import SwiftUI

struct InstanceFormView: View {
  @Environment(\.dismiss) private var dismiss
  @ObservedObject var model: FleetViewModel
  let instance: Instance?
  @State private var name = ""
  @State private var originText = ""
  @State private var tags: [String] = []
  @State private var tagDraft = ""
  @State private var password = ""
  @State private var selectedGroupId: UUID?
  @State private var validationMessage: String?
  @State private var isSaving = false

  init(model: FleetViewModel, instance: Instance? = nil) {
    self.model = model
    self.instance = instance
    _name = State(initialValue: instance?.name ?? "")
    _originText = State(initialValue: instance?.origin.absoluteString ?? "")
    _tags = State(initialValue: instance?.tags ?? [])
    _selectedGroupId = State(initialValue: instance?.groupId)
  }

  private var canSave: Bool {
    !name.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
      && !originText.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
  }

  var body: some View {
    NavigationStack {
      ScrollView {
        VStack(spacing: 12) {
          AICard {
            VStack(alignment: .leading, spacing: 14) {
              field("名称", text: $name, placeholder: "Home Node")
              field("地址", text: $originText, placeholder: "http://192.168.1.10:3000")
              tagEditor
              groupPicker
              field(
                "实例密码",
                text: $password,
                placeholder: instance == nil ? "可选，仅保存在本机" : "留空则不修改密码",
                secure: true
              )
            }
          }
          if let validationMessage {
            AIStatusBanner(
              validationMessage, tint: AITheme.danger, systemImage: "exclamationmark.triangle")
          }
        }
        .padding(16)
        .padding(.bottom, 8)
      }
      .aiBottomActionBar {
        AIActionRow {
          Button("取消") { dismiss() }
            .buttonStyle(AIButtonStyle(kind: .secondary, size: .regular, fillsWidth: true))

          Button {
            save()
          } label: {
            HStack(spacing: 8) {
              if isSaving {
                ProgressView()
                  .controlSize(.small)
              }
              Text(isSaving ? "保存中" : "保存实例")
            }
          }
          .buttonStyle(AIButtonStyle(kind: .primary, size: .regular, fillsWidth: true))
          .disabled(!canSave || isSaving)
        }
      }
      .background(AITheme.canvas.ignoresSafeArea())
      .navigationTitle(instance == nil ? "添加实例" : "编辑实例")
      #if os(iOS)
        .scrollDismissesKeyboard(.interactively)
      #endif
    }
  }

  private var groupPicker: some View {
    VStack(alignment: .leading, spacing: 8) {
      HStack(spacing: 8) {
        AIFieldLabel("分组")
        Spacer()
        Button {
          model.showingGroupManager = true
        } label: {
          Label("管理", systemImage: "folder.badge.gearshape")
        }
        .buttonStyle(AIButtonStyle(kind: .secondary, size: .toolbarInline, fixedWidth: 72))
      }
      Picker("分组", selection: $selectedGroupId) {
        Text("未分组").tag(UUID?.none)
        ForEach(model.groups) { group in
          Text(group.name).tag(UUID?.some(group.id))
        }
      }
      .pickerStyle(.menu)
      .aiSelectSurface()
    }
    .accessibilityElement(children: .contain)
  }

  private var tagEditor: some View {
    VStack(alignment: .leading, spacing: 6) {
      AIFieldLabel("标签")
      TagEditorView(tags: $tags, suggestions: model.allTags)
    }
    .accessibilityElement(children: .contain)
  }

  private func field(
    _ title: String,
    text: Binding<String>,
    placeholder: String,
    secure: Bool = false
  ) -> some View {
    VStack(alignment: .leading, spacing: 6) {
      AIFieldLabel(title)
      if secure {
        SecureField(placeholder, text: text)
          .textFieldStyle(AIFieldStyle())
          .textContentType(.password)
          .accessibilityLabel(title)
      } else {
        TextField(placeholder, text: text)
          .textFieldStyle(AIFieldStyle())
          .accessibilityLabel(title)
          .submitLabel(.done)
          #if os(iOS)
            .keyboardType(title == "地址" ? .URL : .default)
            .textInputAutocapitalization(.never)
          #endif
          .autocorrectionDisabled()
      }
    }
  }

  private func save() {
    guard !isSaving else { return }
    isSaving = true
    let normalizedName = name.trimmingCharacters(in: .whitespacesAndNewlines)
    guard let origin = URL(string: originText.trimmingCharacters(in: .whitespacesAndNewlines)),
      origin.scheme == "http" || origin.scheme == "https",
      origin.host != nil
    else {
      validationMessage = "请输入有效的 HTTP 或 HTTPS 根地址。"
      isSaving = false
      return
    }
    let input = InstanceInput(
      name: normalizedName,
      origin: origin,
      tags: tags,
      groupId: selectedGroupId,
      password: password.isEmpty ? nil : password
    )
    Task {
      do {
        if let instance {
          try await model.update(instance.id, input)
        } else {
          try await model.add(input)
        }
      } catch {
        validationMessage = "保存失败，请检查地址是否重复。"
      }
      isSaving = false
    }
  }
}