import SwiftUI

struct NotificationsView: View {
  @StateObject private var model: NotificationsViewModel
  @State private var pendingDeleteQueueID: String?
  private static let timestampFormatter = ISO8601DateFormatter()
  private static let fractionalTimestampFormatter: ISO8601DateFormatter = {
    let formatter = ISO8601DateFormatter()
    formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
    return formatter
  }()

  init(model: NotificationsViewModel? = nil) {
    _model = StateObject(wrappedValue: model ?? DefaultContainer.makeNotificationsModel())
  }

  var body: some View {
    ScrollView {
        LazyVStack(spacing: 12) {
          if let actionMessage = model.actionMessage {
            AIStatusBanner(
              actionMessage,
              tint: model.actionSucceeded ? AITheme.success : AITheme.danger,
              systemImage: model.actionSucceeded ? "checkmark.circle" : "exclamationmark.triangle"
            )
          }
          if let errorMessage = model.errorMessage {
            AIStatusBanner(
              errorMessage, tint: AITheme.danger, systemImage: "exclamationmark.triangle")
          }

          if let overview = model.overview {
            stats(overview)
            queue(overview)
            channels(overview)
            logs(overview)
            devices(overview)
          } else if model.isLoading {
            AILoadingCard("正在加载通知中心")
          } else {
            empty
          }
        }
        .padding(16)
        .padding(.bottom, 8)
    }
    .aiBottomActionBar {
        Button {
          Task { await model.retryAll() }
        } label: {
          HStack(spacing: 8) {
            if model.isRetryingAll {
              ProgressView()
                .controlSize(.small)
            }
            Text(
              model.isRetryingAll
                ? "投递中"
                : (model.overview?.queue.total == 0 ? "暂无待投递" : "立即投递")
            )
          }
        }
        .buttonStyle(AIButtonStyle(kind: .primary, size: .regular, fillsWidth: true))
        .disabled(model.isLoading || model.isRetryingAll || model.overview?.queue.total == 0)
    }
    .background(AITheme.canvas.ignoresSafeArea())
    .navigationTitle("通知中心")
    .confirmationDialog(
      "删除这条通知队列记录？操作不可恢复。",
      isPresented: Binding(
        get: { pendingDeleteQueueID != nil },
        set: { if !$0 { pendingDeleteQueueID = nil } }
      ),
      titleVisibility: .visible
    ) {
      Button("删除队列记录", role: .destructive) {
        guard let id = pendingDeleteQueueID else { return }
        Task {
          if let item = model.overview?.queue.items.first(where: { $0.id == id }) {
            await model.deleteQueue(item)
          }
        }
      }
      Button("取消", role: .cancel) {}
    }
    .refreshable {
      await model.refresh()
    }
    .task {
      await model.refresh()
    }
  }

  private var empty: some View {
    AICard {
      AIEmptyState(
        systemImage: "bell",
        title: "暂无通知数据",
        message: "下拉刷新后从已配置实例同步。"
      )
    }
  }

  private func stats(_ overview: NotificationOverview) -> some View {
    LazyVGrid(columns: [GridItem(.flexible()), GridItem(.flexible())], spacing: 12) {
      AIStatCard(
        title: "通道",
        value: "\(overview.config.channelEnabled)/\(overview.config.channelCount)",
        detail: "已启用 / 总数",
        tint: AITheme.primary
      )
      AIStatCard(
        title: "规则",
        value: "\(overview.config.ruleEnabled)/\(overview.config.ruleCount)",
        detail: "已启用 / 总数",
        tint: AITheme.primary
      )
      AIStatCard(
        title: "队列",
        value: "\(overview.queue.pending + overview.queue.retrying)",
        detail: "等待与重试",
        tint: AITheme.warning
      )
      AIStatCard(
        title: "失败",
        value: "\(overview.queue.failed + overview.logs.failed)",
        detail: "队列与投递",
        tint: AITheme.danger
      )
    }
  }

  private func devices(_ overview: NotificationOverview) -> some View {
    VStack(alignment: .leading, spacing: 10) {
      AISectionTitle("实例状态", systemImage: "server.rack", detail: "\(overview.devices.count) 个")
      if overview.devices.isEmpty {
        AICard {
          AIEmptyState(
            systemImage: "server.rack", title: "尚未添加实例", message: "先在节点总览中配置 SimAdmin 实例。")
        }
      } else {
        ForEach(overview.devices) { device in
          AIListCard(
            title: device.name,
            status: deviceState(device.state),
            statusTint: deviceTint(device.state)
          )
        }
      }
    }
  }

  private func channels(_ overview: NotificationOverview) -> some View {
    VStack(alignment: .leading, spacing: 10) {
      AISectionTitle(
        "通道类型", systemImage: "square.stack.3d.up", detail: "\(overview.config.channelTypes.count) 类"
      )
      if overview.config.channelTypes.isEmpty {
        AICard {
          AIEmptyState(
            systemImage: "square.stack.3d.up", title: "未配置通知通道", message: "实例侧启用通知通道后会在这里显示。")
        }
      } else {
        ForEach(overview.config.channelTypes) { channel in
          AIListCard(
            title: channelTypeLabel(channel.type),
            status: "\(channel.enabled)/\(channel.total)",
            statusTint: channel.enabled > 0 ? AITheme.success : AITheme.muted
          )
        }
      }
    }
  }

  private func queue(_ overview: NotificationOverview) -> some View {
    VStack(alignment: .leading, spacing: 10) {
      AISectionTitle("投递队列", systemImage: "tray.full", detail: "\(overview.queue.total) 项")
      if overview.queue.items.isEmpty {
        AICard {
          AIEmptyState(
            systemImage: "tray.full",
            title: "投递队列为空",
            message: "新通知触发后会在这里等待投递。"
          )
        }
      } else {
        ForEach(overview.queue.items) { item in
          AIListCard(
            title: eventTypeLabel(item.eventType),
            subtitle: "\(item.instanceName) · \(timestampText(item.createdAt))",
            status: statusLabel(item.status),
            statusTint: statusTint(item.status)
          ) {
            HStack(spacing: 8) {
              Button {
                Task { await model.retryQueue(item) }
              } label: {
                Label("重试", systemImage: "arrow.clockwise")
              }
              .buttonStyle(
                AIButtonStyle(kind: .secondary, size: .compact, fillsWidth: true)
              )
              .disabled(model.busyQueueID != nil)

              Button {
                pendingDeleteQueueID = item.id
              } label: {
                Label("删除", systemImage: "trash")
              }
              .buttonStyle(AIButtonStyle(kind: .danger, size: .compact, fillsWidth: true))
              .disabled(model.busyQueueID != nil)
            }
          }
        }
      }
    }
  }

  private func logs(_ overview: NotificationOverview) -> some View {
    VStack(alignment: .leading, spacing: 10) {
      AISectionTitle(
        "投递日志", systemImage: "clock.arrow.circlepath", detail: "\(overview.logs.total) 条")
      if overview.logs.entries.isEmpty {
        AICard {
          AIEmptyState(
            systemImage: "clock.arrow.circlepath",
            title: "暂无投递日志",
            message: "通知送达或失败后会在这里记录。"
          )
        }
      } else {
        ForEach(overview.logs.entries) { entry in
          AIListCard(
            title: eventTypeLabel(entry.eventType),
            subtitle: "\(entry.channelName ?? "未指定通道") · \(timestampText(entry.createdAt))",
            status: statusLabel(entry.status),
            statusTint: statusTint(entry.status)
          )
        }
      }
    }
  }

  private func timestampText(_ value: String) -> String {
    let date =
      Self.fractionalTimestampFormatter.date(from: value)
      ?? Self.timestampFormatter.date(from: value)
    guard let date else { return value }
    return date.formatted(
      Date.FormatStyle(date: .numeric, time: .shortened)
        .locale(Locale(identifier: "zh_CN"))
    )
  }

  private func deviceState(_ state: NotificationDeviceState) -> String {
    switch state {
    case .ready: return "在线"
    case .unauthorized: return "需登录"
    case .unavailable: return "离线"
    case .failed: return "异常"
    }
  }

  private func deviceTint(_ state: NotificationDeviceState) -> Color {
    switch state {
    case .ready: return AITheme.success
    case .unauthorized: return AITheme.warning
    case .unavailable: return AITheme.muted
    case .failed: return AITheme.danger
    }
  }

  private func channelTypeLabel(_ type: String) -> String {
    switch type {
    case "webhook": return "Webhook"
    case "bark": return "Bark"
    case "pushplus": return "PushPlus"
    case "wecom_app": return "企业微信应用"
    case "wecom_robot": return "企业微信机器人"
    case "dingtalk_robot": return "钉钉机器人"
    case "dingtalk_app": return "钉钉应用"
    case "feishu_robot": return "飞书机器人"
    case "telegram": return "Telegram"
    case "email": return "邮件"
    case "serverchan": return "Server 酱"
    default: return type
    }
  }

  private func eventTypeLabel(_ value: String) -> String {
    switch value {
    case "sms": return "短信"
    case "ddns": return "DDNS"
    case "version": return "版本"
    case "system": return "系统"
    case "device": return "设备"
    case "automation": return "自动化"
    default: return value
    }
  }

  private func statusLabel(_ value: String) -> String {
    switch value {
    case "success", "succeeded": return "成功"
    case "failed": return "失败"
    case "pending": return "等待"
    case "sending": return "发送中"
    case "retrying": return "重试中"
    case "cancelled": return "已取消"
    case "unmatched": return "未匹配"
    case "no_available_channel": return "无可用通道"
    case "quiet_hours": return "免打扰"
    default: return value
    }
  }

  private func statusTint(_ value: String) -> Color {
    switch value {
    case "success", "succeeded": return AITheme.success
    case "pending", "sending", "retrying": return AITheme.warning
    case "failed": return AITheme.danger
    default: return AITheme.muted
    }
  }
}