/*
 * 1. largeSum
 * */

const largeSum = (a, b, limit) => {
  if (
    typeof a !== "number" ||
    typeof b !== "number" ||
    typeof limit !== "number"
  )
    throw new Error(
      "Input values should be number. Exptected for @a: number, @b: number, @limit: number"
    );

  let sum = 0;
  for (let i = 1; a * i < limit || b * i < limit; i++) {
    const _a = a * i;
    const _b = b * i;
    if (_a < limit) {
      sum += _a;
    }
    if (_b < limit && _b % a !== 0) {
      sum += _b;
    }
  }
  return sum;
};

/*
 * 2. sequence
 * */

const isEven = n => !(n % 2);

const f = num => {
  if (isEven(num)) {
    return num / 2;
  } else {
    return 1 + 3 * num;
  }
};

const a = num => {
  if (typeof num !== "number") throw new Error("@n param should be a number");

  const seq = [num];
  while (seq[seq.length - 1] !== 1) {
    seq.push(f(seq[seq.length - 1]));
  }

  return seq.reduce((acc, val) => acc + val);
};

/*
 * 3. countLeapDays
 * */

const hasLeapDay = year => !(year % 400) || (!(year % 4) && !!(year % 100));

const getLeapDay = year => new Date(`Feb 29, ${year}`).getDay();

const countLeapDays = (start, end) => {
  if (
    start > end ||
    typeof start !== "number" ||
    (end && typeof end !== "number")
  ) {
    throw new Error("Please, provide valide time range");
  }

  const dayRow = [
    "Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday",
    "Answer"
  ];
  const dayMap = {
    Sunday: 0,
    Monday: 0,
    Tuesday: 0,
    Wednesday: 0,
    Thursday: 0,
    Friday: 0,
    Saturday: 0
  };
  const leapYears = [];

  if (!end) {
    return dayRow[getLeapDay(start)];
  }

  for (let year = start; year < end; year++) {
    if (hasLeapDay(year)) {
      leapYears.push(year);
    }
  }

  if (leapYears.length) {
    leapYears.forEach(year => {
      return year && (dayMap[dayRow[getLeapDay(year)]] += 1);
    });
  }

  return dayMap;
};

const logSuccess = (values, result) =>
  console.log("✅ Test passed: " + values + " : " + result);
const logFailure = (values, result, exp) =>
  console.error(
    "❌ Test failed: " + values + " : " + result + ". Expected:" + exp
  );

/* 1. */
const test1 = largeSum.call(null, 5, 7, 40);
const test2 = largeSum.call(null, 5, 7, 1000000);
const test3 = largeSum.call(null, 5, 7, 21);
const expectedResult1 = 210;
const expectedResult2 = 157142642861;
const expectedResult3 = 71;

/* 2. */
const test2_1 = a.call(null, 3);
const test2_2 = a.call(null, 9);
const test2_3 = a.call(null, 6171);
const expectedResult2_1 = 49;
const expectedResult2_2 = 339;
const expectedResult2_3 = 12152173;

/* 3. */
const test3_1 = countLeapDays.call(null, 1940);
const test3_2 = countLeapDays.call(null, 2000);
const test3_3 = countLeapDays.call(null, 1900, 2000);
const expectedResult3_1 = "Thursday";
const expectedResult3_2 = "Tuesday";
const expectedResult3_3 = {
  Sunday: 3,
  Monday: 4,
  Tuesday: 3,
  Wednesday: 3,
  Thursday: 4,
  Friday: 3,
  Saturday: 4
};

/*TESTS:
 *  */
console.info("Running test 1...");
(test1 === expectedResult1 ? logSuccess : logFailure)(
  "5, 7, 40",
  test1,
  expectedResult1
);
(test2 === expectedResult2 ? logSuccess : logFailure)(
  "5, 7, 1000000",
  test2,
  expectedResult2
);
(test3 === expectedResult3 ? logSuccess : logFailure)(
  "5, 7, 21",
  test3,
  expectedResult3
);
console.info("Running test 2...");
(test2_1 === expectedResult2_1 ? logSuccess : logFailure)(
  "3",
  test2_1,
  expectedResult2_1
);
(test2_2 === expectedResult2_2 ? logSuccess : logFailure)(
  "9",
  test2_2,
  expectedResult2_2
);
(test2_3 === expectedResult2_3 ? logSuccess : logFailure)(
  "6171",
  test2_3,
  expectedResult2_3
);
console.info("Running test 3...");
(test3_1 === expectedResult3_1 ? logSuccess : logFailure)(
  "1940",
  test3_1,
  expectedResult3_1
);
(test3_2 === expectedResult3_2 ? logSuccess : logFailure)(
  "2000",
  test3_2,
  expectedResult3_2
);
(JSON.stringify(test3_3) === JSON.stringify(expectedResult3_3)
  ? logSuccess
  : logFailure)(
  `{
  Sunday: 3,
  Monday: 4,
  Tuesday: 3,
  Wednesday: 3,
  Thursday: 4,
  Friday: 3,
  Saturday: 4
}`,
  JSON.stringify(test3_3),
  expectedResult3_3
);