SEO Auto Linker Fix

front.php

<?php
class pmgSeoAutoLinkerFront
{
	function __construct()
	{
		add_filter( 'the_content', array( &$this, 'content' ), 1, 1 );
	}
	
	function content( $content )
	{
		if( ! is_singular() ) return $content;
		global $post;
		
		// If there's persistent caching set up on the server, this will work!
		if( $filtered_content = wp_cache_get( 'autolinker_content_' . $post->ID, 'autolinker_content' ) )
			return $filter_content;
		
		// set up some more options
		$opts = get_option( 'pmg_autolinker_options' );
		$kws = isset( $opts['kw'] ) ? (array) $opts['kw'] : array();
		if( empty( $kws ) ) return $content;
		
		// Find all of our <h> tags in the content and replace them with something
		preg_match_all( '/<h[1-6]>.+?<\/h[1-6]>/i', $content, $headers );
		if( $headers[0] )
		{
			$headers_replacements = array();
			$counter = 0;
			foreach( $headers[0] as $h )
			{
				$headers_replacements["<!--seo-auto-links-header-{$counter}--!>"] = $h;
				$counter++;
			}
			$filtered_content = str_replace( array_values( $headers_replacements ), array_keys( $headers_replacements ), $content );
		}
		else
		{
			$filtered_content = $content;
		}
		
		// Find all links currently in the content
		// We'll use the links_counter and links_replacements variables later on too
		$link_counter = 0;
		$links_replacements = array();
		preg_match_all( '/<a(.*?)href="(.*?)"(.*?)>(.*?)<\/a>/i', $filtered_content, $first_links );
		if( $first_links[0] )
		{
			$temp_links = array();
			foreach( $first_links[0] as $l )
			{
				$temp_links["<!--seo-auto-links-link-{$link_counter}-->"] = $l;
				$link_counter++;
			}
			$filtered_content = str_replace( array_values( $temp_links ), array_keys( $temp_links ), $filtered_content );
			$links_replacements = array_merge( $links_replacements, $temp_links );
		}
		
		// strip out images, form fields, and anythign else that might have text we shouldn't over right
		$other_counter = 0;
		$other_replacements = array();
		preg_match_all( '/<(img|input)(.*?) \/?>/i', $filtered_content, $others );
		if( $others[0] )
		{
			foreach( $others[0] as $i )
			{
				$other_replacements["<!--seo-auto-links-others-{$other_counter}-->"] = $i;
				$other_counter++;
			}
			$filtered_content = str_replace( array_values( $other_replacements ), array_keys( $other_replacements ), $filtered_content );
		}
		
		
		foreach( $kws as $index => $kw )
		{
			$nope = isset( $opts['types'][$index] ) && $post->post_type != $opts['types'][$index] ? true : false;
			if( $nope ) continue;
			
			$url = isset( $opts['url'][$index] ) ? $opts['url'][$index] : false;
			if( ! $url ) continue;
			
			$max = isset( $opts['max'][$index] ) ? $opts['max'][$index] : 1;
			
			// Find all the links in the content so we don't overwrite them or get weird stuff
			preg_match_all( '/<a(.*?)href="(.*?)"(.*?)>(.*?)<\/a>/', $filtered_content, $links );
			if( $links[0] )
			{
				$temp_links = array();
				foreach( $links[0] as $l )
				{
					$temp_links["<!--seo-auto-links-link-{$link_counter}--!>"] = $l;
					$link_counter++;
				}
				$filtered_content = str_replace( array_values( $temp_links ), array_keys( $temp_links ), $filtered_content );
				$links_replacements = array_merge( $links_replacements, $temp_links );
			}
			
			// Finally! add our links via preg_replace
			$regex = implode( '|', array_map( 'esc_attr', array_map( 'trim', explode( ',', $kw ) ) ) );
			$filtered_content = preg_replace( '/(' . $regex . ')/i', '<a href="' . esc_url( $url ) . '" title="$1">$1</a>', $filtered_content, absint( $max ) );
		}
		
		// Put the original <h> tags back in
		if( $headers[0] )
			$filtered_content = str_replace( array_keys( $headers_replacements ), array_values( $headers_replacements ), $filtered_content );
		
		// Put links back in
		if( ! empty( $links_replacements ) )
			$filtered_content = str_replace( array_keys( $links_replacements ), array_values( $links_replacements ), $filtered_content );
			
		if( $others[0] )
			$filtered_content = str_replace( array_keys( $other_replacements ), array_values( $other_replacements ), $filtered_content );
		
		$filtered_content = apply_filters( 'pmg_seo_auto_linker_content', $filtered_content, $content );
		
		// set the cache for those folks using persistent caching
		wp_cache_set( 'autolinker_content_' . $post->ID, $filtered_content, 'autolinker_content' );
		
		return $filtered_content;
	}
} // end class;

new pmgSeoAutoLinkerFront();