php - Integrate from JSON file and return value to it -

in linux box running following php code

<?php         //get response server , append timestamp data         function get_server_response() {                 $curl_post_data = null;                 $service_url = 'http://serverip/source.php';                 $curl = curl_init($service_url);                 curl_setopt($curl, curlopt_httpauth, curlauth_basic);                 curl_setopt($curl, curlopt_userpwd, "user:pass");                 curl_setopt($curl, curlopt_returntransfer, true);                 curl_setopt($curl, curlopt_post, true);                 curl_setopt($curl, curlopt_postfields, $curl_post_data);                 curl_setopt($curl, curlopt_ssl_verifypeer, false);                 $curl_response = curl_exec($curl);                 $response = json_decode($curl_response, true);                 curl_close($curl);                 $time = time();                 $check = $time+date("z",$time);                 $data['timestamp'] = array('year' => intval(strftime('%y', $check)), 'month' => intval(strftime('%m', $check)), 'day' => intval(strftime('%d', $check)),                         'hour' => intval(strftime('%h', $check)+3), 'minutes' => intval(strftime('%m', $check)), 'seconds' => intval(strftime('%s', $check)));                  return array_merge($data,$response);         }          if (!file_exists('results.json')) {                 $response = get_server_response();                 $data = new stdclass();                 $data-> data1 = $response;                 //create , data local json file                 $fp = fopen('results.json', 'a+');                 fwrite($fp, json_encode($data, json_pretty_print));                 fclose($fp);         } else {                 //read data existing local json file                 $file = file_get_contents("results.json");                 $data = json_decode($file);                 $object = json_decode(json_encode($data), false);                 unset($file);                 //increment based on last object , append new key-value pair                 end($object);                 $key = key($object);                 $int = filter_var($key, filter_sanitize_number_int);                 ++$int;                 $response = get_server_response();                 $next = 'data' . $int;                 $object-> $next = $response;                 //update local json file                 file_put_contents('results.json', json_encode($object, json_pretty_print));         }  ?> 

which outputs following results.json

{     "data1": {         "timestamp": {             "year": 2015,             "month": 9,             "day": 14,             "hour": 16,             "minutes": 1,             "seconds": 36         },         "cg_uptime": 199481,         "mhs_avg": 2661410.65,         "mhs_5s": 3102456.1,         "mhs_1m": 2806133.89,         "mhs_5m": 2700647.04,         "mhs_15m": 2720732.61,         "mhs_now": "2667260",         "degc_in": "35",         "degc_topout": "59",         "degc_botout": "61",         "unit_uptime": 510403,         "freemem": "403",         "psuvolt_top": "233",         "psuvolt_bot": "235",         "fan": "50",         "vst": "612",         "vsb": "612",         "vmax": "622",         "ac_top": "1100",         "ac_bot": "1100",         "dc_amp": "150",         "psuwall_top": "640",         "psuwatt_top": "(592",         "psuwall_bot": "640",         "psuwatt_bot": "(596",         "total_watts": 1280     },     "data2": {         "timestamp": {             "year": 2015,             "month": 9,             "day": 14,             "hour": 16,             "minutes": 1,             "seconds": 59         },         "cg_uptime": 199504,         "mhs_avg": 2661347.27,         "mhs_5s": 2042760.72,         "mhs_1m": 2595202.5,         "mhs_5m": 2657730.87,         "mhs_15m": 2705433.81,         "mhs_now": "2667260",         "degc_in": "35",         "degc_topout": "59",         "degc_botout": "61",         "unit_uptime": 510426,         "freemem": "403",         "psuvolt_top": "233",         "psuvolt_bot": "235",         "fan": "50",         "vst": "612",         "vsb": "612",         "vmax": "622",         "ac_top": "1100",         "ac_bot": "1100",         "dc_amp": "150",         "psuwall_top": "656",         "psuwatt_top": "(600",         "psuwall_bot": "640",         "psuwatt_bot": "(596",         "total_watts": 1296     },     "data3": {         "timestamp": {             "year": 2015,             "month": 9,             "day": 14,             "hour": 21,             "minutes": 25,             "seconds": 18         },         "cg_uptime": 218903,         "mhs_avg": 2657940.86,         "mhs_5s": 3701517.96,         "mhs_1m": 2658126.3,         "mhs_5m": 2572589.83,         "mhs_15m": 2584535.75,         "mhs_now": "2667260",         "degc_in": "34",         "degc_topout": "57",         "degc_botout": "60",         "unit_uptime": 529826,         "freemem": "405",         "psuvolt_top": "233",         "psuvolt_bot": "235",         "fan": "50",         "vst": "612",         "vsb": "612",         "vmax": "622",         "ac_top": "1100",         "ac_bot": "1100",         "dc_amp": "150",         "psuwall_top": "640",         "psuwatt_top": "(596",         "psuwall_bot": "624",         "psuwatt_bot": "(592",         "total_watts": 1264     } .... .... } 

what want add field in json file (named "total_kwh"), calculates total kilowatt-hours. in other words, integrate "total_watts" value on time , add results each json block. calculation incremental save cpu. @ "data1" start "total_kwh":0 on "data2" calculate time difference in hours (in case, 23 seconds 0.006388 hours), multiply "total_watts" value data2 , new "total_kwh" value. in example, "total_kwh" 0.006388*1.296 = 0.00827. can me modify php code?

it easier add item "timestamp_raw" every data* block calculating time difference between every next pair in data* set:

function get_server_response() { ... curl_close($curl); $time = time(); $check = $time+date("z",$time); $data['timestamp_raw'] = $check; ... } 

then, can through in such way:

...     $key = key($object);     $int = filter_var($key, filter_sanitize_number_int);     ++$int;     $response = get_server_response();     $next = 'data' . $int;     $response["total_kwh"] = number_format(($response["timestamp_raw"] - $obj->$key->timestamp_raw)/60/60, 6) * ($response["total_watts"]/1000);     $object->$next = $response; ...