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

import AppKit

/// A button widget for menus.
public struct MenuButton: MenuWidget {

    /// The button's label.
    var label: String
    /// The button's action handler.
    var handler: () -> Void
    /// The keyboard shortcut.
    var shortcut: KeyboardShortcut?
    /// Whether the button is selected.
    var selected: Bool?
    /// Whether the button is enabled.
    var enabled = true

    /// The action label.
    var filteredLabel: String { label.filter { $0.isLetter || $0.isNumber || $0 == "-" || $0 == "." } }

    /// Initialize a menu button.
    /// - Parameters:
    ///   - label: The buttons label.
    ///   - handler: The button's action handler.
    public init(_ label: String, handler: @escaping () -> Void) {
        self.label = label
        self.handler = handler
    }

    /// 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 button = NSMenuItem()
        let storage = ViewStorage(button)
        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 {
        guard let button = storage.pointer as? NSMenuItem else {
            return
        }
        if enabled {
            button.actionClosure = handler
        } else {
            button.action = nil
        }
        guard updateProperties else {
            return
        }
        let previousState = storage.previousState as? Self
        if previousState?.label != label {
            button.title = label
        }
        if let shortcut, previousState?.shortcut != shortcut {
            button.keyEquivalent = shortcut.character.macOSRepresentation
            button.keyEquivalentModifierMask = shortcut.modifiers
        }
        if let selected, previousState?.selected != selected {
            button.state = selected ? .on : .off
        }
        storage.previousState = self
    }

    /// Create a keyboard shortcut for an application from a button.
    ///
    /// Note that the keyboard shortcut is available after the view has been visible for the first time.
    /// - Parameter shortcut: The keyboard shortcut.
    /// - Returns: The button.
    public func keyboardShortcut(_ shortcut: KeyboardShortcut) -> Self {
        modify { $0.shortcut = shortcut }
    }

    /// Create a keyboard shortcut for an application from a button.
    ///
    /// Note that the keyboard shortcut is available after the view has been visible for the first time.
    /// - Parameter shortcut: The keyboard shortcut.
    /// - Returns: The button.
    public func keyboardShortcut(_ shortcut: Character) -> Self {
        modify { $0.shortcut = .init(shortcut) }
    }

    /// Whether the button is selected.
    /// - Parameter selected: Whether it is selected.
    /// - Returns: The button.
    public func selected(_ selected: Bool = true) -> Self {
        modify { $0.selected = selected }
    }

    /// Whether the button is enabled.
    /// - Parameter enabled: Whether it is enabled.
    /// - Returns: The button.
    public func enabled(_ enabled: Bool = true) -> Self {
        modify { $0.enabled = enabled }
    }

}

extension NSMenuItem {

    /// The closure key.
    private static var closureKey: UInt8 = 0

    /// The action closure.
    var actionClosure: (() -> Void)? {
        get {
            objc_getAssociatedObject(self, &Self.closureKey) as? () -> Void
        }
        set {
            objc_setAssociatedObject(self, &Self.closureKey, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
            self.target = self
            self.action = #selector(menuItemAction)
        }
    }

    /// The action closure.
    @objc
    private func menuItemAction() {
        actionClosure?()
    }

}