Swim Animation Snippet Skript (EN)

#Addons required: ThatPacketAddon, ProtocolLib and skript-mirror 2.0
#Working in 1.15.2 (FIY, the player won't see himself swim but other people will, it's not my fault & it's probably not possible, remember that this is not intended by minecraft and that packets can't do everything)
option ver:
    get:
        return console.getServer().getClass().getPackage().getName().split("\.")[3]
import:
    java.util.Optional
    net.minecraft.server.{@ver}.BlockPosition
    net.minecraft.server.{@ver}.EntityPose
    com.comphenix.protocol.wrappers.WrappedDataWatcher
    com.comphenix.protocol.wrappers.WrappedDataWatcher$Registry as DataWatcherRegistry
    com.comphenix.protocol.wrappers.WrappedDataWatcher$WrappedDataWatcherObject as DataWatcherObject
effect (make|force) [the] %players% [to] (swim|crawl) for %players%:
    trigger:
        set {_PacketMetadata} to new play_server_entity_metadata packet
        set {_WDW} to new WrappedDataWatcher()
        {_WDW}.setObject(6, DataWatcherRegistry.get(EntityPose) and EntityPose.SWIMMING)
        set watchable collection field 0 of {_PacketMetadata} to {_WDW}
        loop expressions-1:
            set int pnum 0 of {_PacketMetadata} to (loop-value-1).getEntityId()
            loop expressions-2:
                send packet {_PacketMetadata} to loop-value-2
                set {IsSwimming::%(loop-value-1).getEntityId()%::%loop-value-2%} to true
effect (make|force) [the] %players% [to] stand [up] for %players%:
    trigger:
        set {_PacketMetadata} to new play_server_entity_metadata packet
        set {_WDW} to new WrappedDataWatcher()
        {_WDW}.setObject(6, DataWatcherRegistry.get(EntityPose) and EntityPose.STANDING)
        set watchable collection field 0 of {_PacketMetadata} to {_WDW}
        loop expressions-1:
            set int pnum 0 of {_PacketMetadata} to (loop-value-1).getEntityId()
            loop expressions-2:
                clear {IsSwimming::%(loop-value-1).getEntityId()%::%loop-value-2%}
                send packet {_PacketMetadata} to loop-value-2
on packet event play_server_entity_metadata: #To avoid the player waking up when he sneaks for instance (if the boolean is true)
    {IsSwimming::%int pnum 0 of event-packet%::%player%} is true
    set {_WC} to watchable collection field 0 of event-packet
    "%{_WC}.getObject(6)%" is not "SWIMMING" or "<none>"
    cancel event #If we replace this field instead of canceling, it causes weird things to happen for the client
on packet event play_server_named_entity_spawn: #To make the player swim when he comes in visible range
    {IsSwimming::%int pnum 0 of event-packet%::%player%} is true
    make {Id::%int pnum 0 of event-packet%} swim for player
on quit: #This means that the player won't swim when he'll log back, you can remove that if you want
    clear {IsSwimming::%player.getEntityId()%::*}
on join: #Mandatory to avoid looping all players to get a player from an entity id
    set {Id::%player.getEntityId()%} to player

command /swim:
    trigger:
        make the player swim for all players
command /stand:
    trigger:
        make the player stand for all players