MessageKit/Sources/Controllers/MessagesViewController+Menu.swift

// MIT License
//
// Copyright (c) 2017-2022 MessageKit
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

import Foundation
import UIKit

extension MessagesViewController {
  // MARK: Internal

  // MARK: - Register / Unregister Observers

  internal func addMenuControllerObservers() {
    NotificationCenter.default.addObserver(
      self,
      selector: #selector(MessagesViewController.menuControllerWillShow(_:)),
      name: UIMenuController.willShowMenuNotification,
      object: nil)
  }

  // MARK: Private

  // MARK: - Helpers

  private var navigationBarFrame: CGRect {
    guard let navigationController = navigationController, !navigationController.navigationBar.isHidden else {
      return .zero
    }
    return navigationController.navigationBar.frame
  }

  // MARK: - Notification Handlers

  /// Show menuController and set target rect to selected bubble
  @objc
  private func menuControllerWillShow(_ notification: Notification) {
    guard
      let currentMenuController = notification.object as? UIMenuController,
      let selectedIndexPath = selectedIndexPathForMenu else { return }

    NotificationCenter.default.removeObserver(self, name: UIMenuController.willShowMenuNotification, object: nil)
    defer {
      NotificationCenter.default.addObserver(
        self,
        selector: #selector(MessagesViewController.menuControllerWillShow(_:)),
        name: UIMenuController.willShowMenuNotification,
        object: nil)
      selectedIndexPathForMenu = nil
    }

    currentMenuController.hideMenu()

    guard let selectedCell = messagesCollectionView.cellForItem(at: selectedIndexPath) as? MessageContentCell else {
      return
    }
    let selectedCellMessageBubbleFrame = selectedCell.convert(selectedCell.messageContainerView.frame, to: view)

    var messageInputBarFrame: CGRect = .zero
    if let messageInputBarSuperview = messageInputBar.superview {
      messageInputBarFrame = view.convert(messageInputBar.frame, from: messageInputBarSuperview)
    }

    var topNavigationBarFrame: CGRect = navigationBarFrame
    if navigationBarFrame != .zero, let navigationBarSuperview = navigationController?.navigationBar.superview {
      topNavigationBarFrame = view.convert(navigationController!.navigationBar.frame, from: navigationBarSuperview)
    }

    let menuHeight = currentMenuController.menuFrame.height

    let selectedCellMessageBubblePlusMenuFrame = CGRect(
      selectedCellMessageBubbleFrame.origin.x,
      selectedCellMessageBubbleFrame.origin.y - menuHeight,
      selectedCellMessageBubbleFrame.size.width,
      selectedCellMessageBubbleFrame.size.height + 2 * menuHeight)

    var targetRect: CGRect = selectedCellMessageBubbleFrame
    currentMenuController.arrowDirection = .default

    /// Message bubble intersects with navigationBar and keyboard
    if
      selectedCellMessageBubblePlusMenuFrame.intersects(topNavigationBarFrame),
      selectedCellMessageBubblePlusMenuFrame.intersects(messageInputBarFrame)
    {
      let centerY = (
        selectedCellMessageBubblePlusMenuFrame.intersection(messageInputBarFrame)
          .minY + selectedCellMessageBubblePlusMenuFrame.intersection(topNavigationBarFrame).maxY) / 2
      targetRect = CGRect(selectedCellMessageBubblePlusMenuFrame.midX, centerY, 1, 1)
    } /// Message bubble only intersects with navigationBar
    else if selectedCellMessageBubblePlusMenuFrame.intersects(topNavigationBarFrame) {
      currentMenuController.arrowDirection = .up
    }

    currentMenuController.showMenu(from: view, rect: targetRect)
  }
}