decaffeinate: rename app/coffee dir to app/js

app/js/OutputFileOptimiser.js

@@ -0,0 +1,86 @@
+/* eslint-disable
+    handle-callback-err,
+    no-return-assign,
+    no-undef,
+    no-unused-vars,
+    node/no-deprecated-api,
+*/
+// TODO: This file was created by bulk-decaffeinate.
+// Fix any style issues and re-enable lint.
+/*
+ * decaffeinate suggestions:
+ * DS102: Remove unnecessary code created because of implicit returns
+ * DS207: Consider shorter variations of null checks
+ * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
+ */
+let OutputFileOptimiser;
+const fs = require("fs");
+const Path = require("path");
+const { spawn } = require("child_process");
+const logger = require("logger-sharelatex");
+const Metrics = require("./Metrics");
+const _ = require("underscore");
+
+module.exports = (OutputFileOptimiser = {
+
+	optimiseFile(src, dst, callback) {
+		// check output file (src) and see if we can optimise it, storing
+		// the result in the build directory (dst)
+		if (callback == null) { callback = function(error) {}; }
+		if (src.match(/\/output\.pdf$/)) {
+			return OutputFileOptimiser.checkIfPDFIsOptimised(src, function(err, isOptimised) {
+				if ((err != null) || isOptimised) { return callback(null); }
+				return OutputFileOptimiser.optimisePDF(src, dst, callback);
+			});
+		} else {
+			return callback((null));
+		}
+	},
+
+	checkIfPDFIsOptimised(file, callback) {
+		const SIZE = 16*1024; // check the header of the pdf
+		const result = new Buffer(SIZE);
+		result.fill(0); // prevent leakage of uninitialised buffer
+		return fs.open(file, "r", function(err, fd) {
+			if (err != null) { return callback(err); }
+			return fs.read(fd, result, 0, SIZE, 0, (errRead, bytesRead, buffer) =>
+				fs.close(fd, function(errClose) {
+					if (errRead != null) { return callback(errRead); }
+					if (typeof errReadClose !== 'undefined' && errReadClose !== null) { return callback(errClose); }
+					const isOptimised = buffer.toString('ascii').indexOf("/Linearized 1") >= 0;
+					return callback(null, isOptimised);
+				})
+			);
+		});
+	},
+
+	optimisePDF(src, dst, callback) {
+		if (callback == null) { callback = function(error) {}; }
+		const tmpOutput = dst + '.opt';
+		const args = ["--linearize", src, tmpOutput];
+		logger.log({args}, "running qpdf command");
+
+		const timer = new Metrics.Timer("qpdf");
+		const proc = spawn("qpdf", args);
+		let stdout = "";
+		proc.stdout.on("data", chunk => stdout += chunk.toString());
+		callback = _.once(callback); // avoid double call back for error and close event
+		proc.on("error", function(err) {
+			logger.warn({err, args}, "qpdf failed");
+			return callback(null);
+		}); // ignore the error
+		return proc.on("close", function(code) {
+			timer.done();
+			if (code !== 0) {
+				logger.warn({code, args}, "qpdf returned error");
+				return callback(null); // ignore the error
+			}
+			return fs.rename(tmpOutput, dst, function(err) {
+				if (err != null) {
+					logger.warn({tmpOutput, dst}, "failed to rename output of qpdf command");
+				}
+				return callback(null);
+			});
+		});
+	} // ignore the error
+});