/**
* logFaces appender sends JSON formatted log events to logFaces receivers.
* There are two types of receivers supported - raw UDP sockets (for server side apps),
* and HTTP (for client side apps). Depending on the usage, this appender
* requires either of the two:
*
* For UDP require 'dgram', see 'https://nodejs.org/api/dgram.html'
* For HTTP require 'axios', see 'https://www.npmjs.com/package/axios'
*
* Make sure your project have relevant dependancy installed before using this appender.
*/

"use strict";
var util = require('util');
var context = {};

function datagram(config){
   var sock = require('dgram').createSocket('udp4');
   var host = config.remoteHost || "127.0.0.1";
   var port = config.port || 55201;

   return function(event){
      var buff = new Buffer(JSON.stringify(event));
      sock.send(buff, 0, buff.length, port, host, function(err, bytes) {
         if(err){
            console.error("log4js.logFacesAppender failed to %s:%d, error: %s",
                          host, port, err);
         }
      });
   };
}

function servlet(config){
   var axios = require('axios').create();
   axios.defaults.baseURL = config.url;
   axios.defaults.timeout = config.timeout || 5000;
   axios.defaults.headers = {'Content-Type': 'application/json'};
   axios.defaults.withCredentials = true;

   return function(lfsEvent){
      axios.post("", lfsEvent)
      .then(function(response){
         if(response.status != 200){
            console.error("log4js.logFacesAppender post to %s failed: %d",
                           config.url, response.status);
         }
      })
      .catch(function(response){
         console.error("log4js.logFacesAppender post to %s excepted: %s",
                          config.url, response.status);
      });
   };
}

/**
* For UDP (node.js) use the following configuration params:
*   {
*      "type": "logFacesAppender",       // must be present for instantiation
*      "application": "LFS-TEST",        // name of the application (domain)
*      "remoteHost": "127.0.0.1",        // logFaces server address (hostname)
*      "port": 55201                     // UDP receiver listening port
*   }
*
* For HTTP (browsers or node.js) use the following configuration params:
*   {
*      "type": "logFacesAppender",       // must be present for instantiation
*      "application": "LFS-TEST",        // name of the application (domain)
*      "url": "http://lfs-server/logs",  // logFaces receiver servlet URL
*   }
*/
function logFacesAppender(config) {
   var send = config.send;
   if(send === undefined){
      send = (config.url === undefined) ? datagram(config) : servlet(config);
   }

   return function log(event) {
      // convert to logFaces compact json format
      var lfsEvent = {
         a: config.application || "",   // application name
         t: event.startTime.getTime(),  // time stamp
         p: event.level.levelStr,       // level (priority)
         g: event.categoryName,         // logger name
         m: format(event.data)          // message text
      };

      // add context variables if exist
      Object.keys(context).forEach(function(key) {
         lfsEvent['p_' + key] = context[key];
      });

      // send to server
      send(lfsEvent);
   };
}

function configure(config) {
   return logFacesAppender(config);
}

function setContext(key, value){
   context[key] = value;
}

function format(logData) {
  var data = Array.isArray(logData) ?
               logData : Array.prototype.slice.call(arguments);
  return util.format.apply(util, wrapErrorsWithInspect(data));
}

function wrapErrorsWithInspect(items) {
  return items.map(function(item) {
    if ((item instanceof Error) && item.stack) {
      return { inspect: function() {
          return util.format(item) + '\n' + item.stack;
       }};
    } else {
      return item;
    }
  });
}

exports.appender = logFacesAppender;
exports.configure = configure;
exports.setContext = setContext;