import SwiftUI

struct FlowLayout: Layout {
    var spacing: CGFloat = 8

    func sizeThatFits(proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) -> CGSize {
        let width = proposal.width ?? .infinity
        var x: CGFloat = 0, y: CGFloat = 0, rowHeight: CGFloat = 0
        for view in subviews {
            let size = view.sizeThatFits(.unspecified)
            if x + size.width > width, x > 0 {
                x = 0
                y += rowHeight + spacing
                rowHeight = 0
            }
            x += size.width + spacing
            rowHeight = max(rowHeight, size.height)
        }
        return CGSize(width: width.isFinite ? width : x, height: y + rowHeight)
    }

    func placeSubviews(in bounds: CGRect, proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) {
        var x = bounds.minX, y = bounds.minY, rowHeight: CGFloat = 0
        for view in subviews {
            let size = view.sizeThatFits(.unspecified)
            if x + size.width > bounds.maxX, x > bounds.minX {
                x = bounds.minX
                y += rowHeight + spacing
                rowHeight = 0
            }
            view.place(at: CGPoint(x: x, y: y), proposal: ProposedViewSize(size))
            x += size.width + spacing
            rowHeight = max(rowHeight, size.height)
        }
    }
}