10: Support constants in alarm configuration

src/main/tjava/com/r35157/jupiterperpsalarm/impl/ref/AlarmConfigurationParser.tjava

@@ -6,9 +6,7 @@ import java.io.IOException;
 import java.math.BigDecimal;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Locale;
+import java.util.*;
 
 public final class AlarmConfigurationParser {
 
@@ -19,12 +17,18 @@ public final class AlarmConfigurationParser {
         for (int lineNumber = 1; lineNumber <= lines.size(); lineNumber++) {
             String line = lines.get(lineNumber - 1);
             String trimmed = line.trim();
-            if (trimmed.isEmpty() || trimmed.startsWith("#")) {
+
+            if(trimmed.isEmpty() || trimmed.startsWith("#")) {
                 continue;
             }
 
             try {
-                alarms.add(parseLine(line));
+                if(isConstantDefinition(trimmed)) {
+                    parseConstantDefinition(constants, line);
+                } else {
+                    String resolvedLine = replaceConstants(line, constants);
+                    alarms.add(parseLine(resolvedLine));
+                }
             } catch (RuntimeException exception) {
                 throw new IllegalArgumentException(
                         path + ":" + lineNumber + ": " + exception.getMessage(),
@@ -218,6 +222,60 @@ public final class AlarmConfigurationParser {
         private int position;
     }
 
+    private static boolean isConstantDefinition(String trimmedLine) {
+        return trimmedLine.startsWith("{{");
+    }
+
+    private static void parseConstantDefinition(
+            Map<String, String> constants,
+            String line
+    ) {
+        Cursor cursor = new Cursor(line);
+
+        String name = cursor.nextToken("constant name");
+        String value = cursor.nextToken("constant value");
+
+        cursor.skipWhitespace();
+        if (!cursor.atEnd() && cursor.current() != '#') {
+            throw new IllegalArgumentException(
+                    "Unexpected text after constant value: " + cursor.remaining()
+            );
+        }
+
+        validateConstantName(name);
+
+        if (constants.putIfAbsent(name, value) != null) {
+            throw new IllegalArgumentException("Duplicate constant: " + name);
+        }
+    }
+
+    private static String replaceConstants(
+            String line,
+            Map<String, String> constants
+    ) {
+        String result = line;
+
+        for (Map.Entry<String, String> entry : constants.entrySet()) {
+            result = result.replace(entry.getKey(), entry.getValue());
+        }
+
+        if (result.contains("{{") || result.contains("}}")) {
+            throw new IllegalArgumentException(
+                    "Unknown or malformed constant in line: " + line
+            );
+        }
+
+        return result;
+    }
+
+    private static void validateConstantName(String name) {
+        if (!name.matches("\\{\\{[A-Z0-9_]+}}")) {
+            throw new IllegalArgumentException("Invalid constant name: " + name);
+        }
+    }
+
     private AlarmConfigurationParser() {
     }
+
+    private static Map<String, String> constants = new LinkedHashMap<>();
 }