import SwiftUI
import ASCollectionView

struct ExampleView: View {
    @State var dataExampleA = (0 ..< 21).map { $0 }
    @State var dataExampleB = (0 ..< 15).map { "ITEM \($0)" }
    
    var body: some View
    {
        ASCollectionView
		{
			ASCollectionViewSection(
				id: 0,
				data: dataExampleA,
				dataID: \.self)
			{ item, _ in
				Color.blue
					.overlay(
						Text("\(item)")
					)
			}
			ASCollectionViewSection(
				id: 1,
				data: dataExampleB,
				dataID: \.self)
			{ item, _ in
				Color.green
					.overlay(
						Text("Complex layout - \(item)")
					)
			}
			.sectionHeader
			{
				HStack
				{
					Text("Section header")
						.padding()
					Spacer()
				}
				.background(Color.yellow)
			}
			.sectionFooter
			{
				Text("This is a section footer!")
					.padding()
			}
		}
		.layout { sectionID in
			switch sectionID {
				case 0:
				// Here we use one of the provided convenience layouts
				return .grid(layoutMode: .adaptive(withMinItemSize: 100),
							 itemSpacing: 5,
							 lineSpacing: 5,
							 itemSize: .absolute(50))
				default:
				return ASCollectionLayoutSection { environment in
					// ...
					// You could return any custom NSCollectionLayoutSection here. For an example see this file: /readmeAssets/SampleUsage.swift
					// ...
				}
			}
		}
	}
}

ASCollectionViewSection(...) { ... }
	.sectionHeader
	{
		Text("Section header")
		.background(Color.yellow)
	}
	.sectionFooter
	{
		Text("Section footer")
		.background(Color.blue)
	}
        .sectionSupplementary(ofKind: "someOtherSupplementaryKindRequestedByYourLayout") {
                Text("Section supplementary")
		.background(Color.green)
        }

struct GroupBackground: View, Decoration
{
	let cornerRadius: CGFloat = 12
	var body: some View
	{
		RoundedRectangle(cornerRadius: cornerRadius)
			.fill(Color(.secondarySystemGroupedBackground))
	}
}

var layout: ASCollectionLayout<Section>
{
	ASCollectionLayout<Section>
	{ 
            // ... Here is an example of including a decoration in a compositional layout.
            let sectionBackgroundDecoration = NSCollectionLayoutDecorationItem.background(elementKind: "groupBackground")
            sectionBackgroundDecoration.contentInsets = section.contentInsets
            section.decorationItems = [sectionBackgroundDecoration]
            // ...
}
.decorationView(GroupBackground.self, forDecorationViewOfKind: "groupBackground") //REGISTER the decoration view type

ASCollectionView(...) { ... }
.layout {
    ASCollectionLayoutSection { layoutEnvironment in
    	//Construct and return a NSCollectionLayoutSection here
    }
}

ASCollectionView(...) { ... }
.layout { sectionID in
    switch sectionID {
    case .userSection:
        return ASCollectionLayoutSection { layoutEnvironment in
            //Construct and return a NSCollectionLayoutSection here
        }
    }
    case .postSection:
        return ASCollectionLayoutSection { layoutEnvironment in
            //Construct and return a NSCollectionLayoutSection here
        }
    }
}

ASCollectionView(...) { ... }
.layout {
    let someCustomLayout = CustomUICollectionViewLayout()
    someCustomLayout.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
    return someCustomLayout
}