//
//  StatusAttachmentsGalleryDataSource.swift
//  Tusker
//
//  Created by Shadowfacts on 3/17/24.
//  Copyright © 2024 Shadowfacts. All rights reserved.
//

import Foundation
import GalleryVC
import Pachyderm
import TuskerComponents
import AVFoundation

class StatusAttachmentsGalleryDataSource: GalleryDataSource {
    let attachments: [Attachment]
    let sourceViews: NSHashTable<AttachmentView>
    
    init(attachments: [Attachment], sourceViews: NSHashTable<AttachmentView>) {
        self.attachments = attachments
        self.sourceViews = sourceViews
    }
    
    func galleryItemsCount() -> Int {
        attachments.count
    }
    
    func galleryContentViewController(forItemAt index: Int) -> any GalleryContentViewController {
        let attachment = attachments[index]
        switch attachment.kind {
        case .image:
            if let view = attachmentView(for: attachment),
               let image = view.image {
                return ImageGalleryContentViewController(
                    url: attachment.url,
                    caption: attachment.description,
                    originalData: view.originalData,
                    image: image,
                    // TODO: if automatically play gifs is off, this will start the source view playing too
                    gifController: view.gifController
                )
            } else {
                return LoadingGalleryContentViewController {
                    let (data, image) = await ImageCache.attachments.get(attachment.url, loadOriginal: true)
                    if let image {
                        let gifController: GIFController? =
                            if attachment.url.pathExtension == "gif",
                               let data {
                                GIFController(gifData: data)
                            } else {
                                nil
                            }
                        return ImageGalleryContentViewController(
                            url: attachment.url,
                            caption: attachment.description,
                            originalData: data,
                            image: image,
                            gifController: gifController
                        )
                    } else {
                        return nil
                    }
                }
            }
        case .gifv:
            let controller: GifvController =
                if Preferences.shared.automaticallyPlayGifs,
                   let view = attachmentView(for: attachment),
                   let controller = view.gifvView?.controller {
                    controller
                } else {
                    GifvController(asset: AVAsset(url: attachment.url))
                }
            return GifvGalleryContentViewController(controller: controller, caption: attachment.description)
        case .video:
            return VideoGalleryContentViewController(url: attachment.url, caption: attachment.description)
        case .audio:
            // TODO: use separate content VC with audio visualization?
            return VideoGalleryContentViewController(url: attachment.url, caption: attachment.description)
        case .unknown:
            return LoadingGalleryContentViewController {
                do {
                    let (data, _) = try await URLSession.shared.data(from: attachment.url)
                    let url = FileManager.default.temporaryDirectory.appendingPathComponent(attachment.url.lastPathComponent)
                    try data.write(to: url)
                    return FallbackGalleryNavigationController(url: url)
                } catch {
                    return nil
                }
            }
        }
    }
    
    func galleryContentTransitionSourceView(forItemAt index: Int) -> UIView? {
        let attachment = attachments[index]
        return attachmentView(for: attachment)
    }
    
    func galleryApplicationActivities(forItemAt index: Int) -> [UIActivity]? {
        [SaveToPhotosActivity()]
    }
    
    private func attachmentView(for attachment: Attachment) -> AttachmentView? {
        return sourceViews.allObjects.first(where: { $0.attachment?.id == attachment.id })
    }
}