// Fill out your copyright notice in the Description page of Project Settings.


#include "SPianoKey.h"

#include "FontMeasure.h"
#include "SlateApplication.h"
#include "SlateOptMacros.h"
#include "Midi/MidiMessage.h"
#include "PluginHost/PluginHost.h"
#include "UI/Style/AronaStyle.h"

BEGIN_SLATE_FUNCTION_BUILD_OPTIMIZATION

bool IsBetweenBlackKey(int32 NoteNumber)
{
	return NoteNumber % 12 == 1 || NoteNumber % 12 == 3 || NoteNumber % 12 == 6 || NoteNumber % 12 == 8 || NoteNumber % 12 == 10;
}

void SPianoKey::Construct(const FArguments& InArgs, FPluginHost* InPluginHost)
{
	PluginHost = InPluginHost;
	KeyHeight = InArgs._KeyHeight;
	KeyWidth = InArgs._KeyWidth;
}

int32 SPianoKey::OnPaint(const FPaintArgs& Args, const FGeometry& AllottedGeometry, const FSlateRect& MyCullingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& InWidgetStyle, bool bParentEnabled) const
{
	const FVector2D Size = AllottedGeometry.GetLocalSize();
	const float BlackKeyHeight = KeyHeight.Get(); // 黑键始终为KeyHeight
	const float SemitoneHeight = BlackKeyHeight * 1.5f; // 半音高度
	const float WholeToneHeight = SemitoneHeight * 2; // 全音高度
	const TSharedRef<FSlateFontMeasure> FontMeasureService = FSlateApplication::Get().GetRenderer()->GetFontMeasureService();

	float CursorY = KeyHeight.Get() * FMidiMessage::MaxNoteNumber - (KeyHeight.Get() * 1.5);
	FSlateFontInfo SlateFontInfo = FAronaStyle::GetFontInfo(DefaultFontName);
	// 画白键
	++LayerId;
	for (int32 i = 0; i < FMidiMessage::MaxNoteNumber + 1; ++i)
	{
		if (FMidiMessage::isMidiNoteBlack(i))
			continue;
		const bool IsBetweenBlack = IsBetweenBlackKey(i);
		const float CurrentKeyHeight = IsBetweenBlack ? SemitoneHeight : WholeToneHeight;
		const FSlateLayoutTransform& InLayoutTransform = FSlateLayoutTransform(FVector2D(0, CursorY));
		
		// 画白键
		FSlateDrawElement::MakeBox(
			OutDrawElements,
			LayerId,
			AllottedGeometry.ToPaintGeometry(FVector2f(Size.X, CurrentKeyHeight), InLayoutTransform),
			FAronaStyle::GetSlateBrush(WhiteKey)
		);
		CursorY -= CurrentKeyHeight;
	}

	// 画黑键
	++LayerId;
	for (int32 i = 0; i < FMidiMessage::MaxNoteNumber + 1; ++i)
	{
		if (FMidiMessage::isMidiNoteWhite(i))
			continue;
		const FSlateLayoutTransform& InLayoutTransform = FSlateLayoutTransform(FVector2D(0, (FMidiMessage::MaxNoteNumber - i) * BlackKeyHeight));
		// AllottedGeometry.ToPaintGeometry(FVector2f(0, (FMidiMessage::MaxNoteNumber - i) * BlackKeyHeight), FVector2f(Size.X * 0.7, BlackKeyHeight))
		// 画黑键
		FSlateDrawElement::MakeBox(
			OutDrawElements,
			LayerId,
			AllottedGeometry.ToPaintGeometry(FVector2f(Size.X * 0.7, BlackKeyHeight), InLayoutTransform),
			FAronaStyle::GetSlateBrush(BlackKey)
		);
	}

	++LayerId;
	// 画字
	for (int i = 0; i < FMidiMessage::MaxNoteNumber + 1; ++i)
	{
		FString MidiNoteName = FMidiMessage::getMidiNoteName(i, true, true);
		// 计算字体大小 
		const float FontSize = FontMeasureService->Measure(MidiNoteName, SlateFontInfo).X;
		const FSlateLayoutTransform& InLayoutTransform = FSlateLayoutTransform(FVector2D(Size.X - FontSize, (FMidiMessage::MaxNoteNumber - i) * BlackKeyHeight));
		
		// 画字
		FSlateDrawElement::MakeText(
			OutDrawElements,
			LayerId,
			AllottedGeometry.ToPaintGeometry(FVector2f(Size.X, BlackKeyHeight), InLayoutTransform),
			MidiNoteName,
			SlateFontInfo,
			ESlateDrawEffect::None,
			FLinearColor::Black
		);
	}
	return LayerId;
}

FVector2D SPianoKey::ComputeDesiredSize(float LayoutScaleMultiplier) const
{
	return FVector2D(KeyWidth.Get(), KeyHeight.Get() * FMidiMessage::MaxNoteNumber);
}

FReply SPianoKey::OnMouseButtonDown(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent)
{
	if (MouseEvent.GetEffectingButton() == EKeys::LeftMouseButton)
	{
		const FVector2D LocalPos = MyGeometry.AbsoluteToLocal(MouseEvent.GetScreenSpacePosition());
		const int32 NoteNumber = HeightToNoteNumber(LocalPos.Y);
		if (NoteNumber >= 0 && NoteNumber <= FMidiMessage::MaxNoteNumber)
		{
			PluginHost->IncomingMidi.addEvent(FMidiMessage::noteOn(1, NoteNumber, WidthToVelocity(LocalPos.X)));
			LastNoteNumber = NoteNumber;
		}
		return FReply::Handled().CaptureMouse(AsShared());
	}
	return FReply::Unhandled();
}

FReply SPianoKey::OnMouseButtonUp(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent)
{
	if (MouseEvent.GetEffectingButton() == EKeys::LeftMouseButton)
	{
		if (LastNoteNumber >= 0 && LastNoteNumber <= FMidiMessage::MaxNoteNumber)
		{
			PluginHost->IncomingMidi.addEvent(FMidiMessage::noteOff(1, LastNoteNumber, 0.f));
		}
		LastNoteNumber = -1;
		return FReply::Handled().ReleaseMouseCapture();
	}
	return FReply::Unhandled();
}

FReply SPianoKey::OnMouseMove(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent)
{
	if (MouseEvent.IsMouseButtonDown(EKeys::LeftMouseButton))
	{
		const int32 CurrentNoteNumber = HeightToNoteNumber(MyGeometry.AbsoluteToLocal(MouseEvent.GetScreenSpacePosition()).Y);
		
		if (LastNoteNumber != CurrentNoteNumber)
		{
			if (LastNoteNumber != -1)
				PluginHost->IncomingMidi.addEvent(FMidiMessage::noteOff(1, LastNoteNumber, 0.f));
			LastNoteNumber = CurrentNoteNumber;

			const float Velocity = WidthToVelocity(MyGeometry.AbsoluteToLocal(MouseEvent.GetScreenSpacePosition()).X);
			PluginHost->IncomingMidi.addEvent(FMidiMessage::noteOn(1, CurrentNoteNumber, Velocity));
		}
		return FReply::Handled();
	}
	return FReply::Unhandled();
}

int32 SPianoKey::HeightToNoteNumber(float Height) const
{
	return FMidiMessage::MaxNoteNumber - Height / KeyHeight.Get();
}

float SPianoKey::WidthToVelocity(float Width) const
{
	return FMath::Min(Width / KeyWidth.Get(), 1.f);
}
END_SLATE_FUNCTION_BUILD_OPTIMIZATION