import Foundation

@MainActor
final class NotificationsViewModel: ObservableObject {
  @Published private(set) var overview: NotificationOverview?
  @Published private(set) var instances: [Instance] = []
  @Published private(set) var isLoading = false
  @Published var errorMessage: String?
  @Published private(set) var actionMessage: String?
  @Published private(set) var actionSucceeded = true
  @Published private(set) var busyQueueID: String?
  @Published private(set) var isRetryingAll = false

  private let repository: any InstanceRepository
  private let service: NotificationService

  init(repository: any InstanceRepository, service: NotificationService) {
    self.repository = repository
    self.service = service
  }

  func refresh() async {
    isLoading = true
    errorMessage = nil
    do {
      let loaded = try await repository.list(InstanceQuery())
      instances = loaded
      overview = try await service.overview(loaded)
    } catch {
      errorMessage = "无法加载通知中心。"
    }
    isLoading = false
  }

  func retryAll() async {
    guard !isRetryingAll && !isLoading else { return }
    isRetryingAll = true
    let result = await service.retryAll(instances)
    actionSucceeded = result.succeeded > 0
    if result.succeeded > 0 {
      actionMessage = "已提交全部队列重试，成功 \(result.succeeded) 个实例。"
    } else if result.skipped > 0 {
      actionMessage = "没有可重试的队列接口。"
    } else {
      actionMessage = "队列重试失败。"
    }
    await refresh()
    isRetryingAll = false
  }

  func retryQueue(_ item: NotificationQueueEntry) async {
    await queueAction(item) { instance, id in
      try await self.service.retryQueue(instance, id: id)
    }
  }

  func deleteQueue(_ item: NotificationQueueEntry) async {
    await queueAction(item) { instance, id in
      try await self.service.deleteQueueItem(instance, id: id)
    }
    await refresh()
  }

  private func queueAction(
    _ item: NotificationQueueEntry,
    action: (Instance, String) async throws -> Void
  ) async {
    guard let instance = instances.first(where: { $0.id == item.instanceID }) else {
      errorMessage = "找不到队列所属实例。"
      return
    }
    busyQueueID = item.id
    do {
      try await action(instance, item.id)
      actionMessage = "队列操作已完成。"
      actionSucceeded = true
      errorMessage = nil
    } catch {
      errorMessage = "队列操作失败。"
      actionSucceeded = false
    }
    busyQueueID = nil
  }
}