Flaro/Packages/FlixyKit/Sources/PlexKit/Auth/TokenStore.swift

import Foundation
import Security

/// Legt Tokens im Schlüsselbund ab.
///
/// Nicht in `UserDefaults`: ein Plex-Token gibt vollen Zugriff auf die
/// Mediathek und bleibt gültig, bis er am Konto zurückgezogen wird. In den
/// Voreinstellungen läge er als Klartext in einer Datei, die jedes Backup
/// mitnimmt.
public protocol TokenStoring: Sendable {
    func store(_ token: String, for account: String) throws
    func token(for account: String) -> String?
    func remove(for account: String)
}

public struct KeychainTokenStore: TokenStoring {
    private let service: String

    public init(service: String) {
        self.service = service
    }

    public enum Failure: Error, Equatable {
        case keychain(status: OSStatus)
    }

    public func store(_ token: String, for account: String) throws {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: service,
            kSecAttrAccount as String: account,
        ]

        let attributes: [String: Any] = [
            kSecValueData as String: Data(token.utf8),
            // Ohne Gerätesperre kein Zugriff, und nicht in Backups übertragbar.
            // Ein Token, der auf einem anderen Gerät wieder auftaucht, wäre
            // ein stiller Zweitzugang zur Mediathek.
            kSecAttrAccessible as String: kSecAttrAccessibleWhenUnlockedThisDeviceOnly,
        ]

        let status = SecItemUpdate(query as CFDictionary, attributes as CFDictionary)
        switch status {
        case errSecSuccess:
            return
        case errSecItemNotFound:
            let insert = query.merging(attributes) { current, _ in current }
            let addStatus = SecItemAdd(insert as CFDictionary, nil)
            guard addStatus == errSecSuccess else { throw Failure.keychain(status: addStatus) }
        default:
            throw Failure.keychain(status: status)
        }
    }

    public func token(for account: String) -> String? {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: service,
            kSecAttrAccount as String: account,
            kSecReturnData as String: true,
            kSecMatchLimit as String: kSecMatchLimitOne,
        ]

        var result: CFTypeRef?
        guard SecItemCopyMatching(query as CFDictionary, &result) == errSecSuccess,
              let data = result as? Data
        else { return nil }

        return String(data: data, encoding: .utf8)
    }

    public func remove(for account: String) {
        let query: [String: Any] = [
            kSecClass as String: kSecClassGenericPassword,
            kSecAttrService as String: service,
            kSecAttrAccount as String: account,
        ]
        SecItemDelete(query as CFDictionary)
    }
}

/// Ein Ablageort im Arbeitsspeicher — für Tests und SwiftUI-Vorschauen.
public final class InMemoryTokenStore: TokenStoring, @unchecked Sendable {
    private let lock = NSLock()
    private var tokens: [String: String] = [:]

    public init() {}

    public func store(_ token: String, for account: String) throws {
        lock.withLock { tokens[account] = token }
    }

    public func token(for account: String) -> String? {
        lock.withLock { tokens[account] }
    }

    public func remove(for account: String) {
        _ = lock.withLock { tokens.removeValue(forKey: account) }
    }
}