Tusker/Packages/TuskerPreferences/Sources/TuskerPreferences/Preferences.swift

//
//  Preferences.swift
//  TuskerPreferences
//
//  Created by Shadowfacts on 4/12/24.
//

import Foundation

public struct Preferences {
    @MainActor
    public static let shared: PreferenceStore = load()
    
    private static var documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
    private static var appGroupDirectory = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.space.vaccor.Tusker")!
    private static var legacyURL = appGroupDirectory.appendingPathComponent("preferences").appendingPathExtension("plist")
    private static var preferencesURL = appGroupDirectory.appendingPathComponent("preferences.v2").appendingPathExtension("plist")
    private static var nonAppGroupURL = documentsDirectory.appendingPathComponent("preferences").appendingPathExtension("plist")

    private init() {}
    
    @MainActor
    public static func save() {
        let encoder = PropertyListEncoder()
        let data = try? encoder.encode(PreferenceCoding(wrapped: shared))
        try? data?.write(to: preferencesURL, options: .noFileProtection)
    }
    
    private static func load() -> PreferenceStore {
        let decoder = PropertyListDecoder()
        if let data = try? Data(contentsOf: preferencesURL),
           let store = try? decoder.decode(PreferenceCoding<PreferenceStore>.self, from: data) {
            return store.wrapped
        } else if let legacyData = (try? Data(contentsOf: legacyURL)) ?? (try? Data(contentsOf: nonAppGroupURL)),
           let legacy = try? decoder.decode(LegacyPreferences.self, from: legacyData) {
            let store = PreferenceStore()
            store.migrate(from: legacy)
            return store
        } else {
            return PreferenceStore()
        }
    }
}