//
//  LargeImageContentView.swift
//  Tusker
//
//  Created by Shadowfacts on 6/17/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm
import AVFoundation
import VisionKit

protocol LargeImageContentView: UIView {
    var animationImage: UIImage? { get }
    var activityItemsForSharing: [Any] { get }
    var owner: LargeImageViewController? { get set }
    func setControlsVisible(_ controlsVisible: Bool)
    func grayscaleStateChanged()
}

class LargeImageImageContentView: UIImageView, LargeImageContentView {
    
    #if !targetEnvironment(macCatalyst)
    @available(iOS 16.0, *)
    private static let analyzer = ImageAnalyzer()
    private var _analysisInteraction: AnyObject?
    @available(iOS 16.0, *)
    private var analysisInteraction: ImageAnalysisInteraction? { _analysisInteraction as? ImageAnalysisInteraction }
    #endif
    
    var animationImage: UIImage? { image! }
    var activityItemsForSharing: [Any] {
        [image!]
    }
    weak var owner: LargeImageViewController?
    
    private var sourceData: Data?
    
    init(image: UIImage) {
        super.init(image: image)
        
        contentMode = .scaleAspectFit
        isUserInteractionEnabled = true
        
        #if !targetEnvironment(macCatalyst)
        if #available(iOS 16.0, *),
           ImageAnalyzer.isSupported {
            let interaction = ImageAnalysisInteraction()
            self._analysisInteraction = interaction
            interaction.delegate = self
            interaction.preferredInteractionTypes = .automatic
            addInteraction(interaction)
            Task {
                do {
                    let result = try await LargeImageImageContentView.analyzer.analyze(image, configuration: ImageAnalyzer.Configuration([.text, .machineReadableCode]))
                    interaction.analysis = result
                } catch {
                    // if analysis fails, we just don't show anything
                }
            }
        }
        #endif
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setControlsVisible(_ controlsVisible: Bool) {
        #if !targetEnvironment(macCatalyst)
        if #available(iOS 16.0, *),
           let analysisInteraction {
            // note: passing animated: true here doesn't seem to do anything by itself as of iOS 16.2 (20C5032e)
            // so the LargeImageViewController handles animating, but we still need to pass true here otherwise it doesn't animate
            analysisInteraction.setSupplementaryInterfaceHidden(!controlsVisible, animated: true)
        }
        #endif
    }
    
    func grayscaleStateChanged() {
        guard let data = sourceData else {
            return
        }
        
        let image: UIImage?
        if Preferences.shared.grayscaleImages {
            image = ImageGrayscalifier.convert(url: nil, data: data)
        } else {
            image = UIImage(data: data)
        }
        
        if let image = image {
            self.image = image
        }
    }
}

#if !targetEnvironment(macCatalyst)
@available(iOS 16.0, *)
extension LargeImageImageContentView: ImageAnalysisInteractionDelegate {
    func presentingViewController(for interaction: ImageAnalysisInteraction) -> UIViewController? {
        return owner
    }
}
#endif

class LargeImageGifContentView: GIFImageView, LargeImageContentView {
    var animationImage: UIImage? { image }
    var activityItemsForSharing: [Any] {
        // todo: should gifs share the data?
        [image].compactMap { $0 }
    }
    weak var owner: LargeImageViewController?
    
    init(gifController: GIFController) {
        super.init(image: gifController.lastFrame?.image)
        
        contentMode = .scaleAspectFit
        
        gifController.attach(to: self)
        // todo: doing this in the init feels wrong
        gifController.startAnimating()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setControlsVisible(_ controlsVisible: Bool) {
    }
    
    func grayscaleStateChanged() {
        // todo
    }
}

class LargeImageGifvContentView: GifvAttachmentView, LargeImageContentView {
    private(set) var animationImage: UIImage?
    var activityItemsForSharing: [Any] {
        // todo: what should we share for gifvs?
        // some SO posts indicate that just sharing a URL to the video should work, but that may need to be a local URL?
        []
    }
    weak var owner: LargeImageViewController?
    
    private let asset: AVURLAsset
    
    // The content view needs to supply an intrinsicContentSize for the LargeImageViewController to handle layout/scrolling/zooming correctly
    override var intrinsicContentSize: CGSize {
        // This is a really sucky workaround for the fact that in the content view, we don't have access to the size of the underlying video.
        // There's probably some way of getting this from the AVPlayer/AVAsset directly
        animationImage?.size ?? CGSize(width: UIView.noIntrinsicMetric, height: UIView.noIntrinsicMetric)
    }

    init(attachment: Attachment, source: UIImageView) {
        precondition(attachment.kind == .gifv)
        
        self.asset = AVURLAsset(url: attachment.url)
        
        super.init(asset: asset, gravity: .resizeAspect)
        
        self.animationImage = source.image
        
        self.player.play()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setControlsVisible(_ controlsVisible: Bool) {
    }
    
    func grayscaleStateChanged() {
        // no-op, GifvAttachmentView observes the grayscale state itself
    }
}