WordPress Image ALT generator (fills in empty alt attributes based on image filenames)

wordpress-post-image-alt-updater.php

<?php
/*
Plugin Name: Image alt updater
Plugin URI: http://woodyhayday.com
Description: Brutal image alt attribute updater - finds images without alt's and does its best (read before using, demo only)
Version: 0.1
Author: <a href="http://woodyhayday.com">Woody Hayday</a>
*/

#} Exit if accessed directly
if ( ! defined( 'ABSPATH' ) ) exit; 

// Works through attachment images and checks all published 
// posts to see if each image has an `alt` attribute
// ... where they don't it makes one up from filename or post title
// Use with caution, and always backup your database before running!
function wordPress_alt_image_updater(){	

	// HAVE YOU BACKED UP YOUR DB? RLY?
	if ( isset( $_GET['i_swear_i_backed_it_up'] ) ){

		// got rights?
		if (!current_user_can('manage_options'))  { wp_die( __('You do not have sufficient permissions to access this page.','projectpages') ); }

		// get image attachments
	    echo '<h2>Image alt attribute updater</h2>';
	    $args = array(
	            'post_type'      => 'attachment',
	            'post_mime_type' => 'image',
	            'numberposts'    => -1
	        );
	    $attachments = get_posts( $args );

	    echo 'Found '.count($attachments).' image attachments<br>';

	    if ( !isset( $_GET['doit'] ) ){

	    	echo 'Add `?doit=1` to your url when you\'re ready, and your database has been backed up.<br>';

	    } else {

		    // general counts
		    $updated_count = 0;
		    $filled_alt_count = 0;
		    $empty_alt_count = 0;

	    	echo '<h2>Processing...</h2>';

	    	global $wpdb;

	    	// if you have LOTS of images, put paging in here
	    	foreach ( $attachments as $attachment_post ){

	    		$image_url = $attachment_post->guid;

	    		echo '<strong>'.$image_url.'</strong><br>';

		    	// get post content of posts with this image
				$sql_results = $wpdb->get_results(
				    $wpdb->prepare( "
				        SELECT *
				            FROM $wpdb->posts
				        WHERE post_content 
				            LIKE %s
				        AND post_status = 'publish'
				         " 
				        ,'%' . like_escape( $image_url ) . '%'
			    	)
			  	);

				// got posts with this image url in?
				if ( is_array( $sql_results ) && count( $sql_results ) > 0 ){

					echo 'Found in '. count( $sql_results ) . ' posts.<br>';

					// this is only hitting first instance, doesn't allow for repeat images
					// you may need to tweak, depending on your image use case
					foreach ( $sql_results as $post ){

						echo '<hr>Post: '.$post->ID.'...<br>';

						$alt = '';

					  	// pull the <img> string
					  	$img_src_pos = strpos( $post->post_content, 'src="' . $image_url . '"' );
					  	if ( $img_src_pos ){

					  		// working backwards, find <img
					  		$img_opening_tag_pos = strrpos( substr( $post->post_content, 0, $img_src_pos ), '<img ' );

					  		if ( $img_opening_tag_pos ){

					  			// get closing tag
					  			$img_closing_tag_pos = strpos( substr( $post->post_content, $img_src_pos ), "/>" ) + 2 + $img_src_pos;

					  			if ( $img_closing_tag_pos ){

					  				$image_html = substr( $post->post_content, $img_opening_tag_pos, ($img_closing_tag_pos - $img_opening_tag_pos) );

					  				echo 'Got image html...<br>';
					  				//echo '<pre>' . esc_html( $image_html ) . '</pre>';

					  				// check for alt
					  				$alt_opening_pos = strpos( $image_html, 'alt="' ) + 5;
					  				if ( $alt_opening_pos ){

					  					// get the alt
					  					$alt = substr( $image_html, $alt_opening_pos, strpos( substr( $image_html, $alt_opening_pos ), '"' ) );

					  					echo 'Image already has a value for alt..."' . $alt . '"<br>';				  					

					  				}

								
									if ( empty( $alt ) ){

										$new_alt = '';
										$empty_alt_count++;

										echo 'Found an image with an empty, or no alt...<br><pre>' . esc_html( $image_html ) . '</pre>';


										// try and generate a new alt
										$src_opening_pos = ( strpos( $image_html, 'src="' ) + 5 );

											// filename
											$image_file_url = substr( $image_html, $src_opening_pos, strpos( substr( $image_html, $src_opening_pos ), '"' ) );

											// parsed path
											$path = parse_url($image_file_url, PHP_URL_PATH);
											$image_file_name = basename($path);
											$image_file_slug = substr($image_file_name, 0 , (strrpos($image_file_name, ".")));

											// split by, and remove - + _ + .
											$image_file_slug = str_replace( '_', ' ', str_replace( '-', ' ', str_replace( '.', ' ', $image_file_slug ) ) );

											if ( !empty( $image_file_slug ) ){

												$new_alt = ucwords( $image_file_slug );

											}

											// remove any trailing -1 -2 etc.
											if ( substr( $new_alt, -2 ) == ' 1' ){ $new_alt = substr( $new_alt, 0, strlen( $new_alt ) - 2 ); }
											if ( substr( $new_alt, -2 ) == ' 2' ){ $new_alt = substr( $new_alt, 0, strlen( $new_alt ) - 2 ); }

											// (+-) post title
											/*$post_title = $post->post_title;

											if ( !empty( $post->post_title ) ){

												if ( !empty( $new_alt ) ){

													// append break
													$new_alt .= ' - ';

												}

												$new_alt .= $post->post_title;

											} */

											// any last minute proj-specific tweaks:
											$new_alt = str_replace( 'Cfs ', 'CFS ', $new_alt );
											$new_alt = str_replace( 'Me ', 'ME ', $new_alt );


											echo 'New alt generated: "' . $new_alt . '"<br>';


											// slice and dice, inject the new <img> html with alt
											$new_img_html = $image_html;
											if ( strpos( $image_html, 'alt=""' ) ){

												// straight replace
												$new_img_html = str_replace( 'alt=""', 'alt="' . esc_attr( $new_alt ) . '"', $image_html );

											} else {
												
												// not found, inject
												$new_img_html = str_replace( '/>', ' alt="' . esc_attr( $new_alt ) . '"/>', $image_html );

											}

											echo 'This:<pre>' . esc_html( $image_html ) . '</pre><br>Will be replaced with:<pre>' . esc_html( $new_img_html ) . '</pre>';

											// update it, if changed
											if ( $new_img_html !== $image_html ){

												$post_to_update = $post;
												$post_to_update->post_content = str_replace( $image_html, $new_img_html, $post->post_content );
												
												$outcome = wp_update_post( $post_to_update );

												echo 'Updated post ' . $post->ID . ': <a href="'.$post->guid.'" target="_blank">View</a><br>';											

											}



										$updated_count++;

									} else {

										$filled_alt_count++;

									}										

					  			}
					  		}

							// useful stop, if you want to step through :) 
							//if ( $updated_count > 5 ) exit();

					  	}

						echo '<hr>';

					}

				} else {

					echo 'Not found in any post html.<br><hr>';
				}

			}

			// summary
			echo '<hr><hr><h1>Summary</h1>';
			echo count( $attachments ) . ' attachments processed<br>';
			echo $filled_alt_count . ' images found with alt already present<br>';
			echo $empty_alt_count . ' images found with no alt<br>';
			echo $updated_count . ' alt updates made to post html<br>';
			echo 'Note! This script is flawed! It was written quickly for a specific use case, it may miss some alts, or mangle your db. Please triple check your data.';

		}

		exit();

	}

} add_action( 'init' , 'wordPress_alt_image_updater');