text: import {isArray} from '../helpers/helpers.core';
  import {log10} from '../helpers/helpers.math';
  
  /**
   * Namespace to hold formatters for different types of ticks
   * @namespace Chart.Ticks.formatters
   */
  const formatters = {
  	/**
  	 * Formatter for value labels
  	 * @method Chart.Ticks.formatters.values
  	 * @param value the value to display
  	 * @return {string|string[]} the label to display
  	 */
  	values(value) {
  		return isArray(value) ? value : '' + value;
  	},
  
  	/**
  	 * Formatter for numeric ticks
  	 * @method Chart.Ticks.formatters.numeric
  	 * @param tickValue {number} the value to be formatted
  	 * @param index {number} the position of the tickValue parameter in the ticks array
  	 * @param ticks {object[]} the list of ticks being converted
  	 * @return {string} string representation of the tickValue parameter
  	 */
  	numeric(tickValue, index, ticks) {
  		if (tickValue === 0) {
  			return '0'; // never show decimal places for 0
  		}
  
  		const locale = this.chart.options.locale;
  
  		// all ticks are small or there huge numbers; use scientific notation
  		const maxTick = Math.max(Math.abs(ticks[0].value), Math.abs(ticks[ticks.length - 1].value));
  		let notation;
  		if (maxTick < 1e-4 || maxTick > 1e+15) {
  			notation = 'scientific';
  		}
  
  		// Figure out how many digits to show
  		// The space between the first two ticks might be smaller than normal spacing
  		let delta = ticks.length > 3 ? ticks[2].value - ticks[1].value : ticks[1].value - ticks[0].value;
  
  		// If we have a number like 2.5 as the delta, figure out how many decimal places we need
  		if (Math.abs(delta) > 1 && tickValue !== Math.floor(tickValue)) {
  			// not an integer
  			delta = tickValue - Math.floor(tickValue);
  		}
  
  		const logDelta = log10(Math.abs(delta));
  		const numDecimal = Math.max(Math.min(-1 * Math.floor(logDelta), 20), 0); // toFixed has a max of 20 decimal places
  
  		const options = {notation, minimumFractionDigits: numDecimal, maximumFractionDigits: numDecimal};
  		Object.assign(options, this.options.ticks.format);
  
  		// @ts-ignore until TypeScript 4.0 because "notation" was previously experimental API
  		return new Intl.NumberFormat(locale, options).format(tickValue);
  	}
  };
  
  /**
   * Formatter for logarithmic ticks
   * @method Chart.Ticks.formatters.logarithmic
   * @param tickValue {number} the value to be formatted
   * @param index {number} the position of the tickValue parameter in the ticks array
   * @param ticks {object[]} the list of ticks being converted
   * @return {string} string representation of the tickValue parameter
   */
  formatters.logarithmic = function(tickValue, index, ticks) {
  	if (tickValue === 0) {
  		return '0';
  	}
  	const remain = tickValue / (Math.pow(10, Math.floor(log10(tickValue))));
  	if (remain === 1 || remain === 2 || remain === 5) {
  		return formatters.numeric.call(this, tickValue, index, ticks);
  	}
  	return '';
  };
  
  /**
   * Namespace to hold static tick generation functions
   * @namespace Chart.Ticks
   */
  export default {formatters};
  