First skeleton of the additional coding task

gCoffee/app/build.gradle

@@ -26,11 +26,11 @@ android {
 }
 
 dependencies {
-    implementation fileTree(dir: "libs", include: ["*.jar"])
     implementation 'androidx.appcompat:appcompat:1.1.0'
     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
     implementation 'com.google.android.material:material:1.1.0'
     implementation 'androidx.cardview:cardview:1.0.0'
+    implementation files('libs/commons-text-1.9.jar')
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test.ext:junit:1.1.1'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

gCoffee/app/src/main/java/com/mborowiec/gcoffee/Order.java

@@ -1,9 +1,5 @@
 package com.mborowiec.gcoffee;
 
-import androidx.annotation.NonNull;
-import androidx.appcompat.app.AlertDialog;
-import androidx.appcompat.app.AppCompatActivity;
-
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.net.Uri;
@@ -15,13 +11,18 @@
 import android.widget.ListView;
 import android.widget.Toast;
 
+import androidx.annotation.NonNull;
+import androidx.appcompat.app.AlertDialog;
+import androidx.appcompat.app.AppCompatActivity;
+
 import com.google.android.material.bottomnavigation.BottomNavigationView;
+
 import java.util.List;
 import java.util.Objects;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
-public class Order extends AppCompatActivity implements AdapterView.OnItemClickListener {
+public class Order extends AppCompatActivity implements AdapterView.OnItemClickListener, OrderMatch{
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -142,14 +143,66 @@ private void handleDeepLinks(Uri data) {
         }
 
         String[] coffeeList = this.getResources().getStringArray(R.array.coffee_list);
-        boolean contains = menuContainsItem(coffee, coffeeList);
+        String menuMatch = findMatch(coffee, coffeeList);
 
-        if (contains) showConfirmationDialog(coffee);
-        else {
+        if (menuMatch == null) {
             Toast.makeText(this, getString(R.string.not_on_menu, coffee),
                     Toast.LENGTH_SHORT).show();
+        }
+        else {
+            showConfirmationDialog(menuMatch);
+        }
+    }
+
+    /**
+     * Looks for the closest match (with closest distance) in the menu.
+     * @param order an input with potential typos
+     * @return the closest order match
+     */
+    public String findMatch(String order, String[] menu) {
+        //TODO: set treshold for Levenshtein distance?
+
+        if (order == null) {
+            return null;
+        }
+
+        StringUtil util = new StringUtil();
+        String normalizedOrder = util.normalize(order);
+
+        // Return null if the string is empty after normalizing
+        if (normalizedOrder.equals("")) {
+            return null;
+        }
+
+        if (menuContainsItem(normalizedOrder, menu)) {
+           return normalizedOrder;
+        }
+        else {
+            int[] distances = new int[menu.length];
+
+            // Check Levenshtein distances between the order and menu items
+            for (int i = 0; i < menu.length; i++) {
+                String normalizedMenuItem = util.normalize(menu[i]);
+                int distance = util.calculateLevenshteinDistance(normalizedOrder,normalizedMenuItem);
+                distances[i] = distance;
+            }
+
+            // Find the item with the smallest distance (most likely to be a match)
+            int indexMin = 0;
+            int min = distances[indexMin];
+
+            for (int i = 1; i < distances.length; i++){
+                if (distances[i] < min) {
+                    min = distances[i];
+                    indexMin = i;
+                }
             }
+            // Return the menu item with smallest distance
+            return menu[indexMin];
+        }
     }
+
+    //TODO: removing "fluff" from the input
 }
 
 

gCoffee/app/src/main/java/com/mborowiec/gcoffee/OrderMatch.java

@@ -0,0 +1,8 @@
+package com.mborowiec.gcoffee;
+
+public interface OrderMatch {
+
+    public boolean menuContainsItem(String item, String[] menu);
+
+    public String findMatch(String order, String[] menu);
+}

gCoffee/app/src/main/java/com/mborowiec/gcoffee/StringUtil.java

@@ -0,0 +1,33 @@
+package com.mborowiec.gcoffee;
+
+import org.apache.commons.text.similarity.LevenshteinDistance;
+
+public class StringUtil {
+
+    /**
+     * Normalizes the string by removing punctuation, removing whitespaces
+     * and making the string lowercase.
+     * @param input input string
+     * @return a normalized string
+     */
+    public String normalize(String input) {
+        String normalized = input.replaceAll("[^a-zA-Z ]" , "")
+                .replaceAll("\\s+", "")
+                .toLowerCase();
+
+        return normalized;
+    }
+
+    /**
+     * Calculates the Levenshtein distance between two strings
+     * @param str1 first input string
+     * @param str2 second input string
+     * @return distance between strings
+     */
+    public Integer calculateLevenshteinDistance(String str1, String str2) {
+        LevenshteinDistance levenshteinDistance = new LevenshteinDistance();
+        int distance = levenshteinDistance.apply(str1, str2);
+
+        return distance;
+    }
+}

gCoffee/app/src/test/java/com/mborowiec/gcoffee/OrderTest.java

@@ -44,4 +44,64 @@ public void testCheckMenuNull() {
         boolean test = testClass.menuContainsItem(null, coffeeList);
         assertFalse(test);
     }
+
+    @Test
+    public void testFindMatchExactMatch() {
+        String testString = testClass.findMatch("latte", coffeeList);
+        assertEquals("latte", testString);
+    }
+
+    @Test
+    public void testFindMatchSimpleTypo() {
+        String testString = testClass.findMatch("flatwhite", coffeeList);
+        assertEquals("Flat White", testString);
+    }
+
+    @Test
+    public void testFindMatchSimpleTypo1() {
+        String testString = testClass.findMatch("capuccino", coffeeList);
+        assertEquals("Cappuccino", testString);
+    }
+
+    @Test
+    public void testFindMatchSimpleTypo2() {
+        String testString = testClass.findMatch("american", coffeeList);
+        assertEquals("Americano", testString);
+    }
+
+    @Test
+    public void testFindMatchSimpleTypo3() {
+        String testString = testClass.findMatch("fatwhite", coffeeList);
+        assertEquals("Flat White", testString);
+    }
+
+    @Test
+    public void testFindMatchSimpleTypo4() {
+        String testString = testClass.findMatch("mcha", coffeeList);
+        assertEquals("Mocha", testString);
+    }
+
+    @Test
+    public void testFindMatchNull() {
+        String testString = testClass.findMatch(null, coffeeList);
+        assertEquals(null, testString);
+    }
+
+    @Test
+    public void testFindMatchEmptyString() {
+        String testString = testClass.findMatch("", coffeeList);
+        assertEquals(null, testString);
+    }
+
+    @Test
+    public void testFindMatchWhitespace() {
+        String testString = testClass.findMatch(" ", coffeeList);
+        assertEquals(null, testString);
+    }
+    //The case not handled yet - returns latte
+    @Test
+    public void testFindMatchNotOnMenu() {
+        String testString = testClass.findMatch("black tea", coffeeList);
+        assertEquals(null, testString);
+    }
 }