// Copyright 2022-present 650 Industries. All rights reserved.

import CommonCrypto
import ABI47_0_0ExpoModulesCore

public class CryptoModule: Module {
  public func definition() -> ModuleDefinition {
    Name("ExpoCrypto")

    AsyncFunction("digestStringAsync", digestString)

    Function("digestString", digestString)
  }
}

private func digestString(algorithm: DigestAlgorithm, str: String, options: DigestOptions) throws -> String {
  guard let data = str.data(using: .utf8) else {
    throw LossyConversionException()
  }

  let length = Int(algorithm.digestLength)
  var digest = [UInt8](repeating: 0, count: length)

  data.withUnsafeBytes { bytes in
    let _ = algorithm.digest(bytes.baseAddress, UInt32(data.count), &digest)
  }

  switch options.encoding {
  case .hex:
    return digest.reduce("") { $0 + String(format: "%02x", $1) }
  case .base64:
    return Data(digest).base64EncodedString()
  }
}

private class LossyConversionException: Exception {
  override var reason: String {
    "Unable to convert given string without losing some information"
  }
}