saveJSON.php

<?php
/**
 * Created by PhpStorm.
 * User: Matt Jaquiery
 * Date: 19/03/2019
 * Time: 10:28
 *
 */

/*
The $_POST[] array will contain a JSON string which decomposes into:
{
    metadata:
        studyId: study identifier (becomes eid below)
        studyVersion: study version
        idCode: participant id
    data:
        JSON string to write to file
    privateData:
        JSON string to write to a protected file
}

Data are saved in the ./data/[public|private]/raw directory as specified in the incoming metadata.

An JSON string is returned with the following properties:
{
    error: description of any error which occurred,
    code: response code,
    content: message
}

*/

//phpinfo();
error_reporting(0);
//ini_set("display_errors", true);
ini_set("auto_detect_line_endings", true);
$log = "";

function sulk($err, $code) {
    $out = array(
        "error" => $err,
        "code" => $code,
    );
    die(json_encode($out));
}

// Unpack POST data
$json = json_decode(file_get_contents("php://input"), true);

$meta = $json["metadata"];
$data = $json["data"];
$privateData = $json["privateData"];

$eid = (string) $meta["studyId"];
$version = (string) $meta["studyVersion"];
$version = str_replace(".", "-", $version);
$pid = $meta["idCode"];

// Check input is valid
function is_alphanumeric($str, $allowHyphen = false) {
    if($allowHyphen)
        return (bool) preg_match('/^[0-9a-z\-]+$/i', $str);
    return (bool) preg_match('/^[0-9a-z]+$/i', $str);
}

if(!is_alphanumeric($version, true))
    sulk("Invalid version format '$version'.", 403);

if(!is_alphanumeric($pid))
    sulk("Invalid id '$pid'.", 403);

if(!is_alphanumeric($eid, true)) {
    sulk("Invalid studyId '$eid'.", 403);
}

const PATH = "./data/";
$prefix = $eid . "_v" . $version;
$body = date('Y-m-d_H-i-s') . "_" . $prefix . "_" . $pid;

foreach(array("private", "public") as $privacy) {
    $filename = PATH . $privacy . "/raw/" . $body . ".json";
    if($privacy == "private")
        $write = $privateData;
    else
        $write = $data;

    $empty = true;

    foreach(json_decode($write) as $x)
        if(count($x)) {
            $empty = false;
            break;
        }

    if(!$empty) {
        if (!file_exists($filename)) {
            if (($handle = fopen($filename, "wb+")) !== false) {
                fwrite($handle, $write);
                fclose($handle);
            } else
                sulk("Unable to create file.", 500);
        } else
            sulk("File already exists!", 500);
    }
}

// Send back the all clear
die(json_encode(array(
    "error" => "",
    "code" => 200,
    "content" => "Data saved successfully."
)));