import Foundation

/// State management for the App Clip card display and save flow.
@MainActor
@Observable
final class ClipCardStore {

    enum State {
        case loading
        case loaded(SharedCardSnapshot)
        case saved
        case error(String)
    }

    private let cloudKit: ClipCloudKitService
    private let contactSave: ContactSaveService

    var state: State = .loading

    /// The currently loaded card snapshot, if any.
    var snapshot: SharedCardSnapshot? {
        if case .loaded(let snap) = state { return snap }
        return nil
    }

    init(
        cloudKit: ClipCloudKitService = ClipCloudKitService(),
        contactSave: ContactSaveService = ContactSaveService()
    ) {
        self.cloudKit = cloudKit
        self.contactSave = contactSave
    }

    /// Loads a shared card from CloudKit.
    /// - Parameter recordName: The record name (UUID) to fetch.
    func load(recordName: String) async {
        state = .loading
        do {
            let snapshot = try await cloudKit.fetchSharedCard(recordName: recordName)
            state = .loaded(snapshot)
        } catch {
            state = .error(userMessage(for: error, fallback: ClipError.fetchFailed))
        }
    }

    /// Saves the currently loaded card to Contacts via CNContactStore.
    /// Note: App Clips cannot use CNContactStore; use the share sheet flow instead.
    func saveToContacts() async {
        guard let snapshot else { return }
        do {
            try await contactSave.saveContact(vCardData: snapshot.vCardData)
            try? await cloudKit.deleteSharedCard(recordName: snapshot.recordName)
            state = .saved
        } catch {
            state = .error(userMessage(for: error, fallback: ClipError.contactSaveFailed))
        }
    }

    /// Best-effort cleanup after user shares the vCard (e.g. via share sheet).
    /// App Clips use the share sheet instead of CNContactStore.
    func cleanupAfterShare() async {
        guard let snapshot else { return }
        try? await cloudKit.deleteSharedCard(recordName: snapshot.recordName)
    }
    
    private func userMessage(for error: Error, fallback: ClipError) -> String {
        if let clipError = error as? ClipError {
            return clipError.localizedDescription
        }
        return fallback.localizedDescription
    }
}