In response to a feature-request on meta, I spent a few hours today creating the feature in php.

This adds a 'review shield' to your GitHub repository (or wherever else you want it).

It looks like the following:

Code Review http://www.zomis.net/codereview/shield/?qid=54737

To use it, use something like this:

[![Code Review](http://www.zomis.net/codereview/shield/?qid=54737)](http://codereview.stackexchange.com/q/54737/31562)

Replace 54737 with the question id you want to direct to, and replace 31562 with your user id (so that you can get the Announcer / Booster / Publicist badges).

I used shields.io to get the basic SVG XML and adapted that.

There are different ways the badge can be shown:

• Unanswered questions shows the question score and a red background
• Answered questions shows the number of answers and an orange background
• Questions with accepted answer shows the view count and a green background

###How the code works

Because of the Stack Exchange API limit of 10000 requests per day, I am avoiding too many API requests by storing previous results in a database table and only performing a new request if it has been more than an hour since the last API request for that particular question.

The code contains these functions:

• buildURL($apiCall, $site, $filter, $apiKey): Creates the URL for the Stack Exchange API call (for future use, I check if the apiCall parameter contains a '?' or not).
• apiCall($apiCall, $site, $filter): Performs an HTTP request to the Stack Exchange API using curl, returns JSON data as a pure string
• fetchQuestion($qid, $db): Uses the JSON data retrieved by apiCall as an associative array, extracts the interesting data from it, updates the database, and calls useData.
• useData($data): Takes an associative array and creates SVG XML for it
• dbOrAPI($qid, $db): Main point of entry. $qid is a Code Review question id and $db is a PDO object. Checks the database for the existence of the qid and uses it if it is somewhat up-to-date, otherwise calls fetchQuestion

This code is also available at https://github.com/Zomis/CodeReview-Shield

<?php

require 'conf.php';

function buildURL($apiCall, $site, $filter, $apiKey) {
    if (strpos($apiCall, '?') === false) {
        $apiCall = $apiCall + "?dummy";
    }
    return "https://api.stackexchange.com/2.2/" . $apiCall
                . "&site=" . $site
                . "&filter=" . $filter . "&key=" . $apiKey;
}

function apiCall($apiCall, $site, $filter) {
    global $apiKey;
    $url = buildURL($apiCall, $site, $filter, $apiKey);
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_ENCODING, 'gzip');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $result = curl_exec($ch);

    if ($result === false) {
        $error = curl_error($ch);
        curl_close($ch);
        throw new Exception("Error calling Stack Exchange API: $error");
    }
    curl_close($ch);
    return $result;
}

function fetchQuestion($qid, $db) {
    $filter = "!)rcjzniPuafk4WNG65yr";
    $data = apiCall("questions/$qid?order=desc&sort=activity", 'codereview', $filter);
    $json = json_decode($data, true);
    $question = $json['items'][0];
    $dbfields = array("is_answered", "view_count", "favorite_count", "answer_count", "score", "accepted_answer_id");


    $sql = 'INSERT INTO cr_badge (question_id, is_answered, favorite_count, answer_count, view_count, score, fetch_time, accepted_answer_id) ' .
        'VALUES (:qid, :is_answered, :favorite_count, :answer_count, :view_count, :score, :time, :accepted_answer_id) ON DUPLICATE KEY UPDATE ' .
        'is_answered = :is_answered, favorite_count = :favorite_count, answer_count = :answer_count, view_count = :view_count, score = :score, fetch_time = :time, accepted_answer_id = :accepted_answer_id ;';
    $stmt = $db->prepare($sql);
    $sql_params = array();
    foreach ($dbfields as $field_name) {
        if (isset($question[$field_name])) {
            $sql_params[':' . $field_name] = $question[$field_name];
        } else {
            $sql_params[':' . $field_name] = 0;
        }
    }
    $sql_params[':qid'] = $qid;
    $sql_params[':time'] = time();
    $result = $stmt->execute($sql_params);
    if ($result) {
        useData($question);
    } else {
        print_r($stmt->errorInfo());
    }


    return $json;
}

function useData($data) {
    header('Content-type: image/svg+xml; charset=utf-8');
    $is_answered = $data['text'];
    $text = 'reviewed';
    if (isset($data['accepted_answer_id']) && $data['accepted_answer_id'] != 0) {
        $color = '97ca00';
        $mode = 'views';
    } elseif ($data['answer_count'] >= 1) {
        $color = 'ff8000';
        $right = $data['score'] . ' score';
        $mode = 'answers';
    } else {
        $color = 'e05d44';
        $text = 'reviewing';
        $mode = 'score';
    }
    if (isset($_GET['mode'])) {
        $mode = $_GET['mode'];
    }
    $data['answers'] = $data['answer_count'];
    $data['views'] = $data['view_count'];
    $right = $data[$mode] . ' ' . $mode;

    $svg = <<<END
<svg xmlns="http://www.w3.org/2000/svg" width="137" height="20">
<linearGradient id="b" x2="0" y2="100%">
<stop offset="0" stop-color="#bbb" stop-opacity=".1"/>
<stop offset="1" stop-opacity=".1"/>
</linearGradient>
<mask id="a">
<rect width="137" height="20" rx="3" fill="#fff"/>
</mask>
<g mask="url(#a)">
<path fill="#555" d="M0 0h62v20H0z"/>
<path fill="#$color" d="M62 0h75v20H62z"/>
<path fill="url(#b)" d="M0 0h137v20H0z"/>
</g>
<g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11">
<text x="31" y="15" fill="#010101" fill-opacity=".3">$text</text>
<text x="31" y="14">$text</text>
<text x="98.5" y="15" fill="#010101" fill-opacity=".3">$right</text>
<text x="98.5" y="14">$right</text>
</g>
</svg>
END;
    echo $svg;
}

function dbOrAPI($qid, $db) {

    $sql = 'SELECT is_answered, favorite_count, answer_count, view_count, score, fetch_time, accepted_answer_id FROM cr_badge WHERE question_id = :qid;';

    $stmt = $db->prepare($sql);
    $result = $stmt->execute(array(':qid' => $qid));
    if ($result) {
        $row = $stmt->fetch(PDO::FETCH_ASSOC);
        $time = $row['fetch_time'];
        if ($time < time() - 3600) { // if time was updated more than one hour ago
            // fetch data again
            fetchQuestion($qid, $db);
        } else {
            useData($row);
        }
    } else {
        print_r($stmt->errorInfo());
    }
}

if (isset($_GET['qid'])) {
    $qid = $_GET['qid'];
} else {
    die("No qid set");
}

try {
    $db = new PDO($dbhostname, $dbuser, $dbpass);
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
    return false;
}

dbOrAPI($qid, $db);

###Primary Concerns

It's been a while since I used PHP, and I am interested if I'm adhering to the PHP conventions if there are any, and if I'm using it as it is meant to be used.

Any comments are welcome.