From b4e37fbd1f8a473525367b976eea63fb6f21d0b2 Mon Sep 17 00:00:00 2001
From: DBotThePony <dbotthepony@yandex.ru>
Date: Wed, 15 Jan 2025 21:27:13 +0700
Subject: [PATCH] Cable segment merging

---
 .../entity/cable/EnergyCableBlockEntity.kt    |  3 +-
 .../block/entity/cable/EnergyCableGraph.kt    | 76 +++++++++++++++----
 2 files changed, 65 insertions(+), 14 deletions(-)

diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableBlockEntity.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableBlockEntity.kt
index 86a0703c2..f5afde287 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableBlockEntity.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableBlockEntity.kt
@@ -99,7 +99,8 @@ abstract class EnergyCableBlockEntity(type: BlockEntityType<*>, blockPos: BlockP
 	}
 
 	inner class Node : GraphNode<Node, EnergyCableGraph>(::EnergyCableGraph) {
-		private var _segment = EnergyCableGraph.Segment(this)
+		@Deprecated("internal property")
+		var _segment = EnergyCableGraph.Segment(this)
 
 		var segment: EnergyCableGraph.Segment
 			get() { return _segment }
diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableGraph.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableGraph.kt
index bd53852f5..3fa115953 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableGraph.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/cable/EnergyCableGraph.kt
@@ -3,6 +3,7 @@ package ru.dbotthepony.mc.otm.block.entity.cable
 import it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet
 import it.unimi.dsi.fastutil.objects.ObjectOpenHashSet
 import it.unimi.dsi.fastutil.objects.Reference2ObjectOpenHashMap
+import it.unimi.dsi.fastutil.objects.ReferenceArraySet
 import it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet
 import net.minecraft.core.BlockPos
 import org.apache.logging.log4j.LogManager
@@ -118,7 +119,6 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 		}
 	}
 
-	// TODO: Actual segment logic (merging segments)
 	class Segment() {
 		constructor(node: EnergyCableBlockEntity.Node) : this() {
 			nodes.add(node)
@@ -136,7 +136,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 
 		private fun checkThroughput() {
 			if (!throughputKnown) {
-				throughput = nodes.maxOf { it.energyThroughput }
+				throughput = nodes.maxOfOrNull { it.energyThroughput } ?: Decimal.ZERO
 				throughputKnown = true
 			}
 		}
@@ -154,6 +154,8 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 		private var lastPoweredStatus = 0
 
 		private fun updateBlockstates(): Boolean {
+			if (nodes.isEmpty()) return false
+
 			if (lastTick + 2 < UNIVERSE_TICKS) {
 				transferredLastTick = Decimal.ZERO
 				lastTick = UNIVERSE_TICKS
@@ -199,6 +201,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 				lastTick = UNIVERSE_TICKS
 			}
 
+			checkThroughput()
 			val currentTransferred = instantSnapshot[this] ?: transferredLastTick
 
 			if (currentTransferred >= throughput || !amount.isPositive) {
@@ -217,6 +220,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 				lastTick = UNIVERSE_TICKS
 			}
 
+			checkThroughput()
 			if (transferredLastTick >= throughput || !amount.isPositive) {
 				return Decimal.ZERO
 			}
@@ -238,33 +242,30 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 					instantSnapshot[this] = maxOf(instantSnapshot[this]!! - amount, Decimal.ZERO)
 				}
 			} else {
-				transferredLastTick = maxOf(transferredLastTick, Decimal.ZERO)
+				transferredLastTick = maxOf(transferredLastTick - amount, Decimal.ZERO)
 			}
 		}
 
 		fun remove(node: EnergyCableBlockEntity.Node) {
 			check(nodes.remove(node)) { "Tried to remove node $node from segment $this, but that node does not belong to this segment" }
 
-			if (nodes.isEmpty())
-				throughput = Decimal.ZERO
-			else
-				throughput = nodes.maxOf { it.energyThroughput }
+			throughputKnown = false
 		}
 
 		fun add(node: EnergyCableBlockEntity.Node) {
 			check(nodes.add(node)) { "Tried to add node $node to segment $this, but we already have that node added" }
-			throughput = maxOf(throughput, node.energyThroughput)
+
+			if (throughputKnown)
+				throughput = maxOf(throughput, node.energyThroughput)
 		}
 
 		fun add(path: SegmentPath) {
-			check(paths.add(path)) { "Path $path should already contain $this" }
+			check(paths.add(path)) { "Path $path shouldn't contain $this" }
 			check(path.segments.add(this)) { "Path set and Segment disagree whenever $this is absent from $path" }
-
-			checkThroughput()
 		}
 
 		fun remove(path: SegmentPath) {
-			check(paths.remove(path)) { "Path $path shouldn't contain $this" }
+			check(paths.remove(path)) { "Path $path should already contain $this" }
 			check(path.segments.remove(this)) { "Path set and Segment disagree whenever $this is present in $path" }
 		}
 
@@ -285,6 +286,7 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 
 				for (v in itr) {
 					v.segment = Segment()
+					v.segment.transferredLastTick = transferredLastTick
 					v.segment.paths.addAll(paths)
 					paths.forEach { it.segments.add(v.segment) }
 					result.add(v.segment)
@@ -293,6 +295,52 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 				return result
 			}
 		}
+
+		private fun combineInto(segment: Segment) {
+			nodes.forEach { it._segment = segment }
+			segment.nodes.addAll(nodes)
+			// this should match on both segments
+			// segment.transferredLastTick = maxOf(segment.transferredLastTick, transferredLastTick)
+			paths.forEach { it.segments.remove(this) }
+			segment.throughputKnown = false
+			nodes.clear() // mark segment as dead
+		}
+
+		private fun tryCombineWith(segment: Segment): Boolean {
+			if (segment === this || segment.nodes.isEmpty()) return false
+
+			// if nodes have same set of paths then it is safe to combine this with target segment
+			if (segment.paths == paths) {
+				if (nodes.size >= segment.nodes.size) {
+					segment.combineInto(this)
+				} else {
+					combineInto(segment)
+				}
+
+				return true
+			}
+
+			return false
+		}
+
+		fun tryCombine() {
+			if (nodes.isEmpty()) return
+
+			// TODO: This is inefficient as fk
+			for (path in paths) {
+				for (segment in path.segments) {
+					if (tryCombineWith(segment)) return
+				}
+			}
+		}
+
+		fun tryCombine(with: Collection<Segment>) {
+			if (nodes.isEmpty()) return
+
+			for (segment in with) {
+				if (tryCombineWith(segment)) return
+			}
+		}
 	}
 
 	fun invalidatePathCache() {
@@ -329,11 +377,13 @@ class EnergyCableGraph : GraphNodeList<EnergyCableBlockEntity.Node, EnergyCableG
 					last = last.parent
 				}
 
-				val touchedSegments = ArrayList<Segment>()
+				val touchedSegments = ReferenceArraySet<Segment>()
 				solution.forEach { touchedSegments.addAll(it.segment.split()) }
 				val path = SegmentPath(a.blockEntity.blockPos, b.blockEntity.blockPos)
 				touchedSegments.forEach { it.add(path) }
 
+				touchedSegments.forEach { it.tryCombine(touchedSegments) }
+
 				return path
 			} else {
 				for (neighbour in first.node.neighboursView.values) {