From 8e896461c2f1bda64e5a9a1781acab9b11f879ff Mon Sep 17 00:00:00 2001
From: bcolloran <brendan@colloran.net>
Date: Fri, 8 Dec 2023 13:54:14 -0800
Subject: [PATCH] Make `formatMsInterval` tighter and add tests (#3669)

* make formatMsInterval tighter and add tests

* cleanup
---
 .../strategies/intervals.spec.ts              | 150 ++++++++++++++++++
 .../number-formatting/strategies/intervals.ts |  76 +++++----
 2 files changed, 187 insertions(+), 39 deletions(-)
 create mode 100644 web-common/src/lib/number-formatting/strategies/intervals.spec.ts

diff --git a/web-common/src/lib/number-formatting/strategies/intervals.spec.ts b/web-common/src/lib/number-formatting/strategies/intervals.spec.ts
new file mode 100644
index 00000000000..cc3f9fbea3c
--- /dev/null
+++ b/web-common/src/lib/number-formatting/strategies/intervals.spec.ts
@@ -0,0 +1,150 @@
+import { describe, it, expect } from "vitest";
+import { formatMsInterval } from "./intervals";
+
+const nonNumericTestCases = [
+  null,
+  undefined,
+  "foo",
+  false,
+  [1, 2, true],
+  { foo: 6, bar: 7 },
+  new Date("1999-9-9"),
+  BigInt(1e300),
+  new Map(),
+  new Set(),
+  new WeakMap(),
+  new WeakSet(),
+  Symbol("foo"),
+  () => "blah",
+];
+describe("formatMsInterval - non numeric inputs", () => {
+  nonNumericTestCases.forEach((input) => {
+    let inputString;
+    try {
+      inputString = JSON.stringify(input);
+    } catch (error) {
+      //@ts-ignore
+      inputString = input.toString();
+    }
+
+    it(`returns the empty string for non numeric input: ${inputString}`, () => {
+      expect(formatMsInterval(input as unknown as number)).toEqual("");
+    });
+  });
+});
+
+const MS = 1;
+const SEC = 1000 * MS;
+const MIN = 60 * SEC;
+const HOUR = 60 * MIN;
+const DAY = 24 * HOUR;
+const MONTH = 30 * DAY; //eslint-disable-line
+const YEAR = 365 * DAY; //eslint-disable-line
+
+const time_formula_normal_cases = [
+  ["1.797", "1.8 ms"],
+  ["123.7989", "0.12 s"],
+  ["793.987", "0.79 s"],
+  ["100.9797", "0.1 s"],
+  ["1 * SEC", "1 s"],
+  ["1.4709879 * SEC", "1.5 s"],
+  ["9.49797 * SEC", "9.5 s"],
+  ["10 * SEC", "10 s"],
+  ["59 * SEC", "59 s"],
+  ["1 * MIN", "60 s"],
+  ["99.9 * SEC", "1.7 m"],
+  ["100 * SEC", "1.7 m"],
+  ["59.23451 * MIN", "59 m"],
+  ["89.411 * MIN", "89 m"],
+  ["89.94353 * MIN", "90 m"],
+  ["99 * MIN", "1.7 h"],
+  ["99.9 * MIN", "1.7 h"],
+  ["100 * MIN", "1.7 h"],
+  ["71.936 * HOUR", "72 h"],
+  ["72 * HOUR", "3 d"],
+  ["99 * HOUR", "4.1 d"],
+  ["89.9 * DAY", "90 d"],
+  ["90 * DAY", "3 mon"],
+  ["99 * DAY", "3.3 mon"],
+  ["7.87978 * MONTH", "7.9 mon"],
+  ["17.923 * MONTH", "18 mon"],
+  ["18 * MONTH", "1.5 y"],
+  ["18.0234234 * MONTH", "1.5 y"],
+  ["36 * MONTH", "3 y"],
+  ["3247 * DAY", "8.9 y"],
+  ["43.34523 * YEAR", "43 y"],
+  ["99 * YEAR", "99 y"],
+  ["99 * YEAR + 6 * SEC", "99 y"],
+  ["99 * YEAR + 6.0004 * SEC", "99 y"],
+  ["99 * YEAR + 6.99999 * SEC", "99 y"],
+  ["99.9 * YEAR", "100 y"],
+];
+
+describe("formatMsInterval - normal cases", () => {
+  time_formula_normal_cases.forEach(([input, output]) => {
+    const ms = eval(input);
+    it(`return "${output}" for input: ${ms.toString()}ms (${input})`, () => {
+      expect(formatMsInterval(ms)).toEqual(output);
+    });
+  });
+});
+
+describe("formatMsInterval - normal cases, negative", () => {
+  time_formula_normal_cases.forEach(([input, output]) => {
+    const ms = -eval(input);
+    it(`return "${output}" for input: ${ms.toString()}ms (${input})`, () => {
+      expect(formatMsInterval(ms)).toEqual("-" + output);
+    });
+  });
+});
+
+const time_formula_special_cases = [
+  ["0", "0 s"],
+  ["0.0011797", "~0 s"],
+  ["0.01231", "~0 s"],
+  ["100.234 * YEAR", ">100 y"],
+  ["123797.239797 * YEAR", ">100 y"],
+  ["123797.239797 * YEAR", ">100 y"],
+  ["123797.239797 * YEAR", ">100 y"],
+
+  // infinitesimals
+  [0.9, "~0 s"],
+  [0.095, "~0 s"],
+  [0.0095, "~0 s"],
+  [0.001, "~0 s"],
+  [0.00095, "~0 s"],
+  [0.000999999, "~0 s"],
+  [0.00012335234, "~0 s"],
+  [0.000_000_999999, "~0 s"],
+  [0.000_000_02341253, "~0 s"],
+  [0.000_000_000_999999, "~0 s"],
+
+  // negative infinitesimals
+  [-0.9, "~0 s"],
+  [-0.095, "~0 s"],
+  [-0.0095, "~0 s"],
+  [-0.001, "~0 s"],
+  [-0.00095, "~0 s"],
+  [-0.000999999, "~0 s"],
+  [-0.00012335234, "~0 s"],
+  [-0.000_000_999999, "~0 s"],
+  [-0.000_000_02341253, "~0 s"],
+  [-0.000_000_000_999999, "~0 s"],
+
+  // huge numbers
+  [1e19, ">100 y"],
+  [3.2e12, ">100 y"],
+
+  // hugely negative numbers
+  [-1e19, "< -100 y"],
+  [-3.2e12, "< -100 y"],
+];
+
+describe("formatMsInterval - special cases", () => {
+  time_formula_special_cases.forEach(([input, output]) => {
+    const ms = eval(input.toString());
+    it(`return "${output}" for input: ${ms.toString()}ms (${input})`, () => {
+      expect(formatMsInterval(ms)).toEqual(output);
+    });
+  });
+});
diff --git a/web-common/src/lib/number-formatting/strategies/intervals.ts b/web-common/src/lib/number-formatting/strategies/intervals.ts
index a7a788a65e1..57d805e9e4d 100644
--- a/web-common/src/lib/number-formatting/strategies/intervals.ts
+++ b/web-common/src/lib/number-formatting/strategies/intervals.ts
@@ -24,19 +24,6 @@ const timeUnits = {
   y: "y",
 };
 
-const ms_breakpoints = [
-  { ms: 0 },
-  { ms: 1 },
-  { ms: 100, divisor: 1, unit: timeUnits.ms },
-  { ms: 90 * MS_PER_SEC, divisor: MS_PER_SEC, unit: timeUnits.s },
-  { ms: 90 * MS_PER_MIN, divisor: MS_PER_MIN, unit: timeUnits.m },
-  { ms: 72 * MS_PER_HOUR, divisor: MS_PER_HOUR, unit: timeUnits.h },
-  { ms: 90 * MS_PER_DAY, divisor: MS_PER_DAY, unit: timeUnits.d },
-  { ms: 18 * MS_PER_MONTH, divisor: MS_PER_MONTH, unit: timeUnits.mon },
-  { ms: 100 * MS_PER_YEAR, divisor: MS_PER_YEAR, unit: timeUnits.y },
-  { ms: Infinity, unit: "TOO_LARGE" },
-];
-
 // TODO: Rewrite this to use the sample and provided options
 export class IntervalFormatter implements Formatter {
   options: FormatterOptionsCommon & FormatterRangeSpecsStrategy;
@@ -74,37 +61,48 @@ export function formatMsInterval(ms: number): string {
     // );
     return "";
   }
-  let negative = false;
-  if (ms < 0) {
-    ms = -ms;
-    negative = true;
-  }
-
-  if (ms === 0) {
-    return `0 ${timeUnits.s}`;
-  } else if (ms < 1) {
-    return `~0 ${timeUnits.s}`;
-  } else if (ms >= 100 * MS_PER_YEAR) {
-    return negative ? `< -100 ${timeUnits.y}` : `>100 ${timeUnits.y}`;
-  }
-
-  const i = ms_breakpoints.findIndex((b) => ms < b.ms);
-
-  const breakpoint = ms_breakpoints[i];
 
-  if (breakpoint.unit === "TOO_LARGE") {
-    return `>100 ${timeUnits.y}`;
-  }
-
-  const unit = breakpoint.unit;
-  const value = ms / breakpoint.divisor;
-  const fmt = Intl.NumberFormat("en-US", {
+  const format = Intl.NumberFormat("en-US", {
     maximumFractionDigits: 1,
     minimumFractionDigits: 0,
     maximumSignificantDigits: 2,
-  }).format(value);
+  }).format;
+
+  let neg: "" | "-" = "";
+  if (ms < 0) {
+    ms = -ms;
+    neg = "-";
+  }
 
-  return `${negative ? "-" : ""}${fmt} ${unit}`;
+  switch (true) {
+    case ms < 0:
+      // THIS SHOULD NEVER HAPPEN, any negative values should
+      // have been made positive above.
+      console.warn(
+        `formatMsInterval: negative value ${ms} was not converted to positive.`
+      );
+      return "0 ms";
+    case ms === 0:
+      return `0 ${timeUnits.s}`;
+    case ms < 1:
+      return `~0 ${timeUnits.s}`;
+    case ms < 100:
+      return `${neg}${format(ms)} ${timeUnits.ms}`;
+    case ms < 90 * MS_PER_SEC:
+      return `${neg}${format(ms / MS_PER_SEC)} ${timeUnits.s}`;
+    case ms < 90 * MS_PER_MIN:
+      return `${neg}${format(ms / MS_PER_MIN)} ${timeUnits.m}`;
+    case ms < 72 * MS_PER_HOUR:
+      return `${neg}${format(ms / MS_PER_HOUR)} ${timeUnits.h}`;
+    case ms < 90 * MS_PER_DAY:
+      return `${neg}${format(ms / MS_PER_DAY)} ${timeUnits.d}`;
+    case ms < 18 * MS_PER_MONTH:
+      return `${neg}${format(ms / MS_PER_MONTH)} ${timeUnits.mon}`;
+    case ms < 100 * MS_PER_YEAR:
+      return `${neg}${format(ms / MS_PER_YEAR)} ${timeUnits.y}`;
+    default:
+      return neg === "-" ? `< -100 ${timeUnits.y}` : `>100 ${timeUnits.y}`;
+  }
 }
 
 /**