disableEndElseCallbackExecute = true;

var emailregex = /(?:[a-z0-9!#$%&'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+\/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])/i
var querystring = require("querystring");
var dns = require("dns");

var MongoClient = require('mongodb').MongoClient;

var mongoURL = "mongodb://localhost/newsletter";
var dbname = "newsletter";
var redirectURL = "https://blog.svrjs.org";
var allowedHosts = [
  "https://blog.svrjs.org"
];

function antiXSS(string) {
  return string.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&quot;").replace(/'/g, "&apos;");
}

function generateUnsubscribeID() {
  const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  let result = "";
  for (let i = 0; i < 32; i++) {
    result += chars.charAt(Math.floor(Math.random() * chars.length));
  }
  return result;
}

function generateUniqueUnsubscribeID(db, callback) {
  var id = generateUnsubscribeID();
  db.collection("emails").find({
    unsubscribeId: id
  }).toArray(function (err, result) {
    if (err) {
      callServerError(500, err);
      return;
    }
    if (result.length > 0) {
      generateUnsubscribeID(db);
    } else {
      callback(id);
    }
  });
}

function escapeRegExp(string) {
  return string.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'); // $& means the whole matched string
}

function connectMongo(callback) {
  // customvar3 is a MongoDB database object
  if (customvar3) {
    callback(customvar3);
  } else {
    MongoClient.connect(mongoURL, function (err, db) {
      if (err) {
        callServerError(500, err);
        return;
      }
      var dbo = db.db(dbname);
      dbo.createCollection("emails", function (err, dbres) {
        customvar3 = dbo;
        callback(dbo);
      });
    });
  }
}

function formatTemplate(templateName, templateData, callback) {
  fs.readFile(__dirname + "/../templates/" + templateName + ".template", function (err, data) {
    if (err) {
      callServerError(500, err);
      return;
    }
    var tD = data.toString();
    Object.keys(templateData).forEach(function (key) {
      tD = tD.replace(new RegExp("\\{\\{" + escapeRegExp(key) + "\\}\\}", "g"), templateData[key]);
    });
    callback(tD);
  });
}
if (href == "/subscribe.svr") {
  if (req.method != "POST") {
    callServerError(405, {
      "Allow": "POST"
    });
    return;
  }
  var baseURL = (req.socket.encrypted ? "https" : "http") + "://" + (req.headers.host ? req.headers.host : req.socket.localAddress);
  var isReferrerValid = false;
  if ((req.headers.referer + "/").substring(0, baseURL.length + 1) == (baseURL + "/")) isReferrerValid = true;
  if (!isReferrerValid) {
    allowedHosts.every(function (allowedHost) {
      allowedHost = allowedHost.replace(/\/+$/, "");
      if ((req.headers.referer + "/").substring(0, allowedHost.length + 1) == (allowedHost + "/")) {
        isReferrerValid = true;
        return false;
      } else {
        return true;
      }
    });
  }
  if (!isReferrerValid) {
    formatTemplate("index.html", {
      "title": "Invalid referrer",
      "paragraph": "<p>Invalid referrer has been detected. There may be a CSRF attack.</p>"
    }, function (data) {
      res.writeHead(400, {
        "Content-Type": "text/html; charset=utf-8"
      });
      res.end(data);
    });
    return;
  }
  var postdata = "";
  req.on("data", function (data) {
    postdata += data.toString();
  });
  req.on("end", function () {
    postdata = querystring.parse(postdata);
    if (!postdata.email) {
      formatTemplate("index.html", {
        "title": "No email address",
        "paragraph": "<p>You didn't send any email address.</p>"
      }, function (data) {
        res.writeHead(400, {
          "Content-Type": "text/html; charset=utf-8"
        });
        res.end(data);
      });
      return;
    } else if (!postdata.email.match(emailregex)) {
      formatTemplate("index.html", {
        "title": "Invalid email address",
        "paragraph": "<p>The email address you sent is invalid.</p>"
      }, function (data) {
        res.writeHead(400, {
          "Content-Type": "text/html; charset=utf-8"
        });
        res.end(data);
      });
      return;
    } else {
      dns.resolveMx(postdata.email.match(/@([\s\S]*)/)[1], function (err, mxRecords) {
        if (err || mxRecords.length == 0) {
          formatTemplate("index.html", {
            "title": "Your email domain is misconfigured",
            "paragraph": "<p>The server has determined, that your email domain is misconfigured (MX records not found). Contact the administrator of the domain for the assistance.</p>"
          }, function (data) {
            res.writeHead(400, {
              "Content-Type": "text/html; charset=utf-8"
            });
            res.end(data);
          });
          return;
        }

        connectMongo(function (db) {
          db.collection("emails").find({
            email: postdata.email
          }).toArray(function (err, result) {
            if (err) {
              callServerError(500, err);
              return;
            }
            if (result.length > 0) {
              formatTemplate("index.html", {
                "title": "You have already subscribed to the newsletter",
                "paragraph": "<p>You have already subscribed to the newsletter.</p>"
              }, function (data) {
                res.writeHead(200, {
                  "Content-Type": "text/html; charset=utf-8"
                });
                res.end(data);
              });
            } else {
              generateUniqueUnsubscribeID(db, function (id) {
                db.collection("emails").insertOne({
                  email: postdata.email,
                  unsubscribeId: id
                }, function (err, dbres) {
                  if (err) {
                    callServerError(500, err);
                    return;
                  }
                  formatTemplate("index.html", {
                    "title": "Thank you for subscribing to our newsletter!",
                    "paragraph": "<p>You can unsubscribe from the newsletter using <a href=\"" + antiXSS(baseURL + "/unsubscribe.svr?id=" + encodeURIComponent(id)) + "\">this link</a>.</p>"
                  }, function (data) {
                    res.writeHead(200, {
                      "Content-Type": "text/html; charset=utf-8"
                    });
                    res.end(data);
                  });
                });
              });
            }
          });
        });
      });
    }
  });
} else if (href == "/unsubscribe.svr") {
  if (!uobject.query.id) {
    formatTemplate("index.html", {
      "title": "Invalid unsubscription link",
      "paragraph": "<p>You didn't provide the unsubscription ID.</p>"
    }, function (data) {
      res.writeHead(400, {
        "Content-Type": "text/html; charset=utf-8"
      });
      res.end(data);
    });
  }
  connectMongo(function (db) {
    db.collection("emails").find({
      unsubscribeId: uobject.query.id
    }).toArray(function (err, result) {
      if (err) {
        callServerError(500, err);
        return;
      }
      if (result.length == 0) {
        formatTemplate("index.html", {
          "title": "Invalid unsubscription link",
          "paragraph": "<p>You have either already unsubscribed from the newsletter, or the unsubscription ID is invalid.</p>"
        }, function (data) {
          res.writeHead(400, {
            "Content-Type": "text/html; charset=utf-8"
          });
          res.end(data);
        });
      } else {
        db.collection("emails").deleteOne({
          unsubscribeId: uobject.query.id
        }, function (err, dbres) {
          if (err) {
            callServerError(500, err);
            return;
          }
          formatTemplate("index.html", {
            "title": "You have been unsubscribed from the newsletter!",
            "paragraph": "<p>You have been unsubscribed from the newsletter.</p>"
          }, function (data) {
            res.writeHead(200, {
              "Content-Type": "text/html; charset=utf-8"
            });
            res.end(data);
          });
        });
      }
    });
  });
} else if (href == "/") {
  redirect(redirectURL);
} else {
  elseCallback();
}