Tutorial : WordPress – Automatically Rename Images On Upload.

<?php
/*
Plugin Name: EasyCodingWithAI - Automatically Rename Images On Upload
Description: Automatically renames images to match post title field.
Version: 1.3
Author: EasyCodingWithAI
*/

function easycoding_filter_filename($title) {
    $title = preg_replace('/[^a-zA-Z0-9\s]/', '', $title);
    $title = str_replace(' ', '-', $title);
    $title = strtolower($title);
    return $title;
}

function easycoding_rename_image_on_upload($file) {
    $default_title = 'untitled-image';
    $alt_text = 'Untitled Image'; // Default alt text

    if (isset($_POST['post_id']) && $post_id = (int)$_POST['post_id']) {
        $post = get_post($post_id);

        // Initialize variables
        $title = '';
        $new_filename = '';

        // Check if post exists
        if ($post) {
            $title = $post->post_title;

            // Check if the title is empty or "Auto Draft"
            if (empty($title) || strtolower($title) === 'auto draft') {
                // Use default title and alt text
                $new_filename = 'image-' . $post_id . '.' . pathinfo($file['name'], PATHINFO_EXTENSION);
            } else {
                // Set the filtered title for the filename
                $filtered_title = easycoding_filter_filename($title);
                $new_filename = $filtered_title . '-' . $post_id . '.' . pathinfo($file['name'], PATHINFO_EXTENSION);
            }
        } else {
            $new_filename = 'image-' . $post_id . '.' . pathinfo($file['name'], PATHINFO_EXTENSION);
        }

        // Set the new filename
        $file['name'] = $new_filename;

        // Set alt text and title for untitled images
        if (empty($title) || strtolower($title) === 'auto draft') {
            add_filter('wp_handle_upload', function($upload) use ($alt_text) {
                // Set alt text for the image in meta after upload
                add_post_meta($upload['id'], '_wp_attachment_image_alt', $alt_text);
                return $upload;
            });

            // Set the post title to "Untitled Image"
            add_action('add_attachment', function($attachment_id) {
                wp_update_post(array(
                    'ID' => $attachment_id,
                    'post_title' => 'Untitled Image' // Set title to "Untitled Image"
                ));
            });
        }
    }

    return $file;
}
add_filter('wp_handle_upload_prefilter', 'easycoding_rename_image_on_upload');

function easycoding_set_image_meta($post_ID) {
    $post = get_post($post_ID);

    if ($post && $post->post_type == 'attachment') {
        $parent_id = $post->post_parent;
        $parent_post = get_post($parent_id);

        if ($parent_post) {
            $base_title = easycoding_filter_filename($parent_post->post_title);
            $attachments = get_posts(array(
                'post_type' => 'attachment',
                'post_parent' => $parent_id,
                'orderby' => 'ID',
                'order' => 'ASC'
            ));

            $index = array_search($post_ID, array_column($attachments, 'ID')) + 1;

            // Update alt text
            if (empty($parent_post->post_title) || strtolower($parent_post->post_title) === 'auto draft') {
                $alt_text = 'Untitled Image #' . $index; // Set alt text for untitled images
            } else {
                $alt_text = ucwords(str_replace('-', ' ', $base_title)) . " #$index"; // Use the base title with an index
            }
            update_post_meta($post_ID, '_wp_attachment_image_alt', $alt_text);

            // Update the title with a readable format
            wp_update_post(array(
                'ID' => $post_ID,
                'post_title' => $alt_text
            ));
        }
    }
}
add_action('add_attachment', 'easycoding_set_image_meta');

function easycoding_update_image_title_and_urls($post_id) {
    $post = get_post($post_id);

    if ($post && $post->post_type != 'attachment') {
        $attachments = get_posts(array(
            'post_type' => 'attachment',
            'post_parent' => $post_id
        ));

        foreach ($attachments as $attachment) {
            $old_url = wp_get_attachment_url($attachment->ID);

            $filtered_title = easycoding_filter_filename($post->post_title);
            $ext = pathinfo($attachment->guid, PATHINFO_EXTENSION);
            $attachment_id = $attachment->ID;

            // Use title-attachment ID format for the filename
            $new_filename = $filtered_title . '-' . $attachment_id . '.' . $ext; // Use title-attachment ID format
            $upload_dir = wp_upload_dir();
            $new_url = trailingslashit($upload_dir['url']) . $new_filename;

            // Update alt text and title if the title is set
            if (!empty($filtered_title) && strtolower($filtered_title) !== 'auto draft') {
                $alt_text = ucwords(str_replace('-', ' ', $filtered_title));
            } else {
                $alt_text = 'Untitled Image'; // Set alt text for untitled images
            }

            update_post_meta($attachment->ID, '_wp_attachment_image_alt', $alt_text);
            wp_update_post(array(
                'ID' => $attachment->ID,
                'post_title' => $alt_text,
            ));

            // Update GUID
            $post_content = $post->post_content;
            $updated_content = str_replace($old_url, $new_url, $post_content);
            if ($updated_content !== $post_content) {
                wp_update_post(array(
                    'ID' => $post_id,
                    'post_content' => $updated_content
                ));
            }
        }
    }
}
add_action('save_post', 'easycoding_update_image_title_and_urls');

function easycoding_rename_auto_draft_images($post_id) {
    // Check if the post is being updated
    if (get_post($post_id) && get_post($post_id)->post_type != 'attachment') {
        $post = get_post($post_id);
        $new_title = easycoding_filter_filename($post->post_title);
        $default_title = 'untitled-image';

        // Only proceed if the post title is not empty or "Auto Draft"
        if (empty($new_title) || strtolower($new_title) === 'auto draft') {
            $new_title = $default_title;
        }

        $attachments = get_posts(array(
            'post_type' => 'attachment',
            'post_parent' => $post_id,
            'numberposts' => -1,
            'post_status' => 'any'
        ));

        foreach ($attachments as $attachment) {
            $old_filename = $attachment->guid; // Get the old filename
            // Check if the filename starts with 'image-' and contains the attachment ID
            if (strpos($old_filename, 'image-') === 0) {
                $ext = pathinfo($old_filename, PATHINFO_EXTENSION); // Get the file extension
                // Construct the new filename
                $new_filename = 'image-' . $attachment->ID . '.' . $ext;

                // Update the attachment's GUID
                $upload_dir = wp_upload_dir();
                $new_url = trailingslashit($upload_dir['url']) . $new_filename;

                // Update the post meta and attachment details
                wp_update_post(array(
                    'ID' => $attachment->ID,
                    'guid' => $new_url,
                    'post_title' => ucwords(str_replace('-', ' ', $new_title)),
                ));

                // Optionally, rename the physical file (if needed)
                rename($old_filename, $new_url);
            }
        }
    }
}
add_action('save_post', 'easycoding_rename_auto_draft_images');