From 536951ac4efc7cadc290a33049f160c100e84ae1 Mon Sep 17 00:00:00 2001
From: 2No2Name <2no2name@web.de>
Date: Fri, 25 Oct 2024 14:44:53 +0200
Subject: [PATCH] Fix fluid flow optimization

---
 .../block/fluid/flow/FlowingFluidMixin.java   | 35 ++++++++++++-------
 .../mixin/block/fluid/flow/package-info.java  |  2 +-
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/FlowingFluidMixin.java b/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/FlowingFluidMixin.java
index ebbb517df..515ed2bc5 100644
--- a/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/FlowingFluidMixin.java
+++ b/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/FlowingFluidMixin.java
@@ -139,11 +139,14 @@ public void getSpread(ServerLevel world, BlockPos pos, BlockState state, Callbac
             }
         }
         if (onlyPossibleFlowDirection != null) {
-            FluidState fluidState;
-            FluidState targetNewFluidState = this.getNewLiquid(world, onlyBlockPos, onlyBlockState);
-            if (this.canPassThrough(world, targetNewFluidState.getType(), pos, state, onlyPossibleFlowDirection, onlyBlockPos, onlyBlockState, onlyBlockState.getFluidState())) {
-                fluidState = targetNewFluidState;
-                flowResultByDirection.put(onlyPossibleFlowDirection, fluidState);
+            FluidState onlyFluidState = onlyBlockState.getFluidState();
+            if (this.canMaybePassThrough(world, pos, state, onlyPossibleFlowDirection, onlyBlockPos, onlyBlockState, onlyFluidState)) {
+                FluidState targetNewFluidState = this.getNewLiquid(world, onlyBlockPos, onlyBlockState);
+                if (canHoldSpecificFluid(world, onlyBlockPos, onlyBlockState, targetNewFluidState.getType())) {
+                    if (onlyFluidState.canBeReplacedWith(world, onlyBlockPos, targetNewFluidState.getType(), onlyPossibleFlowDirection)) {
+                        flowResultByDirection.put(onlyPossibleFlowDirection, targetNewFluidState);
+                    }
+                }
             }
         }
         cir.setReturnValue(flowResultByDirection);
@@ -227,16 +230,22 @@ private void calculateComplexFluidFlowDirections(ServerLevel world, BlockPos sta
 
             BlockState targetBlockState = getBlock(world, flowTargetPos, blockStateCache, blockIndex);
             //TODO use block cache in getUpdatedState
-            FluidState targetNewFluidState = this.getNewLiquid(world, flowTargetPos, targetBlockState);
-
-            //Store the resulting fluid state for each direction, remove later if no closest hole access in this direction.
-            flowResultByDirection.put(flowDirection, targetNewFluidState);
+            if (this.canMaybePassThrough(world, flowTargetPos, startState, flowDirection, flowTargetPos, targetBlockState, targetBlockState.getFluidState())) {
+                FluidState targetNewFluidState = this.getNewLiquid(world, flowTargetPos, targetBlockState);
+                if (canHoldSpecificFluid(world, flowTargetPos, targetBlockState, targetNewFluidState.getType())) {//Store the resulting fluid state for each direction, remove later if no closest hole access in this direction.
+                    // 1.21.2+ Specialty: Only add the direction if the fluid can replace the other fluid. If it cannot, it still counts for the hole search though.
+                    if (targetBlockState.getFluidState().canBeReplacedWith(world, flowTargetPos, targetNewFluidState.getType(), flowDirection)) {
+                        flowResultByDirection.put(flowDirection, targetNewFluidState);
+                    }
 
-            if (this.canPassThrough(world, targetNewFluidState.getType(), startPos, startState, flowDirection, flowTargetPos, targetBlockState, targetBlockState.getFluidState())) {
-                prevPositions.put(blockIndex, (byte) (0b10001 << i));
-                if (isHoleBelow(world, holeCache, blockIndex, flowTargetPos, targetBlockState)) {
-                    holeAccess |= (byte) (1 << i);
+                    if (this.canPassThrough(world, targetNewFluidState.getType(), startPos, startState, flowDirection, flowTargetPos, targetBlockState, targetBlockState.getFluidState())) {
+                        prevPositions.put(blockIndex, (byte) (0b10001 << i));
+                        if (isHoleBelow(world, holeCache, blockIndex, flowTargetPos, targetBlockState)) {
+                            holeAccess |= (byte) (1 << i);
+                        }
+                    }
                 }
+
             }
         }
 
diff --git a/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/package-info.java b/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/package-info.java
index b8ed6a64d..646a203b1 100644
--- a/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/package-info.java
+++ b/common/src/main/java/net/caffeinemc/mods/lithium/mixin/block/fluid/flow/package-info.java
@@ -1,4 +1,4 @@
-@MixinConfigOption(description = "Fluid flow optimization", enabled = false) //TODO this breaks ALL BLOCKS bruh
+@MixinConfigOption(description = "Fluid flow optimization")
 package net.caffeinemc.mods.lithium.mixin.block.fluid.flow;
 
 import net.caffeinemc.gradle.MixinConfigOption;
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