import SwiftUI

struct InstanceGroupManagerView: View {
  @Environment(\.dismiss) private var dismiss
  @ObservedObject var model: FleetViewModel
  @State private var newName = ""
  @State private var editingGroup: InstanceGroup?
  @State private var editingName = ""
  @State private var validationMessage: String?
  @State private var isWorking = false
  @State private var pendingDelete: InstanceGroup?

  var body: some View {
    NavigationStack {
      ScrollView {
        LazyVStack(spacing: 12) {
          AICard {
            VStack(alignment: .leading, spacing: 10) {
              AIFieldLabel("新增分组")
              TextField("例如：家里、外场、测试机", text: $newName)
                .textFieldStyle(AIFieldStyle())
                .submitLabel(.done)
            }
          }

          if let validationMessage {
            AIStatusBanner(
              validationMessage,
              tint: AITheme.danger,
              systemImage: "exclamationmark.triangle"
            )
          }

          if model.groups.isEmpty {
            AICard {
              AIEmptyState(
                systemImage: "folder.badge.plus",
                title: "暂无分组",
                message: "创建分组后，实例可按业务或位置归类。"
              )
            }
          } else {
            ForEach(model.groups) { group in
              AICard {
                HStack(spacing: 12) {
                  Image(systemName: "folder")
                    .font(.subheadline.weight(.semibold))
                    .foregroundStyle(AITheme.primary)
                    .frame(width: 34, height: 34)
                    .background(AITheme.primary.opacity(0.1))
                    .clipShape(RoundedRectangle(cornerRadius: 11, style: .continuous))
                    .accessibilityHidden(true)

                  VStack(alignment: .leading, spacing: 3) {
                    Text(group.name)
                      .font(.subheadline.weight(.semibold))
                      .foregroundStyle(AITheme.ink)
                      .lineLimit(1)
                    Text("\(instanceCount(group.id)) 个实例")
                      .font(.caption)
                      .foregroundStyle(AITheme.muted)
                  }

                  Spacer()

                  AISymbolAction("重命名分组 \(group.name)", systemImage: "pencil", tint: AITheme.muted) {
                    editingGroup = group
                    editingName = group.name
                    validationMessage = nil
                  }

                  AISymbolAction("删除分组 \(group.name)", systemImage: "trash", tint: AITheme.danger) {
                    pendingDelete = group
                  }
                  .disabled(isWorking)
                }
              }
            }
          }
        }
        .padding(16)
        .padding(.bottom, 8)
      }
      .background(AITheme.canvas.ignoresSafeArea())
      .navigationTitle("分组管理")
      #if os(iOS)
        .navigationBarTitleDisplayMode(.inline)
      #endif
      .toolbar {
        ToolbarItem(placement: .cancellationAction) {
          Button("取消") { dismiss() }
        }
        ToolbarItem(placement: .confirmationAction) {
          Button("完成") { dismiss() }
        }
      }
      .aiBottomActionBar {
        AIActionRow {
          Button {
            Task { await create() }
          } label: {
            Label("创建分组", systemImage: "plus")
          }
          .buttonStyle(AIButtonStyle(kind: .primary, size: .regular, fillsWidth: true))
          .disabled(isWorking)
        }
      }
      .alert("编辑分组", isPresented: Binding(
        get: { editingGroup != nil },
        set: { if !$0 { editingGroup = nil } }
      )) {
        TextField("分组名称", text: $editingName)
        Button("保存") {
          Task { await saveEditing() }
        }
        Button("取消", role: .cancel) {}
      } message: {
        Text("分组名称最多 100 个字符。")
      }
      .confirmationDialog(
        pendingDelete == nil
          ? "删除分组？"
          : "删除「\(pendingDelete!.name)」？该分组下的 \(instanceCount(pendingDelete!.id)) 个实例会回到未分组。",
        isPresented: Binding(
          get: { pendingDelete != nil },
          set: { if !$0 { pendingDelete = nil } }
        ),
        titleVisibility: .visible
      ) {
        if let group = pendingDelete {
          Button("删除分组", role: .destructive) {
            Task { await delete(group) }
          }
        }
        Button("取消", role: .cancel) {}
      }
      .task {
        await model.loadGroups()
      }
    }
  }

  private func instanceCount(_ id: UUID) -> Int {
    model.rows.filter { $0.instance.groupId == id }.count
  }

  private func create() async {
    guard !isWorking else { return }
    isWorking = true
    validationMessage = nil
    do {
      try await model.createGroup(named: newName)
      newName = ""
    } catch {
      validationMessage = "创建失败，名称不能为空且不能重复。"
    }
    isWorking = false
  }

  private func saveEditing() async {
    guard let editingGroup else { return }
    isWorking = true
    validationMessage = nil
    do {
      try await model.updateGroup(editingGroup.id, name: editingName)
      self.editingGroup = nil
    } catch {
      validationMessage = "更新失败，名称不能为空且不能重复。"
    }
    isWorking = false
  }

  private func delete(_ group: InstanceGroup) async {
    guard !isWorking else { return }
    isWorking = true
    pendingDelete = nil
    do {
      try await model.deleteGroup(group.id)
    } catch {
      validationMessage = "删除失败，请稍后重试。"
    }
    isWorking = false
  }
}