import SwiftUI

struct MessagesView: View {
  @StateObject private var model: MessagesViewModel
  @State private var pendingDeleteMessage: SMSMessage?

  init(model: MessagesViewModel? = nil) {
    // StateObject 的 wrappedValue 是 autoclosure，在 init 里改它会写到另一个实例上，
    // 所以调试开关必须先落到这个具体的 model 对象。
    let target = model ?? DefaultContainer.makeMessagesModel()
    #if DEBUG
      if DebugLaunch.has("--sheet-send") {
        target.showingSendForm = true
      }
    #endif
    _model = StateObject(wrappedValue: target)
  }

  var body: some View {
    ScrollView {
        LazyVStack(spacing: 12) {
          filterBar
          if model.isLoading && model.filteredRows.isEmpty {
            AILoadingCard("正在同步消息数据")
          } else if model.filteredRows.isEmpty {
            AICard {
              if let errorMessage = model.errorMessage {
                AIEmptyState(
                  systemImage: "arrow.triangle.2.circlepath",
                  title: "未能读取消息",
                  message: errorMessage,
                  actionTitle: "重试"
                ) {
                  Task { await model.refresh() }
                }
              } else {
                AIEmptyState(
                  systemImage: "message",
                  title: "暂无消息",
                  message: "所有节点都没有返回短信。"
                )
              }
            }
          } else {
            if let errorMessage = model.errorMessage {
              AIStatusBanner(
                errorMessage, tint: AITheme.warning, systemImage: "exclamationmark.triangle")
            }
            ForEach(model.filteredRows) { message in
              messageCard(message)
            }
          }
        }
        .padding(16)
        .padding(.bottom, 8)
    }
    .background(AITheme.canvas.ignoresSafeArea())
    .navigationTitle("消息中心")
    .toolbar {
      // 发送入口和节点页的「添加实例」保持一致：放在导航栏右侧，
      // 底部固定条在 TabView 里会被自定义标签栏盖住，之前整条 CTA 是不可达的。
      ToolbarItem(placement: .primaryAction) {
        HStack(spacing: 8) {
          AIIconButton("刷新", systemImage: "arrow.clockwise") {
            Task { await model.refresh() }
          }
          .disabled(model.isLoading)
          AIIconButton("发送消息", systemImage: "paperplane") {
            model.showingSendForm = true
          }
        }
      }
    }
    .confirmationDialog(
      "删除这条消息？操作不可恢复。",
      isPresented: Binding(
        get: { pendingDeleteMessage != nil },
        set: { if !$0 { pendingDeleteMessage = nil } }
      ),
      titleVisibility: .visible
    ) {
      Button("删除消息", role: .destructive) {
        guard let message = pendingDeleteMessage else { return }
        Task { await model.delete(message) }
      }
      Button("取消", role: .cancel) {}
    }
    .refreshable {
      await model.refresh()
    }
    .task {
      await model.refresh()
    }
    .sheet(isPresented: $model.showingSendForm) {
      SendMessageFormView(model: model)
    }
  }

  private var filterBar: some View {
    VStack(spacing: 8) {
      AISegmentedControl(
        "消息方向",
        selection: $model.direction,
        options: MessagesViewModel.DirectionFilter.allCases.map {
          (value: $0, title: $0.rawValue)
        }
      )

      Picker("实例", selection: $model.selectedInstanceID) {
        Text("全部实例").tag(Optional<UUID>.none)
        ForEach(model.instances) { instance in
          Text(instance.name).tag(Optional(instance.id))
        }
      }
      .pickerStyle(.menu)
      .aiSelectSurface(compact: true)
      // 选择器右侧原本是一整片空白，这里补上当前条数，让这一行读完就知道结果规模。
      .overlay(alignment: .trailing) {
        Text("\(model.filteredRows.count) 条")
          .font(.caption.weight(.medium))
          .monospacedDigit()
          .foregroundStyle(AITheme.muted)
          .padding(.trailing, 12)
          .accessibilityHidden(true)
      }

      AISearchField("搜索号码或内容", text: $model.searchText, minHeight: AITheme.compactControlHeight)
    }
  }


  private func messageCard(_ message: SMSMessage) -> some View {
    AICard(padding: 14) {
      VStack(alignment: .leading, spacing: 8) {
        HStack(alignment: .firstTextBaseline, spacing: 8) {
          Text(message.phoneNumber.isEmpty ? "未知号码" : message.phoneNumber)
            .font(.subheadline.weight(.semibold))
            .foregroundStyle(AITheme.ink)
            .lineLimit(1)
            .truncationMode(.middle)
            .layoutPriority(1)
          AITag(
            message.direction.label,
            systemImage: message.direction == .outgoing ? "arrow.up.right" : "arrow.down.left")
          Spacer(minLength: 8)
          Text(TimestampText.short(message.timestamp))
            .font(.caption2.weight(.medium))
            .monospacedDigit()
            .foregroundStyle(AITheme.faint)
            .lineLimit(1)
            .accessibilityLabel("时间 \(message.timestamp)")
        }
        Text(message.content)
          .font(.subheadline)
          .foregroundStyle(AITheme.ink)
          .lineSpacing(2)
          .fixedSize(horizontal: false, vertical: true)
        // 删除按钮的点击区是 44pt，留在行内会把这一行撑到 44 高，正文与落款之间
        // 因此凭空多出一条约 22pt 的空带。这里让落款按自身高度排，点击区挂在
        // 行尾并垂直居中，多出的 12pt 落进卡片内边距，正文右缘留出等宽避让。
        HStack(alignment: .center, spacing: 8) {
          Label(message.instanceName, systemImage: "antenna.radiowaves.left.and.right")
            .font(.caption)
            .labelStyle(.titleAndIcon)
            .imageScale(.small)
            .foregroundStyle(AITheme.muted)
            .lineLimit(1)
            .truncationMode(.middle)
            .layoutPriority(1)
          if let delivery = message.deliveryLabel {
            Text(delivery)
              .font(.caption2.weight(.medium))
              .foregroundStyle(delivery == "发送失败" ? AITheme.danger : AITheme.faint)
              .lineLimit(1)
          }
        }
        .padding(.trailing, 44)
        .frame(maxWidth: .infinity, alignment: .leading)
        .overlay(alignment: .trailing) {
          AISymbolAction("删除这条消息", systemImage: "trash", tint: AITheme.danger, quiet: true) {
            pendingDeleteMessage = message
          }
          // 图标在 44pt 点击区里居中，右移半个内边距让图标右缘与正文右缘对齐。
          .offset(x: 12)
        }
      }
    }
  }
}