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

#include "CreditsScreen.h"
#include "Misc/Paths.h"
#include "HAL/PlatformProcess.h"
#include "Misc/FileHelper.h"
#include "Misc/EngineVersion.h"
#include "Widgets/SBoxPanel.h"
#include "Widgets/SOverlay.h"
#include "Widgets/Images/SImage.h"
#include "Widgets/Text/SRichTextBlock.h"
#include "Widgets/Input/SButton.h"
#include "Widgets/Layout/SScrollBox.h"
#include "EditorStyleSet.h"
#include "Misc/EngineBuildSettings.h"

#define LOCTEXT_NAMESPACE "CreditsScreen"

void SCreditsScreen::Construct(const FArguments& InArgs)
{
    PreviousScrollPosition = 0.0f;
    ScrollPixelsPerSecond  = 50.0f;
    bIsPlaying             = true;

    ActiveTimerHandle      = RegisterActiveTimer(0.f, FWidgetActiveTimerDelegate::CreateSP(this, &SCreditsScreen::RollCredits));

    const FString Version  = FEngineVersion::Current().ToString(FEngineBuildSettings::IsPerforceBuild() ? EVersionComponent::Branch : EVersionComponent::Patch);

    FString CreditsText;
    FFileHelper::LoadFileToString(CreditsText, *(FPaths::EngineContentDir() + TEXT("Editor/Credits.rt")));
    CreditsText.ReplaceInline(TEXT("%VERSION%"), *Version);

    ChildSlot
        [SNew(SOverlay)

         + SOverlay::Slot()
               [SAssignNew(ScrollBox, SScrollBox)
                    .Style(FEditorStyle::Get(), "ScrollBox")
                    .OnUserScrolled(this, &SCreditsScreen::HandleUserScrolled)

                + SScrollBox::Slot()
                      [SNew(SVerticalBox)

                       + SVerticalBox::Slot()
                             .FillHeight(1.0f)
                                 [SNew(SRichTextBlock)
                                      .Text(FText::FromString(CreditsText))
                                      .TextStyle(FEditorStyle::Get(), "Credits.Normal")
                                      .DecoratorStyleSet(&FEditorStyle::Get())
                                      .Justification(ETextJustify::Center) +
                                  SRichTextBlock::HyperlinkDecorator(TEXT("browser"), this, &SCreditsScreen::OnBrowserLinkClicked)]]]

         + SOverlay::Slot()
               .VAlign(VAlign_Bottom)
                   [SNew(SHorizontalBox)

                    + SHorizontalBox::Slot()
                          .AutoWidth()
                              [SNew(SButton)
                                   .ButtonStyle(FEditorStyle::Get(), "Credits.Button")
                                   .OnClicked(this, &SCreditsScreen::HandleTogglePlayPause)
                                       [SNew(SImage)
                                            .Image(this, &SCreditsScreen::GetTogglePlayPauseBrush)]]]];
}

EActiveTimerReturnType SCreditsScreen::RollCredits(double InCurrentTime, float InDeltaTime)
{
    float NewPixelOffset = (ScrollPixelsPerSecond * InDeltaTime);
    ScrollBox->SetScrollOffset(ScrollBox->GetScrollOffset() + NewPixelOffset);
    PreviousScrollPosition = ScrollBox->GetScrollOffset();

    return EActiveTimerReturnType::Continue;
}

FReply SCreditsScreen::HandleTogglePlayPause()
{
    if (bIsPlaying)
    {
        bIsPlaying = false;
        if (ActiveTimerHandle.IsValid())
        {
            UnRegisterActiveTimer(ActiveTimerHandle.Pin().ToSharedRef());
        }
    }
    else
    {
        bIsPlaying = true;
        if (!ActiveTimerHandle.IsValid())
        {
            ActiveTimerHandle = RegisterActiveTimer(0.f, FWidgetActiveTimerDelegate::CreateSP(this, &SCreditsScreen::RollCredits));
        }
    }

    return FReply::Handled();
}

void SCreditsScreen::HandleUserScrolled(float ScrollOffset)
{
    // If the user scrolls up, and we're currently playing, then stop playing.
    if (bIsPlaying && ScrollOffset < PreviousScrollPosition)
    {
        bIsPlaying = false;
        if (ActiveTimerHandle.IsValid())
        {
            UnRegisterActiveTimer(ActiveTimerHandle.Pin().ToSharedRef());
        }
    }

    PreviousScrollPosition = ScrollOffset;
}

const FSlateBrush* SCreditsScreen::GetTogglePlayPauseBrush() const
{
    static FName PauseIcon(TEXT("Credits.Pause"));
    static FName PlayIcon(TEXT("Credits.Play"));

    if (bIsPlaying)
    {
        return FEditorStyle::GetBrush(PauseIcon);
    }
    else
    {
        return FEditorStyle::GetBrush(PlayIcon);
    }
}

void SCreditsScreen::OnBrowserLinkClicked(const FSlateHyperlinkRun::FMetadata& Metadata)
{
    const FString* url = Metadata.Find(TEXT("href"));

    if (url != NULL)
    {
        FPlatformProcess::LaunchURL(**url, NULL, NULL);
    }
}

#undef LOCTEXT_NAMESPACE