Legacy Packet Adapter

[Nixuge]

Very rough edges but had free time so why not

Confirmed to work on 1.7.10 -> 1.12.2 instead of just 1.8.8

TODOs:

• Change the name of RandomUtils
• Actually test other versions (urgent), especially 1.7 & 1.12.2 as those are pretty much the main point of this PR
• Cache more reflections things (See RandomUtils#22)
• Test one thing that I couldn't manage to trigger (See TeamsPacketAdapterImpl.java#97, first part also in the tests for 1.8.8 only and passing)
• Remove the debug print for last point
• (idk?) add a dash in the middle of the packet adapter name (legacy-reflections instead of legacyreflections? Named it like that bc you can't have a - in java classes) & probably some other things I forgot

Maybe TODO:

• Yoink out 1.8.8 packet adapter? This packet adapter is basically the exact same one as the 1.8.8 one but w reflections in it. (Would break people's build.gradle, altho easily fixable)

[vytskalt]

I think we remove the 1.8 adapter and rename this one to just legacy since I don't see a reason for 1.8 to exist anymore (performance diff should be minimal and it doesn't matter anyway since it's all done async). For backwards compat the v1_8_R3 module could stay and would just do something like implementation(project(":legacy")) in the build.gradle.

[Nixuge]

Update: Tested 3 versions:

• 1.8.8 (v1_8_R3)
• 1.7.10 (v1_7_R4)
• 1.12.2 (v1_12_R1)

Out of those three:

• 1.8.8 works just fine (tested with a "somewhat" complex setup, still requires more testing to make sure all of the code is working)
• 1.12.2 seems to work fine with the simple example (needs a lot more testing)
• 1.7.10 unfortunately doesn't work, the following were missing in that version:
  • enumScoreboardActionClass
  • enumScoreboardHealthDisplayClass
  • enumScoreboardHealthDisplayClass

Removing those and trying to build unfortunately doesn't seem to make it work either.

Would guess this works fine for all versions from 1.8 to 1.12.2. Unfortunately not 1.7, may make another PR for those versions. Still begs the question as to if this should be called "legacy" or "1.8-1.12", since if 1.7 requires another adapter that one would need to be named legacy-legacier or smth (depends on if you even want a 1.7- adapter at all in this project)

Also completely forgot on the initial comment, but another urgent thing is to get the "v1_8_R3" , "v1_12_R1" from the server version as of rn it's just hardcoded in RandomUtils

[vytskalt]

FastBoard supports 1.7.10, we can use it as a reference as to what needs changing. https://github.com/MrMicky-FR/FastBoard/blob/master/src/main/java/fr/mrmicky/fastboard/FastBoardBase.java

[Nixuge]

From a quick glance, most likely place that's failing in 1.7 with nothing changed is in sendScore:

  @Override
  public void sendScore(
...
  ) {
    Object packet = packetPlayOutScoreboardScoreConstructor.invoke(entry);
    PacketAccessors.SCORE_OBJECTIVE_NAME_FIELD.set(packet, objectiveName);
    PacketAccessors.SCORE_VALUE_FIELD.set(packet, value);
//    Removed - not in 1.7
//    PacketAccessors.SCORE_ACTION_FIELD.set(packet, enumScoreboardActionChange);
    sender.sendPacket(players, packet);
  }

In FastBoard, they still do something for the action field even in 1.7:

        if (VersionType.V1_8.isHigherOrEqual()) {
            Object enumAction = action == ScoreboardAction.REMOVE
                    ? ENUM_SB_ACTION_REMOVE : ENUM_SB_ACTION_CHANGE;
            setField(packet, ENUM_SB_ACTION, enumAction);
        } else {
            setField(packet, int.class, action.ordinal(), 1); // Action
        }

[Nixuge]

And indeed that was the fix

Added this in PacketAccessors:

  public static final FieldAccessor<Object, Integer> SCORE_ACTION_FIELD_1_7 =
    ReflectUtil.findField(packetPlayOutScoreboardScoreClass, 1, int.class);

Then in ObjectivePacketAdapterImpl replaced:

PacketAccessors.SCORE_ACTION_FIELD.set(packet, enumScoreboardActionChange);

with

PacketAccessors.SCORE_ACTION_FIELD_1_7.set(packet, 0); // 0 = CHANGE, int value yoinked from FastBoard

Pretty sure the other lib's functionalities that i had to remove for 1.7 support were added in 1.8 tho so can't support them

[Nixuge]

Unfortunately, as excepted, 1.6 doesn't work either with that last change.

[Nixuge]

Not sure why the test is failing btw, iirc it worked correctly when I tried it