import SwiftUI

struct FleetView: View {
  @StateObject private var model: FleetViewModel
  @State private var showsDeleteDialog = false

  init(model: FleetViewModel? = nil) {
    _model = StateObject(wrappedValue: model ?? DefaultContainer.makeFleetModel())
  }

  var body: some View {
    ScrollView {
        LazyVStack(spacing: 12) {
          searchField
          if let errorMessage = model.errorMessage {
            AIStatusBanner(
              errorMessage,
              tint: AITheme.danger,
              systemImage: "exclamationmark.triangle"
            )
          }
          if model.selectionMode {
            selectionBar
          }
          if model.isLoading && model.rows.isEmpty {
            AILoadingCard("正在同步实例数据")
          }
          if model.rows.isEmpty && !model.isLoading {
            AICard {
              AIEmptyState(
                systemImage: "server.rack",
                title: "暂无实例",
                message: "添加 SimAdmin 实例后即可开始管理。"
              )
            }
          }
          ForEach(model.rows) { row in
            if model.selectionMode {
              instanceCard(row)
            } else {
              NavigationLink {
                InstanceDetailView(instance: row.instance)
              } label: {
                instanceCard(row)
              }
              .buttonStyle(.plain)
            }
          }
        }
        .padding(16)
        .padding(.bottom, 8)
    }
    .aiBottomActionBar {
        if !model.selectionMode {
          AIActionRow {
            Button {
              model.selectionMode = true
            } label: {
              Label("批量选择", systemImage: "checklist")
            }
            .buttonStyle(AIButtonStyle(kind: .secondary, size: .regular, fillsWidth: true))

            Button {
              model.showingForm = true
            } label: {
              Label("添加实例", systemImage: "plus")
            }
            .buttonStyle(AIButtonStyle(kind: .primary, size: .regular, fillsWidth: true))
          }
        } else {
          AIActionRow {
            Button {
              model.selectionMode = false
              model.selectedIDs.removeAll()
            } label: {
              Label("取消选择", systemImage: "xmark.circle")
            }
            .buttonStyle(AIButtonStyle(kind: .secondary, size: .regular, fillsWidth: true))

            Button {
              showsDeleteDialog = true
            } label: {
              Label(
                model.selectedIDs.isEmpty ? "删除" : "删除 \(model.selectedIDs.count)",
                systemImage: "trash"
              )
            }
            .buttonStyle(AIButtonStyle(kind: .danger, size: .regular, fillsWidth: true))
            .disabled(model.selectedIDs.isEmpty)
          }
        }
    }
    .background(AITheme.canvas.ignoresSafeArea())
    .navigationTitle("节点总览")
    .confirmationDialog(
      "删除已选实例？登录信息也会一并清除。",
      isPresented: $showsDeleteDialog,
      titleVisibility: .visible
    ) {
      Button("删除 \(model.selectedIDs.count) 个实例", role: .destructive) {
        Task { await model.deleteSelected() }
      }
      Button("取消", role: .cancel) {}
    }
    .refreshable {
      await model.refresh()
    }
    .task {
      await model.refresh()
    }
    .sheet(isPresented: $model.showingForm) {
      InstanceFormView(model: model)
    }
  }

  private var searchField: some View {
    AISearchField("搜索实例或地址", text: $model.searchText) {
      Task { await model.refresh() }
    }
  }

  private var selectionBar: some View {
    AICard {
      HStack(spacing: 10) {
        Button {
          if model.selectedIDs.count == model.rows.count {
            model.selectedIDs.removeAll()
          } else {
            model.selectedIDs = Set(model.rows.map(\.id))
          }
        } label: {
          Label(
            model.selectedIDs.count == model.rows.count ? "取消全选" : "全选",
            systemImage: "checkmark.circle"
          )
        }
        .buttonStyle(
          AIButtonStyle(
            kind: .secondary,
            size: .regular,
            fixedWidth: 96
          )
        )

        Spacer()

        Text("已选 \(model.selectedIDs.count)")
          .font(.subheadline.weight(.semibold))
          .foregroundStyle(AITheme.muted)
      }
    }
  }

  private func instanceCard(_ row: FleetViewModel.Row) -> some View {
    AICard {
      HStack(alignment: .top, spacing: 12) {
        if model.selectionMode {
          Button {
            toggle(row.id)
          } label: {
            Image(
              systemName: model.selectedIDs.contains(row.id)
                ? "checkmark.circle.fill" : "circle"
            )
            .font(.system(size: 20))
            .foregroundStyle(model.selectedIDs.contains(row.id) ? AITheme.primary : AITheme.muted)
          }
          .buttonStyle(.plain)
          .frame(width: 44, height: 44)
          .accessibilityLabel(model.selectedIDs.contains(row.id) ? "取消选择" : "选择")
          .accessibilityAddTraits(model.selectedIDs.contains(row.id) ? .isSelected : [])
        }
        VStack(alignment: .leading, spacing: 8) {
          HStack(spacing: 8) {
            Text(row.instance.name)
              .font(.headline)
              .foregroundStyle(AITheme.ink)
              .lineLimit(1)
              .truncationMode(.middle)
              .layoutPriority(1)
            Spacer()
            AITag(row.status.label, tint: statusColor(row.status))
          }
          Text(row.instance.origin.absoluteString)
            .font(.subheadline)
            .foregroundStyle(AITheme.muted)
            .lineLimit(1)
            .truncationMode(.middle)
          if !row.instance.tags.isEmpty {
            HStack(spacing: 6) {
              ForEach(row.instance.tags, id: \.self) { tag in
                AITag(tag)
              }
            }
          }
        }
      }
    }
  }

  private func statusColor(_ status: ConnectionStatus) -> Color {
    switch status {
    case .online: return AITheme.success
    case .offline: return AITheme.danger
    case .authRequired: return AITheme.warning
    case .degraded: return AITheme.warning
    case .unknown: return AITheme.muted
    }
  }

  private func toggle(_ id: UUID) {
    if model.selectedIDs.contains(id) {
      model.selectedIDs.remove(id)
    } else {
      model.selectedIDs.insert(id)
    }
  }
}