135 lines
3.6 KiB
JavaScript
135 lines
3.6 KiB
JavaScript
/**
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* pdf-utils.js — Thin wrappers around poppler-utils CLI tools.
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*
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* Uses pdfinfo + pdftoppm (from poppler-utils) for PDF metadata extraction
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* and page rendering. No external Node dependencies required.
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*/
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const { execFile } = require('child_process');
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const { promisify } = require('util');
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const fs = require('fs');
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const os = require('os');
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const path = require('path');
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const execFileAsync = promisify(execFile);
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const TIMEOUT_MS = 60_000;
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/**
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* Write a buffer to a temporary file. Returns { tmpPath, cleanup }.
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* Caller MUST call cleanup() when done.
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*/
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function bufferToTempFile(buffer, ext = '.bin') {
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const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'refboard-pdf-'));
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const tmpPath = path.join(tmpDir, `file${ext}`);
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fs.writeFileSync(tmpPath, buffer);
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return {
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tmpPath,
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cleanup() {
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try { fs.unlinkSync(tmpPath); } catch {}
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try { fs.rmdirSync(tmpDir); } catch {}
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},
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};
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}
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/**
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* Extract PDF metadata via pdfinfo.
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* Returns { pageCount, dimensions: [{ w, h }, ...] }
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*/
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async function pdfInfo(filePath) {
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// Get basic info (page count)
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const { stdout: basicOut } = await execFileAsync('pdfinfo', [filePath], { timeout: TIMEOUT_MS });
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let pageCount = 0;
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for (const line of basicOut.split('\n')) {
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const match = line.match(/^Pages:\s+(\d+)/);
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if (match) {
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pageCount = parseInt(match[1], 10);
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break;
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}
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}
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if (pageCount === 0) {
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throw new Error('Could not determine PDF page count');
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}
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// Get per-page dimensions
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const dimensions = [];
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const { stdout: dimOut } = await execFileAsync(
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'pdfinfo',
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['-f', '1', '-l', String(pageCount), filePath],
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{ timeout: TIMEOUT_MS }
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);
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// Parse "Page N size: W x H pts" lines
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for (const line of dimOut.split('\n')) {
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const match = line.match(/^Page\s+\d+\s+size:\s+([\d.]+)\s+x\s+([\d.]+)/);
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if (match) {
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dimensions.push({
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w: Math.round(parseFloat(match[1])),
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h: Math.round(parseFloat(match[2])),
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});
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}
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}
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// Fallback: if no per-page sizes found, try global "Page size:"
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if (dimensions.length === 0) {
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for (const line of basicOut.split('\n')) {
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const match = line.match(/^Page size:\s+([\d.]+)\s+x\s+([\d.]+)/);
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if (match) {
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const dim = {
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w: Math.round(parseFloat(match[1])),
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h: Math.round(parseFloat(match[2])),
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};
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for (let i = 0; i < pageCount; i++) {
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dimensions.push(dim);
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}
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break;
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}
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}
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}
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return { pageCount, dimensions };
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}
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/**
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* Render a single PDF page to PNG at the given DPI.
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* Returns a PNG Buffer.
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*/
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async function pdfRenderPage(filePath, pageNum, dpi = 150) {
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const outDir = fs.mkdtempSync(path.join(os.tmpdir(), 'refboard-render-'));
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try {
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const outPrefix = path.join(outDir, 'page');
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await execFileAsync('pdftoppm', [
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'-png',
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'-r', String(dpi),
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'-f', String(pageNum),
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'-l', String(pageNum),
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filePath,
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outPrefix,
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], { timeout: TIMEOUT_MS });
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// pdftoppm names output like page-01.png, page-1.png, etc. — discover it
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const files = fs.readdirSync(outDir).filter(f => f.endsWith('.png'));
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if (files.length === 0) {
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throw new Error(`pdftoppm produced no output for page ${pageNum}`);
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}
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const pngPath = path.join(outDir, files[0]);
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const pngBuffer = fs.readFileSync(pngPath);
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return pngBuffer;
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} finally {
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// Clean up temp dir
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try {
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for (const f of fs.readdirSync(outDir)) {
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fs.unlinkSync(path.join(outDir, f));
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}
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fs.rmdirSync(outDir);
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} catch {}
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}
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}
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module.exports = { pdfInfo, pdfRenderPage, bufferToTempFile };
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