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index.js
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/* eslint-disable prefer-promise-reject-errors */
// node-pdf
const path = require('path');
const fs = require('fs');
const util = require('util');
const { exec } = require('child_process');
function PDFImage(pdfFilePath, options = {}) {
this.pdfFilePath = pdfFilePath;
this.setPdfFileBaseName(options.pdfFileBaseName);
this.setConvertOptions(options.convertOptions);
this.setConvertExtension(options.convertExtension);
this.useGM = options.graphicsMagick || false;
this.combinedImage = options.combinedImage || false;
this.outputDirectory = options.outputDirectory || path.dirname(pdfFilePath);
}
PDFImage.prototype = {
constructGetInfoCommand() {
return util.format(
'pdfinfo "%s"',
this.pdfFilePath,
);
},
parseGetInfoCommandOutput(output) {
const info = {};
output.split('\n').forEach((line) => {
if (line.match(/^(.*?):[ \t]*(.*)$/)) {
info[RegExp.$1] = RegExp.$2;
}
});
return info;
},
getInfo() {
const self = this;
const getInfoCommand = this.constructGetInfoCommand();
const promise = new Promise((resolve, reject) => {
exec(getInfoCommand, (err, stdout, stderr) => {
if (err) {
return reject({
message: "Failed to get PDF'S information",
error: err,
stdout,
stderr,
});
}
return resolve(self.parseGetInfoCommandOutput(stdout));
});
});
return promise;
},
numberOfPages() {
return this.getInfo().then((info) => info.Pages);
},
getOutputImagePathForPage(pageNumber) {
return path.join(
this.outputDirectory,
`${this.pdfFileBaseName}-${pageNumber}.${this.convertExtension}`,
);
},
getOutputImagePathForFile() {
return path.join(
this.outputDirectory,
`${this.pdfFileBaseName}.${this.convertExtension}`,
);
},
setConvertOptions(convertOptions) {
this.convertOptions = convertOptions || {};
},
setPdfFileBaseName(pdfFileBaseName) {
this.pdfFileBaseName = pdfFileBaseName || path.basename(this.pdfFilePath, '.pdf');
},
setConvertExtension(convertExtension) {
this.convertExtension = convertExtension || 'png';
},
constructConvertCommandForPage(pageNumber) {
const { pdfFilePath } = this;
const outputImagePath = this.getOutputImagePathForPage(pageNumber);
const convertOptionsString = this.constructConvertOptions();
return util.format(
'%s %s"%s[%d]" "%s"',
this.useGM ? 'gm convert' : 'convert',
convertOptionsString ? `${convertOptionsString} ` : '',
pdfFilePath,
pageNumber,
outputImagePath,
);
},
constructCombineCommandForFile(imagePaths) {
return util.format(
'%s -append %s "%s"',
this.useGM ? 'gm convert' : 'convert',
imagePaths.join(' '),
this.getOutputImagePathForFile(),
);
},
constructConvertOptions() {
return Object.keys(this.convertOptions).sort().map((optionName) => {
if (this.convertOptions[optionName] !== null) {
return `${optionName} ${this.convertOptions[optionName]}`;
}
return optionName;
}, this).join(' ');
},
combineImages(imagePaths) {
const pdfImage = this;
const combineCommand = pdfImage.constructCombineCommandForFile(imagePaths);
return new Promise((resolve, reject) => {
exec(combineCommand, (err, stdout, stderr) => {
if (err) {
return reject({
message: 'Failed to combine images',
error: err,
stdout,
stderr,
});
}
exec(`rm ${imagePaths.join(' ')}`); // cleanUp
return resolve(pdfImage.getOutputImagePathForFile());
});
});
},
convertFile() {
const pdfImage = this;
return new Promise((resolve, reject) => {
pdfImage.numberOfPages().then((totalPages) => {
// eslint-disable-next-line no-shadow
const convertPromise = new Promise((resolve, reject) => {
const imagePaths = [];
for (let i = 0; i < totalPages; i += 1) {
pdfImage.convertPage(i).then((imagePath) => {
imagePaths.push(imagePath);
if (imagePaths.length === parseInt(totalPages, 10)) {
imagePaths.sort(); // because of asyc pages we have to reSort pages
resolve(imagePaths);
}
}).catch((error) => {
reject(error);
});
}
});
convertPromise.then((imagePaths) => {
if (pdfImage.combinedImage) {
pdfImage.combineImages(imagePaths).then((imagePath) => {
resolve(imagePath);
});
} else {
resolve(imagePaths);
}
}).catch((error) => {
reject(error);
});
});
});
},
convertPage(pageNumber) {
const { pdfFilePath } = this;
const outputImagePath = this.getOutputImagePathForPage(pageNumber);
const convertCommand = this.constructConvertCommandForPage(pageNumber);
const promise = new Promise((resolve, reject) => {
function convertPageToImage() {
exec(convertCommand, (err, stdout, stderr) => {
if (err) {
return reject({
message: 'Failed to convert page to image',
error: err,
stdout,
stderr,
});
}
return resolve(outputImagePath);
});
}
fs.stat(outputImagePath, (err, imageFileStat) => {
const imageNotExists = err && err.code === 'ENOENT';
if (!imageNotExists && err) {
return reject({
message: 'Failed to stat image file',
error: err,
});
}
// convert when (1) image doesn't exits or (2) image exists
// but its timestamp is older than pdf's one
if (imageNotExists) {
// (1)
convertPageToImage();
return null;
}
// image exist. check timestamp.
fs.stat(pdfFilePath, (error, pdfFileStat) => {
if (err) {
return reject({
message: 'Failed to stat PDF file',
error,
});
}
if (imageFileStat.mtime < pdfFileStat.mtime) {
// (2)
convertPageToImage();
return null;
}
return resolve(outputImagePath);
});
return null;
});
});
return promise;
},
};
exports.PDFImage = PDFImage;