ghostty/macos/Sources/Helpers/SplitView/SplitView.Divider.swift

import SwiftUI

extension SplitView {
    /// The split divider that is rendered and can be used to resize a split view.
    struct Divider: View {
        @EnvironmentObject var ghostty: Ghostty.App

        let direction: SplitViewDirection
        let visibleSize: CGFloat
        let invisibleSize: CGFloat
        
        private var visibleWidth: CGFloat? {
            switch (direction) {
            case .horizontal:
                return visibleSize
            case .vertical:
                return nil
            }
        }
        
        private var visibleHeight: CGFloat? {
            switch (direction) {
            case .horizontal:
                return nil
            case .vertical:
                return visibleSize
            }
        }
        
        private var invisibleWidth: CGFloat? {
            switch (direction) {
            case .horizontal:
                return visibleSize + invisibleSize
            case .vertical:
                return nil
            }
        }
        
        private var invisibleHeight: CGFloat? {
            switch (direction) {
            case .horizontal:
                return nil
            case .vertical:
                return visibleSize + invisibleSize
            }
        }

        private var color: Color {
            let backgroundColor = NSColor(ghostty.config.backgroundColor)
            let isLightBackground = backgroundColor.isLightColor
            let newColor = isLightBackground ? backgroundColor.shadow(withLevel: 0.1) : backgroundColor.shadow(withLevel: 0.4)

            return Color(nsColor: newColor ?? .gray.withAlphaComponent(0.5))
        }

        var body: some View {
            ZStack {
                Color.clear
                    .frame(width: invisibleWidth, height: invisibleHeight)
                Rectangle()
                    .fill(color)
                    .frame(width: visibleWidth, height: visibleHeight)
            }
            .onHover { isHovered in
                if (isHovered) {
                    switch (direction) {
                    case .horizontal:
                        NSCursor.resizeLeftRight.push()
                    case .vertical:
                        NSCursor.resizeUpDown.push()
                    }
                } else {
                    NSCursor.pop()
                }
            }
        }
    }
}