Added JsonValueUnmaskFromEndPatternBuilder

ejmask-extensions/src/main/java/com/ebay/ejmask/extenstion/builder/json/JsonValueUnmaskFromEndPatternBuilder.java

@@ -0,0 +1,47 @@
+package com.ebay.ejmask.extenstion.builder.json;
+
+import com.ebay.ejmask.extenstion.builder.AbstractRegexPatternBuilder;
+
+/**
+ * An implementation of IPatternBuilder to support high sensitive JSON field, whose value
+ * need to be partially masked with relative field from end of the field.
+ *
+ * @author ganwu
+ */
+public class JsonValueUnmaskFromEndPatternBuilder extends AbstractRegexPatternBuilder {
+
+    //https://regex101.com/r/LL3EY7/1/
+    private static final String PATTERN_TEMPLATE = "\\\"(%s)(\\\\*\\\"\\s*:\\s*\\\\*\\\")[^\\\"]*([^\\\\\"]{%d})(\\\\?\\\"|)";
+    //group $1 = field name
+    //group $2 =  ":" (with json serialization support)
+    //group $3 =  sensitive information -> unmasked
+    //group $4 =  ending qts
+    private static final String REPLACEMENT_TEMPLATE = "\"$1$2xxxx-$3$4";
+
+    /**
+     * Build pattern to match
+     *
+     * @param visibleCharacters as no of characters to be visible.
+     * @param fieldNames        as list of field names
+     * @return match pattern
+     */
+    @Override
+    public String buildPattern(int visibleCharacters, String... fieldNames) {
+        if (visibleCharacters < 0) {
+            throw new IllegalArgumentException("visibleCharacters must be a value greater than zero instead of " + visibleCharacters);
+        }
+        return String.format(PATTERN_TEMPLATE, super.buildFieldNamesForRegexOr(fieldNames), visibleCharacters);
+    }
+
+    /**
+     * Build pattern to replace.
+     *
+     * @param visibleCharacters as no of characters to be visible.
+     * @param fieldNames        as list of field names
+     * @return match pattern
+     */
+    @Override
+    public String buildReplacement(int visibleCharacters, String... fieldNames) {
+        return REPLACEMENT_TEMPLATE;
+    }
+}