NavidromeApp/Shared/Storage/WidgetSharedState.swift

import Foundation

// ──────────────────────────────────────────────────────────────────────
// WidgetSharedState.swift
// TARGET: Compile into BOTH the main app AND the widget extension.
// Lives in Shared/Storage/ alongside LibraryCache, PlaybackStateStore, etc.
//
// Reads/writes playback state via App Group UserDefaults so the widget
// can display current song info and the app can receive widget commands.
//
// App Group: "group.com.navidromeplayer.shared"
// Add this App Group capability to BOTH targets in Signing & Capabilities.
// ──────────────────────────────────────────────────────────────────────

/// Item in the "Up Next" queue displayed by the large widget.
struct WidgetQueueItem: Codable, Equatable {
    let title: String
    let artist: String
}

/// Commands the widget can send to the main app.
enum WidgetCommand: String, Codable {
    case play
    case pause
    case next
    case previous
    case seekForward15
    case seekBackward15
}

/// Darwin notification name used for widget → app wake-up signal.
/// Darwin notifications are inter-process (no payload — the command
/// is written to App Group UserDefaults before posting).
let kWidgetCommandNotification = "ca.dallasgroot.NavidromePlayer.widgetCommand" as CFString

/// Shared playback state bridge between the main app and the widget extension.
///
/// The main app calls `pushState(...)` whenever playback state changes.
/// The widget's TimelineProvider calls `pullState()` to build entries.
/// Widget AppIntents call `enqueueCommand(...)` then post a Darwin notification.
final class WidgetSharedState {

    static let suiteName = "group.com.navidromeplayer.shared"
    static let shared = WidgetSharedState()

    private let defaults: UserDefaults?

    private init() {
        defaults = UserDefaults(suiteName: Self.suiteName)
    }

    // MARK: - Keys

    private enum K {
        static let title        = "w_title"
        static let artist       = "w_artist"
        static let album        = "w_album"
        static let isPlaying    = "w_isPlaying"
        static let currentTime  = "w_currentTime"
        static let duration     = "w_duration"
        static let coverArt     = "w_coverArt"       // JPEG data, ~80 KB
        static let blurredArt   = "w_blurredArt"     // pre-blurred JPEG, ~30 KB
        static let lastUpdated  = "w_lastUpdated"    // TimeInterval since 1970
        static let queueNext    = "w_queueNext"      // JSON-encoded [WidgetQueueItem]
        static let hasData      = "w_hasData"
        static let command      = "w_pendingCmd"
    }

    // MARK: - Write (main app → shared defaults)

    /// Push the full playback state. Call from AudioPlayer on every meaningful change
    /// (song change, play/pause, seek, queue edit). Lightweight — just UserDefaults writes.
    func pushState(
        title: String,
        artist: String,
        album: String,
        isPlaying: Bool,
        currentTime: TimeInterval,
        duration: TimeInterval,
        coverArtJPEG: Data?,
        blurredArtJPEG: Data?,
        queueNext: [WidgetQueueItem]
    ) {
        let d = defaults
        d?.set(title,                              forKey: K.title)
        d?.set(artist,                             forKey: K.artist)
        d?.set(album,                              forKey: K.album)
        d?.set(isPlaying,                          forKey: K.isPlaying)
        d?.set(currentTime,                        forKey: K.currentTime)
        d?.set(duration,                           forKey: K.duration)
        d?.set(Date().timeIntervalSince1970,       forKey: K.lastUpdated)
        d?.set(true,                               forKey: K.hasData)

        if let art = coverArtJPEG   { d?.set(art, forKey: K.coverArt) }
        if let blur = blurredArtJPEG { d?.set(blur, forKey: K.blurredArt) }

        if let encoded = try? JSONEncoder().encode(queueNext) {
            d?.set(encoded, forKey: K.queueNext)
        }
    }

    /// Lightweight position-only update — call from the periodic time observer
    /// so the widget progress bar stays roughly accurate without pushing full state.
    func pushPosition(currentTime: TimeInterval, isPlaying: Bool) {
        defaults?.set(currentTime,                     forKey: K.currentTime)
        defaults?.set(isPlaying,                       forKey: K.isPlaying)
        defaults?.set(Date().timeIntervalSince1970,    forKey: K.lastUpdated)
    }

    // MARK: - Read (widget → shared defaults)

    var songTitle: String       { defaults?.string(forKey: K.title)   ?? "" }
    var artist: String          { defaults?.string(forKey: K.artist)  ?? "" }
    var album: String           { defaults?.string(forKey: K.album)   ?? "" }
    var isPlaying: Bool         { defaults?.bool(forKey: K.isPlaying) ?? false }
    var currentTime: TimeInterval { defaults?.double(forKey: K.currentTime) ?? 0 }
    var duration: TimeInterval  { defaults?.double(forKey: K.duration) ?? 0 }
    var hasData: Bool           { defaults?.bool(forKey: K.hasData)   ?? false }
    var coverArtData: Data?     { defaults?.data(forKey: K.coverArt) }
    var blurredArtData: Data?   { defaults?.data(forKey: K.blurredArt) }

    /// Seconds since the state was last written by the main app.
    var lastUpdatedDate: Date {
        let ts = defaults?.double(forKey: K.lastUpdated) ?? 0
        return Date(timeIntervalSince1970: ts)
    }

    var queueNext: [WidgetQueueItem] {
        guard let data = defaults?.data(forKey: K.queueNext),
              let items = try? JSONDecoder().decode([WidgetQueueItem].self, from: data)
        else { return [] }
        return items
    }

    // MARK: - Commands (widget → app)

    /// Write a command for the main app to pick up via Darwin notification observer.
    func enqueueCommand(_ cmd: WidgetCommand) {
        defaults?.set(cmd.rawValue, forKey: K.command)
    }

    /// Read and clear the pending command. Called by the app's Darwin observer.
    func dequeueCommand() -> WidgetCommand? {
        guard let raw = defaults?.string(forKey: K.command),
              let cmd = WidgetCommand(rawValue: raw) else { return nil }
        defaults?.removeObject(forKey: K.command)
        return cmd
    }

    // MARK: - Optimistic Toggle (for widget-side instant UI update)

    /// Toggle isPlaying optimistically so the widget re-renders immediately
    /// before the app processes the command.
    func togglePlayingOptimistic() {
        let current = isPlaying
        defaults?.set(!current, forKey: K.isPlaying)
    }

    // MARK: - Clear

    func clearAll() {
        for key in [K.title, K.artist, K.album, K.isPlaying, K.currentTime,
                    K.duration, K.coverArt, K.blurredArt, K.lastUpdated,
                    K.queueNext, K.hasData, K.command] {
            defaults?.removeObject(forKey: key)
        }
    }
}

// MARK: - Darwin Notification Helpers

/// Post a Darwin notification (inter-process, no payload).
func postDarwinNotification(_ name: CFString) {
    CFNotificationCenterPostNotification(
        CFNotificationCenterGetDarwinNotifyCenter(),
        CFNotificationName(name),
        nil, nil, true
    )
}