From 46263e85eb69ab5f85e77f1ba4e3a8911f1cdd1a Mon Sep 17 00:00:00 2001
From: Michal Michalowski <mmichalowski@clickup.com>
Date: Tue, 31 Mar 2026 15:11:04 +0200
Subject: [PATCH] fix(fields): fix NETWORKDAYS for reverse dates and time
 components [CLK-563323]

formulajs NETWORKDAYS has two bugs:
- When start > end, the day-counting loop never runs, returning wrong
  results instead of a negative working-day count
- Date objects with time-of-day produce fractional/off-by-one results
  due to Math.round on the ms difference

Fix by stripping time from Date inputs and computing the forward
result then negating when the initial call returns <= 0.
---
 src/clickup/formulajsProxy.ts                 | 22 +++++++++++++--
 .../parsing/formula/date-time.test.js         | 28 +++++++++++++++++++
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/src/clickup/formulajsProxy.ts b/src/clickup/formulajsProxy.ts
index 86795d5..792b7cb 100644
--- a/src/clickup/formulajsProxy.ts
+++ b/src/clickup/formulajsProxy.ts
@@ -32,8 +32,26 @@ const overrides = {
         hasNil(startDate, endDate) ? Number.NaN : formulajs.YEARFRAC(startDate, endDate, basis),
     WORKDAY: (startDate: unknown, days: unknown, holidays: unknown) =>
         hasNil(startDate) ? Number.NaN : formulajs.WORKDAY(startDate, nilToZero(days), holidays),
-    NETWORKDAYS: (startDate: unknown, endDate: unknown, holidays: unknown) =>
-        hasNil(startDate, endDate) ? Number.NaN : formulajs.NETWORKDAYS(startDate, endDate, holidays),
+    NETWORKDAYS: (startDate: unknown, endDate: unknown, holidays: unknown) => {
+        if (hasNil(startDate, endDate)) return Number.NaN;
+        // Strip time from Date objects. Excel/Sheets ignores time-of-day, but formulajs
+        // uses Math.round on the ms difference which produces fractional results and
+        // off-by-one errors when Date objects have time components. Strings and serial
+        // numbers are unaffected — formulajs.parseDate handles those correctly.
+        const stripTime = (v: unknown): unknown =>
+            v instanceof Date ? new Date(v.getFullYear(), v.getMonth(), v.getDate()) : v;
+        const start = stripTime(startDate);
+        const end = stripTime(endDate);
+        // formulajs NETWORKDAYS doesn't handle start > end: the day-counting loop
+        // never runs when days <= 0, so weekends/holidays aren't subtracted.
+        // Fix by computing the forward result and negating.
+        const result = formulajs.NETWORKDAYS(start, end, holidays);
+        if (typeof result === 'number' && result <= 0) {
+            const reverse = formulajs.NETWORKDAYS(end, start, holidays);
+            if (typeof reverse === 'number' && reverse > 0) return -reverse;
+        }
+        return result;
+    },
 };
 
 export const formulajsProxy = new Proxy(formulajs, {
diff --git a/test/integration/parsing/formula/date-time.test.js b/test/integration/parsing/formula/date-time.test.js
index 4721b1c..af5c62a 100644
--- a/test/integration/parsing/formula/date-time.test.js
+++ b/test/integration/parsing/formula/date-time.test.js
@@ -118,6 +118,34 @@ describe('.parse() date & time formulas', () => {
         expect(parser.parse('NETWORKDAYS(null, "2013-12-05")')).toMatchObject({ error: null, result: Number.NaN });
         expect(parser.parse('NETWORKDAYS("2013-12-05", null)')).toMatchObject({ error: null, result: Number.NaN });
         expect(parser.parse('NETWORKDAYS(null, null)')).toMatchObject({ error: null, result: Number.NaN });
+
+        // Forward: Aug 7 (Wed) to Aug 9 (Fri) — 3 working days inclusive
+        expect(parser.parse('NETWORKDAYS("8/7/2024", "8/9/2024")')).toMatchObject({ error: null, result: 3 });
+
+        // Reverse direction (start > end) — should return negative of forward count
+        expect(parser.parse('NETWORKDAYS("2013-12-05", "2013-12-04")')).toMatchObject({ error: null, result: -2 });
+        expect(parser.parse('NETWORKDAYS("2013-12-05", "2013-11-04")')).toMatchObject({ error: null, result: -24 });
+        expect(parser.parse('NETWORKDAYS("3/1/2013", "10/1/2012", [\'11/22/2012\'])')).toMatchObject({
+            error: null,
+            result: -109,
+        });
+    });
+
+    // Time components in Date objects should be ignored (Excel/Sheets behavior).
+    // ClickUp field values are Date objects that may include time-of-day.
+    it.each([new Parser(), ClickUpParser.create()])('NETWORKDAYS with time components', (parser) => {
+        const vars = {};
+        parser.on('callVariable', (name, done) => done(vars[name]));
+
+        // Aug 7 (Wed) 23:00 → Aug 9 (Fri) 01:00: should be 3, not 2
+        vars.start = new Date(2024, 7, 7, 23, 0, 0);
+        vars.end = new Date(2024, 7, 9, 1, 0, 0);
+        expect(parser.parse('NETWORKDAYS(start, end)')).toMatchObject({ error: null, result: 3 });
+
+        // Aug 7 (Wed) 01:00 → Aug 9 (Fri) 23:00: should be 3, not ~2.9
+        vars.start = new Date(2024, 7, 7, 1, 0, 0);
+        vars.end = new Date(2024, 7, 9, 23, 0, 0);
+        expect(parser.parse('NETWORKDAYS(start, end)')).toMatchObject({ error: null, result: 3 });
     });
 
     it.each([new Parser(), ClickUpParser.create()])('NOW', (parser) => {