Insert AdSense Ad Code after certain number of paragraphs in your WordPress posts dynamically while ignoring some paragraphs in the paragraph checking/count

wp-insert-ad-code.php

<?php
/*
Plugin Name: Insert AdSense Ad Code after certain paragraph
Plugin URI:  https://www.isaumya.com/
Description: Insert AdSense Ad code after certain paragraph number while ignoring some paragraphs
Version:     2.0
Author:      Saumya Majumder
Author URI:  https://www.isaumya.com/
*/

/*Insert Adsense Ad Code in the post page*/
add_filter('the_content', function( $content ) {
	global $post;
 
    if ($post->post_type == 'post') {
    	// Setting up the the HTML Charecter encoding to UTF-8
    	$content = mb_convert_encoding($content, 'HTML-ENTITIES', 'UTF-8');

    	// Starting the main XML creation
	    libxml_use_internal_errors(true);
	    // Initializing a new DOM object
	    $dom = new DOMDocument;
	    // Load HTML content
	    $dom->loadHTML($content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
	    // Initializing a new XPath object
	    $xpath = new DOMXPath($dom);
	    // Query all `p` tags that their parent is not those specific elements
	    /* List of `p` tags that the Query will not take into consideration:
	     * `p` tags which has class name => some_class_1 e.g. <p class="some_class_1">...</p>
	     * `p` tags which has a `div` within it with following classes: some_callout, some_notice, some_other_class
	     * `p` tags which has `pre` tags within it
	     * `p` tags which has `code` tags within it
	     * `p` tags which has `blockquote` tags within it
	     * `p` tags which is under a `div` with class some_parent_class
	     * `p` tags which has only an anchor tags and image tag within it; e.g. <p><a href="some link"><img src="some image url" /></a></p>
	    **/
	    $paragraphs = $xpath->query('//p[not(contains(@class, \'some_class_1\') or ancestor::div[contains(@class, \'some_callout\') or contains(@class, \'some_notice\') or contains(@class, \'some_other_class\')] or ancestor::pre or ancestor::code or ancestor::blockquote or descendant::div[contains(@class, \'some_parent_class\')] or a/img  )]');

	    // Let's intert the ad code after 1st paragraph
	    // Make sure there is at least 3 or more paragraphs present before 
	    // pushing the ad after 1st paragraph
	    if ( $paragraphs->length > 2 ) {
	    	// Set the paragraphNumber after which the ad will me inserted
	    	$paragraphNumber = 1;
	    	// Declaring the ad code for showing after 1st paragraph
	    	/* --------------------------------------------------------------- */
	    	// Please make sure your ad code in enclosed within <div></div> tags
	    	// if you want you may add some class to this outer div that hold the
	    	// ad code like this <div class="some_class">...Your ad code goes here...</div>
	    	// Without the <div></div> enclosement the ad code will not show up and you may face
	    	// broken page content issue
	    	/* --------------------------------------------------------------- */
	    	// Setting up the default ad code value that will show up for normal webpages
	    	$adCode = '<div class="some_ad_class">
				<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
				<!-- Some Responsive Ad Code -->
				<ins class="adsbygoogle"
				style="display:block"
				data-ad-client="ca-pub-XXXXXXXXXXXXXX"
				data-ad-slot="XXXXXXXXXXXXXX"></ins>
				<script>
					(adsbygoogle = window.adsbygoogle || []).push({});
				</script>
				</div>';
			// Check if the site as any AMP enabled pages which is being created by the 
			// official WordPress AMP plugin: https://wordpress.org/plugins/amp/
			if ( function_exists( 'is_amp_endpoint' ) ) {
				// If the user is viewing an AMP page of any article, push the AMP version of
				// AdSense ad code
				if ( is_amp_endpoint() ) {
					$adCode = '<div class="some_amp_ad_class">
					<!-- AMP Ad Code -->
						<amp-ad width=300 height=250
						type="adsense"
						data-ad-client="ca-pub-XXXXXXXXXXXXXX"
						data-ad-slot="XXXXXXXXXXXXXX"></amp-ad>
					</div>';
				}
			} // end if of checking the AMP endpoint

			$newDom = new DOMDocument;
			$newDom->loadHTML($adCode, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
			$node = $newDom->getElementsByTagName('div')->item(0);
			$adNode = $dom->importNode($node, true);
			$paragraphs->item($paragraphNumber)->parentNode->insertBefore($adNode, $paragraphs->item($paragraphNumber));	
	    } // end if for adding ad code after 1st paragraph

	    /*---------------------------------------------------*/

	    // Let's intert the ad code after 9th paragraph
	    // Make sure there is at least 12 or more paragraphs present before 
	    // pushing the ad after 9th paragraph
	    if ( $paragraphs->length > 11 ) {
	    	// Set the paragraphNumber after which the ad will me inserted
	    	$paragraphNumber = 9;
	    	// Declaring the ad code for showing after 9th paragraph
	    	/* --------------------------------------------------------------- */
	    	// Please make sure your ad code in enclosed within <div></div> tags
	    	// if you want you may add some class to this outer div that hold the
	    	// ad code like this <div class="some_class">...Your ad code goes here...</div>
	    	// Without the <div></div> enclosement the ad code will not show up and you may face
	    	// broken page content issue
	    	/* --------------------------------------------------------------- */
	    	// Setting up the default ad code value that will show up for normal webpages
	    	$adCode = '<div class="some_ad_class">
				<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
				<!-- Some Responsive Ad Code -->
				<ins class="adsbygoogle"
				style="display:block"
				data-ad-client="ca-pub-XXXXXXXXXXXXXX"
				data-ad-slot="XXXXXXXXXXXXXX"></ins>
				<script>
					(adsbygoogle = window.adsbygoogle || []).push({});
				</script>
				</div>';
			// Check if the site as any AMP enabled pages which is being created by the 
			// official WordPress AMP plugin: https://wordpress.org/plugins/amp/
			if ( function_exists( 'is_amp_endpoint' ) ) {
				// If the user is viewing an AMP page of any article, push the AMP version of
				// AdSense ad code
				if ( is_amp_endpoint() ) {
					$adCode = '<div class="some_amp_ad_class">
					<!-- AMP Ad Code -->
						<amp-ad width=300 height=250
						type="adsense"
						data-ad-client="ca-pub-XXXXXXXXXXXXXX"
						data-ad-slot="XXXXXXXXXXXXXX"></amp-ad>
					</div>';
				}
			} // end if of checking the AMP endpoint

			$newDom = new DOMDocument;
			$newDom->loadHTML($adCode, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
			$node = $newDom->getElementsByTagName('div')->item(0);
			$adNode = $dom->importNode($node, true);
			$paragraphs->item($paragraphNumber)->parentNode->insertBefore($adNode, $paragraphs->item($paragraphNumber));	
	    } // end if for adding ad code after 9th paragraph

	    /*---------------------------------------------------*/

	    // Let's intert the ad code after 19th paragraph
	    // Make sure there is at least 21 or more paragraphs present before 
	    // pushing the ad after 19th paragraph
	    if ( $paragraphs->length > 21 ) {
	    	// Set the paragraphNumber after which the ad will me inserted
	    	$paragraphNumber = 19;
	    	// Declaring the ad code for showing after 19th paragraph
	    	/* --------------------------------------------------------------- */
	    	// Please make sure your ad code in enclosed within <div></div> tags
	    	// if you want you may add some class to this outer div that hold the
	    	// ad code like this <div class="some_class">...Your ad code goes here...</div>
	    	// Without the <div></div> enclosement the ad code will not show up and you may face
	    	// broken page content issue
	    	/* --------------------------------------------------------------- */
	    	// Setting up the default ad code value that will show up for normal webpages
	    	$adCode = '<div class="some_ad_class">
				<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
				<!-- Some Responsive Ad Code -->
				<ins class="adsbygoogle"
				style="display:block"
				data-ad-client="ca-pub-XXXXXXXXXXXXXX"
				data-ad-slot="XXXXXXXXXXXXXX"></ins>
				<script>
					(adsbygoogle = window.adsbygoogle || []).push({});
				</script>
				</div>';
			// Check if the site as any AMP enabled pages which is being created by the 
			// official WordPress AMP plugin: https://wordpress.org/plugins/amp/
			if ( function_exists( 'is_amp_endpoint' ) ) {
				// If the user is viewing an AMP page of any article, push the AMP version of
				// AdSense ad code
				if ( is_amp_endpoint() ) {
					$adCode = '<div class="some_amp_ad_class">
					<!-- AMP Ad Code -->
						<amp-ad width=300 height=250
						type="adsense"
						data-ad-client="ca-pub-XXXXXXXXXXXXXX"
						data-ad-slot="XXXXXXXXXXXXXX"></amp-ad>
					</div>';
				}
			} // end if of checking the AMP endpoint

			$newDom = new DOMDocument;
			$newDom->loadHTML($adCode, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
			$node = $newDom->getElementsByTagName('div')->item(0);
			$adNode = $dom->importNode($node, true);
			$paragraphs->item($paragraphNumber)->parentNode->insertBefore($adNode, $paragraphs->item($paragraphNumber));	
	    } // end if for adding ad code after 19th paragraph

	    libxml_use_internal_errors(false);
	    // Finally save every changes
        $content = $dom->saveHTML();
    } // end if of checking the post type == post
    return $content; //return the content back to WordPress
}, 20);