sign.swift

import Foundation
import CommonCrypto
import CryptoKit

func generateRapydAPISignature(httpMethod: String, urlPath: String, salt: String, timeStamp: String, accessKey: String, secretKey: String, requestBody: String) -> String {

    let toSign = "\(httpMethod.lowercased())\(urlPath)\(salt)\(timeStamp)\(accessKey)\(secretKey)\(requestBody)"

    guard let secretKeyData = secretKey.data(using: .utf8) else {
        fatalError("Failed to convert the secret key to Data")
    }


    var hmacContext = CCHmacContext()
    CCHmacInit(&hmacContext, CCHmacAlgorithm(kCCHmacAlgSHA256), (secretKeyData as NSData).bytes, secretKeyData.count)
    CCHmacUpdate(&hmacContext, toSign, toSign.count)
    
    var hmacDigest = [UInt8](repeating: 0, count: Int(CC_SHA256_DIGEST_LENGTH))
    CCHmacFinal(&hmacContext, &hmacDigest)

    let signatureData = Data(hmacDigest)

    let signatureHex = signatureData.map { String(format: "%02hhx", $0) }.joined()
    
    guard let signature = signatureHex.data(using: .utf8)?.base64EncodedString() else {
        fatalError("Failed to convert the hash string to base64")
    }
    
    return signature
}