// Setters
const setTimeString = timeUnit => {
  // String representations of time numbers
  const timeStrings = {
    0: "",
    1: "one",
    2: "two",
    3: "three",
    4: "four",
    5: "five",
    6: "six",
    7: "seven",
    8: "eight",
    9: "nine",
    10: "ten",
    11: "eleven",
    12: "twelve",
    13: "thirteen",
    14: "fourteen",
    15: "fifteen",
    16: "sixteen",
    17: "seventeen",
    18: "eighteen",
    19: "nineteen",
    20: "twenty",
    30: "thirty",
    40: "fourty",
    50: "fifty",
    60: "sixty"
  };

  if (timeUnit < 20) {
    return timeStrings[timeUnit];
  } else {
    const digitOne = timeStrings[Math.floor(timeUnit / 10) * 10];
    const digitTwo = timeStrings[timeUnit % 10]
      ? timeStrings[timeUnit % 10]
      : 0;
    if (digitTwo !== 0) {
      return `${digitOne} ${digitTwo}`;
    } else {
      return digitOne;
    }
  }
};

(function() {
  // Getters
  const getDomElements = () => {
    const hourDisplay = document.getElementById("hour-display");
    const minuteDisplay = document.getElementById("minute-display");
    const dayDisplay = document.getElementById("day-display");
    const monthDisplay = document.getElementById("month-display");
    const dateDisplay = document.getElementById("date-display");
    const hourHand = document.getElementById("hour-hand");
    const minuteHand = document.getElementById("minute-hand");
    const secondHand = document.getElementById("second-hand");

    return {
      hourDisplay,
      minuteDisplay,
      dayDisplay,
      monthDisplay,
      dateDisplay,
      hourHand,
      minuteHand,
      secondHand
    };
  };

  const getCurrentTime = () => {
    const date = new Date();
    const time = date.getTime();
    const hours = date.getHours();
    const minutes = date.getMinutes();
    const seconds = date.getSeconds();
    const milliseconds = date.getMilliseconds();

    return {
      date,
      time,
      // Adjust hours to 12 hour clock
      hours: hours > 12 ? hours - 12 : hours,
      minutes,
      seconds,
      milliseconds
    };
  };

  const setDateDisplay = currentTime => {
    const nowDateString = currentTime.toDateString();
    const dayString = nowDateString.slice(0, 3);
    const monthString = nowDateString.slice(4, 7);
    const dateString = nowDateString.slice(8, 10);

    return {
      dayString,
      monthString,
      dateString
    };
  };

  // Rendering
  const rotateHand = (timeUnit, factor, hand) => {
    // -90 degress accomodates for initial css layout position
    const position = timeUnit * factor - 90;
    hand.style.transform = `rotate(${position}deg)`;
  };

  const renderClock = () => {
    const domElements = getDomElements();
    const currentTime = getCurrentTime();
    // Hand values for animation
    // Seconds, minutes, hours reflect 100ms setInterval() iteration
    const seconds =
      (currentTime.seconds * 1000 + currentTime.milliseconds) / 1000;
    const minutes = (currentTime.minutes * 60 + seconds) / 60;
    const hours = (currentTime.hours * 60 + minutes) / 60;

    // Display strings for long-form readout
    const hourString = setTimeString(currentTime.hours);
    const minuteString = setTimeString(currentTime.minutes);
    let { dayString, monthString, dateString } = setDateDisplay(
      currentTime.date
    );

    // Populate DOM Elements
    domElements.hourDisplay.innerHTML = hourString;
    domElements.minuteDisplay.innerHTML = minuteString;
    domElements.dayDisplay.innerHTML = `${dayString} | `;
    domElements.monthDisplay.innerHTML = `${monthString} | `;
    domElements.dateDisplay.innerHTML = dateString;

    // Rotate Hands
    rotateHand(seconds, 6, domElements.secondHand);
    rotateHand(minutes, 6, domElements.minuteHand);
    rotateHand(hours, 30, domElements.hourHand);
  };

  const run = () => {
    setInterval(() => {
      renderClock();
    }, 100);
  };

  run();
})();