forked from zelo72/mastodon-ios
93 lines
3.2 KiB
Swift
93 lines
3.2 KiB
Swift
//
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// MediaPreviewViewModel.swift
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// Mastodon
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//
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// Created by MainasuK Cirno on 2021-4-28.
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//
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import UIKit
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import Combine
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import CoreData
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import CoreDataStack
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import Pageboy
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final class MediaPreviewViewModel: NSObject {
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// input
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let context: AppContext
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let initialItem: PreviewItem
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weak var mediaPreviewImageViewControllerDelegate: MediaPreviewImageViewControllerDelegate?
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// output
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let viewControllers: [UIViewController]
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init(context: AppContext, meta: StatusImagePreviewMeta) {
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self.context = context
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self.initialItem = .status(meta)
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var viewControllers: [UIViewController] = []
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let managedObjectContext = self.context.managedObjectContext
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managedObjectContext.performAndWait {
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let status = managedObjectContext.object(with: meta.statusObjectID) as! Status
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guard let media = status.mediaAttachments?.sorted(by: { $0.index.compare($1.index) == .orderedAscending }) else { return }
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for (entity, image) in zip(media, meta.preloadThumbnailImages) {
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let thumbnail: UIImage? = image.flatMap { $0.size != CGSize(width: 1, height: 1) ? $0 : nil }
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switch entity.type {
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case .image:
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guard let url = URL(string: entity.url) else { continue }
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let meta = MediaPreviewImageViewModel.StatusImagePreviewMeta(url: url, thumbnail: thumbnail)
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let mediaPreviewImageModel = MediaPreviewImageViewModel(meta: meta)
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let mediaPreviewImageViewController = MediaPreviewImageViewController()
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mediaPreviewImageViewController.viewModel = mediaPreviewImageModel
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viewControllers.append(mediaPreviewImageViewController)
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default:
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continue
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}
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}
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}
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self.viewControllers = viewControllers
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super.init()
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}
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}
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extension MediaPreviewViewModel {
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enum PreviewItem {
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case status(StatusImagePreviewMeta)
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case local(LocalImagePreviewMeta)
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}
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struct StatusImagePreviewMeta {
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let statusObjectID: NSManagedObjectID
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let initialIndex: Int
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let preloadThumbnailImages: [UIImage?]
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}
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struct LocalImagePreviewMeta {
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let image: UIImage
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}
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}
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// MARK: - PageboyViewControllerDataSource
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extension MediaPreviewViewModel: PageboyViewControllerDataSource {
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func numberOfViewControllers(in pageboyViewController: PageboyViewController) -> Int {
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return viewControllers.count
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}
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func viewController(for pageboyViewController: PageboyViewController, at index: PageboyViewController.PageIndex) -> UIViewController? {
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let viewController = viewControllers[index]
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if let mediaPreviewImageViewController = viewController as? MediaPreviewImageViewController {
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mediaPreviewImageViewController.delegate = mediaPreviewImageViewControllerDelegate
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}
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return viewController
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}
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func defaultPage(for pageboyViewController: PageboyViewController) -> PageboyViewController.Page? {
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guard case let .status(meta) = initialItem else { return nil }
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return .at(index: meta.initialIndex)
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}
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}
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