hyungi_document_server/clients/ds-app/Sources/AppFeature/Shell/RootView.swift

import SwiftUI
import DSKit

/// DEVONthink-style 3-column shell. RootView only ROUTES; each page owns its own interior treatment
/// (no shell-level auto-inherit). macOS-only target.
public struct RootView: View {
    @Environment(AppModel.self) private var model
    @State private var columnVisibility: NavigationSplitViewVisibility = .all

    public init() {}

    public var body: some View {
        NavigationSplitView(columnVisibility: $columnVisibility) {
            Sidebar()
                .navigationSplitViewColumnWidth(min: 220, ideal: 250)
        } content: {
            ContentColumn()
                .navigationSplitViewColumnWidth(min: 300, ideal: 380)
        } detail: {
            DetailColumn()
        }
        .navigationSplitViewStyle(.balanced)
        .tint(Sage.brand)
        .task { await model.loadInitial() }
    }
}

struct Sidebar: View {
    @Environment(AppModel.self) private var model

    var body: some View {
        let selection = Binding<AppModel.Section?>(
            get: { model.section },
            set: { if let v = $0 { model.section = v } }
        )
        List(selection: selection) {
            Section {
                ForEach(AppModel.Section.allCases) { s in
                    Text(s.title).tag(s)
                }
            }
            if model.section == .documents, !model.tree.isEmpty {
                Section("도메인") {
                    ForEach(model.tree) { node in
                        DomainRow(node: node)
                    }
                }
            }
        }
        .listStyle(.sidebar)
        .background(Sage.sidebar)
    }
}

struct DomainRow: View {
    @Environment(AppModel.self) private var model
    let node: DomainTreeNode

    var body: some View {
        HStack(spacing: 8) {
            Circle().fill(Sage.domainColor(node.name)).frame(width: 8, height: 8)
            Text(node.name).font(.callout).foregroundStyle(Sage.ink)
            Spacer()
            Text("\(node.count)").font(.caption).foregroundStyle(Sage.muted)
        }
        .contentShape(Rectangle())
        .onTapGesture { model.section = .documents }
    }
}

struct ContentColumn: View {
    @Environment(AppModel.self) private var model

    var body: some View {
        Group {
            switch model.section {
            case .dashboard: DashboardView()
            case .documents: DocumentListView()
            case .search: SearchView()
            case .ask: AskView()
            case .memos: MemoListView()
            case .digest: DigestView()
            }
        }
        .navigationTitle(model.section.title)
    }
}

struct DetailColumn: View {
    @Environment(AppModel.self) private var model

    var body: some View {
        Group {
            switch model.section {
            case .documents:
                if let d = model.documentDetail { DocumentDetailView(detail: d) }
                else { EmptyState(text: "문서를 선택하세요") }
            case .memos:
                if let m = model.memoDetail { MemoDetailView(memo: m) }
                else { EmptyState(text: "메모를 선택하세요") }
            default:
                EmptyState(text: model.section.title)
            }
        }
    }
}

struct EmptyState: View {
    let text: String
    var body: some View {
        Text(text)
            .foregroundStyle(Sage.muted)
            .frame(maxWidth: .infinity, maxHeight: .infinity)
            .background(Sage.surface)
    }
}

#if DEBUG
#Preview("DS App — full shell") {
    @Previewable @State var model = AppModel.preview
    RootView()
        .environment(model)
        .task { await model.loadInitial() }
        .frame(minWidth: 1000, minHeight: 660)
}
#endif