import ActivityKit
import SwiftUI
import WidgetKit

// MARK: - Widget configuration

struct DownloadLiveActivityWidget: Widget {
    var body: some WidgetConfiguration {
        ActivityConfiguration(for: DownloadActivityAttributes.self) { context in
            // Lock Screen / Notification Center banner
            DownloadLockScreenView(context: context)
                .activityBackgroundTint(Color(.systemBackground).opacity(0.6))
        } dynamicIsland: { context in
            DynamicIsland {
                // Expanded region shown when the user long-presses the island
                DynamicIslandExpandedRegion(.leading) {
                    Image(systemName: "arrow.down.circle.fill")
                        .foregroundStyle(.green)
                        .font(.title2)
                }
                DynamicIslandExpandedRegion(.center) {
                    Text(context.attributes.itemTitle)
                        .font(.caption.bold())
                        .lineLimit(1)
                        .minimumScaleFactor(0.8)
                }
                DynamicIslandExpandedRegion(.bottom) {
                    VStack(spacing: 4) {
                        ProgressView(value: context.state.progress)
                            .tint(.green)
                        HStack {
                            Text(bytesFormatted(context.state.bytesDownloaded))
                                .font(.caption2)
                                .foregroundStyle(.secondary)
                                .contentTransition(.numericText())
                            Spacer()
                            Text(percentFormatted(context.state.progress))
                                .font(.caption2.bold())
                                .monospacedDigit()
                                .contentTransition(.numericText())
                        }
                    }
                }
            } compactLeading: {
                Image(systemName: "arrow.down.circle.fill")
                    .foregroundStyle(.green)
                    .font(.caption)
            } compactTrailing: {
                Text(percentFormatted(context.state.progress))
                    .font(.caption2.bold())
                    .monospacedDigit()
                    .contentTransition(.numericText())
            } minimal: {
                Image(systemName: "arrow.down.circle.fill")
                    .foregroundStyle(.green)
                    .font(.caption2)
            }
        }
    }
}

// MARK: - Lock Screen view

struct DownloadLockScreenView: View {
    let context: ActivityViewContext<DownloadActivityAttributes>

    var body: some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack(spacing: 8) {
                Image(systemName: "arrow.down.circle.fill")
                    .foregroundStyle(.green)
                Text(context.attributes.itemTitle)
                    .font(.subheadline.bold())
                    .lineLimit(1)
                Spacer()
                Text(percentFormatted(context.state.progress))
                    .font(.subheadline.bold())
                    .monospacedDigit()
                    .contentTransition(.numericText())
            }
            ProgressView(value: context.state.progress)
                .tint(.green)
            Text(bytesFormatted(context.state.bytesDownloaded) + " heruntergeladen")
                .font(.caption)
                .foregroundStyle(.secondary)
                .contentTransition(.numericText())
        }
        .padding()
    }
}

// MARK: - Helpers

private func percentFormatted(_ fraction: Double) -> String {
    String(format: "%.0f%%", fraction * 100)
}

private func bytesFormatted(_ bytes: Int64) -> String {
    let mb = Double(bytes) / (1_024 * 1_024)
    if mb >= 1 { return String(format: "%.1f MB", mb) }
    let kb = Double(bytes) / 1_024
    if kb >= 1 { return String(format: "%.0f KB", kb) }
    return "\(bytes) B"
}

// MARK: - Previews

private let previewAttributes = DownloadActivityAttributes(itemTitle: "The Name of the Wind")

#Preview("Lock Screen", as: .content, using: previewAttributes) {
    DownloadLiveActivityWidget()
} contentStates: {
    DownloadActivityAttributes.ContentState(progress: 0.35, bytesDownloaded: 52_428_800)
    DownloadActivityAttributes.ContentState(progress: 0.9, bytesDownloaded: 135_266_304)
}

#Preview("Dynamic Island Expanded", as: .dynamicIsland(.expanded), using: previewAttributes) {
    DownloadLiveActivityWidget()
} contentStates: {
    DownloadActivityAttributes.ContentState(progress: 0.35, bytesDownloaded: 52_428_800)
    DownloadActivityAttributes.ContentState(progress: 0.9, bytesDownloaded: 135_266_304)
}

#Preview("Dynamic Island Compact", as: .dynamicIsland(.compact), using: previewAttributes) {
    DownloadLiveActivityWidget()
} contentStates: {
    DownloadActivityAttributes.ContentState(progress: 0.35, bytesDownloaded: 52_428_800)
    DownloadActivityAttributes.ContentState(progress: 0.9, bytesDownloaded: 135_266_304)
}

#Preview("Dynamic Island Minimal", as: .dynamicIsland(.minimal), using: previewAttributes) {
    DownloadLiveActivityWidget()
} contentStates: {
    DownloadActivityAttributes.ContentState(progress: 0.35, bytesDownloaded: 52_428_800)
}