//
//  StatusCardView.swift
//  Tusker
//
//  Created by Shadowfacts on 10/25/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm
import SafariServices

class StatusCardView: UIView {
    
    weak var navigationDelegate: TuskerNavigationDelegate?
    
    var card: Card? {
        didSet {
            if let card = card {
                self.updateUI(card: card)
            }
        }
    }
    
    private let activeBackgroundColor = UIColor.secondarySystemFill
    private let inactiveBackgroundColor = UIColor.secondarySystemBackground
    
    private var imageRequest: ImageCache.Request?
    private var isGrayscale = false
    
    private var titleLabel: UILabel!
    private var descriptionLabel: UILabel!
    private var imageView: UIImageView!
    private var placeholderImageView: UIImageView!
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }
    
    private func commonInit() {
        self.clipsToBounds = true
        self.layer.cornerRadius = 6.5
        self.layer.borderWidth = 1
        self.layer.borderColor = UIColor.lightGray.cgColor
        self.backgroundColor = inactiveBackgroundColor
        
        self.addInteraction(UIContextMenuInteraction(delegate: self))
        
        titleLabel = UILabel()
        titleLabel.font = UIFont(descriptor: UIFontDescriptor.preferredFontDescriptor(withTextStyle: .subheadline).withSymbolicTraits(.traitBold)!, size: 0)
        titleLabel.numberOfLines = 2
        
        descriptionLabel = UILabel()
        descriptionLabel.font = UIFont(descriptor: .preferredFontDescriptor(withTextStyle: .caption1), size: 0)
        descriptionLabel.numberOfLines = 2
        descriptionLabel.setContentCompressionResistancePriority(.defaultLow, for: .vertical)
        
        let vStack = UIStackView(arrangedSubviews: [
            titleLabel,
            descriptionLabel
        ])
        vStack.axis = .vertical
        vStack.alignment = .leading
        vStack.distribution = .fill
        vStack.spacing = 0
        
        imageView = UIImageView()
        imageView.contentMode = .scaleAspectFill
        imageView.clipsToBounds = true
        
        let hStack = UIStackView(arrangedSubviews: [
            imageView,
            vStack
        ])
        hStack.translatesAutoresizingMaskIntoConstraints = false
        hStack.axis = .horizontal
        hStack.alignment = .center
        hStack.distribution = .fill
        hStack.spacing = 4
        
        addSubview(hStack)
        
        placeholderImageView = UIImageView(image: UIImage(systemName: "doc.text"))
        placeholderImageView.translatesAutoresizingMaskIntoConstraints = false
        placeholderImageView.contentMode = .scaleAspectFit
        placeholderImageView.tintColor = .gray

        addSubview(placeholderImageView)
        
        NSLayoutConstraint.activate([
            imageView.heightAnchor.constraint(equalTo: heightAnchor),
            imageView.widthAnchor.constraint(equalTo: imageView.heightAnchor),
            
            vStack.heightAnchor.constraint(equalTo: heightAnchor, constant: -8),
            
            hStack.leadingAnchor.constraint(equalTo: leadingAnchor),
            hStack.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -4),
            hStack.topAnchor.constraint(equalTo: topAnchor),
            hStack.bottomAnchor.constraint(equalTo: bottomAnchor),
            
            placeholderImageView.widthAnchor.constraint(equalToConstant: 30),
            placeholderImageView.heightAnchor.constraint(equalToConstant: 30),
            placeholderImageView.centerXAnchor.constraint(equalTo: imageView.centerXAnchor),
            placeholderImageView.centerYAnchor.constraint(equalTo: imageView.centerYAnchor),
        ])
        
        NotificationCenter.default.addObserver(self, selector: #selector(updateUIForPreferences), name: .preferencesChanged, object: nil)
    }
    
    private func updateUI(card: Card) {
        self.imageView.image = nil
        
        updateGrayscaleableUI(card: card)
        updateUIForPreferences()
        
        let title = card.title.trimmingCharacters(in: .whitespacesAndNewlines)
        titleLabel.text = title
        titleLabel.isHidden = title.isEmpty
        
        let description = card.description.trimmingCharacters(in: .whitespacesAndNewlines)
        descriptionLabel.text = description
        descriptionLabel.isHidden = description.isEmpty
    }
    
    @objc private func updateUIForPreferences() {
        if isGrayscale != Preferences.shared.grayscaleImages,
           let card = card {
            updateGrayscaleableUI(card: card)
        }
    }
    
    private func updateGrayscaleableUI(card: Card) {
        isGrayscale = Preferences.shared.grayscaleImages
        
        if let imageURL = card.image {
            placeholderImageView.isHidden = true
            
            imageRequest = ImageCache.attachments.get(imageURL, completion: { (_, image) in
                guard let image = image,
                      let transformedImage = ImageGrayscalifier.convertIfNecessary(url: imageURL, image: image) else {
                    return
                }
                DispatchQueue.main.async {
                    self.imageView.image = transformedImage
                }
            })
            if imageRequest != nil {
                loadBlurHash()
            }
        } else {
            placeholderImageView.isHidden = false
        }
    }
    
    private func loadBlurHash() {
        guard let card = card, let hash = card.blurhash else { return }
        
        let imageViewSize = self.imageView.bounds.size
        
        // todo: merge this code with AttachmentView, use a single DispatchQueue
        DispatchQueue.global(qos: .default).async { [weak self] in
            guard let self = self else { return }
            
            let size: CGSize
            if let width = card.width, let height = card.height {
                size = CGSize(width: width, height: height)
            } else {
                size = imageViewSize
            }
            
            guard let preview = UIImage(blurHash: hash, size: size) else {
                return
            }
            
            DispatchQueue.main.async { [weak self] in
                guard let self = self,
                      self.card?.url == card.url,
                      self.imageView.image == nil else { return }
                
                self.imageView.image = preview
            }
        }
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        backgroundColor = activeBackgroundColor
        setNeedsDisplay()
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        backgroundColor = inactiveBackgroundColor
        setNeedsDisplay()
        
        if let card = card, let delegate = navigationDelegate {
            delegate.selected(url: card.url)
        }
    }
    
    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        backgroundColor = inactiveBackgroundColor
        setNeedsDisplay()
    }

}

extension StatusCardView: MenuPreviewProvider {
}

extension StatusCardView: UIContextMenuInteractionDelegate {
    func contextMenuInteraction(_ interaction: UIContextMenuInteraction, configurationForMenuAtLocation location: CGPoint) -> UIContextMenuConfiguration? {
        guard let card = card else { return nil }
        
        return UIContextMenuConfiguration(identifier: nil) {
            return SFSafariViewController(url: card.url)
        } actionProvider: { (_) in
            let actions = self.actionsForURL(card.url, sourceView: self)
            return UIMenu(title: "", image: nil, identifier: nil, options: [], children: actions)
        }
    }
    
    func contextMenuInteraction(_ interaction: UIContextMenuInteraction, willPerformPreviewActionForMenuWith configuration: UIContextMenuConfiguration, animator: UIContextMenuInteractionCommitAnimating) {
        if let viewController = animator.previewViewController,
           let delegate = navigationDelegate {
            animator.preferredCommitStyle = .pop
            animator.addCompletion {
                if let customPresenting = viewController as? CustomPreviewPresenting {
                    customPresenting.presentFromPreview(presenter: delegate)
                } else {
                    delegate.show(viewController)
                }
            }
        }
    }
}