import Foundation
import Security

struct AuthCredentials {
    let userId: Int
    let token: String
}

actor AuthStorage {
    static let shared = AuthStorage()

    private let serviceName = "com.payfrit.food"
    private let tokenKey = "userToken"
    private let userIdKey = "userId"

    // MARK: - Public Interface
    func saveCredentials(_ credentials: AuthCredentials) {
        saveToKeychain(key: tokenKey, value: credentials.token)
        saveToKeychain(key: userIdKey, value: String(credentials.userId))
        UserDefaults.standard.set(credentials.userId, forKey: userIdKey)
    }

    func loadCredentials() -> AuthCredentials? {
        guard let token = loadFromKeychain(key: tokenKey),
              let userIdString = loadFromKeychain(key: userIdKey),
              let userId = Int(userIdString) else {
            return nil
        }
        return AuthCredentials(userId: userId, token: token)
    }

    func clearAll() {
        deleteFromKeychain(key: tokenKey)
        deleteFromKeychain(key: userIdKey)
        UserDefaults.standard.removeObject(forKey: userIdKey)
    }

    // MARK: - Keychain Operations
    private func saveToKeychain(key: String, value: String) {
        let data = value.data(using: .utf8)!

        // Delete existing item first
        deleteFromKeychain(key: key)

        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: serviceName,
            kSecAttrAccount as String: key,
            kSecValueData as String: data,
            kSecAttrAccessible as String: kSecAttrAccessibleAfterFirstUnlock
        ]

        SecItemAdd(query as CFDictionary, nil)
    }

    private func loadFromKeychain(key: String) -> String? {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: serviceName,
            kSecAttrAccount as String: key,
            kSecReturnData as String: true,
            kSecMatchLimit as String: kSecMatchLimitOne
        ]

        var result: AnyObject?
        let status = SecItemCopyMatching(query as CFDictionary, &result)

        guard status == errSecSuccess,
              let data = result as? Data,
              let value = String(data: data, encoding: .utf8) else {
            return nil
        }

        return value
    }

    private func deleteFromKeychain(key: String) {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: serviceName,
            kSecAttrAccount as String: key
        ]

        SecItemDelete(query as CFDictionary)
    }
}