MessageKit/Example/Sources/Views/SwiftUI/MessagesView.swift

/*
 MIT License

 Copyright (c) 2017-2020 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 SwiftUI
import MessageKit
import InputBarAccessoryView

final class MessageSwiftUIVC: MessagesViewController {
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        // Because SwiftUI wont automatically make our controller the first responder, we need to do it on viewDidAppear
        becomeFirstResponder()
        messagesCollectionView.scrollToLastItem(animated: true)
    }
}

@available(iOS 13.0, *)
struct MessagesView: UIViewControllerRepresentable {
    
    @State var initialized = false
    @Binding var messages: [MessageType]
    
    func makeUIViewController(context: Context) -> MessagesViewController {
        let messagesVC = MessageSwiftUIVC()
        
        messagesVC.messagesCollectionView.messagesDisplayDelegate = context.coordinator
        messagesVC.messagesCollectionView.messagesLayoutDelegate = context.coordinator
        messagesVC.messagesCollectionView.messagesDataSource = context.coordinator
        messagesVC.messageInputBar.delegate = context.coordinator
        messagesVC.scrollsToLastItemOnKeyboardBeginsEditing = true // default false
        messagesVC.maintainPositionOnKeyboardFrameChanged = true // default false
        messagesVC.showMessageTimestampOnSwipeLeft = true // default false
        
        return messagesVC
    }
    
    func updateUIViewController(_ uiViewController: MessagesViewController, context: Context) {
        uiViewController.messagesCollectionView.reloadData()
        scrollToBottom(uiViewController)
    }
    
    private func scrollToBottom(_ uiViewController: MessagesViewController) {
        DispatchQueue.main.async {
            // The initialized state variable allows us to start at the bottom with the initial messages without seeing the inital scroll flash by
            uiViewController.messagesCollectionView.scrollToLastItem(animated: self.initialized)
            self.initialized = true
        }
    }
    
    func makeCoordinator() -> Coordinator {
        return Coordinator(messages: $messages)
    }
    
    final class Coordinator {
        
        let formatter: DateFormatter = {
            let formatter = DateFormatter()
            formatter.dateStyle = .medium
            return formatter
        }()
        
        var messages: Binding<[MessageType]>
        init(messages: Binding<[MessageType]>) {
            self.messages = messages
        }
        
    }

}

@available(iOS 13.0, *)
extension MessagesView.Coordinator: MessagesDataSource {
    func currentSender() -> SenderType {
        return SampleData.shared.currentSender
    }
    
    func messageForItem(at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> MessageType {
        return messages.wrappedValue[indexPath.section]
    }
    
    func numberOfSections(in messagesCollectionView: MessagesCollectionView) -> Int {
        return messages.wrappedValue.count
    }
    
    func messageTopLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
        let name = message.sender.displayName
        return NSAttributedString(string: name, attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption1)])
    }
    
    func messageBottomLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
        let dateString = formatter.string(from: message.sentDate)
        return NSAttributedString(string: dateString, attributes: [NSAttributedString.Key.font: UIFont.preferredFont(forTextStyle: .caption2)])
    }

    func messageTimestampLabelAttributedText(for message: MessageType, at indexPath: IndexPath) -> NSAttributedString? {
        let sentDate = message.sentDate
        let sentDateString = MessageKitDateFormatter.shared.string(from: sentDate)
        let timeLabelFont: UIFont = .boldSystemFont(ofSize: 10)
        let timeLabelColor: UIColor = .systemGray
        return NSAttributedString(string: sentDateString, attributes: [NSAttributedString.Key.font: timeLabelFont, NSAttributedString.Key.foregroundColor: timeLabelColor])
    }
}

@available(iOS 13.0, *)
extension MessagesView.Coordinator: InputBarAccessoryViewDelegate {
    func inputBar(_ inputBar: InputBarAccessoryView, didPressSendButtonWith text: String) {
        let message = MockMessage(text: text, user: SampleData.shared.currentSender, messageId: UUID().uuidString, date: Date())
        messages.wrappedValue.append(message)
        inputBar.inputTextView.text = ""
    }
}

@available(iOS 13.0, *)
extension MessagesView.Coordinator: MessagesLayoutDelegate, MessagesDisplayDelegate {
    func configureAvatarView(_ avatarView: AvatarView, for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) {
        let avatar = SampleData.shared.getAvatarFor(sender: message.sender)
        avatarView.set(avatar: avatar)
    }
    func messageTopLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
        return 20
    }
    
    func messageBottomLabelHeight(for message: MessageType, at indexPath: IndexPath, in messagesCollectionView: MessagesCollectionView) -> CGFloat {
        return 16
    }
}