//
//  GTUIApp.swift
//  Adwaita
//
//  Created by david-swift on 05.08.23.
//

import Libadwaita

/// The GTUI application.
public class GTUIApp: Application {

    /// The handlers which are called when a state changes.
    static var updateHandlers: [() -> Void] = []

    /// The app's content.
    var body: () -> App
    /// The scenes that are displayed.
    var sceneStorage: [WindowStorage] = []
    /// A string signaling that the parent should not be overwritten.
    let overwriteParentID = "overwrite-parent"

    /// Initialize the GTUI application.
    /// - Parameters:
    ///     - id: The application id.
    ///     - body: The application's content.
    init(_ id: String, body: @escaping () -> App) {
        self.body = body
        super.init(name: id)
    }

    /// The entry point of the application.
    override public func onActivate() {
        let body = body()
        for windowScene in body.scene.windows() {
            for _ in 0..<windowScene.open {
                addWindow(windowScene.id)
            }
            setParentWindows()
        }
    }

    /// Focus the window with a certain id. Create the window if it doesn't already exist.
    /// - Parameters:
    ///     - id: The window's id.
    public func showWindow(_ id: String) {
        sceneStorage.last { $0.id == id && !$0.destroy }?.window.show() ?? addWindow(id)
    }

    /// Add a new window with the content of the window with a certain id.
    /// - Parameters:
    ///     - id: The window's id.
    ///     - parent: The parent window.
    public func addWindow(_ id: String, parent: GTUIWindow? = nil) {
        State<Any>.updateViews()
        if let window = body().scene.windows().last(where: { $0.id == id }) {
            let window = window.createWindow(app: self)
            sceneStorage.append(window)
            if let parent {
                window.window.setParentWindow(parent)
                window.window.fields[overwriteParentID] = true
            }
            setParentWindows()
            showWindow(id)
        }
    }

    /// Set the parents of every window having a parent window.
    func setParentWindows() {
      for window in sceneStorage where !(window.window.fields[overwriteParentID] as? Bool ?? false) {
        if let parent = sceneStorage.first(where: { $0.id == window.parentID }) {
            window.window.setParentWindow(parent.window)
        }
      }
    }
}