/*
 * Copyright (c) 2013 DataTorrent, Inc. ALL Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

var redis = require('redis');
var dateFormat = require('dateformat');
var async = require('async');
var config = require('../config');
var _ = require('underscore');

var client;
var demoEnabled = (config.machine.redis.port && config.machine.redis.host);

if (demoEnabled) {
  client = redis.createClient(config.machine.redis.port, config.machine.redis.host);
  if (config.machine.redis.dbIndex) {
    client.select(config.machine.redis.dbIndex);
  }
}

exports.index = function (req, res) {
  if (demoEnabled) {
    res.render('machine');
  } else {
    res.render('error', {
      message: 'Machine Generated Data Demo is not enabled. Please configure Redis.'
    });
  }
};

exports.data = function (req, res) {
  getMinutes(req.query, function (err, result) {
    var forcedDelay = config.machine.forcedDelay;
    if (!forcedDelay) {
      res.json(result);
    } else {
      setTimeout(function () {  // for testing purpose only
        res.json(result);
      }, forcedDelay);
    }
  });
};

function extractMinutes(minuteKeys, replies) {
  var minutes = [];
  var latestKeyWithData = null;

  for (var i = 0; i < replies.length; i++) {
    var reply = replies[i];
    var minuteKey = minuteKeys[i];
    if (reply) {
      if (parseInt(reply.day, 10) === parseInt(minuteKey.day, 10)) {
        var minute = {
          timestamp: minuteKeys[i].timestamp,
          cpu: reply.cpu,
          ram: reply.ram,
          hdd: reply.hdd
        };
        minutes.push(minute);

        if (!latestKeyWithData) {
          latestKeyWithData = minuteKey.key;
        }
      } else if (!_.isEmpty(minutes)) {
        break;
      }
    } else if (!_.isEmpty(minutes)) {
      break;
    }
  }

  var data = {
    minutes: minutes,
    latestKeyWithData: latestKeyWithData
  };

  return data;
}
exports.extractMinutes = extractMinutes;

function getMinutes(query, resCallback) {
  var lookback = query.lookback;
  var lastTimestamp = query.lastTimestamp;
  var keyParams = [query.customer, query.product, query.os, query.software1, query.software2, query.software3, query.deviceId];

  var paramKeyTemplate = '|$index:$param';
  var minuteKeyTemplate = '$date';
  keyParams.forEach(function (param, index) {
    if (param) {
      var paramKey = paramKeyTemplate
        .replace('$index', index)
        .replace('$param', param);
      minuteKeyTemplate += paramKey;
    }
  });

  var minute = (60 * 1000);

  var endTime = Date.now();
  endTime -= (endTime % minute); // round to minute

  if (lastTimestamp) {
    var startTime = lastTimestamp - (lastTimestamp % minute); // round to minute
    var optimizedLookback = Math.floor((endTime - startTime)/minute) + 1;
    if (optimizedLookback <  lookback) {
      lookback = optimizedLookback;
    }
  }

  var minuteKeys = [];
  for (var i = 0; i < lookback; i++) {
    var time = endTime - (i * minute);
    var date = dateFormat(time, 'UTC:HHMM');
    var day = dateFormat(time, 'UTC:d');
    var key = minuteKeyTemplate.replace('$date', date);
    minuteKeys.push({
      timestamp: time,
      day: day,
      key: key
    });
  }

  var multi = client.multi();
  minuteKeys.forEach(function(key) {
    multi.hgetall(key.key);
  });

  var execStartTime = Date.now();
  multi.exec(function (err, replies) {
    var execTime = (Date.now() - execStartTime);

    var minuteData = extractMinutes(minuteKeys, replies);
    var minutes = minuteData.minutes;
    minutes.reverse();
    var lastKey = minuteData.latestKeyWithData;
    var lastKeyQueried = _.first(minuteKeys).key;

    var result = {
      minutes: minutes,
      keysQueried: minuteKeys.length,
      lastKeyQueried: lastKeyQueried,
      lastKey: lastKey,
      queryTime: execTime
    };

    console.log('Redis exec time ' + execTime +
      'ms. Replies: ' + replies.length +
      '. Last key with data: ' + lastKey);

    resCallback(err, result);
  });
}