import UIKit

public class PlayerView: UIView {
  private let titleLabel: UILabel = UILabel()
  private let langLabel: UILabel = UILabel()
  private let langContainer: UIView = UIView()
  private let cnLabel: UILabel = UILabel()
  private let enLabel: UILabel = UILabel()
  private let stackView: UIStackView
  private var lastDynamicTextLines: Int = -1
  private let langRow: UIStackView = UIStackView()
  private var lastBoundsSize: CGSize = .zero
  private var lastLangText: String? = nil
  private var isExpanded: Bool = false
  private let compactPreferredHeight: CGFloat = 72
  private let expandedPreferredHeight: CGFloat = 220

  public override init(frame: CGRect) {
    stackView = UIStackView()
    super.init(frame: frame)
    setupUI()
  }

  public convenience init() {
    self.init(frame: .zero)
  }

  required init?(coder: NSCoder) {
    stackView = UIStackView()
    super.init(coder: coder)
    setupUI()
  }

  private func setupUI() {
    backgroundColor = UIColor(red: 40.0 / 255.0, green: 40.0 / 255.0, blue: 40.0 / 255.0, alpha: 90.0 / 255.0)
    layer.cornerRadius = 16
    layer.borderWidth = 1
    layer.borderColor = UIColor(white: 1.0, alpha: 46.0 / 255.0).cgColor
    layer.shadowColor = UIColor.black.cgColor
    layer.shadowOpacity = 0.35
    layer.shadowRadius = 12
    layer.shadowOffset = CGSize(width: 0, height: 4)

    titleLabel.text = "实时翻译"
    titleLabel.font = .boldSystemFont(ofSize: 22)
    titleLabel.textColor = UIColor(white: 1.0, alpha: 235.0 / 255.0)
    titleLabel.textAlignment = .center
    titleLabel.numberOfLines = 1
    titleLabel.isHidden = true

    langLabel.text = "src -> tgt"
    langLabel.font = .systemFont(ofSize: 12)
    langLabel.textColor = UIColor(white: 1.0, alpha: 235.0 / 255.0)
    langLabel.textAlignment = .center
    langLabel.numberOfLines = 1
    langLabel.lineBreakMode = .byTruncatingTail
    langLabel.translatesAutoresizingMaskIntoConstraints = false
    langLabel.setContentHuggingPriority(.required, for: .horizontal)
    langLabel.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)

    langContainer.backgroundColor = UIColor(white: 1.0, alpha: 36.0 / 255.0)
    langContainer.layer.cornerRadius = 10
    langContainer.translatesAutoresizingMaskIntoConstraints = false
    langContainer.setContentHuggingPriority(.required, for: .horizontal)
    langContainer.setContentCompressionResistancePriority(.required, for: .horizontal)
    langContainer.addSubview(langLabel)
    NSLayoutConstraint.activate([
      langLabel.topAnchor.constraint(equalTo: langContainer.topAnchor, constant: 6),
      langLabel.leadingAnchor.constraint(equalTo: langContainer.leadingAnchor, constant: 10),
      langLabel.trailingAnchor.constraint(equalTo: langContainer.trailingAnchor, constant: -10),
      langLabel.bottomAnchor.constraint(equalTo: langContainer.bottomAnchor, constant: -6),
    ])

    cnLabel.font = .systemFont(ofSize: 14)
    cnLabel.textColor = UIColor(white: 1.0, alpha: 235.0 / 255.0)
    cnLabel.textAlignment = .left
    cnLabel.numberOfLines = 0
    cnLabel.lineBreakMode = .byTruncatingTail
    cnLabel.isHidden = true

    enLabel.font = .systemFont(ofSize: 15)
    enLabel.textColor = UIColor(red: 144.0 / 255.0, green: 202.0 / 255.0, blue: 249.0 / 255.0, alpha: 1.0)
    enLabel.textAlignment = .left
    enLabel.numberOfLines = 0
    enLabel.lineBreakMode = .byTruncatingTail
    enLabel.isHidden = true

    let para = NSMutableParagraphStyle()
    para.lineSpacing = 2
    para.lineHeightMultiple = 1.1
    cnLabel.attributedText = NSAttributedString(string: "", attributes: [.paragraphStyle: para])
    enLabel.attributedText = NSAttributedString(string: "", attributes: [.paragraphStyle: para])

    stackView.axis = .vertical
    stackView.spacing = 10
    stackView.alignment = .fill
    stackView.distribution = .fill
    stackView.translatesAutoresizingMaskIntoConstraints = false
    stackView.addArrangedSubview(titleLabel)
    langRow.axis = .horizontal
    langRow.alignment = .fill
    langRow.distribution = .fill
    langRow.translatesAutoresizingMaskIntoConstraints = false
    let leftSpacer = UIView()
    let rightSpacer = UIView()
    leftSpacer.translatesAutoresizingMaskIntoConstraints = false
    rightSpacer.translatesAutoresizingMaskIntoConstraints = false
    langRow.addArrangedSubview(leftSpacer)
    langRow.addArrangedSubview(langContainer)
    langRow.addArrangedSubview(rightSpacer)
    NSLayoutConstraint.activate([
      leftSpacer.widthAnchor.constraint(equalTo: rightSpacer.widthAnchor),
    ])
    stackView.addArrangedSubview(langRow)
    stackView.addArrangedSubview(cnLabel)
    stackView.addArrangedSubview(enLabel)

    layoutMargins = UIEdgeInsets(top: 10, left: 16, bottom: 10, right: 16)
    addSubview(stackView)

    let guide = layoutMarginsGuide
    NSLayoutConstraint.activate([
      stackView.topAnchor.constraint(equalTo: guide.topAnchor),
      stackView.leadingAnchor.constraint(equalTo: guide.leadingAnchor),
      stackView.trailingAnchor.constraint(equalTo: guide.trailingAnchor),
      stackView.bottomAnchor.constraint(lessThanOrEqualTo: guide.bottomAnchor),
    ])
  }

  public func play() {
  }

  public func pause() {
  }

  public func update(withLang lang: String?, cn: String?, en: String?) {
    if let lang = lang {
      langLabel.text = lang
    }
    let para = NSMutableParagraphStyle()
    para.lineSpacing = 2
    para.lineHeightMultiple = 1.1
    if let cn = cn {
      cnLabel.attributedText = NSAttributedString(string: cn, attributes: [.paragraphStyle: para])
    }
    if let en = en {
      enLabel.attributedText = NSAttributedString(string: en, attributes: [.paragraphStyle: para])
    }
    let currentCn = cnLabel.attributedText?.string ?? ""
    let currentEn = enLabel.attributedText?.string ?? ""
    let hasContent =
      !currentCn.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
      || !currentEn.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
    setExpanded(hasContent)
    setNeedsLayout()
  }

  public override var intrinsicContentSize: CGSize {
    CGSize(width: UIView.noIntrinsicMetric, height: isExpanded ? expandedPreferredHeight : compactPreferredHeight)
  }

  public override func layoutSubviews() {
    super.layoutSubviews()
    layer.cornerRadius = isExpanded ? 16 : 18
    layer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: layer.cornerRadius).cgPath
    let currentLangText = langLabel.text
    if bounds.size != lastBoundsSize || currentLangText != lastLangText {
      lastBoundsSize = bounds.size
      lastLangText = currentLangText
      updateDynamicTextLineLimit()
    }
  }

  private func setExpanded(_ expanded: Bool) {
    if expanded == isExpanded { return }
    isExpanded = expanded
    cnLabel.isHidden = !expanded
    enLabel.isHidden = !expanded
    layoutMargins = expanded
      ? UIEdgeInsets(top: 16, left: 16, bottom: 16, right: 16)
      : UIEdgeInsets(top: 10, left: 16, bottom: 10, right: 16)
    invalidateIntrinsicContentSize()
  }

  private func updateDynamicTextLineLimit() {
    let fittingWidth = max(0, bounds.width - layoutMargins.left - layoutMargins.right)
    if fittingWidth <= 0 { return }

    let visibleArrangedSubviews = stackView.arrangedSubviews.filter { !$0.isHidden }
    let fixedSubviews = visibleArrangedSubviews.filter { $0 !== cnLabel && $0 !== enLabel }
    let fixedHeight = fixedSubviews.reduce(CGFloat(0)) { partialResult, view in
      partialResult
        + view.systemLayoutSizeFitting(
          CGSize(width: fittingWidth, height: UIView.layoutFittingCompressedSize.height),
          withHorizontalFittingPriority: .required,
          verticalFittingPriority: .fittingSizeLevel
        ).height
    }
    let totalSpacing = CGFloat(max(0, visibleArrangedSubviews.count - 1)) * stackView.spacing

    let availableHeight =
      bounds.height
      - layoutMargins.top
      - layoutMargins.bottom
      - fixedHeight
      - totalSpacing

    let cnLineHeight = cnLabel.font.lineHeight * 1.1 + 2
    let enLineHeight = enLabel.font.lineHeight * 1.1 + 2
    let combinedLineHeight = cnLineHeight + enLineHeight

    let perLabelLines = max(1, min(Int(availableHeight / combinedLineHeight), 10))

    if perLabelLines != lastDynamicTextLines {
      lastDynamicTextLines = perLabelLines
      cnLabel.numberOfLines = perLabelLines
      enLabel.numberOfLines = perLabelLines
    }
  }
}