import Foundation

/// URL-keyed cache of AI summaries so views that only know a URL — e.g. the
/// deliberately-decoupled Podcasts tab — can show a bookmark's summary without
/// holding the full `Bookmark`. Written by `BookmarksViewModel` as it enriches
/// and loads bookmarks; read by the episode detail sheet.
enum AISummaryStore {
    private static let key = "aiSummaryByURL"

    static func summary(for url: String) -> String? {
        let store = UserDefaults.standard.dictionary(forKey: key) as? [String: String] ?? [:]
        let value = store[url]
        return (value?.isEmpty ?? true) ? nil : value
    }

    static func set(_ summary: String?, for url: String) {
        var store = UserDefaults.standard.dictionary(forKey: key) as? [String: String] ?? [:]
        if let summary, !summary.isEmpty {
            guard store[url] != summary else { return }   // no-op if unchanged
            store[url] = summary
        } else {
            guard store[url] != nil else { return }
            store.removeValue(forKey: url)
        }
        UserDefaults.standard.set(store, forKey: key)
    }
}