Merge pull request #115 from sauravbhattacharya001/refactor/centralize-edge-type-registry

refactor: centralize edge type metadata into EdgeTypeRegistry

Author: sauravbhattacharya001

Gvisual/src/gvisual/DotExporter.java

@@ -49,17 +49,7 @@ public class DotExporter {
     private String rankDir = null; // TB, LR, BT, RL
     private final Map<String, String> graphAttributes = new LinkedHashMap<>();
 
-    // Default color palette for Edge types
-    private static final Map<String, String> DEFAULT_TYPE_COLORS = new LinkedHashMap<>();
-    static {
-        DEFAULT_TYPE_COLORS.put("f",  "#4CAF50"); // friend = green
-        DEFAULT_TYPE_COLORS.put("fs", "#2196F3"); // friend-stranger = blue
-        DEFAULT_TYPE_COLORS.put("c",  "#FF9800"); // classmate = orange
-        DEFAULT_TYPE_COLORS.put("s",  "#F44336"); // stranger = red
-        DEFAULT_TYPE_COLORS.put("sg", "#9C27B0"); // study group = purple
-    }
-
-    private final Map<String, String> typeColors = new LinkedHashMap<>(DEFAULT_TYPE_COLORS);
+    private final Map<String, String> typeColors = new LinkedHashMap<>(EdgeTypeRegistry.getAllHexColors());
 
     /**
      * Creates a new DOT exporter for the given graph.
@@ -295,17 +285,10 @@ public String exportToString() {
 
     /**
      * Returns a human-readable name for an Edge type code.
+     * Delegates to the centralized {@link EdgeTypeRegistry}.
      */
     private String getTypeName(String type) {
-        if (type == null) return "unknown";
-        switch (type) {
-            case "f":  return "Friend";
-            case "fs": return "Friend-Stranger";
-            case "c":  return "Classmate";
-            case "s":  return "Stranger";
-            case "sg": return "Study Group";
-            default:   return type;
-        }
+        return EdgeTypeRegistry.getName(type);
     }
 
     /**

Gvisual/src/gvisual/EdgeTypeRegistry.java

@@ -0,0 +1,119 @@
+package gvisual;
+
+import java.util.*;
+
+/**
+ * Centralized registry of edge type metadata — names, hex colors, and
+ * RGB tuples.
+ *
+ * <p>Before this class existed, every exporter (DOT, GEXF, JSON, HTML,
+ * Timeline, CSV) maintained its own copy of the type→name and type→color
+ * mappings. Adding a new edge type required updating 5+ files. Now there
+ * is a single source of truth.</p>
+ *
+ * <p>Consumers should call the static methods rather than hard-coding
+ * edge type strings.</p>
+ *
+ * @author zalenix
+ */
+public final class EdgeTypeRegistry {
+
+    private EdgeTypeRegistry() { /* utility class */ }
+
+    // ── Canonical edge type codes ───────────────────────────────────
+    public static final String FRIEND           = "f";
+    public static final String FAMILIAR_STRANGER = "fs";
+    public static final String CLASSMATE        = "c";
+    public static final String STRANGER         = "s";
+    public static final String STUDY_GROUP      = "sg";
+
+    // ── Display names ───────────────────────────────────────────────
+    private static final Map<String, String> NAMES = new LinkedHashMap<>();
+    static {
+        NAMES.put(FRIEND,            "Friend");
+        NAMES.put(FAMILIAR_STRANGER, "Friend-Stranger");
+        NAMES.put(CLASSMATE,         "Classmate");
+        NAMES.put(STRANGER,          "Stranger");
+        NAMES.put(STUDY_GROUP,       "Study Group");
+    }
+
+    // ── Hex colors (for DOT, HTML, SVG, etc.) ───────────────────────
+    private static final Map<String, String> HEX_COLORS = new LinkedHashMap<>();
+    static {
+        HEX_COLORS.put(FRIEND,            "#4CAF50"); // green
+        HEX_COLORS.put(FAMILIAR_STRANGER, "#2196F3"); // blue
+        HEX_COLORS.put(CLASSMATE,         "#FF9800"); // orange
+        HEX_COLORS.put(STRANGER,          "#F44336"); // red
+        HEX_COLORS.put(STUDY_GROUP,       "#9C27B0"); // purple
+    }
+
+    // ── RGB colors (for GEXF and formats needing integer components) ─
+    private static final Map<String, int[]> RGB_COLORS = new LinkedHashMap<>();
+    static {
+        RGB_COLORS.put(FRIEND,            new int[]{0, 200, 0});
+        RGB_COLORS.put(FAMILIAR_STRANGER, new int[]{200, 200, 0});
+        RGB_COLORS.put(CLASSMATE,         new int[]{0, 150, 255});
+        RGB_COLORS.put(STRANGER,          new int[]{180, 180, 180});
+        RGB_COLORS.put(STUDY_GROUP,       new int[]{255, 80, 80});
+    }
+
+    /**
+     * Returns the human-readable name for an edge type code.
+     *
+     * @param typeCode the edge type code (e.g. "f", "sg")
+     * @return display name, or the raw code if unknown
+     */
+    public static String getName(String typeCode) {
+        if (typeCode == null) return "Unknown";
+        return NAMES.getOrDefault(typeCode, typeCode);
+    }
+
+    /**
+     * Returns the hex color for an edge type code.
+     *
+     * @param typeCode the edge type code
+     * @return hex color string (e.g. "#4CAF50"), or "#CCCCCC" if unknown
+     */
+    public static String getHexColor(String typeCode) {
+        return HEX_COLORS.getOrDefault(typeCode, "#CCCCCC");
+    }
+
+    /**
+     * Returns the RGB color components for an edge type code.
+     *
+     * @param typeCode the edge type code
+     * @return int array [r, g, b], or {128,128,128} if unknown
+     */
+    public static int[] getRgbColor(String typeCode) {
+        int[] rgb = RGB_COLORS.get(typeCode);
+        return (rgb != null) ? rgb : new int[]{128, 128, 128};
+    }
+
+    /**
+     * Returns an unmodifiable copy of all known hex colors.
+     * Useful for exporters that need the full palette.
+     *
+     * @return map of type code → hex color
+     */
+    public static Map<String, String> getAllHexColors() {
+        return Collections.unmodifiableMap(new LinkedHashMap<>(HEX_COLORS));
+    }
+
+    /**
+     * Returns an unmodifiable copy of all known RGB colors.
+     *
+     * @return map of type code → int[3]
+     */
+    public static Map<String, int[]> getAllRgbColors() {
+        return Collections.unmodifiableMap(new LinkedHashMap<>(RGB_COLORS));
+    }
+
+    /**
+     * Returns all known type codes in canonical order.
+     *
+     * @return list of type codes
+     */
+    public static List<String> getAllTypeCodes() {
+        return Collections.unmodifiableList(new ArrayList<>(NAMES.keySet()));
+    }
+}

Gvisual/src/gvisual/GexfExporter.java

@@ -49,15 +49,9 @@ public class GexfExporter {
     private String description = "";
     private boolean includeVizData = true;
 
-    // Edge-type → RGB colour mapping (matches the app's colour scheme)
-    private static final Map<String, int[]> TYPE_COLORS = new LinkedHashMap<>();
-    static {
-        TYPE_COLORS.put("f",  new int[]{0, 200, 0});     // friend — green
-        TYPE_COLORS.put("fs", new int[]{255, 165, 0});    // family/sibling — orange
-        TYPE_COLORS.put("c",  new int[]{0, 150, 255});    // classmate — blue
-        TYPE_COLORS.put("s",  new int[]{180, 180, 180});  // stranger — gray
-        TYPE_COLORS.put("sg", new int[]{255, 80, 80});    // study group — red
-    }
+    // Edge-type → RGB colour mapping — delegates to EdgeTypeRegistry for consistency
+    // across all exporters. Local reference kept for backward compatibility of
+    // the getEdgeColor() method.
 
     /**
      * Creates a new GEXF exporter for the given graph.
@@ -207,7 +201,7 @@ public String exportToString() {
 
             // Viz colour by Edge type
             if (includeVizData && type.length() > 0) {
-                int[] rgb = TYPE_COLORS.getOrDefault(type, new int[]{128, 128, 128});
+                int[] rgb = EdgeTypeRegistry.getRgbColor(type);
                 sb.append("        <viz:color r=\"").append(rgb[0])
                   .append("\" g=\"").append(rgb[1])
                   .append("\" b=\"").append(rgb[2])