import CryptoKit
import Foundation
import LocalData

nonisolated
struct ExternalKeyMaterialProvider: KeyMaterialProviding {
    private enum Constants {
        static let keyLength = 32
    }

    func keyMaterial(for keyName: String) async throws -> Data {
        let key = StorageKeys.ExternalKeyMaterialKey()
        if let existing = try await StorageRouter.shared.get(key) as Data? {
            return existing
        }

        let symmetricKey = SymmetricKey(size: .bits256)
        let material = symmetricKey.withUnsafeBytes { Data($0) }
        guard material.count == Constants.keyLength else {
            throw StorageError.securityApplicationFailed
        }

        try await StorageRouter.shared.set(material, for: key)
        return material
    }
}