vChewing-macOS/Source/Modules/UIModules/NotifierUI/NotifierController.swift

// (c) 2021 and onwards Weizhong Yang (MIT License).
// All possible vChewing-specific modifications are of:
// (c) 2021 and onwards The vChewing Project (MIT-NTL License).
// ====================
// This code is released under the MIT license (SPDX-License-Identifier: MIT)
// ... with NTL restriction stating that:
// No trademark license is granted to use the trade names, trademarks, service
// marks, or product names of Contributor, except as required to fulfill notice
// requirements defined in MIT License.

private protocol NotifierWindowDelegate: AnyObject {
  func windowDidBecomeClicked(_ window: NotifierWindow)
}

private class NotifierWindow: NSWindow {
  weak var clickDelegate: NotifierWindowDelegate?

  override func mouseDown(with _: NSEvent) {
    clickDelegate?.windowDidBecomeClicked(self)
  }
}

private let kWindowWidth: CGFloat = 213.0
private let kWindowHeight: CGFloat = 60.0

public class NotifierController: NSWindowController, NotifierWindowDelegate {
  static var message: String = "" {
    didSet {
      if !Self.message.isEmpty {
        NotifierController.initiateWithNoStay(message: message)
        Self.message = ""
      }
    }
  }

  private var messageTextField: NSTextField

  private var message: String = "" {
    didSet {
      let paraStyle = NSMutableParagraphStyle()
      paraStyle.setParagraphStyle(NSParagraphStyle.default)
      paraStyle.alignment = .center
      let attr: [NSAttributedString.Key: AnyObject] = [
        .foregroundColor: foregroundColor,
        .font: NSFont.boldSystemFont(ofSize: NSFont.systemFontSize(for: .regular)),
        .paragraphStyle: paraStyle,
      ]
      let attrString = NSAttributedString(string: message, attributes: attr)
      messageTextField.attributedStringValue = attrString
      let width = window?.frame.width ?? kWindowWidth
      let rect = attrString.boundingRect(
        with: NSSize(width: width, height: 1600), options: .usesLineFragmentOrigin
      )
      let height = rect.height
      let x = messageTextField.frame.origin.x
      let y = ((window?.frame.height ?? kWindowHeight) - height) / 2
      let newFrame = NSRect(x: x, y: y, width: width, height: height)
      messageTextField.frame = newFrame
    }
  }

  private var shouldStay = false
  private var backgroundColor: NSColor = .textBackgroundColor {
    didSet {
      window?.backgroundColor = backgroundColor
    }
  }

  private var foregroundColor: NSColor = .controlTextColor {
    didSet {
      messageTextField.textColor = foregroundColor
    }
  }

  private var waitTimer: Timer?
  private var fadeTimer: Timer?

  private static var instanceCount = 0
  private static var lastLocation = NSPoint.zero

  private static func initiateWithNoStay(message: String) {
    let controller = NotifierController()
    controller.message = message
    controller.show()
  }

  public static func notify(message: String) {
    Self.message = message
  }

  public static func notify(message: String, stay: Bool) {
    let controller = NotifierController()
    controller.message = message
    controller.shouldStay = stay
    controller.show()
  }

  private static func increaseInstanceCount() {
    instanceCount += 1
  }

  private static func decreaseInstanceCount() {
    instanceCount -= 1
    if instanceCount < 0 {
      instanceCount = 0
    }
  }

  private init() {
    let screenRect = NSScreen.main?.visibleFrame ?? NSRect.seniorTheBeast
    let contentRect = NSRect(x: 0, y: 0, width: kWindowWidth, height: kWindowHeight)
    var windowRect = contentRect
    windowRect.origin.x = screenRect.maxX - windowRect.width - 10
    windowRect.origin.y = screenRect.maxY - windowRect.height - 10
    let styleMask: NSWindow.StyleMask = [.fullSizeContentView, .titled]

    let transparentVisualEffect = NSVisualEffectView()
    transparentVisualEffect.blendingMode = .behindWindow
    transparentVisualEffect.state = .active

    let panel = NotifierWindow(
      contentRect: windowRect, styleMask: styleMask, backing: .buffered, defer: false
    )
    panel.contentView = transparentVisualEffect
    panel.isMovableByWindowBackground = true
    panel.level = NSWindow.Level(Int(kCGPopUpMenuWindowLevel))
    panel.hasShadow = true
    panel.backgroundColor = backgroundColor
    panel.title = ""
    panel.titlebarAppearsTransparent = true
    panel.titleVisibility = .hidden
    panel.showsToolbarButton = false
    panel.standardWindowButton(NSWindow.ButtonType.zoomButton)?.isHidden = true
    panel.standardWindowButton(NSWindow.ButtonType.miniaturizeButton)?.isHidden = true
    panel.standardWindowButton(NSWindow.ButtonType.closeButton)?.isHidden = true
    panel.standardWindowButton(NSWindow.ButtonType.zoomButton)?.isHidden = true

    messageTextField = NSTextField()
    messageTextField.frame = contentRect
    messageTextField.isEditable = false
    messageTextField.isSelectable = false
    messageTextField.isBezeled = false
    messageTextField.textColor = foregroundColor
    messageTextField.drawsBackground = false
    messageTextField.font = .boldSystemFont(ofSize: NSFont.systemFontSize(for: .regular))
    panel.contentView?.addSubview(messageTextField)

    super.init(window: panel)

    panel.clickDelegate = self
  }

  @available(*, unavailable)
  required init?(coder _: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  private func show() {
    func setStartLocation() {
      if Self.instanceCount == 0 {
        return
      }
      let lastLocation = Self.lastLocation
      let screenRect = NSScreen.main?.visibleFrame ?? NSRect.seniorTheBeast
      var windowRect = window?.frame ?? NSRect.seniorTheBeast
      windowRect.origin.x = lastLocation.x
      windowRect.origin.y = lastLocation.y - 10 - windowRect.height

      if windowRect.origin.y < screenRect.minY {
        return
      }

      window?.setFrame(windowRect, display: true)
    }

    func moveIn() {
      let afterRect = window?.frame ?? NSRect.seniorTheBeast
      Self.lastLocation = afterRect.origin
      var beforeRect = afterRect
      beforeRect.origin.y += 10
      window?.setFrame(beforeRect, display: true)
      window?.orderFront(self)
      window?.setFrame(afterRect, display: true, animate: true)
    }

    setStartLocation()
    moveIn()
    Self.increaseInstanceCount()
    waitTimer = Timer.scheduledTimer(
      timeInterval: shouldStay ? 5 : 1, target: self, selector: #selector(fadeOut),
      userInfo: nil,
      repeats: false
    )
  }

  @objc private func doFadeOut(_: Timer) {
    let opacity = window?.alphaValue ?? 0
    if opacity <= 0 {
      close()
    } else {
      window?.alphaValue = opacity - 0.2
    }
  }

  @objc private func fadeOut() {
    waitTimer?.invalidate()
    waitTimer = nil
    Self.decreaseInstanceCount()
    fadeTimer = Timer.scheduledTimer(
      timeInterval: 0.01, target: self, selector: #selector(doFadeOut(_:)), userInfo: nil,
      repeats: true
    )
  }

  override public func close() {
    waitTimer?.invalidate()
    waitTimer = nil
    fadeTimer?.invalidate()
    fadeTimer = nil
    super.close()
  }

  fileprivate func windowDidBecomeClicked(_: NotifierWindow) {
    fadeOut()
  }
}