import Feeds
import SwiftUI

/// Which Deep Space Network dishes are talking to which spacecraft right now.
struct DSNSection: View {
    var ink: Color
    var accent: Color
    @State private var status: DSNStatus?
    @State private var failed = false

    private var activeDishes: [DSNStatus.Dish] {
        status?.dishes.filter { !$0.links.isEmpty } ?? []
    }

    var body: some View {
        VStack(alignment: .leading, spacing: 10) {
            Text("Deep Space Network now").font(.caption2.weight(.medium)).textCase(.uppercase).tracking(0.8).dimmed(0.6)
            Text("NASA talks to its deep-space probes through giant dishes at three sites spaced around the world, so one always faces any spacecraft. This is who each site is talking to now.")
                .font(.footnote).dimmed(0.75)
            if let status {
                ForEach(["Goldstone", "Madrid", "Canberra"], id: \.self) { station in
                    let dishes = activeDishes.filter { $0.station == station }
                    VStack(alignment: .leading, spacing: 4) {
                        Text(station).font(.subheadline.weight(.medium))
                        if dishes.isEmpty {
                            Text("No spacecraft in contact").font(.footnote).dimmed(0.6)
                        }
                        ForEach(dishes) { dish in
                            ForEach(dish.links, id: \.self) { link in
                                HStack(alignment: .firstTextBaseline) {
                                    Text(link.spacecraft).font(.footnote)
                                    Spacer()
                                    Text(describe(link, dish: dish)).font(.footnote.monospacedDigit()).dimmed(0.7)
                                }
                                .accessibilityElement(children: .combine)
                            }
                        }
                    }
                    .padding(.vertical, 4)
                }
                Text("Updated \(status.updated.formatted(date: .omitted, time: .shortened)). Data: NASA/JPL Deep Space Network.")
                    .font(.caption2).dimmed(0.5)
            } else if failed {
                Text("Couldn't load Deep Space Network status.").font(.footnote).foregroundStyle(accent)
            } else {
                ProgressView().tint(ink)
            }
        }
        .task {
            while !Task.isCancelled {
                do { status = try await DSNStatus.fetch(); failed = false } catch { failed = status == nil }
                try? await Task.sleep(for: .seconds(30))
            }
        }
    }

    private func describe(_ l: DSNStatus.Link, dish: DSNStatus.Dish) -> String {
        var parts = [dish.name.replacingOccurrences(of: "DSS", with: "DSS ")]
        if l.receiving && l.sending { parts.append("two-way") } else if l.receiving { parts.append("receiving") } else { parts.append("sending") }
        if let r = l.downlinkRate { parts.append(rate(r)) }
        if let rt = l.roundTrip, rt > 60 { parts.append("round trip \(duration(rt))") }
        return parts.joined(separator: " · ")
    }

    private func rate(_ bps: Double) -> String {
        bps >= 1_000_000 ? String(format: "%.1f Mb/s", bps / 1_000_000) : bps >= 1000 ? String(format: "%.0f kb/s", bps / 1000) : String(format: "%.0f b/s", bps)
    }

    private func duration(_ s: Double) -> String {
        let h = Int(s / 3600), m = Int(s.truncatingRemainder(dividingBy: 3600) / 60)
        return h > 0 ? "\(h) h \(m) m" : "\(m) m"
    }
}