import Foundation

/// Quell- und Zielordner, persistiert über Security-Scoped Bookmarks statt
/// roher Pfade — überlebt damit auch einen späteren Wechsel in den App
/// Sandbox (README: "@AppStorage + Security-Scoped Bookmarks").
@MainActor
final class AppSettings: ObservableObject {
    @Published private(set) var sourceFolder: URL?
    @Published private(set) var targetFolder: URL?

    private enum DefaultsKey {
        static let sourceBookmark = "dev.zielke.droptwo.sourceFolderBookmark"
        static let targetBookmark = "dev.zielke.droptwo.targetFolderBookmark"
    }

    init() {
        sourceFolder = Self.resolveBookmark(forKey: DefaultsKey.sourceBookmark)
        targetFolder = Self.resolveBookmark(forKey: DefaultsKey.targetBookmark)
    }

    func setSourceFolder(_ url: URL) {
        sourceFolder = url
        Self.storeBookmark(for: url, key: DefaultsKey.sourceBookmark)
    }

    func setTargetFolder(_ url: URL) {
        targetFolder = url
        Self.storeBookmark(for: url, key: DefaultsKey.targetBookmark)
    }

    private static func storeBookmark(for url: URL, key: String) {
        do {
            let data = try url.bookmarkData(options: .withSecurityScope, includingResourceValuesForKeys: nil, relativeTo: nil)
            UserDefaults.standard.set(data, forKey: key)
        } catch {
            // Best effort: der Ordner bleibt für die laufende Sitzung trotzdem
            // gesetzt, nur der Neustart-Fall geht dann verloren.
        }
    }

    private static func resolveBookmark(forKey key: String) -> URL? {
        guard let data = UserDefaults.standard.data(forKey: key) else { return nil }
        var isStale = false
        guard let url = try? URL(resolvingBookmarkData: data, options: .withSecurityScope, relativeTo: nil, bookmarkDataIsStale: &isStale) else {
            return nil
        }
        _ = url.startAccessingSecurityScopedResource()
        return url
    }
}