//
//  Service.swift
//  I2PLauncher
//
//  Created by Mikal Villa on 12/04/2019.
//  Copyright © 2019 The I2P Project. All rights reserved.
//

import Foundation

public enum ServiceStatus: Int, Comparable {
  case undetermined
  case waiting
  case started
  case notice
  case killed
  case crashed
  case stopped
  case restarting
  
  public static func < (lhs: ServiceStatus, rhs: ServiceStatus) -> Bool {
    return lhs.rawValue < rhs.rawValue
  }
}

protocol ComparableStatus: Comparable {
  var serviceStatus: ServiceStatus { get }
}

extension ComparableStatus {
  public static func < (lhs: Self, rhs: Self) -> Bool {
    return lhs.serviceStatus < rhs.serviceStatus
  }
}

typealias Service = BaseService & RequiredServiceProperties

protocol RequiredServiceProperties {
  var name: String { get }
  //var url: URL { get }
}

extension RequiredServiceProperties {
  // Default implementation of the property `name` is to return the class name
  var name: String { return "\(type(of: self))" }
}

public class BaseService {
  public var status: ServiceStatus = .undetermined {
    didSet {
      if oldValue == .undetermined || status == .undetermined || oldValue == status {
        self.shouldNotify = false
      } else if Preferences.shared().notifyOnStatusChange {
        self.shouldNotify = true
      }
    }
  }
  var message: String = "Loading…"
  var shouldNotify = false
  
  public static func all() -> [BaseService] {
    guard let servicesPlist = Bundle.main.path(forResource: "RouterServices", ofType: "plist"),
      let services = NSDictionary(contentsOfFile: servicesPlist)?["services"] as? [String] else {
        fatalError("The RouterServices.plist file does not exist. The build phase script might have failed.")
    }
    
    return services.map(BaseService.named).compactMap { $0 }
  }
  
  static func named(_ name: String) -> BaseService? {
    return (NSClassFromString("I2PLauncher.\(name)") as? Service.Type)?.init()
  }
  
  public required init() {}
  
  public func updateStatus(callback: @escaping (BaseService) -> Void) {}
  
  func _fail(_ error: Error?) {
    self.status = .undetermined
    self.message = error.debugDescription// ?? "Unexpected error"
  }
  
  func _fail(_ message: String) {
    self.status = .undetermined
    self.message = message
  }
  
  func notifyIfNecessary() {
    guard let realSelf = self as? Service else { fatalError("BaseService should not be used directly.") }
    
    guard shouldNotify else { return }
    
    self.shouldNotify = false
    
    let notification = NSUserNotification()
    let possessiveS = realSelf.name.hasSuffix("s") ? "'" : "'s"
    notification.title = "\(realSelf.name)\(possessiveS) status has changed"
    notification.informativeText = message
    
    NSUserNotificationCenter.default.deliver(notification)
  }
}

extension BaseService: Equatable {
  public static func == (lhs: BaseService, rhs: BaseService) -> Bool {
    guard
      let lhs = lhs as? Service,
      let rhs = rhs as? Service
      else {
        fatalError("BaseService should not be used directly.")
    }
    
    return lhs.name == rhs.name
  }
}

extension BaseService: Comparable {
  public static func < (lhs: BaseService, rhs: BaseService) -> Bool {
    guard
      let lhs = lhs as? Service,
      let rhs = rhs as? Service
      else {
        fatalError("BaseService should not be used directly.")
    }
    
    let sameStatus = lhs.status == rhs.status
    let differentStatus =
      lhs.status != .started && lhs.status != .notice
        && rhs.status == .started || rhs.status == .notice
    return ((lhs.name < rhs.name) && sameStatus) || differentStatus
  }
}