Atoll/DynamicIsland/components/LockScreen/LockScreenLiveActivityOverlay.swift

import SwiftUI

final class LockScreenLiveActivityOverlayModel: ObservableObject {
	@Published var scale: CGFloat = 0.6
	@Published var opacity: Double = 0
}

struct LockScreenLiveActivityOverlay: View {
	@ObservedObject var model: LockScreenLiveActivityOverlayModel
	@ObservedObject var animator: LockIconAnimator
	let notchSize: CGSize

	private var indicatorSize: CGFloat {
		max(0, notchSize.height - 12)
	}

	private var horizontalPadding: CGFloat {
		cornerRadiusInsets.closed.bottom
	}

	private var totalWidth: CGFloat {
		notchSize.width + (indicatorSize * 2) + (horizontalPadding * 2)
	}

	private var collapsedScale: CGFloat {
		Self.collapsedScale(for: notchSize)
	}

	var body: some View {
		HStack(spacing: 0) {
			Color.clear
				.overlay(alignment: .leading) {
					LockIconProgressView(progress: animator.progress)
						.frame(width: indicatorSize, height: indicatorSize)
				}
				.frame(width: indicatorSize, height: notchSize.height)

			Rectangle()
				.fill(.black)
				.frame(width: notchSize.width, height: notchSize.height)

			Color.clear
				.frame(width: indicatorSize, height: notchSize.height)
		}
		.frame(width: notchSize.width + (indicatorSize * 2), height: notchSize.height)
		.padding(.horizontal, horizontalPadding)
		.background(Color.black)
		.clipShape(
			NotchShape(
				topCornerRadius: cornerRadiusInsets.closed.top,
				bottomCornerRadius: cornerRadiusInsets.closed.bottom
			)
		)
		.frame(width: totalWidth, height: notchSize.height)
		.scaleEffect(x: max(model.scale, collapsedScale), y: 1, anchor: .center)
		.opacity(model.opacity)
	}
}

extension LockScreenLiveActivityOverlay {
	static func collapsedScale(for notchSize: CGSize) -> CGFloat {
		let indicatorSize = max(0, notchSize.height - 12)
		let horizontalPadding = cornerRadiusInsets.closed.bottom
		let totalWidth = notchSize.width + (indicatorSize * 2) + (horizontalPadding * 2)
		guard totalWidth > 0 else { return 1 }
		return notchSize.width / totalWidth
	}
}