<?php
/**
* Post revision functions.
*
* @package WordPress
* @subpackage Post_Revisions
*/

/**
* Determines which fields of posts are to be saved in revisions.
*
* @since 2.6.0
* @since 4.5.0 A `WP_Post` object can now be passed to the `$post` parameter.
* @since 4.5.0 The optional `$autosave` parameter was deprecated and renamed to `$deprecated`.
* @access private
*
* @param array|WP_Post $post Optional. A post array or a WP_Post object being processed
* for insertion as a post revision. Default empty array.
* @param bool $deprecated Not used.
* @return string[] Array of fields that can be versioned.
*/
function _wp_post_revision_fields( $post = array(), $deprecated = false ) {
static $fields = null;

if ( ! is_array( $post ) ) {
$post = get_post( $post, ARRAY_A );
}

if ( is_null( $fields ) ) {
// Allow these to be versioned.
$fields = array(
'post_title' => __( 'Title' ),
'post_content' => __( 'Content' ),
'post_excerpt' => __( 'Excerpt' ),
);
}

/**
* Filters the list of fields saved in post revisions.
*
* Included by default: 'post_title', 'post_content' and 'post_excerpt'.
*
* Disallowed fields: 'ID', 'post_name', 'post_parent', 'post_date',
* 'post_date_gmt', 'post_status', 'post_type', 'comment_count',
* and 'post_author'.
*
* @since 2.6.0
* @since 4.5.0 The `$post` parameter was added.
*
* @param string[] $fields List of fields to revision. Contains 'post_title',
* 'post_content', and 'post_excerpt' by default.
* @param array $post A post array being processed for insertion as a post revision.
*/
$fields = apply_filters( '_wp_post_revision_fields', $fields, $post );

// WP uses these internally either in versioning or elsewhere - they cannot be versioned.
foreach ( array( 'ID', 'post_name', 'post_parent', 'post_date', 'post_date_gmt', 'post_status', 'post_type', 'comment_count', 'post_author' ) as $protect ) {
unset( $fields[ $protect ] );
}

return $fields;
}

/**
* Returns a post array ready to be inserted into the posts table as a post revision.
*
* @since 4.5.0
* @access private
*
* @param array|WP_Post $post Optional. A post array or a WP_Post object to be processed
* for insertion as a post revision. Default empty array.
* @param bool $autosave Optional. Is the revision an autosave? Default false.
* @return array Post array ready to be inserted as a post revision.
*/
function _wp_post_revision_data( $post = array(), $autosave = false ) {
if ( ! is_array( $post ) ) {
$post = get_post( $post, ARRAY_A );
}

$fields = _wp_post_revision_fields( $post );

$revision_data = array();

foreach ( array_intersect( array_keys( $post ), array_keys( $fields ) ) as $field ) {
$revision_data[ $field ] = $post[ $field ];
}

$revision_data['post_parent'] = $post['ID'];
$revision_data['post_status'] = 'inherit';
$revision_data['post_type'] = 'revision';
$revision_data['post_name'] = $autosave ? "$post[ID]-autosave-v1" : "$post[ID]-revision-v1"; // "1" is the revisioning system version.
$revision_data['post_date'] = isset( $post['post_modified'] ) ? $post['post_modified'] : '';
$revision_data['post_date_gmt'] = isset( $post['post_modified_gmt'] ) ? $post['post_modified_gmt'] : '';

return $revision_data;
}

/**
* Saves revisions for a post after all changes have been made.
*
* @since 6.4.0
*
* @param int $post_id The post id that was inserted.
* @param WP_Post $post The post object that was inserted.
* @param bool $update Whether this insert is updating an existing post.
*/
function wp_save_post_revision_on_insert( $post_id, $post, $update ) {
if ( ! $update ) {
return;
}

if ( ! has_action( 'post_updated', 'wp_save_post_revision' ) ) {
return;
}

wp_save_post_revision( $post_id );
}

/**
* Creates a revision for the current version of a post.
*
* Typically used immediately after a post update, as every update is a revision,
* and the most recent revision always matches the current post.
*
* @since 2.6.0
*
* @param int $post_id The ID of the post to save as a revision.
* @return int|WP_Error|void Void or 0 if error, new revision ID, if success.
*/
function wp_save_post_revision( $post_id ) {
if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
return;
}

// Prevent saving post revisions if revisions should be saved on wp_after_insert_post.
if ( doing_action( 'post_updated' ) && has_action( 'wp_after_insert_post', 'wp_save_post_revision_on_insert' ) ) {
return;
}

$post = get_post( $post_id );

if ( ! $post ) {
return;
}

if ( ! post_type_supports( $post->post_type, 'revisions' ) ) {
return;
}

if ( 'auto-draft' === $post->post_status ) {
return;
}

if ( ! wp_revisions_enabled( $post ) ) {
return;
}

/*
* Compare the proposed update with the last stored revision verifying that
* they are different, unless a plugin tells us to always save regardless.
* If no previous revisions, save one.
*/
$revisions = wp_get_post_revisions( $post_id );
if ( $revisions ) {
// Grab the latest revision, but not an autosave.
foreach ( $revisions as $revision ) {
if ( str_contains( $revision->post_name, "{$revision->post_parent}-revision" ) ) {
$latest_revision = $revision;
break;
}
}

/**
* Filters whether the post has changed since the latest revision.
*
* By default a revision is saved only if one of the revisioned fields has changed.
* This filter can override that so a revision is saved even if nothing has changed.
*
* @since 3.6.0
*
* @param bool $check_for_changes Whether to check for changes before saving a new revision.
* Default true.
* @param WP_Post $latest_revision The latest revision post object.
* @param WP_Post $post The post object.
*/
if ( isset( $latest_revision ) && apply_filters( 'wp_save_post_revision_check_for_changes', true, $latest_revision, $post ) ) {
$post_has_changed = false;

foreach ( array_keys( _wp_post_revision_fields( $post ) ) as $field ) {
if ( normalize_whitespace( $post->$field ) !== normalize_whitespace( $latest_revision->$field ) ) {
$post_has_changed = true;
break;
}
}

/**
* Filters whether a post has changed.
*
* By default a revision is saved only if one of the revisioned fields has changed.
* This filter allows for additional checks to determine if there were changes.
*
* @since 4.1.0
*
* @param bool $post_has_changed Whether the post has changed.
* @param WP_Post $latest_revision The latest revision post object.
* @param WP_Post $post The post object.
*/
$post_has_changed = (bool) apply_filters( 'wp_save_post_revision_post_has_changed', $post_has_changed, $latest_revision, $post );

// Don't save revision if post unchanged.
if ( ! $post_has_changed ) {
return;
}
}
}

$return = _wp_put_post_revision( $post );

/*
* If a limit for the number of revisions to keep has been set,
* delete the oldest ones.
*/
$revisions_to_keep = wp_revisions_to_keep( $post );

if ( $revisions_to_keep < 0 ) {
return $return;
}

$revisions = wp_get_post_revisions( $post_id, array( 'order' => 'ASC' ) );

/**
* Filters the revisions to be considered for deletion.
*
* @since 6.2.0
*
* @param WP_Post[] $revisions Array of revisions, or an empty array if none.
* @param int $post_id The ID of the post to save as a revision.
*/
$revisions = apply_filters(
'wp_save_post_revision_revisions_before_deletion',
$revisions,
$post_id
);

$delete = count( $revisions ) - $revisions_to_keep;

if ( $delete < 1 ) {
return $return;
}

$revisions = array_slice( $revisions, 0, $delete );

for ( $i = 0; isset( $revisions[ $i ] ); $i++ ) {
if ( str_contains( $revisions[ $i ]->post_name, 'autosave' ) ) {
continue;
}

wp_delete_post_revision( $revisions[ $i ]->ID );
}

return $return;
}

/**
* Retrieves the autosaved data of the specified post.
*
* Returns a post object with the information that was autosaved for the specified post.
* If the optional $user_id is passed, returns the autosave for that user, otherwise
* returns the latest autosave.
*
* @since 2.6.0
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param int $post_id The post ID.
* @param int $user_id Optional. The post author ID. Default 0.
* @return WP_Post|false The autosaved data or false on failure or when no autosave exists.
*/
function wp_get_post_autosave( $post_id, $user_id = 0 ) {
global $wpdb;

$autosave_name = $post_id . '-autosave-v1';
$user_id_query = ( 0 !== $user_id ) ? "AND post_author = $user_id" : null;

// Construct the autosave query.
$autosave_query = "
SELECT *
FROM $wpdb->posts
WHERE post_parent = %d
AND post_type = 'revision'
AND post_status = 'inherit'
AND post_name = %s " . $user_id_query . '
ORDER BY post_date DESC
LIMIT 1';

$autosave = $wpdb->get_results(
$wpdb->prepare(
$autosave_query,
$post_id,
$autosave_name
)
);

if ( ! $autosave ) {
return false;
}

return get_post( $autosave[0] );
}

/**
* Determines if the specified post is a revision.
*
* @since 2.6.0
*
* @param int|WP_Post $post Post ID or post object.
* @return int|false ID of revision's parent on success, false if not a revision.
*/
function wp_is_post_revision( $post ) {
$post = wp_get_post_revision( $post );

if ( ! $post ) {
return false;
}

return (int) $post->post_parent;
}

/**
* Determines if the specified post is an autosave.
*
* @since 2.6.0
*
* @param int|WP_Post $post Post ID or post object.
* @return int|false ID of autosave's parent on success, false if not a revision.
*/
function wp_is_post_autosave( $post ) {
$post = wp_get_post_revision( $post );

if ( ! $post ) {
return false;
}

if ( str_contains( $post->post_name, "{$post->post_parent}-autosave" ) ) {
return (int) $post->post_parent;
}

return false;
}

/**
* Inserts post data into the posts table as a post revision.
*
* @since 2.6.0
* @access private
*
* @param int|WP_Post|array|null $post Post ID, post object OR post array.
* @param bool $autosave Optional. Whether the revision is an autosave or not.
* Default false.
* @return int|WP_Error WP_Error or 0 if error, new revision ID if success.
*/
function _wp_put_post_revision( $post = null, $autosave = false ) {
if ( is_object( $post ) ) {
$post = get_object_vars( $post );
} elseif ( ! is_array( $post ) ) {
$post = get_post( $post, ARRAY_A );
}

if ( ! $post || empty( $post['ID'] ) ) {
return new WP_Error( 'invalid_post', __( 'Invalid post ID.' ) );
}

if ( isset( $post['post_type'] ) && 'revision' === $post['post_type'] ) {
return new WP_Error( 'post_type', __( 'Cannot create a revision of a revision' ) );
}

$post = _wp_post_revision_data( $post, $autosave );
$post = wp_slash( $post ); // Since data is from DB.

$revision_id = wp_insert_post( $post, true );
if ( is_wp_error( $revision_id ) ) {
return $revision_id;
}

if ( $revision_id ) {
/**
* Fires once a revision has been saved.
*
* @since 2.6.0
* @since 6.4.0 The post_id parameter was added.
*
* @param int $revision_id Post revision ID.
* @param int $post_id Post ID.
*/
do_action( '_wp_put_post_revision', $revision_id, $post['post_parent'] );
}

return $revision_id;
}


/**
* Save the revisioned meta fields.
*
* @since 6.4.0
*
* @param int $revision_id The ID of the revision to save the meta to.
* @param int $post_id The ID of the post the revision is associated with.
*/
function wp_save_revisioned_meta_fields( $revision_id, $post_id ) {
$post_type = get_post_type( $post_id );
if ( ! $post_type ) {
return;
}

foreach ( wp_post_revision_meta_keys( $post_type ) as $meta_key ) {
if ( metadata_exists( 'post', $post_id, $meta_key ) ) {
_wp_copy_post_meta( $post_id, $revision_id, $meta_key );
}
}
}

/**
* Gets a post revision.
*
* @since 2.6.0
*
* @param int|WP_Post $post Post ID or post object.
* @param string $output Optional. The required return type. One of OBJECT, ARRAY_A, or ARRAY_N, which
* correspond to a WP_Post object, an associative array, or a numeric array,
* respectively. Default OBJECT.
* @param string $filter Optional sanitization filter. See sanitize_post(). Default 'raw'.
* @return WP_Post|array|null WP_Post (or array) on success, or null on failure.
*/
function wp_get_post_revision( &$post, $output = OBJECT, $filter = 'raw' ) {
$revision = get_post( $post, OBJECT, $filter );

if ( ! $revision ) {
return $revision;
}

if ( 'revision' !== $revision->post_type ) {
return null;
}

if ( OBJECT === $output ) {
return $revision;
} elseif ( ARRAY_A === $output ) {
$_revision = get_object_vars( $revision );
return $_revision;
} elseif ( ARRAY_N === $output ) {
$_revision = array_values( get_object_vars( $revision ) );
return $_revision;
}

return $revision;
}

/**
* Restores a post to the specified revision.
*
* Can restore a past revision using all fields of the post revision, or only selected fields.
*
* @since 2.6.0
*
* @param int|WP_Post $revision Revision ID or revision object.
* @param array $fields Optional. What fields to restore from. Defaults to all.
* @return int|false|null Null if error, false if no fields to restore, (int) post ID if success.
*/
function wp_restore_post_revision( $revision, $fields = null ) {
$revision = wp_get_post_revision( $revision, ARRAY_A );

if ( ! $revision ) {
return $revision;
}

if ( ! is_array( $fields ) ) {
$fields = array_keys( _wp_post_revision_fields( $revision ) );
}

$update = array();
foreach ( array_intersect( array_keys( $revision ), $fields ) as $field ) {
$update[ $field ] = $revision[ $field ];
}

if ( ! $update ) {
return false;
}

$update['ID'] = $revision['post_parent'];

$update = wp_slash( $update ); // Since data is from DB.

$post_id = wp_update_post( $update );

if ( ! $post_id || is_wp_error( $post_id ) ) {
return $post_id;
}

// Update last edit user.
update_post_meta( $post_id, '_edit_last', get_current_user_id() );

/**
* Fires after a post revision has been restored.
*
* @since 2.6.0
*
* @param int $post_id Post ID.
* @param int $revision_id Post revision ID.
*/
do_action( 'wp_restore_post_revision', $post_id, $revision['ID'] );

return $post_id;
}

/**
* Restore the revisioned meta values for a post.
*
* @since 6.4.0
*
* @param int $post_id The ID of the post to restore the meta to.
* @param int $revision_id The ID of the revision to restore the meta from.
*/
function wp_restore_post_revision_meta( $post_id, $revision_id ) {
$post_type = get_post_type( $post_id );
if ( ! $post_type ) {
return;
}

// Restore revisioned meta fields.
foreach ( wp_post_revision_meta_keys( $post_type ) as $meta_key ) {

// Clear any existing meta.
delete_post_meta( $post_id, $meta_key );

_wp_copy_post_meta( $revision_id, $post_id, $meta_key );
}
}

/**
* Copy post meta for the given key from one post to another.
*
* @since 6.4.0
*
* @param int $source_post_id Post ID to copy meta value(s) from.
* @param int $target_post_id Post ID to copy meta value(s) to.
* @param string $meta_key Meta key to copy.
*/
function _wp_copy_post_meta( $source_post_id, $target_post_id, $meta_key ) {

foreach ( get_post_meta( $source_post_id, $meta_key ) as $meta_value ) {
/**
* We use add_metadata() function vs add_post_meta() here
* to allow for a revision post target OR regular post.
*/
add_metadata( 'post', $target_post_id, $meta_key, wp_slash( $meta_value ) );
}
}

/**
* Determine which post meta fields should be revisioned.
*
* @since 6.4.0
*
* @param string $post_type The post type being revisioned.
* @return array An array of meta keys to be revisioned.
*/
function wp_post_revision_meta_keys( $post_type ) {
$registered_meta = array_merge(
get_registered_meta_keys( 'post' ),
get_registered_meta_keys( 'post', $post_type )
);

$wp_revisioned_meta_keys = array();

foreach ( $registered_meta as $name => $args ) {
if ( $args['revisions_enabled'] ) {
$wp_revisioned_meta_keys[ $name ] = true;
}
}

$wp_revisioned_meta_keys = array_keys( $wp_revisioned_meta_keys );

/**
* Filter the list of post meta keys to be revisioned.
*
* @since 6.4.0
*
* @param array $keys An array of meta fields to be revisioned.
* @param string $post_type The post type being revisioned.
*/
return apply_filters( 'wp_post_revision_meta_keys', $wp_revisioned_meta_keys, $post_type );
}

/**
* Check whether revisioned post meta fields have changed.
*
* @since 6.4.0
*
* @param bool $post_has_changed Whether the post has changed.
* @param WP_Post $last_revision The last revision post object.
* @param WP_Post $post The post object.
* @return bool Whether the post has changed.
*/
function wp_check_revisioned_meta_fields_have_changed( $post_has_changed, WP_Post $last_revision, WP_Post $post ) {
foreach ( wp_post_revision_meta_keys( $post->post_type ) as $meta_key ) {
if ( get_post_meta( $post->ID, $meta_key ) !== get_post_meta( $last_revision->ID, $meta_key ) ) {
$post_has_changed = true;
break;
}
}
return $post_has_changed;
}

/**
* Deletes a revision.
*
* Deletes the row from the posts table corresponding to the specified revision.
*
* @since 2.6.0
*
* @param int|WP_Post $revision Revision ID or revision object.
* @return WP_Post|false|null Null or false if error, deleted post object if success.
*/
function wp_delete_post_revision( $revision ) {
$revision = wp_get_post_revision( $revision );

if ( ! $revision ) {
return $revision;
}

$delete = wp_delete_post( $revision->ID );

if ( $delete ) {
/**
* Fires once a post revision has been deleted.
*
* @since 2.6.0
*
* @param int $revision_id Post revision ID.
* @param WP_Post $revision Post revision object.
*/
do_action( 'wp_delete_post_revision', $revision->ID, $revision );
}

return $delete;
}

/**
* Returns all revisions of specified post.
*
* @since 2.6.0
*
* @see get_children()
*
* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
* @param array|null $args Optional. Arguments for retrieving post revisions. Default null.
* @return WP_Post[]|int[] Array of revision objects or IDs, or an empty array if none.
*/
function wp_get_post_revisions( $post = 0, $args = null ) {
$post = get_post( $post );

if ( ! $post || empty( $post->ID ) ) {
return array();
}

$defaults = array(
'order' => 'DESC',
'orderby' => 'date ID',
'check_enabled' => true,
);
$args = wp_parse_args( $args, $defaults );

if ( $args['check_enabled'] && ! wp_revisions_enabled( $post ) ) {
return array();
}

$args = array_merge(
$args,
array(
'post_parent' => $post->ID,
'post_type' => 'revision',
'post_status' => 'inherit',
)
);

$revisions = get_children( $args );

if ( ! $revisions ) {
return array();
}

return $revisions;
}

/**
* Returns the latest revision ID and count of revisions for a post.
*
* @since 6.1.0
*
* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global $post.
* @return array|WP_Error {
* Returns associative array with latest revision ID and total count,
* or a WP_Error if the post does not exist or revisions are not enabled.
*
* @type int $latest_id The latest revision post ID or 0 if no revisions exist.
* @type int $count The total count of revisions for the given post.
* }
*/
function wp_get_latest_revision_id_and_total_count( $post = 0 ) {
$post = get_post( $post );

if ( ! $post ) {
return new WP_Error( 'invalid_post', __( 'Invalid post.' ) );
}

if ( ! wp_revisions_enabled( $post ) ) {
return new WP_Error( 'revisions_not_enabled', __( 'Revisions not enabled.' ) );
}

$args = array(
'post_parent' => $post->ID,
'fields' => 'ids',
'post_type' => 'revision',
'post_status' => 'inherit',
'order' => 'DESC',
'orderby' => 'date ID',
'posts_per_page' => 1,
'ignore_sticky_posts' => true,
);

$revision_query = new WP_Query();
$revisions = $revision_query->query( $args );

if ( ! $revisions ) {
return array(
'latest_id' => 0,
'count' => 0,
);
}

return array(
'latest_id' => $revisions[0],
'count' => $revision_query->found_posts,
);
}

/**
* Returns the url for viewing and potentially restoring revisions of a given post.
*
* @since 5.9.0
*
* @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
* @return string|null The URL for editing revisions on the given post, otherwise null.
*/
function wp_get_post_revisions_url( $post = 0 ) {
$post = get_post( $post );

if ( ! $post instanceof WP_Post ) {
return null;
}

// If the post is a revision, return early.
if ( 'revision' === $post->post_type ) {
return get_edit_post_link( $post );
}

if ( ! wp_revisions_enabled( $post ) ) {
return null;
}

$revisions = wp_get_latest_revision_id_and_total_count( $post->ID );

if ( is_wp_error( $revisions ) || 0 === $revisions['count'] ) {
return null;
}

return get_edit_post_link( $revisions['latest_id'] );
}

/**
* Determines whether revisions are enabled for a given post.
*
* @since 3.6.0
*
* @param WP_Post $post The post object.
* @return bool True if number of revisions to keep isn't zero, false otherwise.
*/
function wp_revisions_enabled( $post ) {
return wp_revisions_to_keep( $post ) !== 0;
}

/**
* Determines how many revisions to retain for a given post.
*
* By default, an infinite number of revisions are kept.
*
* The constant WP_POST_REVISIONS can be set in wp-config to specify the limit
* of revisions to keep.
*
* @since 3.6.0
*
* @param WP_Post $post The post object.
* @return int The number of revisions to keep.
*/
function wp_revisions_to_keep( $post ) {
$num = WP_POST_REVISIONS;

if ( true === $num ) {
$num = -1;
} else {
$num = (int) $num;
}

if ( ! post_type_supports( $post->post_type, 'revisions' ) ) {
$num = 0;
}

/**
* Filters the number of revisions to save for the given post.
*
* Overrides the value of WP_POST_REVISIONS.
*
* @since 3.6.0
*
* @param int $num Number of revisions to store.
* @param WP_Post $post Post object.
*/
$num = apply_filters( 'wp_revisions_to_keep', $num, $post );

/**
* Filters the number of revisions to save for the given post by its post type.
*
* Overrides both the value of WP_POST_REVISIONS and the {@see 'wp_revisions_to_keep'} filter.
*
* The dynamic portion of the hook name, `$post->post_type`, refers to
* the post type slug.
*
* Possible hook names include:
*
* - `wp_post_revisions_to_keep`
* - `wp_page_revisions_to_keep`
*
* @since 5.8.0
*
* @param int $num Number of revisions to store.
* @param WP_Post $post Post object.
*/
$num = apply_filters( "wp_{$post->post_type}_revisions_to_keep", $num, $post );

return (int) $num;
}

/**
* Sets up the post object for preview based on the post autosave.
*
* @since 2.7.0
* @access private
*
* @param WP_Post $post
* @return WP_Post|false
*/
function _set_preview( $post ) {
if ( ! is_object( $post ) ) {
return $post;
}

$preview = wp_get_post_autosave( $post->ID );

if ( is_object( $preview ) ) {
$preview = sanitize_post( $preview );

$post->post_content = $preview->post_content;
$post->post_title = $preview->post_title;
$post->post_excerpt = $preview->post_excerpt;
}

add_filter( 'get_the_terms', '_wp_preview_terms_filter', 10, 3 );
add_filter( 'get_post_metadata', '_wp_preview_post_thumbnail_filter', 10, 3 );
add_filter( 'get_post_metadata', '_wp_preview_meta_filter', 10, 4 );

return $post;
}

/**
* Filters the latest content for preview from the post autosave.
*
* @since 2.7.0
* @access private
*/
function _show_post_preview() {
if ( isset( $_GET['preview_id'] ) && isset( $_GET['preview_nonce'] ) ) {
$id = (int) $_GET['preview_id'];

if ( false === wp_verify_nonce( $_GET['preview_nonce'], 'post_preview_' . $id ) ) {
wp_die( __( 'Sorry, you are not allowed to preview drafts.' ), 403 );
}

add_filter( 'the_preview', '_set_preview' );
}
}

/**
* Filters terms lookup to set the post format.
*
* @since 3.6.0
* @access private
*
* @param array $terms
* @param int $post_id
* @param string $taxonomy
* @return array
*/
function _wp_preview_terms_filter( $terms, $post_id, $taxonomy ) {
$post = get_post();

if ( ! $post ) {
return $terms;
}

if ( empty( $_REQUEST['post_format'] ) || $post->ID !== $post_id
|| 'post_format' !== $taxonomy || 'revision' === $post->post_type
) {
return $terms;
}

if ( 'standard' === $_REQUEST['post_format'] ) {
$terms = array();
} else {
$term = get_term_by( 'slug', 'post-format-' . sanitize_key( $_REQUEST['post_format'] ), 'post_format' );

if ( $term ) {
$terms = array( $term ); // Can only have one post format.
}
}

return $terms;
}

/**
* Filters post thumbnail lookup to set the post thumbnail.
*
* @since 4.6.0
* @access private
*
* @param null|array|string $value The value to return - a single metadata value, or an array of values.
* @param int $post_id Post ID.
* @param string $meta_key Meta key.
* @return null|array The default return value or the post thumbnail meta array.
*/
function _wp_preview_post_thumbnail_filter( $value, $post_id, $meta_key ) {
$post = get_post();

if ( ! $post ) {
return $value;
}

if ( empty( $_REQUEST['_thumbnail_id'] ) || empty( $_REQUEST['preview_id'] )
|| $post->ID !== $post_id || $post_id !== (int) $_REQUEST['preview_id']
|| '_thumbnail_id' !== $meta_key || 'revision' === $post->post_type
) {
return $value;
}

$thumbnail_id = (int) $_REQUEST['_thumbnail_id'];

if ( $thumbnail_id <= 0 ) {
return '';
}

return (string) $thumbnail_id;
}

/**
* Gets the post revision version.
*
* @since 3.6.0
* @access private
*
* @param WP_Post $revision
* @return int|false
*/
function _wp_get_post_revision_version( $revision ) {
if ( is_object( $revision ) ) {
$revision = get_object_vars( $revision );
} elseif ( ! is_array( $revision ) ) {
return false;
}

if ( preg_match( '/^\d+-(?:autosave|revision)-v(\d+)$/', $revision['post_name'], $matches ) ) {
return (int) $matches[1];
}

return 0;
}

/**
* Upgrades the revisions author, adds the current post as a revision and sets the revisions version to 1.
*
* @since 3.6.0
* @access private
*
* @global wpdb $wpdb WordPress database abstraction object.
*
* @param WP_Post $post Post object.
* @param array $revisions Current revisions of the post.
* @return bool true if the revisions were upgraded, false if problems.
*/
function _wp_upgrade_revisions_of_post( $post, $revisions ) {
global $wpdb;

// Add post option exclusively.
$lock = "revision-upgrade-{$post->ID}";
$now = time();
$result = $wpdb->query( $wpdb->prepare( "INSERT IGNORE INTO `$wpdb->options` (`option_name`, `option_value`, `autoload`) VALUES (%s, %s, 'off') /* LOCK */", $lock, $now ) );

if ( ! $result ) {
// If we couldn't get a lock, see how old the previous lock is.
$locked = get_option( $lock );

if ( ! $locked ) {
/*
* Can't write to the lock, and can't read the lock.
* Something broken has happened.
*/
return false;
}

if ( $locked > $now - HOUR_IN_SECONDS ) {
// Lock is not too old: some other process may be upgrading this post. Bail.
return false;
}

// Lock is too old - update it (below) and continue.
}

// If we could get a lock, re-"add" the option to fire all the correct filters.
update_option( $lock, $now );

reset( $revisions );
$add_last = true;

do {
$this_revision = current( $revisions );
$prev_revision = next( $revisions );

$this_revision_version = _wp_get_post_revision_version( $this_revision );

// Something terrible happened.
if ( false === $this_revision_version ) {
continue;
}

/*
* 1 is the latest revision version, so we're already up to date.
* No need to add a copy of the post as latest revision.
*/
if ( 0 < $this_revision_version ) {
$add_last = false;
continue;
}

// Always update the revision version.
$update = array(
'post_name' => preg_replace( '/^(\d+-(?:autosave|revision))[\d-]*$/', '$1-v1', $this_revision->post_name ),
);

/*
* If this revision is the oldest revision of the post, i.e. no $prev_revision,
* the correct post_author is probably $post->post_author, but that's only a good guess.
* Update the revision version only and Leave the author as-is.
*/
if ( $prev_revision ) {
$prev_revision_version = _wp_get_post_revision_version( $prev_revision );

// If the previous revision is already up to date, it no longer has the information we need :(
if ( $prev_revision_version < 1 ) {
$update['post_author'] = $prev_revision->post_author;
}
}

// Upgrade this revision.
$result = $wpdb->update( $wpdb->posts, $update, array( 'ID' => $this_revision->ID ) );

if ( $result ) {
wp_cache_delete( $this_revision->ID, 'posts' );
}
} while ( $prev_revision );

delete_option( $lock );

// Add a copy of the post as latest revision.
if ( $add_last ) {
wp_save_post_revision( $post->ID );
}

return true;
}

/**
* Filters preview post meta retrieval to get values from the autosave.
*
* Filters revisioned meta keys only.
*
* @since 6.4.0
*
* @param mixed $value Meta value to filter.
* @param int $object_id Object ID.
* @param string $meta_key Meta key to filter a value for.
* @param bool $single Whether to return a single value.
* @return mixed Original meta value if the meta key isn't revisioned, the object doesn't exist,
* the post type is a revision or the post ID doesn't match the object ID.
* Otherwise, the revisioned meta value is returned for the preview.
*/
function _wp_preview_meta_filter( $value, $object_id, $meta_key, $single ) {
$post = get_post();

if ( empty( $post )
|| $post->ID !== $object_id
|| ! in_array( $meta_key, wp_post_revision_meta_keys( $post->post_type ), true )
|| 'revision' === $post->post_type
) {
return $value;
}

$preview = wp_get_post_autosave( $post->ID );

if ( false === $preview ) {
return $value;
}

return get_post_meta( $preview->ID, $meta_key, $single );
}