greenshot/_includes/version-check.html

{% assign latest_release = site.github.releases | where:"prerelease",false | where:"draft",false | first %}

<script language="JavaScript">
var release_blog_posts = new Array();
{% if latest_release.tag_name %}
{% for post in site.posts %}{% if post.release_version %}release_blog_posts["{{post.release_version}}"] = "{{post.url}}";
{% endif %}{% endfor %}
{% else %}release_blog_posts["1.2.9.129"] = "/2017/01/28/129-bug-bash/";
{% endif %}

</script>

<div id="currentVersion" class="alert alert-success collapse" role="alert">
<i class="fa fa-check-circle"></i> You are using the most recent version of Greenshot.
<div id="blogPost1" class="collapse">More information about this version can be found <a id="blog1" href="">here</a>.</div>
</div>
<div id="oldVersion" class="alert alert-warning collapse" role="alert">
<i class="fa fa-exclamation-triangle"></i> <strong>You are not using the newest Greenshot version.</strong><br/>
<div id="blogPost2" class="collapse">More information about the version you are using can be found <a id="blog2" href="">here</a>.</div>
You might want to download the newest version, which is {{ latest_release.tag_name }}, from <a href="/downloads/">here</a>. Also always make sure to get Greenshot from <a href="https://getgreenshot.org/">getgreenshot.org</a>, .
</div>

<script>
// The following checks if the passed version in the URL is lower or equal to the known release.
// Depending on the outcome, it will show a warning or a positive message.

// Return 1 if a > b or not checkable
// Return -1 if a < b
// Return 0 if a == b
function compareVersion(a, b) {
    if (a === b) {
       return 0;
    }

    if (!a || !b) {
        return 1;
    }

    var a_components = a.split(".");
    var b_components = b.split(".");

    var len = Math.min(a_components.length, b_components.length);

    // loop while the components are equal
    for (var i = 0; i < len; i++) {
        // A bigger than B
        if (parseInt(a_components[i]) > parseInt(b_components[i])) {
            return 1;
        }

        // B bigger than A
        if (parseInt(a_components[i]) < parseInt(b_components[i])) {
            return -1;
        }
    }

    // If one's a prefix of the other, the longer one is greater.
    if (a_components.length > b_components.length) {
        return 1;
    }

    if (a_components.length < b_components.length) {
        return -1;
    }

    // Otherwise they are the same.
    return 0;
}

function checkVersion(installedVersion) {
    var greenshotTag = {% if latest_release.tag_name %}"{{ latest_release.tag_name }}"{% else %}"Greenshot-Test-1.2.9.129"{% endif %};
    var releaseVersion = /.*(\d+\.\d+\.\d+\.\d+)/.exec(greenshotTag)[1];
    var compare=compareVersion(releaseVersion, installedVersion);
    var matchingBlogPost = release_blog_posts[installedVersion];
    if (matchingBlogPost) {
        jQuery('#blog1').prop("href", matchingBlogPost);
        jQuery('#blogPost1').slideToggle();
        jQuery('#blog2').prop("href", matchingBlogPost);
        jQuery('#blogPost2').slideToggle();
    }
    if (compare >= 1) {
        jQuery('#oldVersion').slideDown();
        jQuery('#currentVersion').slideUp();
    } else if (compare == 0) {
        jQuery('#oldVersion').slideUp();
        jQuery('#currentVersion').slideDown();
    }
}

$(document).ready(function () {
    var versionMatch = /version=([^&]+)/.exec(location);
    if (versionMatch) {
        checkVersion(versionMatch[1]);
    }
});

</script>