DismissInterceptor.swift

import SwiftUI

// MARK: - DismissInterceptor

/// Overrides `@Environment(\.dismiss)` for child views by injecting a custom
/// `Binding<PresentationMode>` via the deprecated `\.presentationMode` key path.
///
/// `DismissAction` internally wraps `Binding<PresentationMode>` and calls its setter
/// when `dismiss()` is invoked. By replacing that binding, we redirect dismiss to our
/// handler instead of letting it close the window (macOS) or presentation (iOS).
///
/// This lets views use `@Environment(\.dismiss)` normally without knowing they're
/// inside a subscreen overlay.
struct DismissInterceptor: ViewModifier {
	let onDismiss: @MainActor () -> Void

	/// presentationMode is get-only at the API level, but EnvironmentKey's subscript
	/// requires a WritableKeyPath — so the runtime cast succeeds.
	/// If Apple changes the internal layout, the cast returns nil and we fall through
	/// to a no-op (dismiss closes the window as before).
	private static let presentationModeKeyPath: WritableKeyPath<EnvironmentValues, Binding<PresentationMode>>? = {
		guard let keyPath = \EnvironmentValues.presentationMode as? WritableKeyPath else {
			assertionFailure()
			return nil
		}
		return keyPath
	}()

	func body(content: Content) -> some View {
		if let keyPath = Self.presentationModeKeyPath {
			let presented = true
			let pm = withUnsafeBytes(of: presented) { $0.load(as: PresentationMode.self) }

			let binding = Binding<PresentationMode>(
				get: { pm },
				set: { _ in onDismiss() },
			)

			content.environment(keyPath, binding)
		} else {
			content
		}
	}
}

// MARK: - View + interceptDismiss

extension View {
	/// Intercepts `@Environment(\.dismiss)` calls from child views,
	/// redirecting them to the provided handler.
	func interceptDismiss(_ handler: @MainActor @escaping () -> Void) -> some View {
		modifier(DismissInterceptor(onDismiss: handler))
	}
}