// --------------------------------------------------------------------------
//  Following code is for utilities
// --------------------------------------------------------------------------

/**
 * @params zeroShift {function} The function you want to test
 * @params debug {boolean} Sets true for including the function result
 */
const checkTests = (targetFunction, debug) => {
  // --------------------------
  // Generates test cases
  // --------------------------
  const tests = [];

  tests.push({
    name: 'test1',
    src: [1, 0, 2, 3, 0, 4, 5, 0],
    expect: [1, 0, 0, 2, 3, 0, 0, 4]
  });

  tests.push({
    name: 'test2',
    src: [1, 2, 3],
    expect: [1, 2, 3]
  });
  tests.push(createTest('test3', 10));
  tests.push(createTest('test4', 100));
  tests.push(createTest('test5', 1000));
  tests.push(createTest('test6', 10000));
  // tests.push(createTest('test7', 100000));

  // --------------------------
  // Do tests
  // --------------------------
  const results = tests.map((test) => {
    let src = test.src;

    // Do the test
    const startTime = performance.now();
    const result = targetFunction(src, debug);
    const endTime = performance.now();

    // Verification
    let pass = Array.isArray(result) && (result.length === test.expect.length);
    if (pass) {
      const size = result.length;
      let i = 0;
      while(pass && (i < size)) {
        pass = (result[i] === test.expect[i]);
        i++;
      }
    }

    let report = {
      name: test.name,
      pass,
      time: endTime - startTime
    };

    if (debug) {
      report.result = result;
    }

    return report;
  });


  // --------------------------
  // Output
  // --------------------------
  let totalTime = 0;
  results.forEach((result) => {
    console.log(result);
    totalTime += result.time;
  });

  console.log(`total = ${(totalTime).toFixed(3)} msec`)
};



/**
 * Create a test object, which contains the src and the expect properties.
 *
 * @params testName {string} Test name
 * @params arrLen {number} Number of array length
 *
 * @returns {object} Test case
 */
const createTest = (testName, arrLen) => {
  let src = [];
  let expect = [];

  for (let index = 0; index < arrLen; index++) {
    let val = Math.floor(Math.random() * 10);

    src.push(val);
    expect.push(val);

    if (val === 0) {
      expect.push(0)
    }
  }
  expect.length = arrLen;

  return {
    name: testName,
    src: src,
    expect
  };
};

// --------------------------------------------------------------------------
//  Following code is the user code
// --------------------------------------------------------------------------

const zeroShift = (srcArray, debug) => {

  for (let index = 0; index < srcArray.length; index++) {
    const element = srcArray[index];
    if (element === 0) {
      srcArray = srcArray
        .slice(0, index + 1)
        .concat(srcArray.slice(index, srcArray.length - 1));
      index++;
    }
  }

  return srcArray;
};


checkTests(zeroShift, false);