_wp_translate_postdata

function _wp_translate_postdata( $update = false, $post_data = null ) {

	if ( empty( $post_data ) ) {
		$post_data = &$_POST;
	}

	if ( $update ) {
		$post_data['ID'] = (int) $post_data['post_ID'];
	}

	$ptype = get_post_type_object( $post_data['post_type'] );

	if ( $update && ! current_user_can( 'edit_post', $post_data['ID'] ) ) {
		if ( 'page' === $post_data['post_type'] ) {
			return new WP_Error( 'edit_others_pages', __( 'Sorry, you are not allowed to edit pages as this user.' ) );
		} else {
			return new WP_Error( 'edit_others_posts', __( 'Sorry, you are not allowed to edit posts as this user.' ) );
		}
	} elseif ( ! $update && ! current_user_can( $ptype->cap->create_posts ) ) {
		if ( 'page' === $post_data['post_type'] ) {
			return new WP_Error( 'edit_others_pages', __( 'Sorry, you are not allowed to create pages as this user.' ) );
		} else {
			return new WP_Error( 'edit_others_posts', __( 'Sorry, you are not allowed to create posts as this user.' ) );
		}
	}

	if ( isset( $post_data['content'] ) ) {
		$post_data['post_content'] = $post_data['content'];
	}

	if ( isset( $post_data['excerpt'] ) ) {
		$post_data['post_excerpt'] = $post_data['excerpt'];
	}

	if ( isset( $post_data['parent_id'] ) ) {
		$post_data['post_parent'] = (int) $post_data['parent_id'];
	}

	if ( isset( $post_data['trackback_url'] ) ) {
		$post_data['to_ping'] = $post_data['trackback_url'];
	}

	$post_data['user_ID'] = get_current_user_id();

	if ( ! empty( $post_data['post_author_override'] ) ) {
		$post_data['post_author'] = (int) $post_data['post_author_override'];
	} else {
		if ( ! empty( $post_data['post_author'] ) ) {
			$post_data['post_author'] = (int) $post_data['post_author'];
		} else {
			$post_data['post_author'] = (int) $post_data['user_ID'];
		}
	}

	if ( isset( $post_data['user_ID'] ) && ( $post_data['post_author'] != $post_data['user_ID'] )
		&& ! current_user_can( $ptype->cap->edit_others_posts ) ) {

		if ( $update ) {
			if ( 'page' === $post_data['post_type'] ) {
				return new WP_Error( 'edit_others_pages', __( 'Sorry, you are not allowed to edit pages as this user.' ) );
			} else {
				return new WP_Error( 'edit_others_posts', __( 'Sorry, you are not allowed to edit posts as this user.' ) );
			}
		} else {
			if ( 'page' === $post_data['post_type'] ) {
				return new WP_Error( 'edit_others_pages', __( 'Sorry, you are not allowed to create pages as this user.' ) );
			} else {
				return new WP_Error( 'edit_others_posts', __( 'Sorry, you are not allowed to create posts as this user.' ) );
			}
		}
	}

	if ( ! empty( $post_data['post_status'] ) ) {
		$post_data['post_status'] = sanitize_key( $post_data['post_status'] );

		// No longer an auto-draft.
		if ( 'auto-draft' === $post_data['post_status'] ) {
			$post_data['post_status'] = 'draft';
		}

		if ( ! get_post_status_object( $post_data['post_status'] ) ) {
			unset( $post_data['post_status'] );
		}
	}

	// What to do based on which button they pressed.
	if ( isset( $post_data['saveasdraft'] ) && '' !== $post_data['saveasdraft'] ) {
		$post_data['post_status'] = 'draft';
	}
	if ( isset( $post_data['saveasprivate'] ) && '' !== $post_data['saveasprivate'] ) {
		$post_data['post_status'] = 'private';
	}
	if ( isset( $post_data['publish'] ) && ( '' !== $post_data['publish'] )
		&& ( ! isset( $post_data['post_status'] ) || 'private' !== $post_data['post_status'] )
	) {
		$post_data['post_status'] = 'publish';
	}
	if ( isset( $post_data['advanced'] ) && '' !== $post_data['advanced'] ) {
		$post_data['post_status'] = 'draft';
	}
	if ( isset( $post_data['pending'] ) && '' !== $post_data['pending'] ) {
		$post_data['post_status'] = 'pending';
	}

	if ( isset( $post_data['ID'] ) ) {
		$post_id = $post_data['ID'];
	} else {
		$post_id = false;
	}
	$previous_status = $post_id ? get_post_field( 'post_status', $post_id ) : false;

	if ( isset( $post_data['post_status'] ) && 'private' === $post_data['post_status'] && ! current_user_can( $ptype->cap->publish_posts ) ) {
		$post_data['post_status'] = $previous_status ? $previous_status : 'pending';
	}

	$published_statuses = array( 'publish', 'future' );

	// Posts 'submitted for approval' are submitted to $_POST the same as if they were being published.
	// Change status from 'publish' to 'pending' if user lacks permissions to publish or to resave published posts.
	if ( isset( $post_data['post_status'] )
		&& ( in_array( $post_data['post_status'], $published_statuses, true )
		&& ! current_user_can( $ptype->cap->publish_posts ) )
	) {
		if ( ! in_array( $previous_status, $published_statuses, true ) || ! current_user_can( 'edit_post', $post_id ) ) {
			$post_data['post_status'] = 'pending';
		}
	}

	if ( ! isset( $post_data['post_status'] ) ) {
		$post_data['post_status'] = 'auto-draft' === $previous_status ? 'draft' : $previous_status;
	}

	if ( isset( $post_data['post_password'] ) && ! current_user_can( $ptype->cap->publish_posts ) ) {
		unset( $post_data['post_password'] );
	}

	if ( ! isset( $post_data['comment_status'] ) ) {
		$post_data['comment_status'] = 'closed';
	}

	if ( ! isset( $post_data['ping_status'] ) ) {
		$post_data['ping_status'] = 'closed';
	}

	foreach ( array( 'aa', 'mm', 'jj', 'hh', 'mn' ) as $timeunit ) {
		if ( ! empty( $post_data[ 'hidden_' . $timeunit ] ) && $post_data[ 'hidden_' . $timeunit ] != $post_data[ $timeunit ] ) {
			$post_data['edit_date'] = '1';
			break;
		}
	}

	if ( ! empty( $post_data['edit_date'] ) ) {
		$aa                     = $post_data['aa'];
		$mm                     = $post_data['mm'];
		$jj                     = $post_data['jj'];
		$hh                     = $post_data['hh'];
		$mn                     = $post_data['mn'];
		$ss                     = $post_data['ss'];
		$aa                     = ( $aa <= 0 ) ? gmdate( 'Y' ) : $aa;
		$mm                     = ( $mm <= 0 ) ? gmdate( 'n' ) : $mm;
		$jj                     = ( $jj > 31 ) ? 31 : $jj;
		$jj                     = ( $jj <= 0 ) ? gmdate( 'j' ) : $jj;
		$hh                     = ( $hh > 23 ) ? $hh - 24 : $hh;
		$mn                     = ( $mn > 59 ) ? $mn - 60 : $mn;
		$ss                     = ( $ss > 59 ) ? $ss - 60 : $ss;
		$post_data['post_date'] = sprintf( '%04d-%02d-%02d %02d:%02d:%02d', $aa, $mm, $jj, $hh, $mn, $ss );
		$valid_date             = wp_checkdate( $mm, $jj, $aa, $post_data['post_date'] );
		if ( ! $valid_date ) {
			return new WP_Error( 'invalid_date', __( 'Invalid date.' ) );
		}
		$post_data['post_date_gmt'] = get_gmt_from_date( $post_data['post_date'] );
	}

	if ( isset( $post_data['post_category'] ) ) {
		$category_object = get_taxonomy( 'category' );
		if ( ! current_user_can( $category_object->cap->assign_terms ) ) {
			unset( $post_data['post_category'] );
		}
	}

	return $post_data;
}