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

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


function copyToTemp(id, texDocument) {
    return new Promise((resolve, reject) => {
        const dirPath = getDirPath(id);

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

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

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

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

module.exports = function(texDocument, callback) {
    const id = uuid.v1();
    return copyToTemp(id, texDocument)
        .then(generateDoc);
};