import SwiftUI
import MetricsProvider

@MainActor
struct NetworkPopoverContent: View {
    let model: NetworkModel

    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            HStack(alignment: .top) {
                rate(model.snapshot.downloadRate, "network.download", .green)
                Spacer()
                rate(model.snapshot.uploadRate, "network.upload", .pink)
            }

            TrafficChart(history: model.history)
                .frame(height: 56)

            HStack {
                peak(model.history.map(\.downloadRate).max() ?? 0, "network.peak.download")
                Spacer()
                peak(model.history.map(\.uploadRate).max() ?? 0, "network.peak.upload")
            }

            Divider()

            Label(connectionName, systemImage: model.snapshot.interfaceKind.symbolName)
                .font(.callout)

            if model.snapshot.interfaceKind == .vpn {
                // Ein VPN verändert, was die Zahlen darüber bedeuten — der
                // Verkehr läuft dann durch den Tunnel, nicht direkt.
                Label("network.vpn.active", systemImage: "lock.shield")
                    .font(.caption)
                    .foregroundStyle(.secondary)
            }

            section("network.addresses")
            field("network.field.interface", model.snapshot.interfaceName)
            field("network.field.ipv4", model.snapshot.ipv4)
            field("network.field.ipv6", model.snapshot.ipv6)
            field("network.field.router", model.snapshot.router)

            section("network.transferred")
            field("network.total.received", bytes(model.snapshot.totalReceived))
            field("network.total.sent", bytes(model.snapshot.totalSent))

            // Kein Durchsatz je Programm: dafür gibt es ohne root keine
            // Schnittstelle, und `nettop` im Sekundentakt zu starten kostete
            // mehr als der gesamte übrige Monitor.
            Text("network.perProcess.unavailable", bundle: .module)
                .font(.caption2)
                .foregroundStyle(.tertiary)
                .fixedSize(horizontal: false, vertical: true)
        }
        .padding(14)
        .frame(width: 280)
    }

    private var connectionName: String {
        if let ssid = model.snapshot.ssid { return ssid }
        if model.snapshot.isWiFiConnected {
            return String(localized: "network.wifi.connected", bundle: .module)
        }
        return model.snapshot.interfaceName
            ?? String(localized: "network.offline", bundle: .module)
    }

    private func rate(_ value: Double, _ key: LocalizedStringKey, _ tint: Color) -> some View {
        VStack(alignment: .leading, spacing: 1) {
            Text(Throughput.formatted(value))
                .font(.system(size: 18, weight: .medium).monospacedDigit())
            HStack(spacing: 4) {
                Circle().fill(tint).frame(width: 6, height: 6)
                Text(key, bundle: .module).font(.caption).foregroundStyle(.secondary)
            }
        }
    }

    private func peak(_ value: Double, _ key: LocalizedStringKey) -> some View {
        HStack(spacing: 4) {
            Text(key, bundle: .module).font(.caption2).foregroundStyle(.secondary)
            Text(Throughput.formatted(value)).font(.caption2.monospacedDigit())
        }
    }

    private func section(_ key: LocalizedStringKey) -> some View {
        Text(key, bundle: .module)
            .font(.caption.weight(.semibold))
            .foregroundStyle(.tint)
            .textCase(.uppercase)
    }

    @ViewBuilder
    private func field(_ key: LocalizedStringKey, _ value: String?) -> some View {
        if let value {
            HStack {
                Text(key, bundle: .module).font(.callout).foregroundStyle(.secondary)
                Spacer(minLength: 12)
                Text(value).font(.callout.monospacedDigit()).textSelection(.enabled)
            }
        }
    }

    private func bytes(_ value: UInt64) -> String {
        ByteCountFormatter.string(fromByteCount: Int64(value), countStyle: .binary)
    }
}

/// Verlauf in beide Richtungen: Download nach unten, Upload nach oben.
///
/// Zwei getrennte Kurven übereinander wären platzsparender, aber schwerer zu
/// lesen — hier sieht man sofort, ob gerade geladen oder gesendet wird, und in
/// welchem Verhältnis. Beide Richtungen teilen sich denselben Maßstab, sonst
/// sähe ein Upload von 20 KB/s genauso hoch aus wie ein Download von 20 MB/s.
private struct TrafficChart: View {
    let history: [NetworkSnapshot]

    var body: some View {
        GeometryReader { geometry in
            let points = history.suffix(60)
            let peak = max(points.map { max($0.downloadRate, $0.uploadRate) }.max() ?? 1, 1)
            let width = geometry.size.width / CGFloat(max(points.count, 1))
            let half = geometry.size.height / 2

            HStack(alignment: .center, spacing: 1) {
                ForEach(Array(points.enumerated()), id: \.offset) { _, snapshot in
                    VStack(spacing: 1) {
                        Rectangle()
                            .fill(.pink)
                            .frame(height: max(half * CGFloat(snapshot.uploadRate / peak), 0.5))
                            .frame(maxHeight: .infinity, alignment: .bottom)
                        Rectangle()
                            .fill(.green)
                            .frame(height: max(half * CGFloat(snapshot.downloadRate / peak), 0.5))
                            .frame(maxHeight: .infinity, alignment: .top)
                    }
                    .frame(width: max(width - 1, 1))
                }
            }
            .frame(width: geometry.size.width, height: geometry.size.height)
        }
    }
}