import SwiftUI
import OnyxDesign
import OnyxWidgetKit
import MetricsProvider

/// Wie `MetricsModel`, aber fürs Netz: eine Messschleife für Panel und
/// Menüleiste, mit Referenzzählung.
@MainActor
@Observable
public final class NetworkModel {

    public private(set) var snapshot = NetworkSnapshot()
    public private(set) var history: [NetworkSnapshot] = []

    public static let historyLength = 60

    private let source = NetworkMetrics()
    private var timer: Timer?
    private var demands: [UUID: TimeInterval] = [:]

    public init() {}

    @discardableResult
    public func addConsumer(interval: TimeInterval = 2) -> UUID {
        let token = UUID()
        demands[token] = min(max(interval, 1), 10)
        restartTimer()
        return token
    }

    public func removeConsumer(_ token: UUID) {
        demands[token] = nil
        restartTimer()
    }

    private func restartTimer() {
        timer?.invalidate()
        timer = nil
        guard let interval = demands.values.min() else {
            history.removeAll()
            return
        }
        sample()
        let timer = Timer(timeInterval: interval, repeats: true) { _ in
            MainActor.assumeIsolated { [weak self] in self?.sample() }
        }
        RunLoop.main.add(timer, forMode: .common)
        self.timer = timer
    }

    private func sample() {
        let value = source.sample()
        snapshot = value
        history.append(value)
        if history.count > Self.historyLength {
            history.removeFirst(history.count - Self.historyLength)
        }
    }

    /// Verläufe, auf den bisherigen Höchstwert normiert.
    ///
    /// Eine feste Obergrenze wäre unbrauchbar: bei 100 Mbit/s wäre eine
    /// Video-Wiedergabe ein flacher Strich, und bei 1 Mbit/s ginge jeder
    /// Download über den Rand. Die Kurve zeigt deshalb den Verlauf relativ zum
    /// bisherigen Maximum — die absoluten Zahlen stehen daneben.
    public func series(download: Bool) -> [Double] {
        let values = history.map { download ? $0.downloadRate : $0.uploadRate }
        guard let peak = values.max(), peak > 0 else { return values.map { _ in 0 } }
        return values.map { $0 / peak }
    }
}

// MARK: - Widget

public struct NetworkWidget: OnyxWidget {
    public let id = "network"
    public var displayName: String { String(localized: "network.name", bundle: .module) }
    public let symbolName = "network"
    public let supportedSizes: [WidgetSize] = [.small, .medium, .large]

    private let model: NetworkModel

    public init(model: NetworkModel) { self.model = model }

    public func makeView(size: WidgetSize) -> AnyView {
        AnyView(NetworkWidgetView(model: model, size: size))
    }
}

private struct NetworkWidgetView: View {
    let model: NetworkModel
    let size: WidgetSize
    @State private var token: UUID?

    var body: some View {
        VStack(alignment: .leading, spacing: 5) {
            HStack(spacing: 6) {
                Image(systemName: model.snapshot.interfaceKind.symbolName)
                    .font(.system(size: 11))
                    .foregroundStyle(Onyx.Color.accent)
                Text(connectionName)
                    .font(Onyx.Font.caption)
                    .foregroundStyle(Onyx.Color.textSecondary)
                    .lineLimit(1)
            }

            Rates(snapshot: model.snapshot, compact: size == .small)

            if size != .small {
                Sparkline(values: model.series(download: true), tint: Onyx.Color.accent)
                    .frame(height: 18)
            }

            if size == .large {
                Divider().overlay(Onyx.Color.hairline)
                Details(snapshot: model.snapshot)
            }

            Spacer(minLength: 0)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .topLeading)
        .onAppear { token = model.addConsumer(interval: 1) }
        .onDisappear {
            if let token { model.removeConsumer(token) }
            token = nil
        }
    }

    /// Der Netzwerkname, wenn macOS ihn herausgibt — sonst die Verbindungsart.
    ///
    /// Seit macOS 14 liefert die SSID nur mit Ortungsberechtigung einen Wert.
    /// Fehlt sie, wäre ein leeres Feld eine Falschaussage: verbunden ist man ja.
    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 struct Rates: View {
    let snapshot: NetworkSnapshot
    let compact: Bool

    var body: some View {
        VStack(alignment: .leading, spacing: 1) {
            row("arrow.down", Throughput.formatted(snapshot.downloadRate), Onyx.Color.accent)
            row("arrow.up", Throughput.formatted(snapshot.uploadRate), Onyx.Color.positive)
        }
    }

    private func row(_ symbol: String, _ text: String, _ tint: Color) -> some View {
        HStack(spacing: 3) {
            Image(systemName: symbol)
                .font(.system(size: 8, weight: .bold))
                .foregroundStyle(tint)
            Text(text)
                .font(compact ? Onyx.Font.metricSmall : Onyx.Font.metricSmall)
                .foregroundStyle(Onyx.Color.textPrimary)
                .lineLimit(1)
        }
    }
}

private struct Details: View {
    let snapshot: NetworkSnapshot

    var body: some View {
        VStack(alignment: .leading, spacing: 2) {
            field("network.field.interface", snapshot.interfaceName)
            field("network.field.ipv4", snapshot.ipv4)
            field("network.field.router", snapshot.router)
        }
    }

    @ViewBuilder
    private func field(_ label: LocalizedStringKey, _ value: String?) -> some View {
        if let value {
            HStack(spacing: 4) {
                Text(label, bundle: .module)
                    .font(.system(size: 9))
                    .foregroundStyle(Onyx.Color.textTertiary)
                Text(value)
                    .font(.system(size: 9))
                    .monospacedDigit()
                    .foregroundStyle(Onyx.Color.textSecondary)
                    .textSelection(.enabled)
                    .lineLimit(1)
            }
        }
    }
}