wp_insert_post( array $postarr, bool $wp_error = false, bool $fire_after_hooks = true )

function wp_insert_post( $postarr, $wp_error = false ) {
	global $wpdb;

	// Capture original pre-sanitized array for passing into filters.
	$unsanitized_postarr = $postarr;

	$user_id = get_current_user_id();

	$defaults = array(
		'post_author' => $user_id,
		'post_content' => '',
		'post_content_filtered' => '',
		'post_title' => '',
		'post_excerpt' => '',
		'post_status' => 'draft',
		'post_type' => 'post',
		'comment_status' => '',
		'ping_status' => '',
		'post_password' => '',
		'to_ping' =>  '',
		'pinged' => '',
		'post_parent' => 0,
		'menu_order' => 0,
		'guid' => '',
		'import_id' => 0,
		'context' => '',
	);

	$postarr = wp_parse_args($postarr, $defaults);

	unset( $postarr[ 'filter' ] );

	$postarr = sanitize_post($postarr, 'db');

	// Are we updating or creating?
	$post_ID = 0;
	$update = false;
	$guid = $postarr['guid'];

	if ( ! empty( $postarr['ID'] ) ) {
		$update = true;

		// Get the post ID and GUID.
		$post_ID = $postarr['ID'];
		$post_before = get_post( $post_ID );
		if ( is_null( $post_before ) ) {
			if ( $wp_error ) {
				return new WP_Error( 'invalid_post', __( 'Invalid post ID.' ) );
			}
			return 0;
		}

		$guid = get_post_field( 'guid', $post_ID );
		$previous_status = get_post_field('post_status', $post_ID );
	} else {
		$previous_status = 'new';
	}

	$post_type = empty( $postarr['post_type'] ) ? 'post' : $postarr['post_type'];

	$post_title = $postarr['post_title'];
	$post_content = $postarr['post_content'];
	$post_excerpt = $postarr['post_excerpt'];
	if ( isset( $postarr['post_name'] ) ) {
		$post_name = $postarr['post_name'];
	} elseif ( $update ) {
		// For an update, don't modify the post_name if it wasn't supplied as an argument.
		$post_name = $post_before->post_name;
	}

	$maybe_empty = 'attachment' !== $post_type
		&& ! $post_content && ! $post_title && ! $post_excerpt
		&& post_type_supports( $post_type, 'editor' )
		&& post_type_supports( $post_type, 'title' )
		&& post_type_supports( $post_type, 'excerpt' );

	/**
	 * Filters whether the post should be considered "empty".
	 *
	 * The post is considered "empty" if both:
	 * 1. The post type supports the title, editor, and excerpt fields
	 * 2. The title, editor, and excerpt fields are all empty
	 *
	 * Returning a truthy value to the filter will effectively short-circuit
	 * the new post being inserted, returning 0. If $wp_error is true, a WP_Error
	 * will be returned instead.
	 *
	 * @since WP-3.3.0
	 *
	 * @param bool  $maybe_empty Whether the post should be considered "empty".
	 * @param array $postarr     Array of post data.
	 */
	if ( apply_filters( 'wp_insert_post_empty_content', $maybe_empty, $postarr ) ) {
		if ( $wp_error ) {
			return new WP_Error( 'empty_content', __( 'Content, title, and excerpt are empty.' ) );
		} else {
			return 0;
		}
	}

	$post_status = empty( $postarr['post_status'] ) ? 'draft' : $postarr['post_status'];
	if ( 'attachment' === $post_type && ! in_array( $post_status, array( 'inherit', 'private', 'trash', 'auto-draft' ), true ) ) {
		$post_status = 'inherit';
	}

	if ( ! empty( $postarr['post_category'] ) ) {
		// Filter out empty terms.
		$post_category = array_filter( $postarr['post_category'] );
	}

	// Make sure we set a valid category.
	if ( empty( $post_category ) || 0 == count( $post_category ) || ! is_array( $post_category ) ) {
		// 'post' requires at least one category.
		if ( 'post' == $post_type && 'auto-draft' != $post_status ) {
			$post_category = array( get_option('default_category') );
		} else {
			$post_category = array();
		}
	}

	// Don't allow contributors to set the post slug for pending review posts.
	if ( 'pending' == $post_status && !current_user_can( 'publish_posts' ) ) {
		$post_name = '';
	}

	/*
	 * Create a valid post name. Drafts and pending posts are allowed to have
	 * an empty post name.
	 */
	if ( empty($post_name) ) {
		if ( !in_array( $post_status, array( 'draft', 'pending', 'auto-draft' ) ) ) {
			$post_name = sanitize_title($post_title);
		} else {
			$post_name = '';
		}
	} else {
		// On updates, we need to check to see if it's using the old, fixed sanitization context.
		$check_name = sanitize_title( $post_name, '', 'old-save' );
		if ( $update && strtolower( urlencode( $post_name ) ) == $check_name && get_post_field( 'post_name', $post_ID ) == $check_name ) {
			$post_name = $check_name;
		} else { // new post, or slug has changed.
			$post_name = sanitize_title($post_name);
		}
	}

	/*
	 * If the post date is empty (due to having been new or a draft) and status
	 * is not 'draft' or 'pending', set date to now.
	 */
	if ( empty( $postarr['post_date'] ) || '0000-00-00 00:00:00' == $postarr['post_date'] ) {
		if ( empty( $postarr['post_date_gmt'] ) || '0000-00-00 00:00:00' == $postarr['post_date_gmt'] ) {
			$post_date = current_time( 'mysql' );
		} else {
			$post_date = get_date_from_gmt( $postarr['post_date_gmt'] );
		}
	} else {
		$post_date = $postarr['post_date'];
	}

	// Validate the date.
	$mm = substr( $post_date, 5, 2 );
	$jj = substr( $post_date, 8, 2 );
	$aa = substr( $post_date, 0, 4 );
	$valid_date = wp_checkdate( $mm, $jj, $aa, $post_date );
	if ( ! $valid_date ) {
		if ( $wp_error ) {
			return new WP_Error( 'invalid_date', __( 'Invalid date.' ) );
		} else {
			return 0;
		}
	}

	if ( empty( $postarr['post_date_gmt'] ) || '0000-00-00 00:00:00' == $postarr['post_date_gmt'] ) {
		if ( ! in_array( $post_status, array( 'draft', 'pending', 'auto-draft' ) ) ) {
			$post_date_gmt = get_gmt_from_date( $post_date );
		} else {
			$post_date_gmt = '0000-00-00 00:00:00';
		}
	} else {
		$post_date_gmt = $postarr['post_date_gmt'];
	}

	if ( $update || '0000-00-00 00:00:00' == $post_date ) {
		$post_modified     = current_time( 'mysql' );
		$post_modified_gmt = current_time( 'mysql', 1 );
	} else {
		$post_modified     = $post_date;
		$post_modified_gmt = $post_date_gmt;
	}

	if ( 'attachment' !== $post_type ) {
		if ( 'publish' == $post_status ) {
			$now = gmdate('Y-m-d H:i:59');
			if ( mysql2date('U', $post_date_gmt, false) > mysql2date('U', $now, false) ) {
				$post_status = 'future';
			}
		} elseif ( 'future' == $post_status ) {
			$now = gmdate('Y-m-d H:i:59');
			if ( mysql2date('U', $post_date_gmt, false) <= mysql2date('U', $now, false) ) {
				$post_status = 'publish';
			}
		}
	}

	// Comment status.
	if ( empty( $postarr['comment_status'] ) ) {
		if ( $update ) {
			$comment_status = 'closed';
		} else {
			$comment_status = get_default_comment_status( $post_type );
		}
	} else {
		$comment_status = $postarr['comment_status'];
	}

	// These variables are needed by compact() later.
	$post_content_filtered = $postarr['post_content_filtered'];
	$post_author = isset( $postarr['post_author'] ) ? $postarr['post_author'] : $user_id;
	$ping_status = empty( $postarr['ping_status'] ) ? get_default_comment_status( $post_type, 'pingback' ) : $postarr['ping_status'];
	$to_ping = isset( $postarr['to_ping'] ) ? sanitize_trackback_urls( $postarr['to_ping'] ) : '';
	$pinged = isset( $postarr['pinged'] ) ? $postarr['pinged'] : '';
	$import_id = isset( $postarr['import_id'] ) ? $postarr['import_id'] : 0;

	/*
	 * The 'wp_insert_post_parent' filter expects all variables to be present.
	 * Previously, these variables would have already been extracted
	 */
	if ( isset( $postarr['menu_order'] ) ) {
		$menu_order = (int) $postarr['menu_order'];
	} else {
		$menu_order = 0;
	}

	$post_password = isset( $postarr['post_password'] ) ? $postarr['post_password'] : '';
	if ( 'private' == $post_status ) {
		$post_password = '';
	}

	if ( isset( $postarr['post_parent'] ) ) {
		$post_parent = (int) $postarr['post_parent'];
	} else {
		$post_parent = 0;
	}

	$new_postarr = array_merge(
		array(
			'ID' => $post_ID,
		),
		compact( array_diff( array_keys( $defaults ), array( 'context', 'filter' ) ) )
	);

	/**
	 * Filters the post parent -- used to check for and prevent hierarchy loops.
	 *
	 * @since WP-3.1.0
	 *
	 * @param int   $post_parent Post parent ID.
	 * @param int   $post_ID     Post ID.
	 * @param array $new_postarr Array of parsed post data.
	 * @param array $postarr     Array of sanitized, but otherwise unmodified post data.
	 */
	$post_parent = apply_filters( 'wp_insert_post_parent', $post_parent, $post_ID, $new_postarr, $postarr );

	/*
	 * If the post is being untrashed and it has a desired slug stored in post meta,
	 * reassign it.
	 */
	if ( 'trash' === $previous_status && 'trash' !== $post_status ) {
		$desired_post_slug = get_post_meta( $post_ID, '_wp_desired_post_slug', true );
		if ( $desired_post_slug ) {
			delete_post_meta( $post_ID, '_wp_desired_post_slug' );
			$post_name = $desired_post_slug;
		}
	}

	// If a trashed post has the desired slug, change it and let this post have it.
	if ( 'trash' !== $post_status && $post_name ) {
		wp_add_trashed_suffix_to_post_name_for_trashed_posts( $post_name, $post_ID );
	}

	// When trashing an existing post, change its slug to allow non-trashed posts to use it.
	if ( 'trash' === $post_status && 'trash' !== $previous_status && 'new' !== $previous_status ) {
		$post_name = wp_add_trashed_suffix_to_post_name_for_post( $post_ID );
	}

	$post_name = wp_unique_post_slug( $post_name, $post_ID, $post_status, $post_type, $post_parent );

	// Don't unslash.
	$post_mime_type = isset( $postarr['post_mime_type'] ) ? $postarr['post_mime_type'] : '';

	// Expected_slashed (everything!).
	$data = compact( 'post_author', 'post_date', 'post_date_gmt', 'post_content', 'post_content_filtered', 'post_title', 'post_excerpt', 'post_status', 'post_type', 'comment_status', 'ping_status', 'post_password', 'post_name', 'to_ping', 'pinged', 'post_modified', 'post_modified_gmt', 'post_parent', 'menu_order', 'post_mime_type', 'guid' );

	$emoji_fields = array( 'post_title', 'post_content', 'post_excerpt' );

	foreach ( $emoji_fields as $emoji_field ) {
		if ( isset( $data[ $emoji_field ] ) ) {
			$charset = $wpdb->get_col_charset( $wpdb->posts, $emoji_field );
			if ( 'utf8' === $charset ) {
				$data[ $emoji_field ] = wp_encode_emoji( $data[ $emoji_field ] );
			}
		}
	}

	if ( 'attachment' === $post_type ) {
		/**
		 * Filters attachment post data before it is updated in or added to the database.
		 *
		 * @since WP-3.9.0
		 * @since WP-4.9.14 `$unsanitized_postarr` argument added.
		 *
		 * @param array $data                An array of slashed, sanitized, and processed attachment post data.
		 * @param array $postarr             An array of slashed and sanitized attachment post data, but not processed.
		 * @param array $unsanitized_postarr An array of slashed yet *unsanitized* and unprocessed attachment post data
		 *                                   as originally passed to wp_insert_post().
		 */
		$data = apply_filters( 'wp_insert_attachment_data', $data, $postarr, $unsanitized_postarr );
	} else {
		/**
		 * Filters slashed post data just before it is inserted into the database.
		 *
		 * @since WP-2.7.0
		 * @since WP-4.9.14 `$unsanitized_postarr` argument added.
		 *
		 * @param array $data                An array of slashed, sanitized, and processed post data.
		 * @param array $postarr             An array of sanitized (and slashed) but otherwise unmodified post data.
		 * @param array $unsanitized_postarr An array of slashed yet *unsanitized* and unprocessed post data as
		 *                                   originally passed to wp_insert_post().
		 */
		$data = apply_filters( 'wp_insert_post_data', $data, $postarr, $unsanitized_postarr );
	}
	$data = wp_unslash( $data );
	$where = array( 'ID' => $post_ID );

	if ( $update ) {
		/**
		 * Fires immediately before an existing post is updated in the database.
		 *
		 * @since WP-2.5.0
		 *
		 * @param int   $post_ID Post ID.
		 * @param array $data    Array of unslashed post data.
		 */
		do_action( 'pre_post_update', $post_ID, $data );
		if ( false === $wpdb->update( $wpdb->posts, $data, $where ) ) {
			if ( $wp_error ) {
				return new WP_Error('db_update_error', __('Could not update post in the database'), $wpdb->last_error);
			} else {
				return 0;
			}
		}
	} else {
		// If there is a suggested ID, use it if not already present.
		if ( ! empty( $import_id ) ) {
			$import_id = (int) $import_id;
			if ( ! $wpdb->get_var( $wpdb->prepare("SELECT ID FROM $wpdb->posts WHERE ID = %d", $import_id) ) ) {
				$data['ID'] = $import_id;
			}
		}
		if ( false === $wpdb->insert( $wpdb->posts, $data ) ) {
			if ( $wp_error ) {
				return new WP_Error('db_insert_error', __('Could not insert post into the database'), $wpdb->last_error);
			} else {
				return 0;
			}
		}
		$post_ID = (int) $wpdb->insert_id;

		// Use the newly generated $post_ID.
		$where = array( 'ID' => $post_ID );
	}

	if ( empty( $data['post_name'] ) && ! in_array( $data['post_status'], array( 'draft', 'pending', 'auto-draft' ) ) ) {
		$data['post_name'] = wp_unique_post_slug( sanitize_title( $data['post_title'], $post_ID ), $post_ID, $data['post_status'], $post_type, $post_parent );
		$wpdb->update( $wpdb->posts, array( 'post_name' => $data['post_name'] ), $where );
		clean_post_cache( $post_ID );
	}

	if ( is_object_in_taxonomy( $post_type, 'category' ) ) {
		wp_set_post_categories( $post_ID, $post_category );
	}

	if ( isset( $postarr['tags_input'] ) && is_object_in_taxonomy( $post_type, 'post_tag' ) ) {
		wp_set_post_tags( $post_ID, $postarr['tags_input'] );
	}

	// New-style support for all custom taxonomies.
	if ( ! empty( $postarr['tax_input'] ) ) {
		foreach ( $postarr['tax_input'] as $taxonomy => $tags ) {
			$taxonomy_obj = get_taxonomy($taxonomy);
			if ( ! $taxonomy_obj ) {
				/* translators: %s: taxonomy name */
				_doing_it_wrong( __FUNCTION__, sprintf( __( 'Invalid taxonomy: %s.' ), $taxonomy ), 'WP-4.4.0' );
				continue;
			}

			// array = hierarchical, string = non-hierarchical.
			if ( is_array( $tags ) ) {
				$tags = array_filter($tags);
			}
			if ( current_user_can( $taxonomy_obj->cap->assign_terms ) ) {
				wp_set_post_terms( $post_ID, $tags, $taxonomy );
			}
		}
	}

	if ( ! empty( $postarr['meta_input'] ) ) {
		foreach ( $postarr['meta_input'] as $field => $value ) {
			update_post_meta( $post_ID, $field, $value );
		}
	}

	$current_guid = get_post_field( 'guid', $post_ID );

	// Set GUID.
	if ( ! $update && '' == $current_guid ) {
		$wpdb->update( $wpdb->posts, array( 'guid' => get_permalink( $post_ID ) ), $where );
	}

	if ( 'attachment' === $postarr['post_type'] ) {
		if ( ! empty( $postarr['file'] ) ) {
			update_attached_file( $post_ID, $postarr['file'] );
		}

		if ( ! empty( $postarr['context'] ) ) {
			add_post_meta( $post_ID, '_wp_attachment_context', $postarr['context'], true );
		}
	}

	// Set or remove featured image.
	if ( isset( $postarr['_thumbnail_id'] ) ) {
		$thumbnail_support = current_theme_supports( 'post-thumbnails', $post_type ) && post_type_supports( $post_type, 'thumbnail' ) || 'revision' === $post_type;
		if ( ! $thumbnail_support && 'attachment' === $post_type && $post_mime_type ) {
			if ( wp_attachment_is( 'audio', $post_ID ) ) {
				$thumbnail_support = post_type_supports( 'attachment:audio', 'thumbnail' ) || current_theme_supports( 'post-thumbnails', 'attachment:audio' );
			} elseif ( wp_attachment_is( 'video', $post_ID ) ) {
				$thumbnail_support = post_type_supports( 'attachment:video', 'thumbnail' ) || current_theme_supports( 'post-thumbnails', 'attachment:video' );
			}
		}

		if ( $thumbnail_support ) {
			$thumbnail_id = intval( $postarr['_thumbnail_id'] );
			if ( -1 === $thumbnail_id ) {
				delete_post_thumbnail( $post_ID );
			} else {
				set_post_thumbnail( $post_ID, $thumbnail_id );
			}
		}
	}

	clean_post_cache( $post_ID );

	$post = get_post( $post_ID );

	if ( ! empty( $postarr['page_template'] ) ) {
		$post->page_template = $postarr['page_template'];
		$page_templates = wp_get_theme()->get_page_templates( $post );
		if ( 'default' != $postarr['page_template'] && ! isset( $page_templates[ $postarr['page_template'] ] ) ) {
			if ( $wp_error ) {
				return new WP_Error( 'invalid_page_template', __( 'Invalid page template.' ) );
			}
			update_post_meta( $post_ID, '_wp_page_template', 'default' );
		} else {
			update_post_meta( $post_ID, '_wp_page_template', $postarr['page_template'] );
		}
	}

	if ( 'attachment' !== $postarr['post_type'] ) {
		wp_transition_post_status( $data['post_status'], $previous_status, $post );
	} else {
		if ( $update ) {
			/**
			 * Fires once an existing attachment has been updated.
			 *
			 * @since WP-2.0.0
			 *
			 * @param int $post_ID Attachment ID.
			 */
			do_action( 'edit_attachment', $post_ID );
			$post_after = get_post( $post_ID );

			/**
			 * Fires once an existing attachment has been updated.
			 *
			 * @since WP-4.4.0
			 *
			 * @param int     $post_ID      Post ID.
			 * @param WP_Post $post_after   Post object following the update.
			 * @param WP_Post $post_before  Post object before the update.
			 */
			do_action( 'attachment_updated', $post_ID, $post_after, $post_before );
		} else {

			/**
			 * Fires once an attachment has been added.
			 *
			 * @since WP-2.0.0
			 *
			 * @param int $post_ID Attachment ID.
			 */
			do_action( 'add_attachment', $post_ID );
		}

		return $post_ID;
	}

	if ( $update ) {
		/**
		 * Fires once an existing post has been updated.
		 *
		 * @since WP-1.2.0
		 *
		 * @param int     $post_ID Post ID.
		 * @param WP_Post $post    Post object.
		 */
		do_action( 'edit_post', $post_ID, $post );
		$post_after = get_post($post_ID);

		/**
		 * Fires once an existing post has been updated.
		 *
		 * @since WP-3.0.0
		 *
		 * @param int     $post_ID      Post ID.
		 * @param WP_Post $post_after   Post object following the update.
		 * @param WP_Post $post_before  Post object before the update.
		 */
		do_action( 'post_updated', $post_ID, $post_after, $post_before);
	}

	/**
	 * Fires once a post has been saved.
	 *
	 * The dynamic portion of the hook name, `$post->post_type`, refers to
	 * the post type slug.
	 *
	 * @since WP-3.7.0
	 *
	 * @param int     $post_ID Post ID.
	 * @param WP_Post $post    Post object.
	 * @param bool    $update  Whether this is an existing post being updated or not.
	 */
	do_action( "save_post_{$post->post_type}", $post_ID, $post, $update );

	/**
	 * Fires once a post has been saved.
	 *
	 * @since WP-1.5.0
	 *
	 * @param int     $post_ID Post ID.
	 * @param WP_Post $post    Post object.
	 * @param bool    $update  Whether this is an existing post being updated or not.
	 */
	do_action( 'save_post', $post_ID, $post, $update );

	/**
	 * Fires once a post has been saved.
	 *
	 * @since WP-2.0.0
	 *
	 * @param int     $post_ID Post ID.
	 * @param WP_Post $post    Post object.
	 * @param bool    $update  Whether this is an existing post being updated or not.
	 */
	do_action( 'wp_insert_post', $post_ID, $post, $update );

	return $post_ID;
}