//
//  AppLocalization.swift
//  App for Indeed
//
//  English-first localization using Localizable.strings (same pattern as the LinkedIn app).
//  Add more locales by creating `<locale>.lproj/Localizable.strings` and extending AppLanguage.
//

import Foundation

enum AppLanguage: CaseIterable {
    case english
    case arabic
    case chineseSimplified

    var localeIdentifier: String {
        switch self {
        case .english:
            return "en"
        case .arabic:
            return "ar"
        case .chineseSimplified:
            return "zh-Hans"
        }
    }

    static var systemLanguage: AppLanguage {
        let preferred = Locale.preferredLanguages.first ?? "en"
        if preferred.lowercased().hasPrefix("zh") {
            return .chineseSimplified
        }
        for language in AppLanguage.allCases where preferred.hasPrefix(language.localeIdentifier) {
            return language
        }
        return .english
    }

    /// Settings language picker labels — fixed English names, not localized.
    var localizedDisplayName: String {
        switch self {
        case .english:
            return "English"
        case .arabic:
            return "Arabic"
        case .chineseSimplified:
            return "Chinese (Simplified)"
        }
    }
}

func appLocalized(_ key: String, language: AppLanguage) -> String {
    guard let path = Bundle.main.path(forResource: language.localeIdentifier, ofType: "lproj"),
          let bundle = Bundle(path: path) else {
        return key
    }
    return bundle.localizedString(forKey: key, value: key, table: nil)
}

func currentAppLanguage() -> AppLanguage {
    let code = UserDefaults.standard.string(forKey: "com.appforindeed.preferredLanguage") ?? "en"
    return AppLanguage.allCases.first(where: { $0.localeIdentifier == code }) ?? .english
}

/// Resolves copy for the user’s currently selected language.
func L(_ key: String) -> String {
    appLocalized(key, language: currentAppLanguage())
}

/// Localized CV template title; `name` is always the English localization key.
func localizedTemplateName(_ nameKey: String) -> String {
    L(nameKey)
}

@MainActor
final class AppLanguageManager {
    static let shared = AppLanguageManager()

    static let didChangeNotification = Notification.Name("AppLanguageManager.didChange")

    private enum UserDefaultsKey {
        static let preferredLanguage = "com.appforindeed.preferredLanguage"
    }

    var current: AppLanguage {
        currentAppLanguage()
    }

    func applyStoredPreferenceOnLaunch() {
        // UI copy uses `appLocalized`; do not drive layout from `AppleLanguages` (Arabic forces RTL and breaks CV templates).
        UserDefaults.standard.removeObject(forKey: "AppleLanguages")
        if UserDefaults.standard.string(forKey: UserDefaultsKey.preferredLanguage) == nil {
            setLanguage(AppLanguage.systemLanguage, notify: false)
        }
    }

    func setLanguage(_ language: AppLanguage, notify: Bool = true) {
        let code = language.localeIdentifier
        UserDefaults.standard.set(code, forKey: UserDefaultsKey.preferredLanguage)
        UserDefaults.standard.removeObject(forKey: "AppleLanguages")
        if notify {
            NotificationCenter.default.post(name: Self.didChangeNotification, object: self)
        }
    }

    func setLanguage(code: String, notify: Bool = true) {
        guard let language = AppLanguage.allCases.first(where: { $0.localeIdentifier == code }) else { return }
        setLanguage(language, notify: notify)
    }
}