fix(split): extract pages with qpdf and decouple ZIP from output mode

2026-11-07 00:28:39 +01:00 · 2026-06-26 00:32:27 +05:30
parent 71ced499e7
commit d2dc459ba9
3 changed files with 536 additions and 108 deletions
@@ -0,0 +1,148 @@
+import type { QpdfInstanceExtended } from '@/types';
+
+export function parseRangeGroups(
+  input: string,
+  totalPages: number
+): { groups: number[][]; indices: number[] } {
+  const groups: number[][] = [];
+  const indices: number[] = [];
+
+  for (const range of input.split(',')) {
+    const trimmedRange = range.trim();
+    if (!trimmedRange) continue;
+
+    const groupIndices: number[] = [];
+    if (trimmedRange.includes('-')) {
+      const [start, end] = trimmedRange.split('-').map(Number);
+      if (
+        isNaN(start) ||
+        isNaN(end) ||
+        start < 1 ||
+        end > totalPages ||
+        start > end
+      )
+        continue;
+      for (let i = start; i <= end; i++) groupIndices.push(i - 1);
+    } else {
+      const pageNum = Number(trimmedRange);
+      if (isNaN(pageNum) || pageNum < 1 || pageNum > totalPages) continue;
+      groupIndices.push(pageNum - 1);
+    }
+
+    if (groupIndices.length > 0) {
+      groups.push(groupIndices);
+      indices.push(...groupIndices);
+    }
+  }
+
+  return { groups, indices };
+}
+
+export function evenOddIndices(
+  choice: 'even' | 'odd',
+  totalPages: number
+): number[] {
+  const indices: number[] = [];
+  for (let i = 0; i < totalPages; i++) {
+    if (choice === 'even' && (i + 1) % 2 === 0) indices.push(i);
+    if (choice === 'odd' && (i + 1) % 2 !== 0) indices.push(i);
+  }
+  return indices;
+}
+
+export function allPagesIndices(totalPages: number): number[] {
+  return Array.from({ length: totalPages }, (_, i) => i);
+}
+
+export function nTimesGroups(nValue: number, totalPages: number): number[][] {
+  const groups: number[][] = [];
+  const numSplits = Math.ceil(totalPages / nValue);
+  for (let i = 0; i < numSplits; i++) {
+    const startPage = i * nValue;
+    const endPage = Math.min(startPage + nValue - 1, totalPages - 1);
+    groups.push(
+      Array.from(
+        { length: endPage - startPage + 1 },
+        (_, idx) => startPage + idx
+      )
+    );
+  }
+  return groups;
+}
+
+export function bookmarkSplitGroups(
+  splitPages: number[],
+  totalPages: number
+): number[][] {
+  const sorted = [...splitPages].sort((a, b) => a - b);
+  const groups: number[][] = [];
+  for (let i = 0; i < sorted.length; i++) {
+    const startPage = i === 0 ? 0 : sorted[i];
+    const endPage = i < sorted.length - 1 ? sorted[i + 1] - 1 : totalPages - 1;
+    groups.push(
+      Array.from(
+        { length: endPage - startPage + 1 },
+        (_, idx) => startPage + idx
+      )
+    );
+  }
+  return groups;
+}
+
+export function groupFilename(group: number[]): string {
+  const minPage = Math.min(...group) + 1;
+  const maxPage = Math.max(...group) + 1;
+  return minPage === maxPage
+    ? `page-${minPage}.pdf`
+    : `pages-${minPage}-${maxPage}.pdf`;
+}
+
+export function uniqueZipName(
+  name: string,
+  usedNames: Map<string, number>
+): string {
+  const seen = usedNames.get(name);
+  if (seen !== undefined) {
+    usedNames.set(name, seen + 1);
+    return name.replace(/\.pdf$/, `-${seen + 1}.pdf`);
+  }
+  usedNames.set(name, 0);
+  return name;
+}
+
+export function pagesToSpec(indices: number[]): string {
+  return indices.map((index) => index + 1).join(',');
+}
+
+export function extractPagesWithQpdf(
+  qpdf: QpdfInstanceExtended,
+  inputPath: string,
+  indices: number[],
+  outputPath = '/split-output.pdf'
+): Uint8Array {
+  const exitCode = qpdf.callMain([
+    inputPath,
+    '--remove-unreferenced-resources=yes',
+    '--pages',
+    '.',
+    pagesToSpec(indices),
+    '--',
+    outputPath,
+  ]);
+  try {
+    if (exitCode !== 0 && exitCode !== 3) {
+      throw new Error(`Failed to extract pages (qpdf exit code ${exitCode}).`);
+    }
+    const bytes = qpdf.FS.readFile(outputPath, { encoding: 'binary' });
+    if (!bytes || bytes.length === 0) {
+      throw new Error('Page extraction produced an empty PDF.');
+    }
+    return bytes;
+  } finally {
+    try {
+      qpdf.FS.unlink(outputPath);
+    } catch (cleanupError) {
+      console.warn('Failed to clean up qpdf output file:', cleanupError);
+    }
+  }
+}