import { TraceID } from "./tracecontext";

/**
 * traceIDToString converts a trace ID to a string using the custom base 32 encoding
 * that Encore uses.
 */
export function traceIDToString(traceID: TraceID): string {
  return encoreBase32Encoding(traceID);
}

/**
 * Custom Base32 encoder using a character set "0123456789abcdefghijklmnopqrstuv".
 */
function encoreBase32Encoding(data: Uint8Array): string {
  const charset = "0123456789abcdefghijklmnopqrstuv";
  let output = "";
  let buffer = 0;
  let bufferLength = 0;

  // eslint-disable-next-line @typescript-eslint/prefer-for-of
  for (let i = 0; i < data.length; i++) {
    buffer = (buffer << 8) | data[i];
    bufferLength += 8;

    while (bufferLength >= 5) {
      output += charset[(buffer >> (bufferLength - 5)) & 0x1f];
      bufferLength -= 5;
    }
  }

  // Handle remaining data in buffer, if any
  if (bufferLength > 0) {
    output += charset[(buffer << (5 - bufferLength)) & 0x1f];
  }

  return output;
}