/* eslint-disable no-return-assign */
const chalk = require('chalk');
const ora = require('ora');
const R = require('ramda');
const prettyMs = require('pretty-ms');

/**
 * Creates progress bar with appendable statuses.
 * @param {String} [title=''] Top title of the bar.
 * @param {String} [fillChar=chalk.cyan('-')] Filling character.
 * @param {String} [bgChar=' '] Background character
 * @param {String} [startingChar=chalk.gray('[')] [description]
 * @param {String} [endingChar=chalk.gray(']')] [description]
 * @param {Number} [total=10] Aka length of the bar.
 * @returns {Object} With tick and append functions.
 */
const createProgressBar = ({
  title = '',
  fillChar = chalk.cyan('-'),
  bgChar = ' ',
  startingChar = chalk.gray('['),
  endingChar = chalk.gray(']'),
  total = 10,
}) => {
  const MAX_SCREEN_LENGTH = 10;
  const barLength = total > MAX_SCREEN_LENGTH ? MAX_SCREEN_LENGTH : total;
  const getCompleteness = progress => Math.round((barLength * progress) / total);
  let currentProgress = 0;

  const fillProgress = () => fillChar.repeat(getCompleteness(currentProgress));
  const fillSpace = () => bgChar.repeat(barLength - getCompleteness(currentProgress));

  const spinner = ora();
  // mutation of spinner text causes it to update
  const updateProgress = text => (spinner.text = text);

  const appendedLines = [];
  const executionTimes = [];
  let timeOfLastTick;

  return {
    tick() {
      let prependedHeader = '';
      // const normalizedProgress = getNormalizedProgress(currentProgress);

      // start the spinner on first tick
      if (currentProgress === 0) {
        spinner.start();
      } else {
        const [, nanoseconds] = process.hrtime(timeOfLastTick);
        const timeBetweenTwoTicksInMs = nanoseconds / 1e6;
        executionTimes.push(timeBetweenTwoTicksInMs);

        const mean = R.mean(executionTimes);
        const roundMeanStr = `${Math.round(mean)}ms`;
        const estTimeLeftStr = prettyMs(Math.round((mean * (total - currentProgress)) / 1000));

        prependedHeader = chalk.grey(
          `Avg exec time: ${chalk.white(roundMeanStr)}, est. time left: ` +
            `${chalk.white(estTimeLeftStr)}`,
        );
      }

      currentProgress += 1;

      if (currentProgress >= total) {
        if (spinner.isSpinning) {
          spinner.succeed(`${title} 🎉`);
        }

        return;
      }

      const currentProgressFrame =
        `${title}\n` +
        `${currentProgress}/${total} ${startingChar}` +
        `${fillProgress()}${fillSpace()}${endingChar}\n` +
        `${prependedHeader ? `\n${prependedHeader}\n` : ''}` +
        `\n${appendedLines.join('\n')}`;

      timeOfLastTick = process.hrtime();
      updateProgress(currentProgressFrame);
    },

    append(text) {
      appendedLines.push(text);
    },
  };
};

module.exports = createProgressBar;