import AppKit
import SwiftUI
import OnyxMenuBar
import MetricsProvider

/// Das Netzwerk in der Menüleiste.
///
/// Anders als die Hardwaregrößen hat es **zwei** Werte, die beide interessieren.
/// Sie untereinander zu setzen ist der einzige Weg, beide in der Höhe einer
/// Menüleiste unterzubringen — nebeneinander bräuchte es die doppelte Breite,
/// und die hat man dort nicht.
@MainActor
public final class NetworkMenuBarModule: MenuBarModule {

    public let id = "network"
    public var displayName: String { String(localized: "network.name", bundle: .module) }

    private let model: NetworkModel
    private var token: UUID?
    private var view: NetworkStatusView?

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

    public func makeStatusView(presentation: MenuBarPresentation) -> NSView {
        let view = NetworkStatusView(presentation: presentation)
        view.update(model.snapshot, history: model.series(download: true))
        self.view = view
        return view
    }

    public func makePopoverView() -> AnyView {
        AnyView(NetworkPopoverContent(model: model))
    }

    public func activate() {
        guard token == nil else { return }
        token = model.addConsumer(interval: 2)
        startObserving()
    }

    public func deactivate() {
        if let token { model.removeConsumer(token) }
        token = nil
        view = nil
    }

    private func startObserving() {
        withObservationTracking {
            _ = model.snapshot
        } onChange: {
            Task { @MainActor [weak self] in
                guard let self, token != nil else { return }
                view?.update(model.snapshot, history: model.series(download: true))
                startObserving()
            }
        }
    }
}

final class NetworkStatusView: NSView {

    private let presentation: MenuBarPresentation
    private var snapshot = NetworkSnapshot()
    private var history: [Double] = []

    init(presentation: MenuBarPresentation) {
        self.presentation = presentation
        super.init(frame: NSRect(x: 0, y: 0, width: Self.width(presentation), height: 22))
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) { fatalError() }

    /// Breiter als die Hardwaremodule: „↓ 2,4 MB/s" braucht schlicht mehr Platz
    /// als „46 %".
    static func width(_ presentation: MenuBarPresentation) -> CGFloat {
        switch presentation {
        case .symbol: 22
        case .graph: 34
        case .bars: 30
        case .value, .valueAndGraph: 76
        }
    }

    override var intrinsicContentSize: NSSize {
        NSSize(width: Self.width(presentation), height: 22)
    }

    func update(_ snapshot: NetworkSnapshot, history: [Double]) {
        self.snapshot = snapshot
        self.history = history
        needsDisplay = true
    }

    override func draw(_ dirtyRect: NSRect) {
        let color = NSColor.labelColor

        switch presentation {
        case .symbol:
            guard let image = NSImage(systemSymbolName: snapshot.interfaceKind.symbolName,
                                      accessibilityDescription: nil) else { return }
            image.isTemplate = true
            color.set()
            image.draw(in: NSRect(x: bounds.midX - 7.5, y: bounds.midY - 7.5,
                                  width: 15, height: 15))

        case .graph, .bars:
            drawGraph(color: color, in: bounds.insetBy(dx: 2, dy: 5))

        case .value, .valueAndGraph:
            drawRates(color: color,
                      in: presentation == .value ? bounds
                          : NSRect(x: 0, y: 0, width: bounds.width - 26, height: bounds.height))
            if presentation == .valueAndGraph {
                drawGraph(color: color,
                          in: NSRect(x: bounds.width - 24, y: 5, width: 22, height: 12))
            }
        }
    }

    /// Zwei Zeilen à 9 pt — die einzige Art, Hoch und Runter in 22 pt Höhe
    /// unterzubringen.
    private func drawRates(color: NSColor, in rect: NSRect) {
        let attributes: [NSAttributedString.Key: Any] = [
            .font: NSFont.monospacedDigitSystemFont(ofSize: 9, weight: .regular),
            .foregroundColor: color,
        ]
        let down = NSAttributedString(string: "↓ " + Throughput.formatted(snapshot.downloadRate),
                                      attributes: attributes)
        let up = NSAttributedString(string: "↑ " + Throughput.formatted(snapshot.uploadRate),
                                    attributes: attributes)
        down.draw(at: NSPoint(x: rect.minX + 2, y: rect.midY - 0.5))
        up.draw(at: NSPoint(x: rect.minX + 2, y: rect.midY - 10.5))
    }

    private func drawGraph(color: NSColor, in rect: NSRect) {
        guard history.count > 1, let context = NSGraphicsContext.current?.cgContext else { return }
        let step = rect.width / CGFloat(history.count - 1)
        context.setStrokeColor(color.withAlphaComponent(0.85).cgColor)
        context.setLineWidth(1)
        for (index, value) in history.enumerated() {
            let point = CGPoint(x: rect.minX + CGFloat(index) * step,
                                y: rect.minY + rect.height * CGFloat(min(max(value, 0), 1)))
            index == 0 ? context.move(to: point) : context.addLine(to: point)
        }
        context.strokePath()
    }
}