//
//  AppDelegate.swift
//  ScrollSwitcher
//
//  Created by Shadowfacts on 8/31/21.
//

import Cocoa

let defaultsKey = "com.apple.swipescrolldirection"

class AppDelegate: NSObject, NSApplicationDelegate {
    
    // things that need to be retained to keep them from disappearing
    private var prefPanesSupport: Bundle!
    private var item: NSStatusItem!
    
    func applicationDidFinishLaunching(_ aNotification: Notification) {
        item = NSStatusBar.system.statusItem(withLength: NSStatusItem.squareLength)
        item.button!.target = self
        item.button!.action = #selector(menuItemClicked)
        updateIcon()
        
        // update the icon when system prefs changes
        DistributedNotificationCenter.default().addObserver(self, selector: #selector(updateIcon), name: .swipeScrollDirectionDidChangeNotification, object: nil)
    }
    
    @objc private func updateIcon() {
        item.button!.image = Direction.current.image
    }
    
    @objc private func menuItemClicked() {
        if let event = NSApp.currentEvent, event.modifierFlags.contains(.shift) {
            item.menu = createMenu()
            item.button!.performClick(nil)
        } else {
            toggleScrollDirection()
        }
    }
    
    private func createMenu() -> NSMenu {
        let menu = NSMenu()
        menu.delegate = self
        let state = Direction.current == .natural ? "On" : "Off"
        let status = NSMenuItem(title: "Natural Scrolling: \(state)", action: nil, keyEquivalent: "")
        menu.addItem(status)
        let verb = Direction.current == .natural ? "Disable" : "Enable"
        let toggleItem = NSMenuItem(title: "\(verb) Natural Scrolling", action: #selector(toggleScrollDirection), keyEquivalent: "")
        menu.addItem(toggleItem)
        menu.addItem(NSMenuItem.separator())
        menu.addItem(withTitle: "Quit", action: #selector(NSApplication.terminate(_:)), keyEquivalent: "q")
        return menu
    }
    
    @objc private func toggleScrollDirection() {
        setDirection(.current == Direction.natural ? .normal : .natural)
    }
    
    private func setDirection(_ new: Direction) {
        // can't construct a UserDefaults with NSGlobalDomain, so set it via the command line
        let proc = Process()
//        let out = Pipe()
//        let err = Pipe()
        proc.launchPath = "/usr/bin/env"
        let newVal = new == .normal ? "NO" : "YES"
        proc.arguments = ["defaults", "write", "-g", "com.apple.swipescrolldirection", "-bool", newVal]
//        proc.standardOutput = out
//        proc.standardError = err
        proc.launch()
        proc.waitUntilExit()

//        let outData = out.fileHandleForReading.readDataToEndOfFile()
//        let errData = err.fileHandleForReading.readDataToEndOfFile()
        if proc.terminationStatus != 0 {
            fatalError("uh oh, exit code: \(proc.terminationStatus)")
        }
        
        // makes system preferences update
        DistributedNotificationCenter.default().postNotificationName(.swipeScrollDirectionDidChangeNotification, object: nil, userInfo: nil, deliverImmediately: false)
        // make the actual input behavior update
        setSwipeScrollDirection(new == .natural)
    }

}

extension AppDelegate: NSMenuDelegate {
    func menuDidClose(_ menu: NSMenu) {
        // remove the menu so the next time the item is clicked, it performs the primary action
        item.menu = nil
    }
}

enum Direction: Equatable {
    case normal, natural
    
    static var current: Direction {
        let value = UserDefaults.standard.bool(forKey: defaultsKey)
        if value {
            return .natural
        } else {
            return .normal
        }
    }
    
    var image: NSImage {
        switch self {
        case .normal:
            return NSImage(systemSymbolName: "scroll", accessibilityDescription: nil)!
        case .natural:
            return NSImage(systemSymbolName: "scroll.fill", accessibilityDescription: nil)!
        }
    }
}

extension Notification.Name {
    static let swipeScrollDirectionDidChangeNotification = Notification.Name(rawValue: "SwipeScrollDirectionDidChangeNotification")
}