//
//  Submenu.swift
//  MacBackend
//
//  Created by david-swift on 22.10.23.
//

import AppKit

/// A submenu widget.
public struct Menu: MenuWidget {

    /// The label of the submenu.
    var label: String
    /// The content of the submenu.
    var content: Body

    /// Initialize a submenu.
    /// - Parameters:
    ///     - label: The submenu's label.
    ///     - content: The content of the section.
    public init(_ label: String, @ViewBuilder content: () -> Body) {
        self.label = label
        self.content = content()
    }

    /// The view storage.
    /// - Parameters:
    ///     - data: The widget data.
    ///     - type: The type of the views.
    /// - Returns: The view storage.
    public func container<Data>(
        data: WidgetData,
        type: Data.Type
    ) -> ViewStorage where Data: ViewRenderData {
        let item = NSMenuItem()
        let menu = NSMenu()
        item.submenu = menu
        let storage = ViewStorage(item)
        let content = MenuCollection { self.content }.getMenu(data: data, menu: menu)
        storage.content[.mainContent] = [content]
        update(storage, data: data, updateProperties: true, type: type)
        return storage
    }

    /// Update the stored content.
    /// - Parameters:
    ///     - storage: The storage to update.
    ///     - data: The widget data.
    ///     - updateProperties: Whether to update the properties.
    ///     - type: The type of the views.
    public func update<Data>(
        _ storage: ViewStorage,
        data: WidgetData,
        updateProperties: Bool,
        type: Data.Type
    ) where Data: ViewRenderData {
        if let content = storage.content[.mainContent]?.first {
            MenuCollection { self.content }.update(content, data: data, updateProperties: updateProperties, type: type)
        }
        guard updateProperties, let item = storage.pointer as? NSMenuItem else {
            return
        }
        let previousState = storage.previousState as? Self
        if previousState?.label != label {
            item.title = label
        }
        storage.previousState = self
    }

}