fix(office): support xlsx date formulas

Co-authored-by: Codex (GPT 5.5) <codex@openai.com>

Author: phodal

docs/issues/2026-05-01-office-document-viewer-wasm-reader.md

@@ -133,6 +133,7 @@ Routa 应能在 session canvas 或 artifact tab 中直接预览 Office 文档（
 - XLSX conditional formula evaluation now supports multi-condition aggregate helpers `AVERAGEIFS`, `MINIFS`, and `MAXIFS` on sparse ranges.
 - XLSX conditional formula evaluation now supports lookup helpers `INDEX`, `MATCH`, `VLOOKUP`, and `XLOOKUP` for threshold-table-driven formatting rules.
 - XLSX conditional formula evaluation now supports statistical/ranking helpers `COUNTA`, `COUNTBLANK`, `MEDIAN`, `LARGE`, `SMALL`, `RANK`, `RANK.EQ`, `PERCENTILE`, and `PERCENTILE.INC`.
+- XLSX conditional formula evaluation now supports date boundary and working-day helpers `EDATE`, `EOMONTH`, `NETWORKDAYS`, `WORKDAY`, and `DATEDIF`.
 
 ## Codex 技术方案逆向分析
 

src/app/debug/office-wasm-poc/__tests__/spreadsheet-conditional-visuals.test.ts

@@ -1252,6 +1252,84 @@ describe("spreadsheet conditional visuals", () => {
     expect(visuals.get("4:3")?.background).toBe("#BBF7D0");
   });
 
+  it("evaluates date boundary and working-day helpers in conditional format formulas", () => {
+    const visuals = buildSpreadsheetConditionalVisuals({
+      conditionalFormattings: [
+        {
+          ranges: ["A2:A5"],
+          rules: [
+            {
+              fillColor: "BAE6FD",
+              formulas: ["=EOMONTH(A2,0)=DATE(2026,5,31)"],
+              type: "expression",
+            },
+          ],
+        },
+        {
+          ranges: ["B2:B5"],
+          rules: [
+            {
+              fillColor: "FDE68A",
+              formulas: ["=AND(MONTH(EDATE(B2,1))=6,DAY(EDATE(B2,1))=4)"],
+              type: "expression",
+            },
+          ],
+        },
+        {
+          ranges: ["C2:C5"],
+          rules: [
+            {
+              fillColor: "DDD6FE",
+              formulas: ["=NETWORKDAYS(C2,D2,$E$2:$E$2)<=4"],
+              type: "expression",
+            },
+          ],
+        },
+        {
+          ranges: ["F2:F5"],
+          rules: [
+            {
+              fillColor: "BBF7D0",
+              formulas: ["=WORKDAY(F2,5,$E$2:$E$2)=DATE(2026,5,12)"],
+              type: "expression",
+            },
+          ],
+        },
+        {
+          ranges: ["G2:G5"],
+          rules: [
+            {
+              fillColor: "FECACA",
+              formulas: ["=DATEDIF(G2,H2,\"D\")>5"],
+              type: "expression",
+            },
+          ],
+        },
+      ],
+      rows: [
+        { cells: [{ address: "A2", value: 46146 }, { address: "B2", value: 46146 }, { address: "C2", value: 46146 }, { address: "D2", value: 46150 }, { address: "E2", value: 46148 }, { address: "F2", value: 46146 }, { address: "G2", value: 46146 }, { address: "H2", value: 46152 }], index: 2 },
+        { cells: [{ address: "A3", value: 46177 }, { address: "B3", value: 46177 }, { address: "C3", value: 46146 }, { address: "D3", value: 46153 }, { address: "F3", value: 46147 }, { address: "G3", value: 46146 }, { address: "H3", value: 46150 }], index: 3 },
+        { cells: [{ address: "A4", value: 45778 }, { address: "B4", value: 45778 }, { address: "C4", value: 46149 }, { address: "D4", value: 46150 }, { address: "F4", value: 46146 }, { address: "G4", value: 46146 }, { address: "H4", value: 46151 }], index: 4 },
+      ],
+    });
+
+    expect(visuals.get("2:0")?.background).toBe("#BAE6FD");
+    expect(visuals.get("3:0")).toBeUndefined();
+    expect(visuals.get("4:0")).toBeUndefined();
+    expect(visuals.get("2:1")?.background).toBe("#FDE68A");
+    expect(visuals.get("3:1")).toBeUndefined();
+    expect(visuals.get("4:1")).toBeUndefined();
+    expect(visuals.get("2:2")?.background).toBe("#DDD6FE");
+    expect(visuals.get("3:2")).toBeUndefined();
+    expect(visuals.get("4:2")?.background).toBe("#DDD6FE");
+    expect(visuals.get("2:5")?.background).toBe("#BBF7D0");
+    expect(visuals.get("3:5")).toBeUndefined();
+    expect(visuals.get("4:5")?.background).toBe("#BBF7D0");
+    expect(visuals.get("2:6")?.background).toBe("#FECACA");
+    expect(visuals.get("3:6")).toBeUndefined();
+    expect(visuals.get("4:6")).toBeUndefined();
+  });
+
   it("evaluates arithmetic and rounding helpers in conditional format formulas", () => {
     const visuals = buildSpreadsheetConditionalVisuals({
       conditionalFormattings: [

src/app/debug/office-wasm-poc/spreadsheet-conditional-formula.ts

@@ -312,6 +312,39 @@ function evaluateFormulaFunction(name: string, args: string[], context: Conditio
     }
     return Number.NaN;
   }
+  if (normalizedName === "EDATE") {
+    return addExcelSerialMonths(
+      Number(evaluateFormulaValue(args[0] ?? "", context)),
+      Number(evaluateFormulaValue(args[1] ?? "0", context)),
+    );
+  }
+  if (normalizedName === "EOMONTH") {
+    return endOfExcelSerialMonth(
+      Number(evaluateFormulaValue(args[0] ?? "", context)),
+      Number(evaluateFormulaValue(args[1] ?? "0", context)),
+    );
+  }
+  if (normalizedName === "NETWORKDAYS") {
+    return networkDaysFormulaNumber(
+      Number(evaluateFormulaValue(args[0] ?? "", context)),
+      Number(evaluateFormulaValue(args[1] ?? "", context)),
+      formulaNumericArgs([args[2] ?? ""], context),
+    );
+  }
+  if (normalizedName === "WORKDAY") {
+    return workdayFormulaNumber(
+      Number(evaluateFormulaValue(args[0] ?? "", context)),
+      Number(evaluateFormulaValue(args[1] ?? "", context)),
+      formulaNumericArgs([args[2] ?? ""], context),
+    );
+  }
+  if (normalizedName === "DATEDIF") {
+    return datedifFormulaNumber(
+      Number(evaluateFormulaValue(args[0] ?? "", context)),
+      Number(evaluateFormulaValue(args[1] ?? "", context)),
+      asString(evaluateFormulaValue(args[2] ?? "\"D\"", context)),
+    );
+  }
   if (normalizedName === "YEAR" || normalizedName === "MONTH" || normalizedName === "DAY" || normalizedName === "WEEKDAY") {
     return excelSerialDatePart(Number(evaluateFormulaValue(args[0] ?? "", context)), normalizedName, Number(evaluateFormulaValue(args[1] ?? "1", context)));
   }
@@ -879,9 +912,14 @@ function excelSerialDay(year: number, month: number, day: number): number {
   return Math.floor((Date.UTC(year, month - 1, day) - EXCEL_SERIAL_EPOCH_UTC) / DAY_MS);
 }
 
+function excelSerialUtcDate(value: number): Date | null {
+  if (!Number.isFinite(value)) return null;
+  return new Date(EXCEL_SERIAL_EPOCH_UTC + Math.floor(value) * DAY_MS);
+}
+
 function excelSerialDatePart(value: number, part: string, weekdayReturnType: number): number {
-  if (!Number.isFinite(value)) return Number.NaN;
-  const date = new Date(EXCEL_SERIAL_EPOCH_UTC + Math.floor(value) * DAY_MS);
+  const date = excelSerialUtcDate(value);
+  if (!date) return Number.NaN;
   if (part === "YEAR") return date.getUTCFullYear();
   if (part === "MONTH") return date.getUTCMonth() + 1;
   if (part === "DAY") return date.getUTCDate();
@@ -891,6 +929,78 @@ function excelSerialDatePart(value: number, part: string, weekdayReturnType: num
   return weekday + 1;
 }
 
+function addExcelSerialMonths(value: number, months: number): number {
+  const date = excelSerialUtcDate(value);
+  if (!date || !Number.isFinite(months)) return Number.NaN;
+  const targetMonthIndex = date.getUTCMonth() + Math.trunc(months);
+  const targetYear = date.getUTCFullYear() + Math.floor(targetMonthIndex / 12);
+  const targetMonth = modulo(targetMonthIndex, 12) + 1;
+  const targetDay = Math.min(date.getUTCDate(), daysInUtcMonth(targetYear, targetMonth));
+  return excelSerialDay(targetYear, targetMonth, targetDay);
+}
+
+function endOfExcelSerialMonth(value: number, months: number): number {
+  const date = excelSerialUtcDate(value);
+  if (!date || !Number.isFinite(months)) return Number.NaN;
+  const targetMonthIndex = date.getUTCMonth() + Math.trunc(months);
+  const targetYear = date.getUTCFullYear() + Math.floor(targetMonthIndex / 12);
+  const targetMonth = modulo(targetMonthIndex, 12) + 1;
+  return excelSerialDay(targetYear, targetMonth, daysInUtcMonth(targetYear, targetMonth));
+}
+
+function networkDaysFormulaNumber(startValue: number, endValue: number, holidays: number[]): number {
+  if (!Number.isFinite(startValue) || !Number.isFinite(endValue)) return Number.NaN;
+  const start = Math.floor(startValue);
+  const end = Math.floor(endValue);
+  const direction = start <= end ? 1 : -1;
+  const holidaySet = new Set(holidays.map(Math.floor));
+  let count = 0;
+  for (let serial = start; direction > 0 ? serial <= end : serial >= end; serial += direction) {
+    if (isExcelWorkingDay(serial, holidaySet)) count += direction;
+  }
+  return count;
+}
+
+function workdayFormulaNumber(startValue: number, daysValue: number, holidays: number[]): number {
+  if (!Number.isFinite(startValue) || !Number.isFinite(daysValue)) return Number.NaN;
+  const direction = daysValue < 0 ? -1 : 1;
+  let remaining = Math.abs(Math.trunc(daysValue));
+  let serial = Math.floor(startValue);
+  const holidaySet = new Set(holidays.map(Math.floor));
+  while (remaining > 0) {
+    serial += direction;
+    if (isExcelWorkingDay(serial, holidaySet)) remaining -= 1;
+  }
+  return serial;
+}
+
+function datedifFormulaNumber(startValue: number, endValue: number, unit: string): number {
+  const start = excelSerialUtcDate(startValue);
+  const end = excelSerialUtcDate(endValue);
+  if (!start || !end || endValue < startValue) return Number.NaN;
+  const normalizedUnit = unit.trim().toUpperCase();
+  if (normalizedUnit === "D") return Math.floor(endValue) - Math.floor(startValue);
+
+  const years = end.getUTCFullYear() - start.getUTCFullYear();
+  const monthDelta = years * 12 + end.getUTCMonth() - start.getUTCMonth() - (end.getUTCDate() < start.getUTCDate() ? 1 : 0);
+  if (normalizedUnit === "M") return Math.max(0, monthDelta);
+  if (normalizedUnit === "Y") return Math.max(0, Math.floor(monthDelta / 12));
+  return Number.NaN;
+}
+
+function isExcelWorkingDay(serial: number, holidays: ReadonlySet<number>): boolean {
+  const weekday = excelSerialDatePart(serial, "WEEKDAY", 2);
+  return weekday >= 1 && weekday <= 5 && !holidays.has(serial);
+}
+
+function daysInUtcMonth(year: number, month: number): number {
+  return new Date(Date.UTC(year, month, 0)).getUTCDate();
+}
+
+function modulo(value: number, divisor: number): number {
+  return ((value % divisor) + divisor) % divisor;
+}
+
 function parseFunctionCall(value: string): { args: string[]; name: string } | null {
   const nameMatch = value.match(/^([A-Z][A-Z0-9.]*)\(/i);
   if (!nameMatch || !value.endsWith(")")) return null;