import { spawn } from 'child_process';
import xml2js from 'xml2js';

const parser = new xml2js.Parser();
const builder = new xml2js.Builder({ headless: true });

const invokeDot = (input, format) => new Promise((resolve, reject) =>
{
    const dot = spawn('dot', [`-T${format}`]);
    let stdout = '';

    dot.stdout.on('data', data => stdout += data);

    dot.on('close', code => {
        if (code !== 0)
        {
            reject(new Error(`dot returned error code ${code}`));
        }
        else
        {
            resolve(stdout);
        }
    });

    dot.on('error', reject);
    dot.stdin.write(input);
    dot.stdin.end();
});

export const toSVG = async input =>
{
    const svg = await invokeDot(input, 'svg');
    const parsed = await parser.parseStringPromise(svg);
    return builder.buildObject(parsed);
};