import Foundation
import UIKit

@MainActor
final class ShareViewModel: ObservableObject {
  @Published var title = ""
  @Published var previewText = ""
  @Published var previewImage: UIImage?
  @Published var isLoading = true
  @Published var isSaving = false
  @Published var hasSaved = false
  @Published var errorMessage: String?

  var actionTitle: String {
    "Open AFFiNE"
  }

  var canSave: Bool {
    !isLoading
      && !isSaving
      && !title.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
      && draft?.content != nil
  }

  private var draft: SharePayloadDraft?
  private let store: ShareInboxStore

  init(store: ShareInboxStore = .shared) {
    self.store = store
  }

  func load(from extensionContext: NSExtensionContext?) async {
    isLoading = true
    defer { isLoading = false }

    let items = extensionContext?.inputItems.compactMap { $0 as? NSExtensionItem } ?? []
    let built = await SharePayloadBuilder.build(from: items)
    draft = built
    title = built.title
    previewText = built.previewText
    errorMessage = built.errorMessage
    if let file = built.file {
      previewImage = UIImage(data: file.data)?
        .preparingThumbnail(of: CGSize(width: 480, height: 480))
    }
  }

  func save() async -> Bool {
    guard !isSaving, !hasSaved else { return false }
    isSaving = true
    defer { isSaving = false }

    let trimmedTitle = title.trimmingCharacters(in: .whitespacesAndNewlines)
    guard !trimmedTitle.isEmpty else {
      errorMessage = "Title is required."
      return false
    }
    guard let draft, let content = draft.content else {
      errorMessage = draft?.errorMessage ?? "Nothing to share."
      return false
    }

    let itemId = UUID().uuidString
    var attachments: [ShareInboxAttachment] = []
    var attachmentData: [(ShareInboxAttachment, Data)] = []
    if let file = draft.file {
      let attachment = ShareInboxAttachment(
        fileName: file.fileName,
        mimeType: file.mimeType,
        relativePath: "\(itemId)/\(file.fileName)"
      )
      attachments = [attachment]
      attachmentData = [(attachment, file.data)]
    }

    let item = ShareInboxItem(
      id: itemId,
      title: trimmedTitle,
      content: content,
      previewText: draft.previewText,
      attachments: attachments
    )

    do {
      try store.enqueue(item, attachmentData: attachmentData)
      hasSaved = true
      return true
    } catch {
      errorMessage = "Failed to save shared content."
      return false
    }
  }
}