Implement Manage Versions feature in media library

[shreyasikhar]

Summary

Adds a Manage Versions feature to the WordPress Media Library attachment details panel, enabling users to:

• View all available versions for a media item
• Set any version as the active version
• Add a new version by selecting/uploading a file from the Media Library
• Delete non-default versions

This includes the UI (modal + styles), client-side interactions (AJAX + polling), and server-side AJAX handlers to integrate with GoDAM’s versions APIs and update URLs/metadata across the site when a version changes.

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What’s included

UI / UX

• Adds a “Manage Versions” action button in attachment details (works for all media types).
• Introduces a custom modal (template printed in admin_footer) with:
  • Versions list with Default/Active chips
  • “Set Active” action per version
  • Delete action for non-default versions
  • “Add New Version” button with max-version guard
• Snackbar improvements:
  • Adds success and error variants
  • Prevents overlapping timeouts (clears previous timeout before showing a new message)

Client-side (Media Library)

• Fetch versions via AJAX (godam_get_media_versions) and render modal using WP templates.
• Add-version flow:
  • Opens WP media frame filtered to same attachment type
  • Calls replace endpoint to start version creation
  • Polls for new version (up to 24 attempts, 5s interval)
  • Finalizes pending replace and refreshes current attachment UI (URL field + download link + reselect current attachment)
• Set-active flow:
  • Optimistic UI update while switching active version
  • Refreshes versions + attachment data on success

Server-side (AJAX + GoDAM API integration)

Adds AJAX endpoints:

• godam_get_media_versions
• godam_switch_active_version
• godam_delete_version
• godam_replace_media_version
• godam_finalize_media_version_replace

Also adds:

• Callback hook rtgodam_handle_callback_finished to finalize URL replacements when GoDAM finishes processing.
• URL replacement across site content + attachment guid updates, plus post cache cleanup.
• Updates relevant attachment meta (e.g., transcoded URLs, thumbnail, HLS/transcript where applicable) and refreshes rtgodam_image_sizes from selected source attachment when needed.

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Files changed

• assets/src/js/media-library/views/attachment-detail-two-column.js
• assets/src/css/media-library.scss
• inc/classes/class-assets.php
• inc/classes/class-media-library-ajax.php

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Testing notes

1. Open WP Admin → Media Library → select an attachment.
2. In attachment details, click Manage Versions.
3. Verify:
   • Versions list loads and shows Default/Active states
   • Set Active updates the active version and refreshes the attachment URL + download link
   • Add New Version opens media frame, starts upload/replace, then updates the modal after processing
   • Delete works for versions >= 2 and updates the list
4. Confirm snackbar messages show correct success/error styles.

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Notes / Caveats

• Polling is used to wait for GoDAM to register the newly created version before finalizing URL replacement.
• Delete is restricted to non-default versions (Version 1 cannot be deleted).