NavidromeApp/iOS/Data/BackupManager.swift

import Foundation
import UIKit
import ZIPFoundation

// ──────────────────────────────────────────────────────────────────────
// BackupManager.swift
// Export and import .nvdbackup files (zip archives) containing all app
// state except server passwords and downloaded audio files.
//
// Export: collects UserDefaults, server configs (passwords stripped),
//         DJ profiles, custom covers, pending ops → zip → share sheet.
// Import: unzips, validates manifest, restores everything, marks
//         servers as needing re-authentication.
// ──────────────────────────────────────────────────────────────────────

struct BackupManifest: Codable {
    let version: Int          // backup format version
    let appVersion: String
    let exportDate: Date
    let deviceName: String
    let deviceModel: String
    
    static let currentVersion = 1
}

class BackupManager {
    static let shared = BackupManager()
    private init() {}
    
    enum BackupError: LocalizedError {
        case noData
        case invalidManifest
        case versionMismatch(Int)
        case zipCreationFailed
        case missingFile(String)
        
        var errorDescription: String? {
            switch self {
            case .noData: return "No backup data found"
            case .invalidManifest: return "Invalid backup file — missing manifest"
            case .versionMismatch(let v): return "Unsupported backup version: \(v)"
            case .zipCreationFailed: return "Failed to create backup archive"
            case .missingFile(let f): return "Missing file in backup: \(f)"
            }
        }
    }
    
    // MARK: - UserDefaults keys to backup
    
    private let settingsKeys: [String] = [
        "cache_bitrate", "cache_format",
        "cell_bitrate", "cell_format",
        "wifi_bitrate", "wifi_format",
        "scrobble_enabled",
        "debug_console_enabled", "debug_track_view_bodies",
        "smart_crossfade_enabled", "smart_crossfade_duration",
        "smart_skip_silence", "smart_target_lufs",
    ]
    
    private let companionKeys: [String] = [
        "companion_enabled", "companion_host", "companion_port",
        "companion_smart_dj",
    ]
    
    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    // MARK: - EXPORT
    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    
    /// Build a .nvdbackup file and return its URL for the share sheet.
    func exportBackup() throws -> URL {
        let fm = FileManager.default
        let tempDir = fm.temporaryDirectory.appendingPathComponent("nvdbackup_\(UUID().uuidString)")
        try fm.createDirectory(at: tempDir, withIntermediateDirectories: true)
        
        defer { try? fm.removeItem(at: tempDir) }
        
        // 1. Manifest
        let manifest = BackupManifest(
            version: BackupManifest.currentVersion,
            appVersion: Bundle.main.infoDictionary?["CFBundleShortVersionString"] as? String ?? "1.0",
            exportDate: Date(),
            deviceName: UIDevice.current.name,
            deviceModel: UIDevice.current.model
        )
        try writeJSON(manifest, to: tempDir.appendingPathComponent("manifest.json"))
        
        // 2. Server configs (passwords stripped — already blanked in UserDefaults)
        if let serverData = UserDefaults.standard.data(forKey: "navidrome_servers") {
            try serverData.write(to: tempDir.appendingPathComponent("servers.json"))
        }
        if let activeData = UserDefaults.standard.data(forKey: "navidrome_active_server") {
            try activeData.write(to: tempDir.appendingPathComponent("active_server.json"))
        }
        
        // 3. App settings
        var settings: [String: Any] = [:]
        for key in settingsKeys {
            if let val = UserDefaults.standard.object(forKey: key) {
                settings[key] = val
            }
        }
        let settingsData = try JSONSerialization.data(withJSONObject: settings, options: .prettyPrinted)
        try settingsData.write(to: tempDir.appendingPathComponent("settings.json"))
        
        // 4. Companion settings
        var companion: [String: Any] = [:]
        for key in companionKeys {
            if let val = UserDefaults.standard.object(forKey: key) {
                companion[key] = val
            }
        }
        let companionData = try JSONSerialization.data(withJSONObject: companion, options: .prettyPrinted)
        try companionData.write(to: tempDir.appendingPathComponent("companion_settings.json"))
        
        // 5. Visualizer settings
        let visSettings = VisualizerSettings.shared
        let visDict: [String: Any] = [
            "realAudioAnalysis": visSettings.realAudioAnalysis,
            "barCount": visSettings.barCount,
            "gain": visSettings.gain,
            "colorScheme": visSettings.colorScheme,
        ]
        let visData = try JSONSerialization.data(withJSONObject: visDict, options: .prettyPrinted)
        try visData.write(to: tempDir.appendingPathComponent("visualizer_settings.json"))
        
        // 6. Playback state
        if let state = PlaybackStateStore.shared.exportData() {
            try state.write(to: tempDir.appendingPathComponent("playback_state.json"))
        }
        
        // 7. Smart DJ profiles (bulk cache)
        let djCacheURL = fm.urls(for: .cachesDirectory, in: .userDomainMask).first!
            .appendingPathComponent("dj_profiles_bulk.json")
        if fm.fileExists(atPath: djCacheURL.path) {
            try fm.copyItem(at: djCacheURL, to: tempDir.appendingPathComponent("dj_profiles_bulk.json"))
        }
        
        // 8. Offline catalog (metadata only, not actual audio files)
        if let catalogData = UserDefaults.standard.data(forKey: "offline_catalog") {
            try catalogData.write(to: tempDir.appendingPathComponent("offline_catalog.json"))
        }
        
        // 9. Pending operations
        if let opsData = PendingOperationsQueue.shared.exportData() {
            try opsData.write(to: tempDir.appendingPathComponent("pending_operations.json"))
        }
        
        // 10. Custom covers
        let coversDir = tempDir.appendingPathComponent("covers")
        try fm.createDirectory(at: coversDir, withIntermediateDirectories: true)
        
        let albumCoversDir = coversDir.appendingPathComponent("albums")
        try fm.createDirectory(at: albumCoversDir, withIntermediateDirectories: true)
        copyCovers(from: albumCoverDirectory(), to: albumCoversDir)
        
        let artistCoversDir = coversDir.appendingPathComponent("artists")
        try fm.createDirectory(at: artistCoversDir, withIntermediateDirectories: true)
        copyCovers(from: artistCoverDirectory(), to: artistCoversDir)
        
        // Package into zip
        let backupURL = fm.temporaryDirectory.appendingPathComponent(
            "NavidromeBackup_\(dateString()).nvdbackup"
        )
        try? fm.removeItem(at: backupURL) // remove stale
        try fm.zipItem(at: tempDir, to: backupURL, shouldKeepParent: false)
        
        DebugLogger.shared.log(
            "Backup exported: \(backupURL.lastPathComponent) (\(fileSize(backupURL)))",
            category: "Backup"
        )
        
        return backupURL
    }
    
    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    // MARK: - IMPORT
    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    
    /// Import a .nvdbackup file. Returns the manifest for UI display.
    /// Servers are restored with passwords cleared — user must re-authenticate.
    @discardableResult
    func importBackup(from url: URL) throws -> BackupManifest {
        let fm = FileManager.default
        let tempDir = fm.temporaryDirectory.appendingPathComponent("nvdimport_\(UUID().uuidString)")
        try fm.createDirectory(at: tempDir, withIntermediateDirectories: true)
        
        defer { try? fm.removeItem(at: tempDir) }
        
        // Access security-scoped resource (AirDrop / Files)
        let accessing = url.startAccessingSecurityScopedResource()
        defer { if accessing { url.stopAccessingSecurityScopedResource() } }
        
        // Unzip
        try fm.unzipItem(at: url, to: tempDir)
        
        // 1. Validate manifest
        let manifestURL = tempDir.appendingPathComponent("manifest.json")
        guard fm.fileExists(atPath: manifestURL.path) else {
            throw BackupError.invalidManifest
        }
        let manifestData = try Data(contentsOf: manifestURL)
        let manifest = try JSONDecoder().decode(BackupManifest.self, from: manifestData)
        
        guard manifest.version <= BackupManifest.currentVersion else {
            throw BackupError.versionMismatch(manifest.version)
        }
        
        // 2. Restore servers (passwords blank — user re-enters)
        let serversURL = tempDir.appendingPathComponent("servers.json")
        if fm.fileExists(atPath: serversURL.path) {
            let data = try Data(contentsOf: serversURL)
            UserDefaults.standard.set(data, forKey: "navidrome_servers")
        }
        let activeURL = tempDir.appendingPathComponent("active_server.json")
        if fm.fileExists(atPath: activeURL.path) {
            let data = try Data(contentsOf: activeURL)
            UserDefaults.standard.set(data, forKey: "navidrome_active_server")
        }
        
        // 3. Restore app settings
        let settingsURL = tempDir.appendingPathComponent("settings.json")
        if fm.fileExists(atPath: settingsURL.path),
           let data = try? Data(contentsOf: settingsURL),
           let dict = try? JSONSerialization.jsonObject(with: data) as? [String: Any] {
            for (key, value) in dict {
                UserDefaults.standard.set(value, forKey: key)
            }
        }
        
        // 4. Restore companion settings
        let companionURL = tempDir.appendingPathComponent("companion_settings.json")
        if fm.fileExists(atPath: companionURL.path),
           let data = try? Data(contentsOf: companionURL),
           let dict = try? JSONSerialization.jsonObject(with: data) as? [String: Any] {
            for (key, value) in dict {
                UserDefaults.standard.set(value, forKey: key)
            }
        }
        
        // 5. Restore visualizer settings
        let visURL = tempDir.appendingPathComponent("visualizer_settings.json")
        if fm.fileExists(atPath: visURL.path),
           let data = try? Data(contentsOf: visURL),
           let dict = try? JSONSerialization.jsonObject(with: data) as? [String: Any] {
            let vis = VisualizerSettings.shared
            if let v = dict["realAudioAnalysis"] as? Bool { vis.realAudioAnalysis = v }
            if let v = dict["barCount"] as? Int { vis.barCount = v }
            if let v = dict["gain"] as? Double { vis.gain = Float(v) }
            if let v = dict["colorScheme"] as? String { vis.colorScheme = v }
        }
        
        // 6. Restore playback state
        let playbackURL = tempDir.appendingPathComponent("playback_state.json")
        if fm.fileExists(atPath: playbackURL.path) {
            let data = try Data(contentsOf: playbackURL)
            PlaybackStateStore.shared.importData(data)
        }
        
        // 7. Restore DJ profiles
        let djURL = tempDir.appendingPathComponent("dj_profiles_bulk.json")
        if fm.fileExists(atPath: djURL.path),
           let data = try? Data(contentsOf: djURL),
           let profiles = try? JSONDecoder().decode([String: SmartDJProfile].self, from: data) {
            SmartDJCache.shared.bulkImport(profiles)
        }
        
        // 8. Restore offline catalog (metadata only)
        let catalogURL = tempDir.appendingPathComponent("offline_catalog.json")
        if fm.fileExists(atPath: catalogURL.path) {
            let data = try Data(contentsOf: catalogURL)
            UserDefaults.standard.set(data, forKey: "offline_catalog")
        }
        
        // 9. Restore pending operations
        let opsURL = tempDir.appendingPathComponent("pending_operations.json")
        if fm.fileExists(atPath: opsURL.path) {
            let data = try Data(contentsOf: opsURL)
            PendingOperationsQueue.shared.importData(data)
        }
        
        // 10. Restore custom covers
        let albumCoversSource = tempDir.appendingPathComponent("covers/albums")
        if fm.fileExists(atPath: albumCoversSource.path) {
            copyCovers(from: albumCoversSource, to: albumCoverDirectory())
        }
        let artistCoversSource = tempDir.appendingPathComponent("covers/artists")
        if fm.fileExists(atPath: artistCoversSource.path) {
            copyCovers(from: artistCoversSource, to: artistCoverDirectory())
        }
        
        DebugLogger.shared.log(
            "Backup imported: v\(manifest.version) from \(manifest.deviceName) (\(manifest.exportDate))",
            category: "Backup"
        )
        
        return manifest
    }
    
    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    // MARK: - Helpers
    // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    
    private func writeJSON<T: Encodable>(_ value: T, to url: URL) throws {
        let encoder = JSONEncoder()
        encoder.dateEncodingStrategy = .iso8601
        encoder.outputFormatting = .prettyPrinted
        let data = try encoder.encode(value)
        try data.write(to: url, options: .atomic)
    }
    
    private func albumCoverDirectory() -> URL {
        let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        let dir = docs.appendingPathComponent("AlbumCovers", isDirectory: true)
        try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        return dir
    }
    
    private func artistCoverDirectory() -> URL {
        let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
        let dir = docs.appendingPathComponent("ArtistCovers", isDirectory: true)
        try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        return dir
    }
    
    private func copyCovers(from source: URL, to dest: URL) {
        let fm = FileManager.default
        guard let files = try? fm.contentsOfDirectory(at: source, includingPropertiesForKeys: nil) else { return }
        for file in files {
            let target = dest.appendingPathComponent(file.lastPathComponent)
            try? fm.removeItem(at: target)
            try? fm.copyItem(at: file, to: target)
        }
    }
    
    private func dateString() -> String {
        let df = DateFormatter()
        df.dateFormat = "yyyy-MM-dd"
        return df.string(from: Date())
    }
    
    private func fileSize(_ url: URL) -> String {
        guard let attrs = try? FileManager.default.attributesOfItem(atPath: url.path),
              let size = attrs[.size] as? Int else { return "?" }
        if size < 1024 { return "\(size) B" }
        if size < 1024 * 1024 { return "\(size / 1024) KB" }
        return String(format: "%.1f MB", Double(size) / 1024.0 / 1024.0)
    }
}