import sendgrid from 'sendgrid';
import config from 'config';

const sg = sendgrid(config.get('sendgrid.key'));

export default function sendEmail(template, to, params, from = null) {
    if (process.env.NODE_ENV !== 'production') {
        console.log(`mail: to <${to}>, from <${from}>, template ${template} (not sent due to not production env)`);
        return;
    }
    const tmpl_id = config.get('sendgrid.templates')[template];
    if (!tmpl_id) throw new Error(`can't find template ${template}`);

    const request = sg.emptyRequest({
        method: 'POST',
        path: '/v3/mail/send',
        body: {
            template_id: tmpl_id,
            personalizations: [
                {to: [{email: to}],
                 substitutions: params},
            ],
            from: {email: from || config.get('sendgrid.from')}
        }
    });

    sg.API(request)
    .then(response => {
        console.log(`sent '${template}' email to '${to}'`, response.statusCode);
    })
    .catch(error => {
        console.error(`failed to send '${template}' email to '${to}'`, error);
    });
}
