PG basis

/*global require,module,process*/

var postgres = require('pg');

var winston = require('winston');

(function () {

  'use strict';

  // A postgres document store

  var PostgresDocumentStore = function (options) {

    this.expireJS = options.expire * 1000;

    this.connectionString = process.env.DATABASE_URL;

  };

  PostgresDocumentStore.prototype = {

    // Set a given key

    set: function (key, data, callback, skipExpire) {

      var now = new Date().getTime() / 1000;

      var that = this;

      this.safeConnect(function (err, client, done) {

        if (err) { return callback(false); }

        client.query('INSERT INTO entries (key, value, expiration) VALUES ($1, $2, $3)', [

          key,

          data,

          that.expireJS && !skipExpire ? now + that.expireJS : null

        ], function (err, result) {

          if (err) {

            winston.error('error persisting value to postgres', { error: err });

            return callback(false);

          }

          callback(true);

          done();

        });

      });

    },

    // Get a given key's data

    get: function (key, callback, skipExpire) {

      var now = new Date().getTime() / 1000;

      var that = this;

      this.safeConnect(function (err, client, done) {

        if (err) { return callback(false); }

        client.query('SELECT value from entries where KEY = $1 AND (expiration IS NULL or expiration < $2)', [

          key,

          that.expireJS ? now - that.expireJS : 0

        ], function (err, result) {

          if (err) {

            winston.error('error retrieving value from postgres', { error: err });

            return callback(false);

          }

          callback(result.rows.length ? result.rows[0].value : false);

        });

      });

    },

    // A connection wrapper

    safeConnect: function (callback) {

      postgres.connect(this.connectionString, function (err, client, done) {

        if (err) {

          winston.error('error connecting to postgres', { error: err });

          callback(err);

        } else {

          callback(undefined, client, done);

        }

      });

    }

  };

  module.export = PostgresDocumentStore;

}());