/// The size of a view.
public struct ViewSize: Hashable, Sendable {
    /// The zero view size.
    public static let zero = Self(0, 0)

    /// The view's width.
    public var width: Double
    /// The view's height.
    public var height: Double

    /// Creates a view size.
    ///
    /// - Parameters:
    ///   - width: The view's width.
    ///   - height: The view's height.
    public init(_ width: Double, _ height: Double) {
        self.width = width
        self.height = height
    }

    /// Creates a view size from an integer vector.
    ///
    /// - Parameter vector: The vector to create the view size from. The
    ///   X component becomes the width, and the Y component becomes the
    ///   height.
    init(_ vector: SIMD2<Int>) {
        width = Double(vector.x)
        height = Double(vector.y)
    }

    /// Gets the view size as a vector.
    @_spi(Backends) public var vector: SIMD2<Int> {
        SIMD2<Int>(
            LayoutSystem.roundSize(width),
            LayoutSystem.roundSize(height)
        )
    }

    /// The size component associated with the given orientation.
    ///
    /// - Parameter orientation: The orientation.
    /// - Returns: The component corresponding to `orientation`.
    public subscript(component orientation: Orientation) -> Double {
        get {
            switch orientation {
                case .horizontal:
                    width
                case .vertical:
                    height
            }
        }
        set {
            switch orientation {
                case .horizontal:
                    width = newValue
                case .vertical:
                    height = newValue
            }
        }
    }

    /// The size component associated with the given axis.
    ///
    /// - Parameter axis: The axis.
    /// - Returns: The component corresponding to `axis`.
    public subscript(component axis: Axis) -> Double {
        get {
            self[component: axis.orientation]
        }
        set {
            self[component: axis.orientation] = newValue
        }
    }
}