mathoid/lib/render.js

Render TeX to SVG and MathML using MathJax. Based on svgtex.

'use strict';

const Mocks = require( 'mock-express-response' );
const mathoid = require( './math.js' );
const BBPromise = require( 'bluebird' );
const fs = BBPromise.promisifyAll( require( 'fs' ) );
const mjAPI = require( 'mathoid-mathjax-node' );
const yaml = require( 'js-yaml' );

function getError( msg, detail ) {
	return new BBPromise( ( ( res ) => {
		res( { success: false, error: msg, detail } );
	} ) );
}

function handleRequest( req, response, q, type, outformat, features, logger, conf, api ) {
	return BBPromise.try( () => mathoid.handleRequest( response,
		q,
		type,
		outformat,
		features,
		logger,
		conf,
		api )
		.then( () => {
			let jsonResult;
			const contentType = response.get( 'Content-Type' );
			if ( /json/.test( contentType ) ) {
				// eslint-disable-next-line no-underscore-dangle
				jsonResult = response._getJSON();
			} else if ( /xml/.test( contentType ) ) {
				// eslint-disable-next-line no-underscore-dangle
				jsonResult = response._getString();
			} else {
				// eslint-disable-next-line no-underscore-dangle
				jsonResult = Buffer.concat( response._responseData );
			}
			return { req, res: jsonResult };
		} ) ).catch( ( e ) => { return { req, res: e }; } );
}

function render( data, conf ) {
	if ( !data ) {
		return getError( 'empty input data' );
	}
	try {
		data = JSON.parse( data );
	} catch ( e ) {
		return getError( `invalid json input: ${e.message}` );
	}
	const renderings = BBPromise.map( data, ( req ) => {
		const response = new Mocks();
		return handleRequest( req,
			response,
			req.query.q,
			req.query.type,
			req.query.outformat,
			req.query.features,
			{},
			conf,
			mjAPI );
	} );
	return BBPromise.reduce( renderings, ( out, el ) => {
		if ( el.req.query.hash ) {
			const key = el.req.query.hash;
			out[ key ] = el.res;
		} else {
			out.nohash.push( el );
		}
		return out;
	}, { nohash: [], success: true } );
}

function getConfig( configLocation ) {
	const config = yaml.load( fs.readFileSync( configLocation ) );
	const myServiceIdx = config.services.length - 1;
	const conf = config.services[ myServiceIdx ].conf;
	if ( conf.png ) {
		let rsvgVersion = false;
		try {
			// eslint-disable-next-line node/no-missing-require
			rsvgVersion = require( 'librsvg/package.json' ).version;
		} catch ( e ) {
		}
		if ( !rsvgVersion ) {
			conf.png = false;
		}
	}
	return conf;
}

function startMathJax( configLocation ) {
	const conf = getConfig( configLocation );
	mjAPI.config( conf.mj_config );
	// This call is not required but it might improve the performance slightly
	mjAPI.start();
	return conf;
}

module.exports = {
	render,
	config: getConfig,
	start: startMathJax
};