Signal-iOS/Signal/src/ViewControllers/ConversationView/ConversationViewController+MessageActions.swift

//
//  Copyright (c) 2021 Open Whisper Systems. All rights reserved.
//

import Foundation

extension ConversationViewController {

    func presentMessageActions(_ messageActions: [MessageAction],
                               withFocusedCell cell: UICollectionViewCell,
                               itemViewModel: CVItemViewModelImpl) {
        guard let window = view.window,
              let navigationController = navigationController else {
            owsFailDebug("Missing window or navigationController.")
            return
        }
        let messageActionsViewController = MessageActionsViewController(itemViewModel: itemViewModel,
                                                                        focusedView: cell,
                                                                        actions: messageActions)
        messageActionsViewController.delegate = self

        self.messageActionsViewController = messageActionsViewController

        setupMessageActionsState(forCell: cell)

        messageActionsViewController.present(on: window,
                                             prepareConstraints: {
                                                // In order to ensure the bottom bar remains above the keyboard, we pin it
                                                // to our bottom bar which follows the inputAccessoryView
                                                messageActionsViewController.bottomBar.autoPinEdge(.bottom,
                                                                                                   to: .bottom,
                                                                                                   of: self.bottomBar)

                                                // We only want the message actions to show up over the detail view, in
                                                // the case where we are expanded. So match its edges to our nav controller.
                                                messageActionsViewController.view.autoPinEdges(toEdgesOf: navigationController.view)
                                             },
                                             animateAlongside: {
                                                self.bottomBar.alpha = 0
                                             },
                                             completion: nil)
    }

    func updateMessageActionsState(forCell cell: UIView) {
        // While presenting message actions, cache the original content offset.
        // This allows us to restore the user to their original scroll position
        // when they dismiss the menu.
        self.messageActionsOriginalContentOffset = self.collectionView.contentOffset
        self.messageActionsOriginalFocusY = self.view.convert(cell.frame.origin, from: self.collectionView).y
    }

    func setupMessageActionsState(forCell cell: UIView) {
        guard let navigationController = navigationController else {
            owsFailDebug("Missing navigationController.")
            return
        }
        updateMessageActionsState(forCell: cell)

        // While the menu actions are presented, temporarily use extra content
        // inset padding so that interactions near the top or bottom of the
        // collection view can be scrolled anywhere within the viewport.
        // This allows us to keep the message position constant even when
        // messages dissappear above / below the focused message to the point
        // that we have less than one screen worth of content.
        let navControllerSize = navigationController.view.frame.size
        self.messageActionsExtraContentInsetPadding = max(navControllerSize.width, navControllerSize.height)

        var contentInset = self.collectionView.contentInset
        contentInset.top += self.messageActionsExtraContentInsetPadding
        contentInset.bottom += self.messageActionsExtraContentInsetPadding
        self.collectionView.contentInset = contentInset
    }

    func clearMessageActionsState() {
        self.bottomBar.alpha = 1

        var contentInset = self.collectionView.contentInset
        contentInset.top -= self.messageActionsExtraContentInsetPadding
        contentInset.bottom -= self.messageActionsExtraContentInsetPadding
        self.collectionView.contentInset = contentInset

        // TODO: This isn't safe. We should capture a token that represents scroll state.
        self.collectionView.contentOffset = self.messageActionsOriginalContentOffset
        self.messageActionsOriginalContentOffset = .zero
        self.messageActionsExtraContentInsetPadding = 0
        self.messageActionsViewController = nil
    }

    @objc
    public var isPresentingMessageActions: Bool {
        self.messageActionsViewController != nil
    }

    @objc
    public func dismissMessageActions(animated: Bool) {
        dismissMessageActions(animated: animated, completion: nil)
    }

    public typealias MessageActionsCompletion = () -> Void

    @objc
    public func dismissMessageActions(animated: Bool, completion: MessageActionsCompletion?) {
        Logger.verbose("")

        guard let messageActionsViewController = messageActionsViewController else {
            return
        }

        if animated {
            messageActionsViewController.dismiss(animateAlongside: {
                self.bottomBar.alpha = 1
            }, completion: {
                self.clearMessageActionsState()
                completion?()
            })
        } else {
            messageActionsViewController.dismissWithoutAnimating()
            clearMessageActionsState()
            completion?()
        }
    }

    func dismissMessageActionsIfNecessary() {
        if shouldDismissMessageActions {
            dismissMessageActions(animated: true)
        }
    }

    var shouldDismissMessageActions: Bool {
        guard let messageActionsViewController = messageActionsViewController else {
            return false
        }
        let messageActionInteractionId = messageActionsViewController.focusedInteraction.uniqueId
        // Check whether there is still a view item for this interaction.
        return self.indexPath(forInteractionUniqueId: messageActionInteractionId) == nil
    }
}