/*
 * Declare the type of the denomination function's parameters.
 */

export interface DenominateType {
  input: string;
  denomination?: number;
  decimals?: number;
  showLastNonZeroDecimal?: boolean;
  addCommas?: boolean;
}

/*
 * Declare function itself and return the denominated value as a string.
 */

export const denominate = (parameters: DenominateType) => {
  const { denomination, decimals, showLastNonZeroDecimal = false, addCommas = true } = parameters;
  let { input } = parameters;

  if (input === "...") {
    return input;
  }
  if (input === "" || input === "0" || input === undefined) {
    input = "0";
  }

  const format = (
    big: string,
    denomination = 18,
    decimals = 2,
    showLastNonZeroDecimal: boolean,
    addCommas: boolean,
  ) => {
    const showLastNonZeroDecimalCheck =
      typeof showLastNonZeroDecimal !== "undefined" ? showLastNonZeroDecimal : false;

    let array = big.toString().split("");
    if (denomination !== 0) {
      // make sure we have enough characters
      while (array.length < denomination + 1) {
        array.unshift("0");
      }
      // add our dot
      array.splice(array.length - denomination, 0, ".");
      // make sure there are enough decimals after the dot
      while (array.length - array.indexOf(".") <= decimals) {
        array.push("0");
      }

      if (showLastNonZeroDecimalCheck) {
        let nonZeroDigitIndex = 0;
        for (let i = array.length - 1; i > 0; i--) {
          if (array[i] !== "0") {
            nonZeroDigitIndex = i + 1;
            break;
          }
        }
        const decimalsIndex = array.indexOf(".") + decimals + 1;
        const sliceIndex = Math.max(decimalsIndex, nonZeroDigitIndex);
        array = array.slice(0, sliceIndex);
      } else {
        // trim unnecessary characters after the dot
        array = array.slice(0, array.indexOf(".") + decimals + 1);
      }
    }
    if (addCommas) {
      // add comas every 3 characters
      array = array.reverse();
      const reference = denomination ? array.length - array.indexOf(".") - 1 : array.length;
      const count = Math.floor(reference / 3);
      for (let i = 1; i <= count; i++) {
        const position = array.indexOf(".") + 3 * i + i;
        if (position !== array.length) {
          array.splice(position, 0, ",");
        }
      }
      array = array.reverse();
    }

    const allDecimalsZero = array
      .slice(array.indexOf(".") + 1)
      .every(digit => digit.toString() === "0");

    const string = array.join("");

    if (allDecimalsZero) {
      return string.split(".")[0];
    }

    return decimals === 0 ? string.split(".").join("") : string;
  };

  return format(input, denomination, decimals, showLastNonZeroDecimal, addCommas);
};