#if os(macOS)
import SwiftUI

// 桌面根界面：NavigationSplitView 侧栏（传输 / 文件 / 消息 / 设备 / 设置）+ 详情 NavigationStack，
// 替代 iOS 的标签栏。当前为脚手架：各区详情为占位（MacPlaceholder），随后续阶段接入复用视图
// 与桌面专属功能。分区标签暂硬编中文；接入 i18n（Shared/I18n）后改走 t()（与 iOS 单一真源一致）。
struct MacRootView: View
{
    @State private var selection: MacSection = .transfers

    var body: some View
    {
        NavigationSplitView
        {
            List(selection: $selection)
            {
                brandHeader
                    .listRowInsets(EdgeInsets(top: 10, leading: 8, bottom: 14, trailing: 8))
                    .listRowSeparator(.hidden)
                    .selectionDisabled()
                Section
                {
                    ForEach(MacSection.sidebar)
                    { section in
                        Label(section.title, systemImage: section.icon)
                            .tag(section)
                    }
                }
            }
            .navigationSplitViewColumnWidth(min: 200, ideal: 220, max: 280)
            .navigationTitle("Commilitia Drop")
        }
        detail:
        {
            NavigationStack
            {
                detail
            }
        }
    }

    @ViewBuilder
    private var detail: some View
    {
        switch selection
        {
        case .transfers:
            MacPlaceholder(section: .transfers)
        case .files:
            MacPlaceholder(section: .files)
        case .messages:
            MacPlaceholder(section: .messages)
        case .devices:
            MacPlaceholder(section: .devices)
        case .settings:
            MacPlaceholder(section: .settings)
        }
    }

    private var brandHeader: some View
    {
        HStack(spacing: 10)
        {
            Image(systemName: "paperplane.fill")
                .font(.title2)
                .foregroundStyle(.tint)
            Text("Commilitia Drop")
                .font(.title3.weight(.semibold))
                .lineLimit(1)
        }
    }
}

// 侧栏分区。与 iOS 标签一致：传输 / 文件 / 消息 / 设备 / 设置。
enum MacSection: Hashable, Identifiable, CaseIterable
{
    case transfers, files, messages, devices, settings

    var id: Self { self }

    var title: String
    {
        switch self
        {
        case .transfers: return "传输"
        case .files: return "文件"
        case .messages: return "消息"
        case .devices: return "设备"
        case .settings: return "设置"
        }
    }

    var icon: String
    {
        switch self
        {
        case .transfers: return "arrow.up.arrow.down"
        case .files: return "folder"
        case .messages: return "bubble.left.and.bubble.right"
        case .devices: return "laptopcomputer.and.iphone"
        case .settings: return "gearshape"
        }
    }

    static var sidebar: [MacSection] { MacSection.allCases }
}

// 阶段占位详情：标明该区将接入的功能，随后续阶段替换为实际视图。
struct MacPlaceholder: View
{
    let section: MacSection

    var body: some View
    {
        ContentUnavailableView
        {
            Label(section.title, systemImage: section.icon)
        }
        description:
        {
            Text("即将接入（原生数据面复用 iOS 引擎，桌面功能适配中）。")
        }
        .navigationTitle(section.title)
    }
}
#endif