/**
 * Copyright (c) 2010-2017 Brian Carlson (brian.m.carlson@gmail.com)
 * All rights reserved.
 *
 * This source code is licensed under the MIT license found in the
 * README.md file in the root directory of this source tree.
 */

var url = require('url');
var dns = require('dns');

var defaults = require('./defaults');

var val = function(key, config, envVar) {
  if (envVar === undefined) {
    envVar = process.env[ 'PG' + key.toUpperCase() ];
  } else if (envVar === false) {
    // do nothing ... use false
  } else {
    envVar = process.env[ envVar ];
  }

  return config[key] ||
    envVar ||
    defaults[key];
};

//parses a connection string
var parse = require('pg-connection-string').parse;

var useSsl = function() {
  switch(process.env.PGSSLMODE) {
  case "disable":
    return false;
  case "prefer":
  case "require":
  case "verify-ca":
  case "verify-full":
    return true;
  }
  return defaults.ssl;
};

var ConnectionParameters = function(config) {
  //if a string is passed, it is a raw connection string so we parse it into a config
  config = typeof config == 'string' ? parse(config) : (config || {});
  //if the config has a connectionString defined, parse IT into the config we use
  //this will override other default values with what is stored in connectionString
  if(config.connectionString) {
    config = parse(config.connectionString);
  }
  this.user = val('user', config);
  this.database = val('database', config);
  this.port = parseInt(val('port', config), 10);
  this.host = val('host', config);
  this.password = val('password', config);
  this.binary = val('binary', config);
  this.ssl = typeof config.ssl === 'undefined' ? useSsl() : config.ssl;
  this.client_encoding = val("client_encoding", config);
  this.replication = val("replication", config);
  //a domain socket begins with '/'
  this.isDomainSocket = (!(this.host||'').indexOf('/'));

  this.application_name = val('application_name', config, 'PGAPPNAME');
  this.fallback_application_name = val('fallback_application_name', config, false);
};

// Convert arg to a string, surround in single quotes, and escape single quotes and backslashes
var quoteParamValue = function(value) {
  return "'" + ('' + value).replace(/\\/g, "\\\\").replace(/'/g, "\\'") + "'";
};

var add = function(params, config, paramName) {
  var value = config[paramName];
  if(value) {
    params.push(paramName + "=" + quoteParamValue(value));
  }
};

ConnectionParameters.prototype.getLibpqConnectionString = function(cb) {
  var params = [];
  add(params, this, 'user');
  add(params, this, 'password');
  add(params, this, 'port');
  add(params, this, 'application_name');
  add(params, this, 'fallback_application_name');

  var ssl = typeof this.ssl === 'object' ? this.ssl : {sslmode: this.ssl};
  add(params, ssl, 'sslmode');
  add(params, ssl, 'sslca');
  add(params, ssl, 'sslkey');
  add(params, ssl, 'sslcert');
  
  if(this.database) {
    params.push("dbname=" + quoteParamValue(this.database));
  }
  if(this.replication) {
    params.push("replication=" + quoteParamValue(this.replication));
  }
  if(this.host) {
    params.push("host=" + quoteParamValue(this.host));
  }
  if(this.isDomainSocket) {
    return cb(null, params.join(' '));
  }
  if(this.client_encoding) {
    params.push("client_encoding=" + quoteParamValue(this.client_encoding));
  }
  dns.lookup(this.host, function(err, address) {
    if(err) return cb(err, null);
    params.push("hostaddr=" + quoteParamValue(address));
    return cb(null, params.join(' '));
  });
};

module.exports = ConnectionParameters;