import { Cbor } from "./";

const read = (value: string) => {
  if (value.charAt(0) === "4") {
    return value.substring(
      2,
      2 + parseInt(Cbor.read(value.substring(1, 2)), 16) * 2
    );
  } else if (value.charAt(0) === "5") {
    switch (value.charAt(1).toLowerCase()) {
      case "8":
        return value.substring(
          4,
          4 + parseInt(Cbor.read(value.substring(2, 4)), 16) * 2
        );
      case "9":
        return value.substring(
          4,
          4 + parseInt(Cbor.read(value.substring(2, 6)), 16) * 2
        );
      case "a":
        return value.substring(
          4,
          4 + parseInt(Cbor.read(value.substring(2, 10)), 16) * 2
        );
      case "b":
        return value.substring(
          4,
          4 + parseInt(Cbor.read(value.substring(2, 18)), 16) * 2
        );
      case "f":
        throw "Unsupported byte size"; // TODO: Read byte until a break is found to determine the size
      default:
        const size = parseInt(Cbor.read(value.substring(1, 2)), 16);
        return value.substring(2, 2 + (size + 16) * 2);
    }
  } else {
    console.trace("invalid byte", value);
    throw "Not a byte";
  }
};

const getLength = (value: string) => {
  const firstByte = Cbor.read(value);
  if (firstByte === "58") {
    return 4 + parseInt(value.substring(2, 4), 16) * 2;
  } else if (firstByte === "59") {
    return 6 + parseInt(value.substring(2, 6), 16) * 2;
  } else if (firstByte === "5a") {
    return 10 + parseInt(value.substring(2, 10), 16) * 2;
  } else if (firstByte === "5b") {
    return 18 + parseInt(value.substring(2, 18), 16) * 2;
  } else if (value.charAt(0) === "4") {
    return 2 + parseInt(value.substring(1, 2), 16) * 2;
  } else if (value.charAt(0) === "5") {
    return 2 + (parseInt(value.substring(1, 2), 16) + 16) * 2;
  } else {
    throw "Not a byte";
  }
};

const encode = (value: string): string => {
  const byteLength = value.length / 2;

  if (byteLength <= 15) {
    return `4${byteLength.toString(16)}${value}`;
  } else if (byteLength >= 16 && byteLength <= 23) {
    return `5${(byteLength - 16).toString(16)}${value}`;
  } else if (byteLength >= 24 && byteLength <= 255) {
    return `58${byteLength.toString(16).padStart(2, "0")}${value}`;
  } else if (byteLength >= 256 && byteLength <= 65535) {
    return `59${byteLength.toString(16).padStart(4, "0")}${value}`;
  } else {
    throw "Byte is too long, not supported.";
  }
};

export const CborByte = {
  read,
  encode,
  getLength,
};