'use latest';
import nodemailer from 'nodemailer@2.5.0';
import request from 'request@2.81.0';

module.exports = function(context, cb) {
  const url = context.query.url;
  const kindleAddress = context.query.address || context.secrets.KINDLE_ADDRESS;
  
  if (!url) {
    return cb(null, "missing url parameter");
  }
  if (!context.secrets.PDFLAYER_APIKEY) {
    return cb(null, 'missing PDFLAYER_APIKEY');
  }
  if (!context.secrets.SMTP_CONFIG) {
    return cb(null, 'missing SMTP_CONFIG');
  }
  if (!kindleAddress) {
    return cb(null, 'missing kindle email address');
  }
  
  let filename = "";

  return getTitle(url)
  .then(title => {
    filename = `${title || 'document'}.pdf`;
    return htmlToPDF(context.secrets.PDFLAYER_APIKEY, context.secrets.PDFLAYER_SANDBOX, url);
  })
  .then(pdf => sendToKindle(context.secrets.SMTP_CONFIG, kindleAddress, [{
    filename,
    content: pdf,
  }]))
  .then(info => cb(null,info))
  .catch(cb);
};

/**
* Validates url and returns page title
*/
function getTitle(url){
  return new Promise((resolve, reject)=>{
    request(url, (err, res, body) => {
      if(err || res.statusCode !== 200) {
        return reject(err || res.statusCode);
      }
      const matches = body.match(/title>(.*?)<\/title/i);
      return resolve(matches? matches[1]: '');
    });    
  });
}

/**
* sends attachments to kindle address
*/
function sendToKindle(smtpconfig, address, attachments){
  return new Promise((resolve, reject)=>{
    var transporter = nodemailer.createTransport(smtpconfig);
    var mailOptions = {
        to: address,
        subject: 'document',
        attachments
    };
    transporter.sendMail(mailOptions, (err, info)=> {
      if(err){
        return reject(err);
      } 
      return resolve(info);
    });
  });
}

/**
* converts any url to pdf using pdflayer.com
*/
function htmlToPDF(apiKey, sandbox, source){
  let url = `http://api.pdflayer.com/api/convert?access_key=${apiKey}&document_url=${source}&margin_top=0&margin_bottom=0&margin_left=0&margin_right=0&use_print_media=1`;
  if (sandbox) {
      url += "&test=1";
  }
  return new Promise((resolve, reject) => {
    request({
      url,
      encoding: null,
    }, (err, res, body)=> {
      if(err || res.statusCode !== 200) {
        return reject(err || res.statusCode);
      }
      return resolve(body);
    });
  });
}