import Foundation

// MARK: - BookVoicePreferences
// Manages per-book voice overrides with global fallback.
// Persisted in UserDefaults as a slug → voice dictionary.

@MainActor
final class BookVoicePreferences: ObservableObject {
    static let shared = BookVoicePreferences()

    @Published private(set) var bookVoices: [String: String] = [:]

    private let key = "v2.bookVoicePreferences"

    private init() {
        if let data    = UserDefaults.standard.data(forKey: key),
           let decoded = try? JSONDecoder().decode([String: String].self, from: data) {
            bookVoices = decoded
        }
    }

    // MARK: - Public API

    func voice(for slug: String) -> String? {
        bookVoices[slug]
    }

    /// Voice priority: book override → globalVoice → "af_bella"
    func voiceWithFallback(for slug: String, globalVoice: String) -> String {
        bookVoices[slug] ?? globalVoice
    }

    func setVoice(_ voice: String, for slug: String) {
        bookVoices[slug] = voice
        save()
    }

    func removeVoice(for slug: String) {
        bookVoices.removeValue(forKey: slug)
        save()
    }

    func hasOverride(for slug: String) -> Bool {
        bookVoices[slug] != nil
    }

    func clearAll() {
        bookVoices.removeAll()
        save()
    }

    // MARK: - Persistence

    private func save() {
        if let encoded = try? JSONEncoder().encode(bookVoices) {
            UserDefaults.standard.set(encoded, forKey: key)
        }
    }
}