<?php
class JsonBuilder
{
    function __construct()
    {
        $this->jsonData = array();
    }

    function getJson()
    {
        return json_encode($this->jsonData, JSON_FORCE_OBJECT);
    }

    function getArray()
    {
        return $this->jsonData;
    }

    function addRecords(array $records)
    {
        $columns = array(
            "record_id" => "",
            "start_time" => "",
            "end_time" => "",
            "duration" => "",
            "user_id" => "",
            "project_id" => "",
            "start_device_id" => ""
        );

        foreach ($records as $record) {
            $this->jsonData['records'] = array();
            $this->jsonData['records'][] = $this->createJsonArray($record, $columns);
        }
        return $this;
    }

    private function createJsonArray(array $data, array $columns)
    {
        $jsonArray = array();
        foreach ($columns as $key => $column) {
            if ($column === "") {
                $column = $key;
            }
            $jsonArray[$key] = $data[$column];
        }
        return $jsonArray;
    }
}