import { Decimal128 } from "bson";

const assertions = []

function removeDecimalPoint(str: string): string {
  return str.replace(".", "");
}

function truncateByOne(str: string): string {
  return str.slice(0, -1);
}

const bytes = Buffer.from("b2d734fc610c88c439e6222a4fed0330", "hex");
const d128 = new Decimal128(bytes);
const str = d128.toString();



function constructs(str: string): Decimal128 | Error {
  try {
    return Decimal128.fromString(str);
  } catch (e) {
    return e;
  }
}

assertions.push(str === "1000.5500000000000682121026329696178")
const constructionResult = constructs(str) as Error;
assertions.push(constructionResult instanceof Error)
const errorMessage = (constructionResult as Error).message;
assertions.push(errorMessage === "\"1000.5500000000000682121026329696178\" is not a valid Decimal128 string - inexact rounding")

//The decimal128 format supports 34 decimal digits of significand - https://en.wikipedia.org/wiki/Decimal128_floating-point_format#Format
assertions.push(removeDecimalPoint(str).length === 35)

// It works with one digit removed
const truncatedStr = truncateByOne(str);
assertions.push(truncatedStr === "1000.550000000000068212102632969617") // missing final 8
const truncatedConstructionResult = constructs(truncatedStr) as Decimal128;
assertions.push(truncatedConstructionResult instanceof Decimal128);

let i = 1;
for (const assertion of assertions) {
  if (!assertion) {
    // This won't happen. Assertions will pass
    console.error(`❌ Assertion ${i} failed`);
    process.exit(1);
  }
  i++;
}

console.log("✅ All assertions passed");
process.exit(0);