post shortcode converter

app/src/main/java/awais/instagrabber/utils/TextUtils.java

@@ -10,11 +10,13 @@ import android.util.Patterns;
 import androidx.annotation.NonNull;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
 import java.util.List;
 import java.util.Locale;
 import java.util.regex.Matcher;
+import java.util.stream.Collectors;
 
 public final class TextUtils {
     // extracted from String class
@@ -106,4 +108,15 @@ public final class TextUtils {
         }
         return urls;
     }
+
+    // https://github.com/notslang/instagram-id-to-url-segment
+    public static long shortcodeToId(final String shortcode) {
+        long result = 0L;
+        for (int i = 0; i < shortcode.length() && i < 11; i++){
+            final char c = shortcode.charAt(i);
+            final int k = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_".indexOf(c);
+            result = result * 64 + k;
+        }
+        return result;
+    }
 }

app/src/test/java/awais/instagrabber/utils/TextUtilsTest.java

@@ -1,10 +1,11 @@
 package awais.instagrabber.utils;
 
 import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
 
 class TextUtilsTest {
 
-    @org.junit.jupiter.api.Test
+    @Test
     void testMillisToTimeString() {
         String timeString = TextUtils.millisToTimeString(18000000);
         Assertions.assertEquals("05:00:00", timeString);
@@ -15,4 +16,12 @@ class TextUtilsTest {
         timeString = TextUtils.millisToTimeString(300000, true);
         Assertions.assertEquals("00:05:00", timeString);
     }
+
+    @Test
+    void testShortcodeConversion() {
+        long conversion = TextUtils.shortcodeToId("CA0YnOonSfS");
+        Assertions.assertEquals(2320587956892280786L, conversion);
+        conversion = TextUtils.shortcodeToId("B_7n8mblwx6gv1ZaNvA5ZhAs2qslMnRiMMYW1c0");
+        Assertions.assertEquals(2304611322577751162L, conversion);
+    }
 }