//
//  SHA512.swift
//  Befund
//
//  Created by Irakli Abetschkhrischwili on 29.04.22.
//  Copyright © 2022 MVZ Dr. Stein und Kollegen. All rights reserved.
//

import Foundation
import CryptoKit

extension Core.Security
{
    public class SHA512
    {
        public static let VerificatorHashingValue = "U{u)DT~!CV@y9P8U4#,T%KY~D>YRj388"
        
        /**
         * Encrypts a string value in SHA512 hash
         *
         * @param value - string value that should be encrypted in SHA512 hash
         * @return - Returns SHA512 hash
         */
        static func Encrypt(value: String) -> String
        {
            let digest = CryptoKit.SHA512.hash(data: value.data(using: .utf8) ?? Data())

            return digest.map {
                String(format: "%02hhx", $0)
            }.joined()
        }
        
        /**
         * Encrypts a byte array in SHA512 hash
         *
         * @param value - byte array that should be encrypted in SHA512 hash
         * @return - Returns SHA512 hash
         */
        static func Encrypt(data: Data) -> String
        {
            let digest = CryptoKit.SHA512.hash(data: data)

            return digest.map {
                String(format: "%02hhx", $0)
            }.joined()
        }
        
        /**
         * Generates SHA512 HMAC Hash with key
         *
         * @param message - message that should be signed by sha512 hmac
         * @param key - key that should be used for signing
         * @return returns SHA512 HMAC
         */
        static func HMAC(message: Data, key: SymmetricKey) -> String
        {
            let signature = CryptoKit.HMAC<CryptoKit.SHA512>.authenticationCode(for: message, using: key)
            return Data(signature).map { String(format: "%02hhx", $0) }.joined()
        }
        
        /**
         * Generates SHA512 HMAC Hash with key
         *
         * @param message - message that should be signed by sha512 hmac
         * @param key - key that should be used for signing
         * @return returns SHA512 HMAC
         */
        static func HMAC(message: Data, key: String) -> String
        {
            let symmetricKey = CryptoKit.SymmetricKey(data: key.data(using: .utf8)!)
            return SHA512.HMAC(message: message, key: symmetricKey)
        }
        
        /**
         * Validates HMAC with message and key
         *
         * @param hmac - HMAC from the partner
         * @param message - message that should be signed by sha512 hmac
         * @param key - key that should be used for signing
         * @return returns true if success
         */
        static func isValidAuthenticationCode(hmac: String, message: Data, key: SymmetricKey) -> Bool
        {
            return (hmac == self.HMAC(message: message, key: key))
        }
    }
}