import SwiftUI
import UIKit

struct ScoresTickerView: View {
    var gamesOverride: [Game]? = nil

    @Environment(GamesViewModel.self) private var viewModel

    private var entries: [Game] {
        gamesOverride ?? viewModel.games
    }

    var body: some View {
        if !entries.isEmpty {
            TickerMarqueeView(text: tickerText)
                .frame(maxWidth: .infinity, alignment: .leading)
                .frame(height: 22)
                .padding(.horizontal, 18)
                .padding(.vertical, 14)
                .background(
                    RoundedRectangle(cornerRadius: 18, style: .continuous)
                        .fill(.black.opacity(0.72))
                        .overlay {
                            RoundedRectangle(cornerRadius: 18, style: .continuous)
                                .strokeBorder(.white.opacity(0.08), lineWidth: 1)
                        }
                )
                .accessibilityHidden(true)
        }
    }

    private var tickerText: String {
        entries.map(tickerSummary(for:)).joined(separator: "   |   ")
    }

    private func tickerSummary(for game: Game) -> String {
        let matchup = "\(game.awayTeam.code) \(game.awayTeam.score.map(String.init) ?? "-") - \(game.homeTeam.code) \(game.homeTeam.score.map(String.init) ?? "-")"

        if game.isLive, let linescore = game.linescore {
            let inning = linescore.currentInningOrdinal ?? game.currentInningDisplay ?? "LIVE"
            let state = (linescore.inningState ?? linescore.inningHalf ?? "Live").uppercased()
            let outs = linescore.outs ?? 0
            return "\(matchup)  \(state) \(inning.uppercased()) • \(outs) OUT\(outs == 1 ? "" : "S")"
        }

        if game.isFinal {
            return "\(matchup)  FINAL"
        }

        if let startTime = game.startTime {
            return "\(matchup)  \(startTime.uppercased())"
        }

        return "\(matchup)  \(game.status.label.uppercased())"
    }
}

private struct TickerMarqueeView: UIViewRepresentable {
    let text: String

    func makeUIView(context: Context) -> TickerMarqueeContainerView {
        let view = TickerMarqueeContainerView()
        view.setText(text)
        return view
    }

    func updateUIView(_ uiView: TickerMarqueeContainerView, context: Context) {
        uiView.setText(text)
    }
}

private final class TickerMarqueeContainerView: UIView {
    private let trackView = UIView()
    private let primaryLabel = UILabel()
    private let secondaryLabel = UILabel()
    private let spacing: CGFloat = 48
    private let pointsPerSecond: CGFloat = 64

    private var currentText = ""
    private var previousBoundsWidth: CGFloat = 0
    private var previousContentWidth: CGFloat = 0

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

        clipsToBounds = true
        isUserInteractionEnabled = false

        let baseFont = UIFont.systemFont(ofSize: 15, weight: .bold)
        let roundedFont = UIFont(descriptor: baseFont.fontDescriptor.withDesign(.rounded) ?? baseFont.fontDescriptor, size: 15)

        [primaryLabel, secondaryLabel].forEach { label in
            label.font = roundedFont
            label.textColor = UIColor.white.withAlphaComponent(0.92)
            label.numberOfLines = 1
            label.lineBreakMode = .byClipping
            trackView.addSubview(label)
        }

        addSubview(trackView)
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    func setText(_ text: String) {
        guard currentText != text else { return }
        currentText = text
        primaryLabel.text = text
        secondaryLabel.text = text
        previousContentWidth = 0
        setNeedsLayout()
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        guard bounds.width > 0, bounds.height > 0 else { return }

        let contentWidth = ceil(primaryLabel.sizeThatFits(CGSize(width: .greatestFiniteMagnitude, height: bounds.height)).width)
        let contentHeight = bounds.height

        primaryLabel.frame = CGRect(x: 0, y: 0, width: contentWidth, height: contentHeight)
        secondaryLabel.frame = CGRect(x: contentWidth + spacing, y: 0, width: contentWidth, height: contentHeight)

        let cycleWidth = contentWidth + spacing

        if contentWidth <= bounds.width {
            trackView.layer.removeAllAnimations()
            secondaryLabel.isHidden = true
            trackView.frame = CGRect(x: 0, y: 0, width: bounds.width, height: contentHeight)
            primaryLabel.frame = CGRect(x: 0, y: 0, width: bounds.width, height: contentHeight)
            primaryLabel.textAlignment = .left
            previousBoundsWidth = bounds.width
            previousContentWidth = contentWidth
            return
        }

        primaryLabel.textAlignment = .left
        secondaryLabel.isHidden = false
        trackView.frame = CGRect(x: 0, y: 0, width: contentWidth * 2 + spacing, height: contentHeight)

        let shouldRestart = abs(previousBoundsWidth - bounds.width) > 0.5
            || abs(previousContentWidth - contentWidth) > 0.5
            || trackView.layer.animation(forKey: "tickerMarquee") == nil

        previousBoundsWidth = bounds.width
        previousContentWidth = contentWidth

        guard shouldRestart else { return }

        trackView.layer.removeAllAnimations()
        trackView.transform = .identity

        let animation = CABasicAnimation(keyPath: "transform.translation.x")
        animation.fromValue = 0
        animation.toValue = -cycleWidth
        animation.duration = Double(cycleWidth / pointsPerSecond)
        animation.repeatCount = .infinity
        animation.timingFunction = CAMediaTimingFunction(name: .linear)
        animation.isRemovedOnCompletion = false

        trackView.layer.add(animation, forKey: "tickerMarquee")
    }
}