//
//  UserDefaultsStorage.swift
//  TUIKit
//
//  UserDefaults-compatible storage backend for all platforms.
//

import Foundation

// MARK: - UserDefaults Storage (Apple Platforms)

#if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
/// A storage backend that uses UserDefaults.
///
/// Useful when running on Apple platforms with standard app conventions.
public final class UserDefaultsStorage: StorageBackend, @unchecked Sendable {
    /// The shared instance using standard UserDefaults.
    public static let shared = UserDefaultsStorage()

    /// The underlying UserDefaults.
    private let defaults: UserDefaults

    /// Creates a UserDefaults storage with standard defaults.
    public init() {
        self.defaults = .standard
    }

    /// Creates a UserDefaults storage with a custom suite.
    public init(suiteName: String?) {
        self.defaults = UserDefaults(suiteName: suiteName) ?? .standard
    }

    public func value<T: Codable>(forKey key: String) -> T? {
        guard let data = defaults.data(forKey: key) else { return nil }

        do {
            return try JSONDecoder().decode(T.self, from: data)
        } catch {
            return nil
        }
    }

    public func setValue<T: Codable>(_ value: T, forKey key: String) {
        do {
            let data = try JSONEncoder().encode(value)
            defaults.set(data, forKey: key)
        } catch {
            // Encoding failed
        }
    }

    public func removeValue(forKey key: String) {
        defaults.removeObject(forKey: key)
    }

    public func synchronize() {
        defaults.synchronize()
    }
}

// MARK: - UserDefaults Storage (Linux)

#elseif os(Linux)
/// A storage backend that emulates UserDefaults on Linux.
///
/// Uses a JSON file at `~/.local/share/[appName]/UserDefaults.json` to store data,
/// following the XDG Base Directory Specification.
public final class UserDefaultsStorage: StorageBackend, @unchecked Sendable {
    /// The shared instance (standard defaults equivalent).
    public static let shared = UserDefaultsStorage()

    /// The underlying file storage.
    private let storage: JSONFileStorage

    /// The suite name (nil for standard defaults).
    private let suiteName: String?

    /// Creates a UserDefaults-compatible storage with standard defaults.
    public init() {
        self.suiteName = nil
        self.storage = Self.createStorage(suiteName: nil)
    }

    /// Creates a UserDefaults-compatible storage with a custom suite.
    ///
    /// On Linux, each suite gets its own JSON file.
    public init(suiteName: String?) {
        self.suiteName = suiteName
        self.storage = Self.createStorage(suiteName: suiteName)
    }

    private static func createStorage(suiteName: String?) -> JSONFileStorage {
        let appName = ProcessInfo.processInfo.processName

        // Use XDG Base Directory: ~/.local/share/[appName]/
        let dataHome: URL
        if let xdgDataHome = ProcessInfo.processInfo.environment["XDG_DATA_HOME"] {
            dataHome = URL(fileURLWithPath: xdgDataHome)
        } else {
            dataHome = FileManager.default.homeDirectoryForCurrentUser
                .appendingPathComponent(".local")
                .appendingPathComponent("share")
        }

        let appDir = dataHome.appendingPathComponent(appName)

        // Create directory if needed
        try? FileManager.default.createDirectory(at: appDir, withIntermediateDirectories: true)

        // Use suite name in filename if provided
        let filename: String
        if let suite = suiteName {
            filename = "UserDefaults-\(suite).json"
        } else {
            filename = "UserDefaults.json"
        }

        let fileURL = appDir.appendingPathComponent(filename)
        return JSONFileStorage(fileURL: fileURL)
    }

    public func value<T: Codable>(forKey key: String) -> T? {
        storage.value(forKey: key)
    }

    public func setValue<T: Codable>(_ value: T, forKey key: String) {
        storage.setValue(value, forKey: key)
    }

    public func removeValue(forKey key: String) {
        storage.removeValue(forKey: key)
    }

    public func synchronize() {
        storage.synchronize()
    }

    // MARK: - UserDefaults-compatible convenience methods

    /// Returns the string value for the given key.
    public func string(forKey key: String) -> String? {
        value(forKey: key)
    }

    /// Returns the integer value for the given key.
    public func integer(forKey key: String) -> Int {
        value(forKey: key) ?? 0
    }

    /// Returns the double value for the given key.
    public func double(forKey key: String) -> Double {
        value(forKey: key) ?? 0.0
    }

    /// Returns the boolean value for the given key.
    public func bool(forKey key: String) -> Bool {
        value(forKey: key) ?? false
    }

    /// Returns the data value for the given key.
    public func data(forKey key: String) -> Data? {
        value(forKey: key)
    }

    /// Returns the array value for the given key.
    public func array<T: Codable>(forKey key: String) -> [T]? {
        value(forKey: key)
    }

    /// Returns the dictionary value for the given key.
    public func dictionary<K: Codable & Hashable, V: Codable>(forKey key: String) -> [K: V]? {
        value(forKey: key)
    }

    /// Sets a string value for the given key.
    public func set(_ value: String?, forKey key: String) {
        if let value = value {
            setValue(value, forKey: key)
        } else {
            removeValue(forKey: key)
        }
    }

    /// Sets an integer value for the given key.
    public func set(_ value: Int, forKey key: String) {
        setValue(value, forKey: key)
    }

    /// Sets a double value for the given key.
    public func set(_ value: Double, forKey key: String) {
        setValue(value, forKey: key)
    }

    /// Sets a boolean value for the given key.
    public func set(_ value: Bool, forKey key: String) {
        setValue(value, forKey: key)
    }

    /// Sets a data value for the given key.
    public func set(_ value: Data?, forKey key: String) {
        if let value = value {
            setValue(value, forKey: key)
        } else {
            removeValue(forKey: key)
        }
    }
}
#endif