import Foundation
import OrgSocialKit

@Observable
@MainActor
final class ThreadViewModel {
    private let postURL: String
    private let relayURL: URL
    private let fetcher = ThreadFetcher()

    var thread: OrgSocialThread?
    var isLoading = false
    var errorMessage: String?

    init(postURL: String, relayURL: URL) {
        self.postURL = postURL
        self.relayURL = relayURL
    }

    var useRelay: Bool {
        UserDefaults.standard.object(forKey: "useRelay") as? Bool ?? true
    }

    func load() async {
        // Skip if another load is already in flight, or if we already have data
        // (the .task modifier re-fires when the view reappears after navigation).
        guard !isLoading else { return }
        guard thread == nil else { return }
        guard useRelay else {
            errorMessage = "Threads require a relay. Enable Use Relay in Settings."
            return
        }
        isLoading = true
        errorMessage = nil
        do {
            thread = try await fetcher.fetchThread(for: postURL, from: relayURL)
        } catch {
            errorMessage = error.localizedDescription
        }
        isLoading = false
    }
}