence->GetClass();
    const UClass* NewSequenceClass = NewFocusedSequence->GetClass();
	return OldSequenceClass != NewSequenceClass;
}