⚡️(frontend) improve export table width calculation

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to
   - #1282
 - ♻️(backend) fallback to email identifier when no name #1298
 - 🐛(backend) allow ASCII characters in user sub field #1295 
+- ⚡️(frontend) improve fallback width calculation #1333
 
 ### Fixed
 

src/frontend/apps/impress/src/features/docs/doc-export/__tests__/TablePDF.test.tsx

@@ -0,0 +1,64 @@
+import { describe, expect, it } from 'vitest';
+
+import { utilTable } from '../blocks-mapping/tablePDF';
+
+/**
+ * Tests for utilTable utility.
+ * Scenarios covered:
+ *  - All widths specified and below full width
+ *  - Mix of known / unknown widths (fallback distribution)
+ *  - All widths unknown
+ *  - Widths exceeding full table width (clamping & scale=100)
+ *  - Sum exceeding full width without unknowns (no division by zero side-effects)
+ */
+
+describe('utilTable', () => {
+  it('returns unchanged widths and correct scale when all widths are known and below full width', () => {
+    const input = [165, 200];
+    const { columnWidths, tableScale } = utilTable(730, input);
+    expect(columnWidths).toEqual(input); // unchanged
+    expect(tableScale).toBe(50);
+  });
+
+  it('distributes fallback width equally among unknown columns', () => {
+    const input: (number | undefined)[] = [100, undefined, 200, undefined];
+    const { columnWidths, tableScale } = utilTable(730, input);
+    expect(columnWidths).toEqual([100, 215, 200, 215]);
+    expect(tableScale).toBe(100); // fills full width exactly
+  });
+
+  it('handles all columns unknown', () => {
+    const input: (number | undefined)[] = [undefined, undefined];
+    const { columnWidths, tableScale } = utilTable(730, input);
+    expect(columnWidths).toEqual([365, 365]);
+    expect(tableScale).toBe(100);
+  });
+
+  it('clamps total width to full width when sum exceeds it (single large column)', () => {
+    const input = [800];
+    const { columnWidths, tableScale } = utilTable(730, input);
+    expect(columnWidths).toEqual([800]);
+    expect(tableScale).toBe(100);
+  });
+
+  it('clamps total width to full width when multiple columns exceed it', () => {
+    const input = [500, 300]; // sum = 800 > 730
+    const { columnWidths, tableScale } = utilTable(730, input);
+    expect(columnWidths).toEqual([500, 300]);
+    expect(tableScale).toBe(100);
+  });
+
+  it('does not assign fallback when there are no unknown widths (avoid division by zero impact)', () => {
+    const input = [400, 400];
+    const { columnWidths, tableScale } = utilTable(730, input);
+    expect(columnWidths).toEqual([400, 400]);
+    expect(tableScale).toBe(100);
+  });
+
+  it('computes proportional scale with custom fullWidth', () => {
+    const input = [100, 200]; // total 300
+    const { columnWidths, tableScale } = utilTable(1000, input);
+    expect(columnWidths).toEqual([100, 200]);
+    expect(tableScale).toBe(30);
+  });
+});

src/frontend/apps/impress/src/features/docs/doc-export/blocks-mapping/tablePDF.tsx

@@ -13,6 +13,7 @@ import { StyleSheet, Text } from '@react-pdf/renderer';
 
 import { DocsExporterPDF } from '../types';
 const PIXELS_PER_POINT = 0.75;
+const FULL_WIDTH = 730;
 const styles = StyleSheet.create({
   tableContainer: {
     border: '1px solid #ddd',
@@ -47,16 +48,10 @@ export const blockMappingTablePDF: DocsExporterPDF['mappings']['blockMapping']['
       true,
     ) as boolean[];
 
-    /**
-     * Calculate the table scale based on the column widths.
-     */
-    const columnWidths = blockContent.columnWidths.map((w) => w || 120);
-    const fullWidth = 730;
-    const totalWidth = Math.min(
-      columnWidths.reduce((sum, w) => sum + w, 0),
-      fullWidth,
+    const { columnWidths, tableScale } = utilTable(
+      FULL_WIDTH,
+      blockContent.columnWidths,
     );
-    const tableScale = (totalWidth * 100) / fullWidth;
 
     return (
       <Table style={[styles.tableContainer, { width: `${tableScale}%` }]}>
@@ -124,3 +119,34 @@ export const blockMappingTablePDF: DocsExporterPDF['mappings']['blockMapping']['
       </Table>
     );
   };
+
+/**
+ * Utility function to calculate the table column widths and scale.
+ * @param columnWidths - Array of column widths.
+ * @returns An object containing the resized column widths and the table scale.
+ */
+export const utilTable = (
+  fullWidth: number,
+  columnWidths: (number | undefined)[],
+) => {
+  const totalColumnWidthKnown = columnWidths.reduce(
+    (sum: number, w) => sum + (w ?? 0),
+    0,
+  );
+  const nbColumnWidthUnknown = columnWidths.filter((w) => !w).length;
+
+  const fallbackWidth =
+    (fullWidth - totalColumnWidthKnown) / nbColumnWidthUnknown;
+
+  const columnWidthsResized = columnWidths.map((w) => w || fallbackWidth);
+  const totalWidth = Math.min(
+    columnWidthsResized.reduce((sum: number, w) => sum + w, 0),
+    fullWidth,
+  );
+  const tableScale = Math.round(((totalWidth * 100) / fullWidth) * 1000) / 1000;
+
+  return {
+    columnWidths: columnWidthsResized,
+    tableScale,
+  };
+};