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

/*Parsing the command line arguments*/
var count = 0;
var output = '';
var maxCount = '';
var queryString = '';
var queryObj = {};
var projectionString = '';
var projectionObj = {};

if (process.argv[2].substr(0,8) === '--output') {
  output = process.argv[2].split('=')[1];          //output = output           count = 2
  count++;
}
if (process.argv[2+count].substr(0,10) === '--maxcount') {
  maxCount = parseInt(process.argv[2+count].split('=')[1]);          //maxcount = number          count =2
  count++;
}

  queryString = JSON.stringify(process.argv[4].split('=')[1]);                //querystring = process 4
  if (queryString[0] != '-') {
    queryObj = JSON.parse('' + queryString + '');
console.log(queryObj);

  }
  else {
    queryObj = JSON.parse(queryString);
console.log(queryObj);
  }


if (process.argv.length === 4+count) {                                                    //projection = process 5
  projectionString = JSON.stringify(process.argv[3+count].split('=')[1]);
  if (projectionString[0] != '{') {
    projectionObj = JSON.parse('' + projectionString + '');
console.log(projectionObj);
  }
  else {
    projectionObj = JSON.parse(projectionString);
console.log(projectionObj);
  }
}

/* end argument parsing */

/*A short function to check if arguments exist*/
var argExists = function(arg) {
  return arg != '';
}

/*Connect to the persistent-logs database*/
mc.connect('mongodb://localhost/log-demo', function(err, db) {

  var toArrayCallback = function(err, data) {
    if (argExists(output)) {
      fs.writeFile(output, JSON.stringify(data));
    }
    else {
      console.log(JSON.stringify(data));
    }
    process.exit(0);
  }

  var logCollection = db.collection('logs');

    if (argExists(maxCount)) {
      logCollection.find(queryObj, projectionObj).limit(maxCount).toArray(toArrayCallback);
    }
    else {
      logCollection.find(queryObj, projectionObj).toArray(toArrayCallback);
    }


});