const fs = require('fs');
const spawn = require('child_process').spawn;
const uuid = require('uuid');

const {getDirPath, getDocPath} = require('./utils');


function copyToTemp(id, texDocument, callback) {
    const dirPath = getDirPath(id);

    fs.mkdir(dirPath, (err) => {
        if (err) {
            callback(err);
            return;
        }

        const docPath = getDocPath(id);
        fs.writeFile(docPath, texDocument, (err) => {
            if (err) {
                callback(err);
            }
            callback(null);
        });
    });
}

function generateDoc(id, callback) {
    const pdflatex = spawn('pdflatex', [getDocPath(id), '-interaction', 'nonstopmode'], {cwd: getDirPath(id)});
    pdflatex.stderr.on('data', (data) => {
        console.error('onData', data);
    });

    pdflatex.on('close', (code) => {
        if (code > 0) {
            callback(`pdflatex returned with code ${code}`);
            return;
        }
        console.log(`PDF ${id} generated`);
        callback(null, id);
    });
}

module.exports = (texDocument, callback) => {
    const id = uuid.v1();
    copyToTemp(id, texDocument, (err) => {
        if (err) {
            callback(err);
            return;
        }
        generateDoc(id, callback);
    });
};