//
//  TrayIconController.swift
//  PrivadoVPN
//
//  Created by Juraldinio on 12/7/20.
//  Copyright © 2020 Privado LLC. All rights reserved.
//

import Foundation
import AppKit

protocol TrayIconMenuItem {
    var title: String { get }
    var enabled: Bool { get }
    var keyEquivalent: String? { get }
}

protocol TrayIconControllerInput: AnyObject {
    func icon(named: String)
    func icon(by url: URL)
    func refresh()
    func menu(enabled: Bool)
}

protocol TrayIconControllerOutput: AnyObject {
    func showRequired()
    func hideRequired()
    func actionRequired()
    //
    func menuItemsCount() -> Int
    func menuItem(at index: Int) -> TrayIconMenuItem?
    func menuItem(selected row: Int)
}

final class TrayIconController: NSObject, TrayIconControllerModule, TrayIconControllerInput {
    
    private let output: TrayIconControllerOutput
    private let statusItem: NSStatusItem
    private let menu = NSMenu()

    init(output: TrayIconControllerOutput) {
        self.output = output
        self.statusItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.squareLength)
        
        super.init()
        
        self.menu.delegate = self
    }
    
    // MARK: - Private

    @objc
    private func menuItemHandler(_ sender: Any?) {
        guard let menuItem = sender as? NSMenuItem else { return }
        self.output.menuItem(selected: menuItem.tag)
    }
    
    @objc
    private func onAction() {
        self.output.actionRequired()
    }
    
    // MARK: - TrayIconControllerModule
    
    var button: NSButton? { self.statusItem.button }
    
    func show() {
        self.output.showRequired()
    }
    
    func hide() {
        self.output.hideRequired()
    }
    
    // MARK: - TrayIconControllerInput
    
    func icon(named: String) {
        let image = NSImage(named: NSImage.Name(named))
        guard let button = self.statusItem.button else { return }
        button.image = image
    }
    
    func icon(by url: URL) {
        let image = NSImage(byReferencing: url)
        guard let button = self.statusItem.button else { return }
        button.image = image
    }
    
    func refresh() {
        self.statusItem.menu?.update()
    }
    
    func menu(enabled: Bool) {
        
        if enabled {
            self.statusItem.menu = self.menu
            
            if let button = self.statusItem.button {
                button.target = nil
                button.action = nil
            }
            
        } else {
            
            self.statusItem.menu = nil
            
            if let button = self.statusItem.button {
                button.target = self
                button.action = #selector(self.onAction)
            }
        }
    }
    
}

extension TrayIconController: NSMenuDelegate {
    
    func numberOfItems(in menu: NSMenu) -> Int {
        return self.output.menuItemsCount()
    }

    func menu(_ menu: NSMenu, update item: NSMenuItem, at index: Int, shouldCancel: Bool) -> Bool {
        
        guard let menuItem = self.output.menuItem(at: index) else {
            return false
        }
        
        guard menuItem.title != "-" else {
            menu.removeItem(item)
            menu.insertItem(NSMenuItem.separator(), at: index)
            return true
        }

        if let key = menuItem.keyEquivalent {
            item.keyEquivalent = key
        }
        
        item.title = menuItem.title
        item.tag = index
        if menuItem.enabled {
            item.action = #selector(self.menuItemHandler)
            item.target = self
        } else {
            item.action = nil
            item.target = nil
        }

        return true
        
    }
}