import Foundation

/// One stem as the widgets draw it. [level] is the fader position (0.8 is unity), [percent] the gain the mixer shows.
struct WidgetStem: Codable, Hashable, Identifiable {
    var name: String
    var label: String
    var color: UInt32
    var level: Double
    var percent: Int
    var muted = false
    var solo = false
    var id: String { name }
}

/// What's playing and how it's mixed, written by the app for the widgets and the lock screen control.
struct WidgetSnapshot: Codable, Equatable {
    var title = ""
    var artist = ""
    /// The current mix ("Karaoke", "Custom Mix"…), empty unless stems are playing.
    var mix = ""
    /// What the Mix button moves to.
    var next = ""
    var playing = false
    /// Empty unless stems are playing.
    var stems: [WidgetStem] = []
    /// The art key the saved artwork belongs to, nil while it isn't saved yet.
    var art: String?

    var hasTrack: Bool { !title.isEmpty }
    var hasStems: Bool { !stems.isEmpty }
    /// Muted, or left out by another stem's solo.
    func silent(_ s: WidgetStem) -> Bool { s.muted || stems.contains(where: \.solo) && !s.solo }
}

enum WidgetStore {
    static let group = Bundle.main.object(forInfoDictionaryKey: "StemifyAppGroup") as? String ?? "group.org.cdnutter.stemify"
    static let mixerKind = "org.cdnutter.stemify.mixer"
    static let mixKind = "org.cdnutter.stemify.mix"
    static let controlKind = "org.cdnutter.stemify.mix-control"
    private static let key = "widgetSnapshot"

    /// Without the App Group (some sideloading tools drop it) this is a private store and the widgets show Nothing Playing.
    private static var defaults: UserDefaults? { UserDefaults(suiteName: group) }

    static var artURL: URL? {
        FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: group)?.appendingPathComponent("art.jpg")
    }

    static func load() -> WidgetSnapshot {
        guard let d = defaults?.data(forKey: key), let s = try? JSONDecoder().decode(WidgetSnapshot.self, from: d) else { return WidgetSnapshot() }
        return s
    }

    static func save(_ s: WidgetSnapshot) {
        guard let d = try? JSONEncoder().encode(s) else { return }
        defaults?.set(d, forKey: key)
    }
}