Files
letro-ios/ElementX/Sources/Screens/MediaEventsTimelineScreen/MediaEventsTimelineScreenViewModel.swift

128 lines
5.0 KiB
Swift

//
// Copyright 2022-2024 New Vector Ltd.
//
// SPDX-License-Identifier: AGPL-3.0-only
// Please see LICENSE in the repository root for full details.
//
import Combine
import SwiftUI
typealias MediaEventsTimelineScreenViewModelType = StateStoreViewModel<MediaEventsTimelineScreenViewState, MediaEventsTimelineScreenViewAction>
class MediaEventsTimelineScreenViewModel: MediaEventsTimelineScreenViewModelType, MediaEventsTimelineScreenViewModelProtocol {
private let mediaTimelineViewModel: TimelineViewModelProtocol
private let filesTimelineViewModel: TimelineViewModelProtocol
private let userIndicatorController: UserIndicatorControllerProtocol
private var isOldestItemVisible = false
private var activeTimelineViewModel: TimelineViewModelProtocol {
switch state.bindings.screenMode {
case .media:
mediaTimelineViewModel
case .files:
filesTimelineViewModel
}
}
private let actionsSubject: PassthroughSubject<MediaEventsTimelineScreenViewModelAction, Never> = .init()
var actionsPublisher: AnyPublisher<MediaEventsTimelineScreenViewModelAction, Never> {
actionsSubject.eraseToAnyPublisher()
}
init(mediaTimelineViewModel: TimelineViewModelProtocol,
filesTimelineViewModel: TimelineViewModelProtocol,
mediaProvider: MediaProviderProtocol,
screenMode: MediaEventsTimelineScreenMode = .media,
userIndicatorController: UserIndicatorControllerProtocol) {
self.mediaTimelineViewModel = mediaTimelineViewModel
self.filesTimelineViewModel = filesTimelineViewModel
self.userIndicatorController = userIndicatorController
super.init(initialViewState: .init(bindings: .init(screenMode: screenMode)), mediaProvider: mediaProvider)
mediaTimelineViewModel.context.$viewState.sink { [weak self] timelineViewState in
guard let self, state.bindings.screenMode == .media else {
return
}
updateWithTimelineViewState(timelineViewState)
}
.store(in: &cancellables)
filesTimelineViewModel.context.$viewState.sink { [weak self] timelineViewState in
guard let self, state.bindings.screenMode == .files else {
return
}
updateWithTimelineViewState(timelineViewState)
}
.store(in: &cancellables)
updateWithTimelineViewState(activeTimelineViewModel.context.viewState)
}
// MARK: - Public
override func process(viewAction: MediaEventsTimelineScreenViewAction) {
MXLog.info("View model: received view action: \(viewAction)")
switch viewAction {
case .changedScreenMode:
updateWithTimelineViewState(activeTimelineViewModel.context.viewState)
case .oldestItemDidAppear:
isOldestItemVisible = true
backPaginateIfNecessary(paginationStatus: activeTimelineViewModel.context.viewState.timelineState.paginationState.backward)
case .oldestItemDidDisappear:
isOldestItemVisible = false
case .tappedItem(let item):
handleItemTapped(item)
}
}
// MARK: - Private
private func updateWithTimelineViewState(_ timelineViewState: TimelineViewState) {
state.items = timelineViewState.timelineState.itemViewStates.filter { itemViewState in
switch itemViewState.type {
case .image, .video:
state.bindings.screenMode == .media
case .audio, .file:
state.bindings.screenMode == .files
default:
false
}
}.reversed()
state.isBackPaginating = (timelineViewState.timelineState.paginationState.backward == .paginating)
backPaginateIfNecessary(paginationStatus: timelineViewState.timelineState.paginationState.backward)
}
private func backPaginateIfNecessary(paginationStatus: PaginationStatus) {
if paginationStatus == .idle, isOldestItemVisible {
activeTimelineViewModel.context.send(viewAction: .paginateBackwards)
}
}
private func handleItemTapped(_ item: RoomTimelineItemViewState) {
let item: EventBasedMessageTimelineItemProtocol? = switch item.type {
case .audio(let audioItem): audioItem
case .file(let fileItem): fileItem
case .image(let imageItem): imageItem
case .video(let videoItem): videoItem
default: nil
}
guard let item, let mediaProvider = context.mediaProvider else {
MXLog.error("Unexpected item type (or the media provider is missing).")
return
}
let viewModel = TimelineMediaPreviewViewModel(previewItems: [item],
mediaProvider: mediaProvider,
userIndicatorController: userIndicatorController)
state.bindings.mediaPreviewViewModel = viewModel
}
}