import APIClient
import SwiftUI

/// T-iOS-26 · Projects 列表屏（镜像 web v0.6 projects 面板）：namespace 分组
/// 折叠分区 + 收藏星标 + dirty 徽标 + Active now 置顶 + 搜索。纯呈现 ——
/// 分组/收藏/折叠/导航信号全部是 `ProjectsViewModel` 逻辑（单测覆盖）。
///
/// 安全：项目名/路径/分支是**不可信服务器字节** —— 一律 `Text(verbatim:)`
/// （绝不 LocalizedStringKey/Markdown），单行截断。
struct ProjectsScreen: View {
    @Bindable var viewModel: ProjectsViewModel
    /// "在此仓库开新会话" 导航钩子（AppCoordinator.openProject 消费）。
    var onOpen: (ProjectOpenRequest) -> Void = { _ in }

    private enum Metrics {
        static let rowSpacing: CGFloat = 2
        static let chipSpacing: CGFloat = 6
    }

    var body: some View {
        list
            .navigationTitle(ProjectsCopy.title)
            .navigationBarTitleDisplayMode(.inline)
            .searchable(text: $viewModel.searchText, prompt: ProjectsCopy.searchPrompt)
            .refreshable { await viewModel.refresh() }
            .task { await viewModel.load() }
            .onChange(of: viewModel.openRequest) { _, request in
                guard let request else { return }
                onOpen(request)
            }
            .navigationDestination(for: ProjectRoute.self) { route in
                ProjectDetailScreen(
                    viewModel: viewModel.makeDetailViewModel(path: route.path),
                    endpoint: viewModel.host.endpoint,
                    http: viewModel.http,
                    onOpenClaude: { viewModel.requestOpenClaude(cwd: $0) }
                )
            }
    }

    // MARK: - List

    private var list: some View {
        List {
            errorRows
            if let message = viewModel.emptyStateMessage {
                Text(message)
                    .foregroundStyle(.secondary)
                    .frame(maxWidth: .infinity, alignment: .center)
                    .listRowSeparator(.hidden)
            }
            ForEach(viewModel.groups) { group in
                groupSection(group)
            }
        }
        .listStyle(.insetGrouped)
        .overlay {
            if !viewModel.hasLoadedOnce && viewModel.fetchErrorMessage == nil {
                ProgressView()
            }
        }
    }

    /// 显式错误行（刷新失败留旧列表、prefs 失败降级本地 —— 都要可见）。
    @ViewBuilder private var errorRows: some View {
        ForEach(
            [
                viewModel.fetchErrorMessage,
                viewModel.prefsErrorMessage,
                viewModel.prefsSyncErrorMessage,
                viewModel.openErrorMessage,
            ].compactMap(\.self),
            id: \.self
        ) { message in
            Label(message, systemImage: "exclamationmark.triangle")
                .font(.footnote)
                .foregroundStyle(.orange)
                .listRowSeparator(.hidden)
        }
    }

    // MARK: - Group section（flat 无 chrome；namespace/other 可折叠）

    @ViewBuilder private func groupSection(_ group: ProjectGroup) -> some View {
        let isCollapsed = viewModel.isCollapsed(group)
        Section {
            if !isCollapsed {
                ForEach(group.projects, id: \.path) { project in
                    projectRow(project, group: group)
                }
            }
        } header: {
            if group.kind != .flat {
                groupHeader(group, isCollapsed: isCollapsed)
            }
        }
    }

    private func groupHeader(_ group: ProjectGroup, isCollapsed: Bool) -> some View {
        HStack(spacing: Metrics.chipSpacing) {
            if group.isCollapsible {
                Image(systemName: isCollapsed ? "chevron.right" : "chevron.down")
                    .font(.caption2)
            }
            // namespace label 来自服务器仓库名 → verbatim。
            Text(verbatim: group.label)
                .lineLimit(1)
            Text(verbatim: "\(group.projects.count)")
                .foregroundStyle(.secondary)
            // 折叠的分区绝不悄悄埋掉活跃会话（镜像 web 组头徽标）。
            if group.kind != .active && group.activeCount > 0 {
                Text(ProjectsCopy.activeCountBadge(group.activeCount))
                    .font(.caption2)
                    .foregroundStyle(.green)
            }
            Spacer(minLength: 0)
        }
        .contentShape(Rectangle())
        .onTapGesture {
            guard group.isCollapsible else { return }
            Task { await viewModel.toggleCollapsed(key: group.key) }
        }
        .accessibilityAddTraits(group.isCollapsible ? .isButton : [])
    }

    // MARK: - Project row

    private func projectRow(_ project: ProjectInfo, group: ProjectGroup) -> some View {
        NavigationLink(value: ProjectRoute(path: project.path)) {
            HStack(spacing: Metrics.chipSpacing) {
                favouriteButton(project)
                VStack(alignment: .leading, spacing: Metrics.rowSpacing) {
                    Text(verbatim: ProjectGrouping.displayLabel(
                        name: project.name, groupKey: group.key
                    ))
                    .font(.body.weight(.medium))
                    .lineLimit(1)
                    projectChips(project)
                }
                Spacer(minLength: 0)
                if ProjectGrouping.hasRunningSession(project) {
                    Image(systemName: "circle.fill")
                        .font(.caption2)
                        .foregroundStyle(.green)
                        .accessibilityLabel(ProjectsCopy.activeCountBadge(1))
                }
            }
        }
    }

    private func favouriteButton(_ project: ProjectInfo) -> some View {
        Button {
            Task { await viewModel.toggleFavourite(path: project.path) }
        } label: {
            Image(systemName: viewModel.isFavourite(project.path) ? "star.fill" : "star")
                .foregroundStyle(.yellow)
        }
        .buttonStyle(.borderless) // List 行内独立可点
    }

    @ViewBuilder private func projectChips(_ project: ProjectInfo) -> some View {
        HStack(spacing: Metrics.chipSpacing) {
            if let branch = project.branch {
                Label {
                    Text(verbatim: branch).lineLimit(1)
                } icon: {
                    Image(systemName: "arrow.triangle.branch")
                }
                .font(.caption)
                .foregroundStyle(.secondary)
            }
            if project.dirty == true {
                Text(ProjectsCopy.dirtyBadge)
                    .font(.caption2)
                    .foregroundStyle(.orange)
            }
        }
    }
}

/// 详情屏的 push 路由值（value-based navigation）。
struct ProjectRoute: Hashable {
    let path: String
}