const fs = require('fs');
const readline = require('readline');

const PRECISION = 60;

/* see https://en.wikipedia.org/wiki/Parasitic_number */

function getSmallestParasiticNumber(n, k) {
  if (n > k) {
    return '0';
  }

  if (n > 9 || k > 9) {
    throw new Error('Args should be smaller then or equal 9');
  }

  const number = 10 * Number(n) - 1;
  const primes = primeFactors(number);

  for (const prime of primes) {
    if (prime !== 2 && prime !== 5) {
      return getNumber(k, number);
    }
  }
}

function isPrime(num) {
  for (let i = 2; i <= Math.sqrt(num); i++) {
    return num % i !== 0 ? true : false;
  }
}

function primeFactors(num) {
  const result = new Set();
  for (let i = 2; i <= num; i++) {
    while (isPrime(i) && num % i === 0) {
      result.add(i); // using set, so no duplicates
      num = Math.floor(num / i);
    }
  }
  return result;
}

function getNumber(k, d) {
  const number = [];
  const storage = new Map();
  let n = k;

  for (var i = 0; i < PRECISION; i++) {
    if (storage.has(n)) {
      return number.slice(storage.get(n)).join('');
    }

    storage.set(n, i);
    number.push(Math.floor(n / d));

    n = n % d * 10;
  }
}

function run() {
  const args = process.argv.slice(2);

  switch (args[0]) {
    case 'file': {
      const file = args[1];
      if (!file) {
        throw new Error('need file');
      }

      const fileStream = fs.createReadStream(file);
      const lines = readline.createInterface({
        input: fileStream,
        crlfDelay: Infinity
      });

      let skipFirst = true;
      lines.on('line', (line) => {
        if (skipFirst) {
          skipFirst = false;
          return;
        }

        const nums = line.split(' ');
        if (nums.length !== 2) {
          throw new Error('Each line must contain 2 numbers');
        }

        console.log(getSmallestParasiticNumber(parseInt(nums[0]), parseInt(nums[1])));
      });
      break;
    }
    case 'test': {
      /*
       * I decided not to use assert, instead I made the tests more visual.
       */
      console.log(`getSmallestParasiticNumber(1, 0) = ${getSmallestParasiticNumber(1, 0)} should be 0`);
      console.log(`getSmallestParasiticNumber(1, 1) = ${getSmallestParasiticNumber(1, 1)} should be 1`);
      console.log(`getSmallestParasiticNumber(2, 2) = ${getSmallestParasiticNumber(2, 2)} should be 105263157894736842`);
      console.log(`getSmallestParasiticNumber(6, 6) = ${getSmallestParasiticNumber(6, 6)} should be 1016949152542372881355932203389830508474576271186440677966`);
      console.log(`getSmallestParasiticNumber(4, 5) = ${getSmallestParasiticNumber(9, 9)} should be 10112359550561797752808988764044943820224719`);
      break;
    }
    default: {
      throw new Error('You should call: "node number.js test" or "node number.js file <filename>"');
    }
  }
}

run();