1 files changed, 119 insertions, 0 deletions
diff --git a/app/assets/javascripts/lib/utils/unit_format/formatter_factory.js b/app/assets/javascripts/lib/utils/unit_format/formatter_factory.js
new file mode 100644
index 00000000000..432a9254558
--- /dev/null
+++ b/app/assets/javascripts/lib/utils/unit_format/formatter_factory.js
@@ -0,0 +1,119 @@
+/**
+ * Formats a number as string using `toLocaleString`.
+ *
+ * @param {Number} number to be converted
+ * @param {params} Parameters
+ * @param {params.fractionDigits} Number of decimal digits
+ * to display, defaults to using `toLocaleString` defaults.
+ * @param {params.maxLength} Max output char lenght at the
+ * expense of precision, if the output is longer than this,
+ * the formatter switches to using exponential notation.
+ * @param {params.factor} Value is multiplied by this factor,
+ * useful for value normalization.
+ * @returns Formatted value
+ */
+function formatNumber(
+  value,
+  { fractionDigits = undefined, valueFactor = 1, style = undefined, maxLength = undefined },
+) {
+  if (value === null) {
+    return '';
+  }
+
+  const num = value * valueFactor;
+  const formatted = num.toLocaleString(undefined, {
+    minimumFractionDigits: fractionDigits,
+    maximumFractionDigits: fractionDigits,
+    style,
+  });
+
+  if (maxLength !== undefined && formatted.length > maxLength) {
+    // 123456 becomes 1.23e+8
+    return num.toExponential(2);
+  }
+  return formatted;
+}
+
+/**
+ * Formats a number as a string scaling it up according to units.
+ *
+ * While the number is scaled down, the units are scaled up.
+ *
+ * @param {Array} List of units of the scale
+ * @param {Number} unitFactor - Factor of the scale for each
+ * unit after which the next unit is used scaled.
+ */
+const scaledFormatter = (units, unitFactor = 1000) => {
+  if (unitFactor === 0) {
+    return new RangeError(`unitFactor cannot have the value 0.`);
+  }
+
+  return (value, fractionDigits) => {
+    if (value === null) {
+      return '';
+    }
+    if (
+      value === Number.NEGATIVE_INFINITY ||
+      value === Number.POSITIVE_INFINITY ||
+      Number.isNaN(value)
+    ) {
+      return value.toLocaleString(undefined);
+    }
+
+    let num = value;
+    let scale = 0;
+    const limit = units.length;
+
+    while (Math.abs(num) >= unitFactor) {
+      scale += 1;
+      num /= unitFactor;
+
+      if (scale >= limit) {
+        return 'NA';
+      }
+    }
+
+    const unit = units[scale];
+
+    return `${formatNumber(num, { fractionDigits })}${unit}`;
+  };
+};
+
+/**
+ * Returns a function that formats a number as a string.
+ */
+export const numberFormatter = (style = 'decimal', valueFactor = 1) => {
+  return (value, fractionDigits, maxLength) => {
+    return `${formatNumber(value, { fractionDigits, maxLength, valueFactor, style })}`;
+  };
+};
+
+/**
+ * Returns a function that formats a number as a string with a suffix.
+ */
+export const suffixFormatter = (unit = '', valueFactor = 1) => {
+  return (value, fractionDigits, maxLength) => {
+    const length = maxLength !== undefined ? maxLength - unit.length : undefined;
+    return `${formatNumber(value, { fractionDigits, maxLength: length, valueFactor })}${unit}`;
+  };
+};
+
+/**
+ * Returns a function that formats a number scaled using SI units notation.
+ */
+export const scaledSIFormatter = (unit = '', prefixOffset = 0) => {
+  const fractional = ['y', 'z', 'a', 'f', 'p', 'n', 'µ', 'm'];
+  const multiplicative = ['k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'];
+  const symbols = [...fractional, '', ...multiplicative];
+
+  const units = symbols.slice(fractional.length + prefixOffset).map(prefix => {
+    return `${prefix}${unit}`;
+  });
+
+  if (!units.length) {
+    // eslint-disable-next-line @gitlab/i18n/no-non-i18n-strings
+    throw new RangeError('The unit cannot be converted, please try a different scale');
+  }
+
+  return scaledFormatter(units);
+};