import SwiftUI

/// 批量归类：点一个分组就把目标实例移进去并立即生效，不再需要二次“保存”。
struct InstanceGroupEditorView: View {
  @Environment(\.dismiss) private var dismiss
  @ObservedObject var model: FleetViewModel
  let targetIDs: [UUID]
  let onSaved: () -> Void

  @State private var isCreatingGroup = false
  @State private var newGroupName = ""
  @State private var isWorking = false
  @State private var errorMessage: String?

  private var targets: [UUID] {
    targetIDs.isEmpty ? model.visibleRows.map(\.id) : targetIDs
  }

  private var targetGroupIDs: [UUID?] {
    let owner = Dictionary(model.rows.map { ($0.id, $0.instance.groupId) }, uniquingKeysWith: { a, _ in a })
    return targets.compactMap { owner[$0] }
  }

  /// 目标实例当前是否同属一个分组；nil 表示 mixed，不显示对勾。
  private var uniformGroup: UUID?? {
    guard let first = targetGroupIDs.first else { return nil }
    return targetGroupIDs.allSatisfy { $0 == first } ? .some(first) : nil
  }

  private var trimmedName: String {
    newGroupName.trimmingCharacters(in: .whitespacesAndNewlines)
  }

  var body: some View {
    NavigationStack {
      ScrollView {
        LazyVStack(spacing: 12) {
          if let errorMessage {
            AIStatusBanner(
              errorMessage,
              tint: AITheme.danger,
              systemImage: "exclamationmark.triangle"
            )
          }

          AISectionTitle(
            "移动到",
            systemImage: "folder",
            detail: "\(targets.count) 台实例"
          )

          if isCreatingGroup {
            AICard(padding: 16) {
              VStack(alignment: .leading, spacing: 12) {
                AIFieldLabel("新分组名称")
                TextField("例如：家里、外场、测试机", text: $newGroupName)
                  .textFieldStyle(AIFieldStyle())
                  .submitLabel(.done)
                  .onSubmit { Task { await createAndAssign() } }
                AIActionRow(spacing: 8) {
                  Button("取消") {
                    isCreatingGroup = false
                    newGroupName = ""
                    errorMessage = nil
                  }
                  .buttonStyle(AIButtonStyle(kind: .secondary, size: .regular, fillsWidth: true))
                  .disabled(isWorking)

                  Button {
                    Task { await createAndAssign() }
                  } label: {
                    Label("创建并移入", systemImage: "folder.badge.plus")
                  }
                  .buttonStyle(AIButtonStyle(kind: .primary, size: .regular, fillsWidth: true))
                  .disabled(trimmedName.isEmpty || isWorking)
                }
              }
            }
          }

          AICard(padding: 8) {
            VStack(spacing: 2) {
              groupRow(
                title: "未分组",
                subtitle: "不归属任何分组",
                systemImage: "square.dashed",
                groupID: nil
              )

              ForEach(model.groups) { group in
                Divider()
                  .overlay(AITheme.line.opacity(0.55))
                groupRow(
                  title: group.name,
                  subtitle: "\(instanceCount(group.id)) 台在此",
                  systemImage: "folder",
                  groupID: group.id
                )
              }
            }
          }
          .opacity(isWorking ? 0.55 : 1)
        }
        .padding(16)
      }
      .background(AITheme.canvas.ignoresSafeArea())
      .navigationTitle("实例分组")
      #if os(iOS)
        .navigationBarTitleDisplayMode(.inline)
      #endif
      .toolbar {
        ToolbarItem(placement: .cancellationAction) {
          Button("取消") { dismiss() }
        }
        ToolbarItem(placement: .primaryAction) {
          AIIconButton("新建分组", systemImage: "plus") {
            errorMessage = nil
            isCreatingGroup = true
          }
          .disabled(isWorking)
        }
      }
    }
  }

  private func groupRow(
    title: String,
    subtitle: String,
    systemImage: String,
    groupID: UUID?
  ) -> some View {
    Button {
      guard uniformGroup != groupID else {
        dismiss()
        return
      }
      Task { await apply(groupID: groupID) }
    } label: {
      HStack(spacing: 12) {
        Image(systemName: systemImage)
          .font(.subheadline.weight(.semibold))
          .foregroundStyle(isCurrent(groupID) ? AITheme.primary : AITheme.muted)
          .frame(width: 32, height: 32)
          .background((isCurrent(groupID) ? AITheme.primary : AITheme.muted).opacity(0.10))
          .clipShape(RoundedRectangle(cornerRadius: 10, style: .continuous))
          .overlay {
            // 深色下 10% 色洗几乎看不出边界，补一圈同色淡描边保住方块轮廓。
            RoundedRectangle(cornerRadius: 10, style: .continuous)
              .strokeBorder((isCurrent(groupID) ? AITheme.primary : AITheme.muted).opacity(0.20))
          }
          .accessibilityHidden(true)

        VStack(alignment: .leading, spacing: 2) {
          Text(title)
            .font(.subheadline.weight(.semibold))
            .foregroundStyle(AITheme.ink)
            .lineLimit(1)
          Text(subtitle)
            .font(.caption)
            .foregroundStyle(AITheme.muted)
            .lineLimit(1)
        }

        Spacer(minLength: 8)

        Group {
          if isWorking {
            EmptyView()
          } else if isCurrent(groupID) {
            Image(systemName: "checkmark")
              .font(.system(size: 14, weight: .bold))
              .foregroundStyle(AITheme.primary)
          }
        }
        .frame(width: 20, alignment: .trailing)
      }
      .padding(.horizontal, 12)
      .padding(.vertical, 8)
      .frame(minHeight: 54)
      .clipShape(RoundedRectangle(cornerRadius: 12, style: .continuous))
      .contentShape(Rectangle())
      .accessibilityElement(children: .combine)
      .accessibilityLabel(isCurrent(groupID) ? "\(title)，当前分组" : "移动到\(title)")
      .accessibilityAddTraits(.isButton)
    }
    .buttonStyle(.plain)
    .disabled(isWorking)
  }

  private func isCurrent(_ groupID: UUID?) -> Bool {
    uniformGroup == groupID && targetGroupIDs.isEmpty == false
  }

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

  private func apply(groupID: UUID?) async {
    guard !isWorking else { return }
    isWorking = true
    errorMessage = nil
    do {
      try await model.assign(groupID: groupID, to: targets)
      onSaved()
      dismiss()
    } catch {
      errorMessage = "分组保存失败，请重试。"
      isWorking = false
    }
  }

  private func createAndAssign() async {
    guard !isWorking, trimmedName.isEmpty == false else { return }
    isWorking = true
    errorMessage = nil
    do {
      let group = try await model.createGroup(named: trimmedName)
      try await model.assign(groupID: group.id, to: targets)
      onSaved()
      dismiss()
    } catch {
      errorMessage = "创建分组失败，名称不能为空且不能重复。"
      isWorking = false
    }
  }
}