get_attachment_fields_to_edit( WP_Post $post, array $errors = null )

function get_attachment_fields_to_edit($post, $errors = null) {
	if ( is_int($post) )
		$post = get_post($post);
	if ( is_array($post) )
		$post = new WP_Post( (object) $post );

	$image_url = wp_get_attachment_url($post->ID);

	$edit_post = sanitize_post($post, 'edit');

	$form_fields = array(
		'post_title'   => array(
			'label'      => __('Title'),
			'value'      => $edit_post->post_title
		),
		'image_alt'   => array(),
		'post_excerpt' => array(
			'label'      => __('Caption'),
			'input'      => 'html',
			'html'       => wp_caption_input_textarea($edit_post)
		),
		'post_content' => array(
			'label'      => __('Description'),
			'value'      => $edit_post->post_content,
			'input'      => 'textarea'
		),
		'url'          => array(
			'label'      => __('Link URL'),
			'input'      => 'html',
			'html'       => image_link_input_fields($post, get_option('image_default_link_type')),
			'helps'      => __('Enter a link URL or click above for presets.')
		),
		'menu_order'   => array(
			'label'      => __('Order'),
			'value'      => $edit_post->menu_order
		),
		'image_url'	=> array(
			'label'      => __('File URL'),
			'input'      => 'html',
			'html'       => "<input type='text' class='text urlfield' readonly='readonly' name='attachments[$post->ID][url]' value='" . esc_attr($image_url) . "' /><br />",
			'value'      => wp_get_attachment_url($post->ID),
			'helps'      => __('Location of the uploaded file.')
		)
	);

	foreach ( get_attachment_taxonomies($post) as $taxonomy ) {
		$t = (array) get_taxonomy($taxonomy);
		if ( ! $t['public'] || ! $t['show_ui'] )
			continue;
		if ( empty($t['label']) )
			$t['label'] = $taxonomy;
		if ( empty($t['args']) )
			$t['args'] = array();

		$terms = get_object_term_cache($post->ID, $taxonomy);
		if ( false === $terms )
			$terms = wp_get_object_terms($post->ID, $taxonomy, $t['args']);

		$values = array();

		foreach ( $terms as $term )
			$values[] = $term->slug;
		$t['value'] = join(', ', $values);

		$form_fields[$taxonomy] = $t;
	}

	// Merge default fields with their errors, so any key passed with the error (e.g. 'error', 'helps', 'value') will replace the default
	// The recursive merge is easily traversed with array casting: foreach ( (array) $things as $thing )
	$form_fields = array_merge_recursive($form_fields, (array) $errors);

	// This was formerly in image_attachment_fields_to_edit().
	if ( substr($post->post_mime_type, 0, 5) == 'image' ) {
		$alt = get_post_meta($post->ID, '_wp_attachment_image_alt', true);
		if ( empty($alt) )
			$alt = '';

		$form_fields['post_title']['required'] = true;

		$form_fields['image_alt'] = array(
			'value' => $alt,
			'label' => __('Alternative Text'),
			'helps' => __('Alt text for the image, e.g. &#8220;The Mona Lisa&#8221;')
		);

		$form_fields['align'] = array(
			'label' => __('Alignment'),
			'input' => 'html',
			'html'  => image_align_input_fields($post, get_option('image_default_align')),
		);

		$form_fields['image-size'] = image_size_input_fields( $post, get_option('image_default_size', 'medium') );

	} else {
		unset( $form_fields['image_alt'] );
	}

	/**
	 * Filters the attachment fields to edit.
	 *
	 * @since WP-2.5.0
	 *
	 * @param array   $form_fields An array of attachment form fields.
	 * @param WP_Post $post        The WP_Post attachment object.
	 */
	$form_fields = apply_filters( 'attachment_fields_to_edit', $form_fields, $post );

	return $form_fields;
}