Change command type parsing to be flexible

src/main/java/lawrence/command/CommandType.java

@@ -1,5 +1,7 @@
 package lawrence.command;
 
+import java.util.ArrayList;
+
 /**
  * Represents the different commands that can be issued by the user.
  */
@@ -30,27 +32,41 @@ public enum CommandType {
     }
 
     /**
-     * Converts a text string into its relevant enum counterpart.
+     * Converts a text string into its relevant enum counterpart. Full string matching
+     * and partial string matching are both done.
      * <p>
      * If input does not match any known types, the {@link #INVALID} type
      * is returned.
+     * IF the input matches multiple types, the {@link #INVALID} type is also returned.
      * </p>
      *
      * @param input the text containing an enum value
      * @return an enum type matching the input
      */
     public static CommandType fromString(String input) {
+        ArrayList<CommandType> matches = new ArrayList<>();
         for (CommandType type : CommandType.values()) {
             // do not attempt to match with type INVALID as it is reserved to signify a failed parse
             if (type == INVALID) {
                 continue;
             }
 
-            if (type.getCommandType().equalsIgnoreCase(input)) {
-                return type;
+            String typeString = type.getCommandType();
+            if (typeString.equalsIgnoreCase(input)) {
+                matches.add(type);
+                continue;
+            }
+
+            // Check for partial match
+            if (typeString.startsWith(input.toLowerCase())) {
+                matches.add(type);
             }
         }
-        return INVALID;
+
+        if (matches.size() != 1) {
+            return INVALID;
+        }
+        return matches.get(0);
     }
 
     /**