import UIKit

class GIFCollectionViewCell: UICollectionViewCell {

  private let gifPlayerView: GIFPlayerView = {
    let player = GIFPlayerView()
    player.layer.cornerRadius = 8
    player.clipsToBounds = true
    return player
  }()

  private let loadingIndicator: UIActivityIndicatorView = {
    let indicator = UIActivityIndicatorView(style: .medium)
    indicator.hidesWhenStopped = true
    return indicator
  }()

  private let placeholderLabel: UILabel = {
    let label = UILabel()
    label.text = "GIF"
    label.textAlignment = .center
    label.font = .systemFont(ofSize: 12, weight: .medium)
    label.textColor = .systemGray
    return label
  }()

  private var currentTask: URLSessionDataTask?

  override init(frame: CGRect) {
    super.init(frame: frame)
    setupUI()
  }

  required init?(coder: NSCoder) {
    super.init(coder: coder)
    setupUI()
  }
  
  override func prepareForReuse() {
    super.prepareForReuse()
    currentTask?.cancel()
    currentTask = nil
    gifPlayerView.stopAnimating()
    placeholderLabel.isHidden = false
    loadingIndicator.stopAnimating()
  }

  private func setupUI() {
    contentView.addSubview(gifPlayerView)
    contentView.addSubview(loadingIndicator)
    contentView.addSubview(placeholderLabel)

    gifPlayerView.translatesAutoresizingMaskIntoConstraints = false
    loadingIndicator.translatesAutoresizingMaskIntoConstraints = false
    placeholderLabel.translatesAutoresizingMaskIntoConstraints = false

    NSLayoutConstraint.activate([
      gifPlayerView.topAnchor.constraint(equalTo: contentView.topAnchor),
      gifPlayerView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor),
      gifPlayerView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor),
      gifPlayerView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),

      loadingIndicator.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
      loadingIndicator.centerYAnchor.constraint(equalTo: contentView.centerYAnchor),

      placeholderLabel.centerXAnchor.constraint(equalTo: contentView.centerXAnchor),
      placeholderLabel.centerYAnchor.constraint(equalTo: contentView.centerYAnchor),
    ])

    contentView.layer.cornerRadius = 8
    contentView.layer.borderWidth = 1
    contentView.layer.borderColor = UIColor.systemGray4.cgColor
  }

  func configure(with urlString: String) {
    // Cancel any existing task
    currentTask?.cancel()

    // Reset UI
    gifPlayerView.stopAnimating()
    placeholderLabel.isHidden = false
    loadingIndicator.startAnimating()

    guard let url = URL(string: urlString) else {
      loadingIndicator.stopAnimating()
      return
    }

    // Load the GIF
    currentTask = URLSession.shared.dataTask(with: url) { [weak self] data, _, error in
      DispatchQueue.main.async {
        guard let self = self else { return }
        self.loadingIndicator.stopAnimating()
        
        if let data = data, error == nil {
          self.gifPlayerView.loadGIF(from: data)
          self.gifPlayerView.startAnimating()
          self.placeholderLabel.isHidden = true
        } else {
          self.placeholderLabel.isHidden = false
        }
      }
    }

    currentTask?.resume()
  }
}