From 302b755ee64bfe7db8c6f6d8102ea87ded245dc7 Mon Sep 17 00:00:00 2001
From: Arne Keller <arne.keller01@yahoo.de>
Date: Tue, 18 Feb 2020 14:35:39 +0100
Subject: [PATCH] Correctly handle crashes of more than two trains

---
 .../model/ModelRailwaySimulation.java         | 60 ++++++++++---------
 testcoverage_input.txt                        | 11 +++-
 testcoverage_output.txt                       |  9 +++
 3 files changed, 52 insertions(+), 28 deletions(-)

diff --git a/src/edu/kit/informatik/model/ModelRailwaySimulation.java b/src/edu/kit/informatik/model/ModelRailwaySimulation.java
index b089d52..dba0fdb 100644
--- a/src/edu/kit/informatik/model/ModelRailwaySimulation.java
+++ b/src/edu/kit/informatik/model/ModelRailwaySimulation.java
@@ -466,36 +466,42 @@ public class ModelRailwaySimulation {
             }
         });
         // check for block collisions
-        trains.values().stream().filter(train -> train.isPlaced() && collisions.stream().noneMatch((x) -> x.contains(train))).forEach(train -> {
-            Set<Rail> occupiedByThisTrain = nextOccupiedRails.get(train);
-            trains.values().stream().filter((x) -> x != train).forEach((otherTrain) -> {
-                Set<Rail> occupiedByOtherTrainPreviously = occupiedRails.get(otherTrain);
-                Set<Rail> occupiedByOtherTrain = nextOccupiedRails.get(otherTrain);
-                if (occupiedByOtherTrain == null || occupiedByOtherTrainPreviously == null) {
-                    return;
-                }
-                boolean anyIntersection = occupiedByOtherTrain.stream().anyMatch(occupiedByThisTrain::contains)
-                        || occupiedByOtherTrainPreviously.stream().anyMatch(occupiedByThisTrain::contains);
-                if (anyIntersection) {
-                    train.removeFromRails();
-                    // try to find/merge existing collisions
-                    Set<Train> existingCollision = null;
-                    for (Set<Train> collision : collisions) {
-                        if (collision.contains(otherTrain)) {
+        trains.values().stream().filter(train -> train.isPlaced()
+                && collisions.stream().noneMatch((x) -> x.contains(train))).forEach(train -> {
+                    Set<Rail> occupiedByThisTrain = nextOccupiedRails.get(train);
+                    trains.values().stream().filter((x) -> x != train).forEach((otherTrain) -> {
+                        Set<Rail> occupiedByOtherTrainPreviously = occupiedRails.get(otherTrain);
+                        Set<Rail> occupiedByOtherTrain = nextOccupiedRails.get(otherTrain);
+                        if (occupiedByOtherTrain == null || occupiedByOtherTrainPreviously == null) {
+                            return;
+                        }
+                        boolean anyIntersection = occupiedByOtherTrain.stream().anyMatch(occupiedByThisTrain::contains)
+                                || occupiedByOtherTrainPreviously.stream().anyMatch(occupiedByThisTrain::contains);
+                        if (anyIntersection) {
+                            train.removeFromRails();
+                            // try to find/merge existing collisions
+                            Set<Train> existingCollision = null;
+                            for (Set<Train> collision : collisions) {
+                                if (collision.contains(otherTrain) || collision.contains(train)) {
+                                    if (existingCollision == null) {
+                                        existingCollision = collision;
+                                        collision.add(train);
+                                        collision.add(otherTrain);
+                                    } else {
+                                        existingCollision.addAll(collision);
+                                        existingCollision.add(train);
+                                        existingCollision.add(otherTrain);
+                                        collisions.remove(collision);
+                                        break;
+                                    }
+                                }
+                            }
                             if (existingCollision == null) {
-                                existingCollision = collision;
-                                collision.add(train);
-                            } else {
-                                existingCollision.addAll(collision);
+                                collisions.add(new HashSet<>(Arrays.asList(train, otherTrain)));
                             }
                         }
-                    }
-                    if (existingCollision == null) {
-                        collisions.add(new HashSet<>(Arrays.asList(train, otherTrain)));
-                    }
-                }
-            });
-        });
+                    });
+                });
         return collisions;
     }
 
diff --git a/testcoverage_input.txt b/testcoverage_input.txt
index 63bc8fd..4cec915 100644
--- a/testcoverage_input.txt
+++ b/testcoverage_input.txt
@@ -60,4 +60,13 @@ add train 2 T2-Rho
 add track (1,0) -> (10,0)
 put train 1 at (7,0) in direction -1,0
 put train 5 at (0,0) in direction -1,0
-step 8
\ No newline at end of file
+step 8
+delete track 1
+delete track 2
+add track (0,0) -> (10,0)
+add track (10,0) -> (20,0)
+add track (20,0) -> (30,0)
+put train 1 at (10,0) in direction 1,0
+put train 2 at (15,0) in direction 1,0
+put train 5 at (20,0) in direction -1,0
+step 1
diff --git a/testcoverage_output.txt b/testcoverage_output.txt
index 8378a14..91d936d 100644
--- a/testcoverage_output.txt
+++ b/testcoverage_output.txt
@@ -78,3 +78,12 @@ OK
 OK
 Crash of train 1
 Crash of train 5
+OK
+OK
+1
+2
+3
+OK
+OK
+OK
+Crash of train 1,2,5