add Code#asin and Code#imei (#167)

* add Code#asin and Code#imei

* add Code#ean8, Code#gtin8, Code#ean13 and Code#gtin13

src/main/java/com/github/javafaker/Code.java

@@ -1,6 +1,9 @@
 package com.github.javafaker;
 
+import org.apache.commons.lang3.ArrayUtils;
+
 public class Code {
+
     private final Faker faker;
 
     Code(Faker faker) {
@@ -43,4 +46,89 @@ public class Code {
         isbn13.append(check);
         return isbn13.toString();
     }
+
+    public String asin() {
+        return faker.resolve("code.asin");
+    }
+
+    public String imei() {
+        char[] str = new char[15];
+        int len = str.length;
+
+        // Fill in the first two values of the string based with the specified prefix.
+        String arr = faker.options().option(REPORTING_BODY_IDENTIFIERS);
+        str[0] = arr.charAt(0);
+        str[1] = arr.charAt(1);
+
+        // Fill all the remaining numbers except for the last one with random values.
+        for (int i=2; i < len - 1; i++) {
+            str[i] = Character.forDigit(faker.number().numberBetween(0, 9), 10);
+        }
+
+        // Calculate the Luhn checksum of the values thus far
+        int lenOffset = (len + 1) % 2;
+        int t = 0;
+        int sum = 0;
+        for (int i = 0; i < len - 1; i++) {
+            if ((i + lenOffset) % 2 != 0) {
+                t = Character.getNumericValue(str[i]) * 2;
+
+                if (t > 9) {
+                    t -= 9;
+                }
+
+                sum += t;
+            } else {
+                sum += Character.getNumericValue(str[i]);
+            }
+        }
+
+        // Choose the last digit so that it causes the entire string to pass the checksum.
+        str[len - 1] = Character.forDigit(((10 - (sum % 10)) % 10), 10);
+
+        return new String(str);
+    }
+
+    private static final String [] REPORTING_BODY_IDENTIFIERS 
+        = {"01", "10", "30", "33", "35", "44", "45", "49", "50", "51", "52", "53", "54", "86", "91", "98", "99"};
+
+    public String ean8() {
+        return gtin8();
+    }
+
+    public String gtin8() {
+        char[] values = faker.regexify("\\d{7}").toCharArray();
+        int sum = 0;
+        for (int i = 0; i < values.length; i++) {
+            sum += Character.getNumericValue(values[i]) * GTIN_8_CHECK_DIGITS[i];
+        }
+        int checkDigit = 10 - sum % 10;
+        if (checkDigit == 10) {
+            return new String(ArrayUtils.add(values, Character.forDigit(0, 10)));
+        } else {
+            return new String(ArrayUtils.add(values, Character.forDigit(checkDigit, 10)));
+        }
+    }
+
+    public String ean13() {
+        return gtin13();
+    }
+
+    public String gtin13() {
+        char[] values = faker.regexify("\\d{12}").toCharArray();
+        int sum = 0;
+        for (int i = 0; i < values.length; i++) {
+            sum += Character.getNumericValue(values[i]) * GTIN_13_CHECK_DIGITS[i];
+        }
+        int checkDigit = 10 - sum % 10;
+        if (checkDigit == 10) {
+            return new String(ArrayUtils.add(values, Character.forDigit(0, 10)));
+        } else {
+            return new String(ArrayUtils.add(values, Character.forDigit(checkDigit, 10)));
+        }
+    }
+
+    private static final int[] GTIN_8_CHECK_DIGITS = { 3, 1, 3, 1, 3, 1, 3 };
+    private static final int[] GTIN_13_CHECK_DIGITS = { 1, 3, 1, 3, 1, 3, 1, 3, 1, 3, 1, 3 };
+
 }

src/test/java/com/github/javafaker/CodeTest.java

@@ -1,12 +1,15 @@
 package com.github.javafaker;
 
-import org.junit.Test;
-
+import static com.github.javafaker.matchers.MatchesRegularExpression.matchesRegularExpression;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
 
+import org.apache.commons.validator.routines.checkdigit.EAN13CheckDigit;
+import org.apache.commons.validator.routines.checkdigit.LuhnCheckDigit;
+import org.junit.Test;
+
 public class CodeTest extends AbstractFakerTest{
 
     @Test
@@ -50,4 +53,41 @@ public class CodeTest extends AbstractFakerTest{
             assertThat(sum % 10, is(0L));
         }
     }
-}
+
+    @Test
+    public void asin() {
+        assertThat(faker.code().asin(), matchesRegularExpression("B000([A-Z]|\\d){6}"));
+    }
+
+    @Test
+    public void imei() {
+        String imei = faker.code().imei();
+
+        assertThat(imei, matchesRegularExpression("\\A[\\d\\.\\:\\-\\s]+\\z"));
+        assertThat(LuhnCheckDigit.LUHN_CHECK_DIGIT.isValid(imei), is(true));
+    }
+
+    @Test
+    public void ean8() {
+        assertThat(faker.code().ean8(), matchesRegularExpression("\\d{8}"));
+    }
+
+    @Test
+    public void gtin8() {
+        assertThat(faker.code().gtin8(), matchesRegularExpression("\\d{8}"));
+    }
+
+    @Test
+    public void ean13() {
+        String ean13 = faker.code().ean13();
+        assertThat(ean13, matchesRegularExpression("\\d{13}"));
+        assertThat(EAN13CheckDigit.EAN13_CHECK_DIGIT.isValid(ean13), is(true));
+    }
+
+    @Test
+    public void gtin13() {
+        String gtin13 = faker.code().gtin13();
+        assertThat(gtin13, matchesRegularExpression("\\d{13}"));
+        assertThat(EAN13CheckDigit.EAN13_CHECK_DIGIT.isValid(gtin13), is(true));
+    }
+}