Fix issues related to invalid/overlapping patterns (#938)

Author: SamsTheNerd

Common/src/main/java/at/petrak/hexcasting/api/casting/math/HexAngle.kt

@@ -5,4 +5,19 @@ enum class HexAngle {
 
     fun rotatedBy(a: HexAngle) = values()[(this.ordinal + a.ordinal) % values().size]
     operator fun times(a: HexAngle) = this.rotatedBy(a)
+
+    companion object {
+        fun fromChar(c: Char): HexAngle? {
+            return when (c) {
+                'w' -> FORWARD
+                'e' -> RIGHT
+                'd' -> RIGHT_BACK
+                // for completeness ...
+                's' -> BACK
+                'a' -> LEFT_BACK
+                'q' -> LEFT
+                else -> null
+            }
+        }
+    }
 }

Common/src/main/java/at/petrak/hexcasting/api/casting/math/HexPattern.kt

@@ -9,6 +9,7 @@ import com.mojang.serialization.codecs.RecordCodecBuilder
 import net.minecraft.nbt.CompoundTag
 import net.minecraft.nbt.Tag
 import net.minecraft.world.phys.Vec2
+import kotlin.jvm.Throws
 
 /**
  * Sequence of angles to define a pattern traced.
@@ -130,11 +131,12 @@ data class HexPattern(val startDir: HexDir, val angles: MutableList<HexAngle> =
         const val TAG_ANGLES = "angles"
 
         @JvmField
-        val CODEC: Codec<HexPattern> = RecordCodecBuilder.create({instance -> instance.group(
-            Codec.STRING.fieldOf(TAG_START_DIR).forGetter(HexPattern::anglesSignature),
-            HexDir.CODEC.fieldOf(TAG_ANGLES).forGetter(HexPattern::startDir)
-        ).apply(instance, HexPattern::fromAngles)
-        })
+        val CODEC: Codec<HexPattern> = RecordCodecBuilder.create { instance ->
+            instance.group(
+                Codec.STRING.fieldOf(TAG_START_DIR).forGetter(HexPattern::anglesSignature),
+                HexDir.CODEC.fieldOf(TAG_ANGLES).forGetter(HexPattern::startDir)
+            ).apply(instance, HexPattern::fromAnglesUnchecked)
+        }
 
         @JvmStatic
         fun isPattern(tag: CompoundTag): Boolean {
@@ -149,30 +151,61 @@ data class HexPattern(val startDir: HexDir, val angles: MutableList<HexAngle> =
             return HexPattern(startDir, angles.toMutableList())
         }
 
+        /**
+         * Construct a [HexPattern] from an angle signature and starting direction.
+         *
+         * Throws if the signature contains an invalid character, or if the resulting pattern would contain overlaps.
+         */
         @JvmStatic
+        @Throws(IllegalArgumentException::class, IllegalStateException::class)
         fun fromAngles(signature: String, startDir: HexDir): HexPattern {
             val out = HexPattern(startDir)
+
+            var cursor = HexCoord.Origin
             var compass = startDir
+            val linesSeen = mutableSetOf(
+                cursor to compass,
+                cursor + compass to compass.rotatedBy(HexAngle.BACK),
+            )
 
             for ((idx, c) in signature.withIndex()) {
-                val angle = when (c) {
-                    'w' -> HexAngle.FORWARD
-                    'e' -> HexAngle.RIGHT
-                    'd' -> HexAngle.RIGHT_BACK
-                    // for completeness ...
-                    's' -> HexAngle.BACK
-                    'a' -> HexAngle.LEFT_BACK
-                    'q' -> HexAngle.LEFT
-                    else -> throw IllegalArgumentException("Cannot match $c at idx $idx to a direction")
-                }
+                val angle = HexAngle.fromChar(c)
+                    ?: throw IllegalArgumentException("Cannot match $c at idx $idx to a direction")
+
+                cursor += compass
                 compass *= angle
-                val success = out.tryAppendDir(compass)
-                if (!success) {
+
+                if (
+                    !linesSeen.add(cursor to compass)
+                    // Line from here to there also blocks there to here
+                    || !linesSeen.add(cursor + compass to compass.rotatedBy(HexAngle.BACK))
+                ) {
                     throw IllegalStateException("Adding the angle $c at index $idx made the pattern invalid by looping back on itself")
                 }
+
+                out.angles.add(angle)
             }
+
             return out
         }
 
+        /**
+         * Construct a [HexPattern] from an angle signature and starting direction, without checking for overlaps.
+         *
+         * Throws if the signature contains an invalid character.
+         */
+        @JvmStatic
+        @Throws(IllegalArgumentException::class)
+        fun fromAnglesUnchecked(signature: String, startDir: HexDir): HexPattern {
+            val out = HexPattern(startDir)
+
+            for ((idx, c) in signature.withIndex()) {
+                val angle = HexAngle.fromChar(c)
+                    ?: throw IllegalArgumentException("Cannot match $c at idx $idx to a direction")
+                out.angles.add(angle)
+            }
+
+            return out
+        }
     }
 }

Common/src/main/java/at/petrak/hexcasting/common/casting/PatternRegistryManifest.java

@@ -128,6 +128,6 @@ public static HexPattern getCanonicalStrokesPerWorld(ResourceKey<ActionRegistryE
 
         var sig = pair.getFirst();
         var entry = pair.getSecond();
-        return HexPattern.fromAngles(sig, entry.canonicalStartDir());
+        return HexPattern.fromAnglesUnchecked(sig, entry.canonicalStartDir());
     }
 }

Common/src/main/java/at/petrak/hexcasting/common/command/ListPerWorldPatternsCommand.java

@@ -96,7 +96,7 @@ private static int giveAll(CommandSourceStack source, Collection<ServerPlayer> t
                     var found = save.lookupReverse(key);
                     var signature = found.getFirst();
                     var startDir = found.getSecond().canonicalStartDir();
-                    var pat = HexPattern.fromAngles(signature, startDir);
+                    var pat = HexPattern.fromAnglesUnchecked(signature, startDir);
 
                     var tag = new CompoundTag();
                     tag.putString(ItemScroll.TAG_OP_ID, key.location().toString());

Common/src/main/java/at/petrak/hexcasting/common/loot/AddHexToAncientCypherFunc.java

@@ -44,7 +44,7 @@ public static ItemStack doStatic(ItemStack stack, RandomSource rand) {
         var patsTag = new ListTag();
         for (var patString : hex.getSecond()){
             var pieces = patString.split(" ");
-            var pat = HexPattern.fromAngles(pieces[1],HexDir.fromString(pieces[0]));
+            var pat = HexPattern.fromAnglesUnchecked(pieces[1],HexDir.fromString(pieces[0]));
             patsTag.add(IotaType.serialize(new PatternIota(pat)));
         }
 

Common/src/main/java/at/petrak/hexcasting/interop/inline/HexPatternMatcher.java

@@ -53,7 +53,7 @@ public Tuple<InlineMatch, Integer> getMatchAndGroup(MatchResult regexMatch, Matc
             angleSigs = "";
         }
         try{
-            pat = HexPattern.fromAngles(angleSigs.toLowerCase(), dir);
+            pat = HexPattern.fromAnglesUnchecked(angleSigs.toLowerCase(), dir);
             InlinePatternData patData = new InlinePatternData(pat);
             Style patDataStyle = patData.getExtraStyle();
             if(sizeModString != null && sizeModString.equals("+"))

Common/src/main/java/at/petrak/hexcasting/interop/patchouli/ManualPatternComponent.java

@@ -33,7 +33,7 @@ public List<HexPattern> getPatterns(UnaryOperator<IVariable> lookup) {
             RawPattern raw = new Gson().fromJson(json, RawPattern.class);
 
             var dir = HexDir.fromString(raw.startdir);
-            var pat = HexPattern.fromAngles(raw.signature, dir);
+            var pat = HexPattern.fromAnglesUnchecked(raw.signature, dir);
             out.add(pat);
         }