import DesignSystem
import MusubiCore
import SwiftUI

/// Cards for all connected screens; drop a source on a card to show it fullscreen there.
struct ScreensView: View {
    let outputs: OutputController

    var body: some View {
        ScrollView {
            VStack(alignment: .leading, spacing: Theme.Space.card) {
                Text("Bildschirme")
                    .font(Theme.Font.title)
                    .foregroundStyle(Theme.Color.washi)
                if outputs.outputs.isEmpty {
                    Text("Noch keine Szene. Zieh eine Quelle auf einen Bildschirm.")
                        .font(Theme.Font.body)
                        .foregroundStyle(Theme.Color.nezumi)
                }
                LazyVGrid(columns: [GridItem(.adaptive(minimum: 260), spacing: Theme.Space.card)], spacing: Theme.Space.card) {
                    ForEach(outputs.screens) { screen in
                        ScreenCard(screen: screen, output: outputs.outputs[screen.id], tick: outputs.tick) {
                            outputs.stop(screen.id)
                        }
                        .dropDestination(for: String.self) { names, _ in
                            guard let name = names.first else { return false }
                            outputs.show(Source(ndiName: name), on: screen.id)
                            return true
                        }
                    }
                }
            }
            .padding(Theme.Space.card)
        }
        .background(Theme.Color.sumi)
    }
}

private struct ScreenCard: View {
    let screen: ScreenInfo
    let output: ActiveOutput?
    let tick: Int
    let onStop: () -> Void

    var body: some View {
        VStack(alignment: .leading, spacing: Theme.Space.unit) {
            Text(verbatim: screen.name)
                .font(Theme.Font.title)
                .foregroundStyle(Theme.Color.washi)
            Text(verbatim: "\(screen.width) × \(screen.height) · \(screen.refreshRate.formatted(.number.precision(.fractionLength(0...2)))) Hz")
                .font(Theme.Font.number)
                .foregroundStyle(Theme.Color.nezumi)

            Divider().overlay(Theme.Color.usuzumi)

            if let output {
                OutputStatus(output: output, tick: tick)
                Button("Ausgabe beenden", action: onStop)
                    .buttonStyle(.bordered)
            } else {
                Text("Quelle hierher ziehen")
                    .font(Theme.Font.body)
                    .foregroundStyle(Theme.Color.nezumi)
            }
        }
        .frame(maxWidth: .infinity, minHeight: 150, alignment: .topLeading)
        .padding(Theme.Space.card)
        .background(Theme.Color.kasumi, in: RoundedRectangle(cornerRadius: Theme.Radius.card))
        .overlay(
            RoundedRectangle(cornerRadius: Theme.Radius.card)
                .strokeBorder(output == nil ? Theme.Color.usuzumi : Theme.Color.ai, lineWidth: output == nil ? Theme.Stroke.line : Theme.Stroke.cord)
        )
    }
}

private struct OutputStatus: View {
    let output: ActiveOutput
    let tick: Int

    var body: some View {
        let snapshot = output.snapshot
        VStack(alignment: .leading, spacing: Theme.Space.unit / 2) {
            Text(verbatim: output.source.label)
                .font(Theme.Font.body)
                .foregroundStyle(Theme.Color.washi)

            switch snapshot.state {
            case .connecting:
                Text("Verbinde …")
                    .font(Theme.Font.caption)
                    .foregroundStyle(Theme.Color.nezumi)
            case .live:
                HStack(spacing: Theme.Space.unit / 2) {
                    Circle().fill(Theme.Color.moegi).frame(width: Theme.Stroke.knot, height: Theme.Stroke.knot)
                    Text(verbatim: "\(snapshot.width) × \(snapshot.height) · \(snapshot.frameRate.formatted(.number.precision(.fractionLength(0...2)))) fps")
                        .font(Theme.Font.number)
                        .foregroundStyle(Theme.Color.nezumi)
                }
            case .stalled(let retryIn):
                Text("\(output.source.label) antwortet nicht mehr. Neuer Versuch in \(Int(retryIn.rounded(.up))) s.")
                    .font(Theme.Font.caption)
                    .foregroundStyle(Theme.Color.kohaku)
            }

            let lost = snapshot.stats.missing + snapshot.stats.droppedByReceiver
            Text("\(lost) Frames verloren (\(snapshot.stats.lossRate.formatted(.percent.precision(.fractionLength(2)))))")
                .font(Theme.Font.number)
                .foregroundStyle(snapshot.stats.lossRate >= 0.001 ? Theme.Color.kohaku : Theme.Color.nezumi)
        }
    }
}