MessageKit/Sources/Controllers/MessagesViewController+TypingIndicator.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

// MARK: - Typing Indicator API

extension MessagesViewController {
    /// Sets the typing indicator sate by inserting/deleting the `TypingBubbleCell`
    ///
    /// - Parameters:
    ///   - isHidden: A Boolean value that is to be the new state of the typing indicator
    ///   - animated: A Boolean value determining if the insertion is to be animated
    ///   - updates: A block of code that will be executed during `performBatchUpdates`
    ///              when `animated` is `TRUE` or before the `completion` block executes
    ///              when `animated` is `FALSE`
    ///   - completion: A completion block to execute after the insertion/deletion
    open func setTypingIndicatorViewHidden(_ isHidden: Bool, animated: Bool, whilePerforming updates: (() -> Void)? = nil, completion: ((Bool) -> Void)? = nil) {
        guard isTypingIndicatorHidden != isHidden else {
            completion?(false)
            return
        }

        let section = messagesCollectionView.numberOfSections
        messagesCollectionView.setTypingIndicatorViewHidden(isHidden)

        if animated {
            messagesCollectionView.performBatchUpdates({ [weak self] in
                self?.performUpdatesForTypingIndicatorVisability(at: section)
                updates?()
            }, completion: completion)
        } else {
            performUpdatesForTypingIndicatorVisability(at: section)
            updates?()
            completion?(true)
        }
    }

    /// A method that by default checks if the section is the last in the
    /// `messagesCollectionView` and that `isTypingIndicatorViewHidden`
    /// is FALSE
    ///
    /// - Parameter section
    /// - Returns: A Boolean indicating if the TypingIndicator should be presented at the given section
    public func isSectionReservedForTypingIndicator(_ section: Int) -> Bool {
        return !messagesCollectionView.isTypingIndicatorHidden && section == self.numberOfSections(in: messagesCollectionView) - 1
    }


    public var isTypingIndicatorHidden: Bool {
        return messagesCollectionView.isTypingIndicatorHidden
    }
    
    /// Performs a delete or insert on the `MessagesCollectionView` on the provided section
    ///
    /// - Parameter section: The index to modify
    private func performUpdatesForTypingIndicatorVisability(at section: Int) {
        if isTypingIndicatorHidden {
            messagesCollectionView.deleteSections([section - 1])
        } else {
            messagesCollectionView.insertSections([section])
        }
    }
}