From 43fa521d1450dd0a1646ef3d92809e1484598354 Mon Sep 17 00:00:00 2001
From: Adam Cowley <adam@adamcowley.co.uk>
Date: Mon, 11 Sep 2017 11:02:04 +0100
Subject: [PATCH] Added apoc.text.random(length, [valid_chars]) - Fixes #563

---
 src/main/java/apoc/text/Strings.java     | 27 +++++++++++++++++++++++-
 src/test/java/apoc/text/StringsTest.java | 24 +++++++++++++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/src/main/java/apoc/text/Strings.java b/src/main/java/apoc/text/Strings.java
index 4d9096e567..8e3b5f6720 100644
--- a/src/main/java/apoc/text/Strings.java
+++ b/src/main/java/apoc/text/Strings.java
@@ -11,11 +11,14 @@
 import java.net.URLEncoder;
 import java.text.Normalizer;
 import java.util.*;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
 import org.apache.commons.lang3.StringUtils;
+
+import static java.lang.Math.toIntExact;
 import static java.util.Arrays.asList;
 
 /**
@@ -197,7 +200,7 @@ public String format(@Name("text") String text, @Name("params") List<Object> par
         if (params == null) return text;
         return String.format(Locale.ENGLISH,text, params.toArray());
     }
-    
+
     @UserFunction
     @Description("apoc.text.slug(text, delim) - slug the text with the given delimiter")
     public String slug(@Name("text") String text, @Name(value = "delim", defaultValue = "-") String delim) {
@@ -205,4 +208,26 @@ public String slug(@Name("text") String text, @Name(value = "delim", defaultValu
         if (delim == null) return null;
         return text.trim().replaceAll("[\\W\\s]+", delim);
     }
+
+
+    private static final String lower = "abcdefghijklmnopqrstuvwxyz";
+    private static final String upper = lower.toUpperCase();
+    private static final String numeric = "0123456789";
+
+    @UserFunction
+    @Description("apoc.text.random(length, valid) YIELD value - generate a random string")
+    public String random(final @Name("length") long length, @Name(value = "valid", defaultValue = "A-Za-z0-9") String valid) {
+        valid = valid.replaceAll("A-Z", upper).replaceAll("a-z", lower).replaceAll("0-9", numeric);
+
+        StringBuilder output = new StringBuilder( toIntExact(length) );
+
+        ThreadLocalRandom rand = ThreadLocalRandom.current();
+
+        while ( output.length() < length ) {
+            output.append( valid.charAt( rand.nextInt(valid.length()) ) );
+        }
+
+        return output.toString();
+    }
+
 }
diff --git a/src/test/java/apoc/text/StringsTest.java b/src/test/java/apoc/text/StringsTest.java
index 535ad20f3a..2036683dd1 100644
--- a/src/test/java/apoc/text/StringsTest.java
+++ b/src/test/java/apoc/text/StringsTest.java
@@ -8,16 +8,20 @@
 import org.neo4j.helpers.collection.Iterators;
 import org.neo4j.test.TestGraphDatabaseFactory;
 
+import static java.lang.Math.toIntExact;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import static apoc.util.MapUtil.map;
 import static apoc.util.TestUtil.testCall;
 import static apoc.util.TestUtil.testResult;
 import static org.junit.Assert.*;
 
+
 /**
  * @author mh
  * @since 05.05.16
@@ -326,4 +330,24 @@ public void testSlug() {
         testCall(db, "RETURN apoc.text.slug('a- b','-') AS value", row -> assertEquals("a-b", row.get("value")));
         testCall(db, "RETURN apoc.text.slug('a b c') AS value", row -> assertEquals("a-b-c", row.get("value")));
     }
+
+    @Test
+    public void testRandom() {
+        Long length = 10L;
+        String valid = "A-Z0-9";
+
+        testCall(
+                db,
+                "RETURN apoc.text.random({length}, {valid}) as value",
+                map("length", length, "valid", valid),
+                row -> {
+                    String value = row.get("value").toString();
+
+                    Pattern pattern = Pattern.compile("^(["+valid+"]{"+ toIntExact(length) +"})$");
+                    Matcher matcher = pattern.matcher(value);
+
+                    assertTrue("String +" +value+ "+ should match the supplied pattern "+ pattern.toString(), matcher.matches());
+                }
+        );
+    }
 }