diff --git a/.idea/deploymentTargetSelector.xml b/.idea/deploymentTargetSelector.xml
index 1ad60c3..505df14 100644
--- a/.idea/deploymentTargetSelector.xml
+++ b/.idea/deploymentTargetSelector.xml
@@ -2,8 +2,16 @@
 <project version="4">
   <component name="deploymentTargetSelector">
     <selectionStates>
-      <SelectionState runConfigName="App">
+      <SelectionState runConfigName="app">
         <option name="selectionMode" value="DROPDOWN" />
+        <DropdownSelection timestamp="2024-10-25T10:12:16.462253700Z">
+          <Target type="DEFAULT_BOOT">
+            <handle>
+              <DeviceId pluginId="PhysicalDevice" identifier="serial=RZCW922HJDB" />
+            </handle>
+          </Target>
+        </DropdownSelection>
+        <DialogSelection />
       </SelectionState>
     </selectionStates>
   </component>
diff --git a/.idea/misc.xml b/.idea/misc.xml
index 8978d23..74dd639 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,6 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="jbr-17" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="jbr-21" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">
diff --git a/.idea/runConfigurations.xml b/.idea/runConfigurations.xml
index 931b96c..16660f1 100644
--- a/.idea/runConfigurations.xml
+++ b/.idea/runConfigurations.xml
@@ -5,8 +5,12 @@
       <set>
         <option value="com.intellij.execution.junit.AbstractAllInDirectoryConfigurationProducer" />
         <option value="com.intellij.execution.junit.AllInPackageConfigurationProducer" />
+        <option value="com.intellij.execution.junit.PatternConfigurationProducer" />
         <option value="com.intellij.execution.junit.TestInClassConfigurationProducer" />
         <option value="com.intellij.execution.junit.UniqueIdConfigurationProducer" />
+        <option value="com.intellij.execution.junit.testDiscovery.JUnitTestDiscoveryConfigurationProducer" />
+        <option value="org.jetbrains.kotlin.idea.junit.KotlinJUnitRunConfigurationProducer" />
+        <option value="org.jetbrains.kotlin.idea.junit.KotlinPatternConfigurationProducer" />
       </set>
     </option>
   </component>
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..c5f3f6b
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+    "java.configuration.updateBuildConfiguration": "interactive"
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/mukudev/easy2do/Fragments/Fragment2DayRule.java b/app/src/main/java/com/mukudev/easy2do/Fragments/Fragment2DayRule.java
index ca3c254..8b10893 100644
--- a/app/src/main/java/com/mukudev/easy2do/Fragments/Fragment2DayRule.java
+++ b/app/src/main/java/com/mukudev/easy2do/Fragments/Fragment2DayRule.java
@@ -1,40 +1,191 @@
+
 package com.mukudev.easy2do.Fragments;
 
 import android.os.Bundle;
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.widget.Button;
+import java.util.Set;
+import java.util.HashSet;
+import java.util.Calendar;
+import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.Fragment;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.CalendarView;
 import android.widget.Toast;
+import android.widget.TextView;
 
 import com.mukudev.easy2do.R;
 
 public class Fragment2DayRule extends Fragment {
+    private Button markDoneButton;
+    private Set<String> markedDays;
+    private SharedPreferences sharedPreferences;
+    private CalendarView calendarView;
+    private TextView streakTextView;
+
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
-
         View view = inflater.inflate(R.layout.fragment_2day_rule, container, false);
 
-        // Initialize the CalendarView
-        CalendarView calendarView = view.findViewById(R.id.calendarView);
+        calendarView = view.findViewById(R.id.calendarView);
+        markDoneButton = view.findViewById(R.id.markDoneButton);
+        streakTextView = view.findViewById(R.id.streakTextView);
 
-        // Set OnDateChangeListener to capture date changes
-        calendarView.setOnDateChangeListener(new CalendarView.OnDateChangeListener() {
-            @Override
-            public void onSelectedDayChange(CalendarView view, int year, int month, int dayOfMonth) {
+        sharedPreferences = requireContext().getSharedPreferences("HabitTracker", Context.MODE_PRIVATE);
+        markedDays = new HashSet<>(sharedPreferences.getStringSet("markedDays", new HashSet<>()));
 
-                String selectedDate = dayOfMonth + "/" + (month + 1) + "/" + year;
+        setupCalendarView();
+        setupMarkDoneButton();
+        updateStreak();
+
+        return view;
+    }
 
-                // Add functionality to save the mark date and it should be asserted because it cannot change after its marked
-                Toast.makeText(getContext(), "Selected Date: " + selectedDate, Toast.LENGTH_SHORT).show();
+    private void setupCalendarView() {
+        Calendar today = Calendar.getInstance();
+        calendarView.setMaxDate(today.getTimeInMillis());
 
+        calendarView.setOnDateChangeListener((view, year, month, dayOfMonth) -> {
+            Calendar selectedDate = Calendar.getInstance();
+            selectedDate.set(year, month, dayOfMonth);
+            Calendar currentDate = Calendar.getInstance();
+
+            if (selectedDate.before(currentDate)) {
+                showPastDatePopup();
+            } else if (selectedDate.after(currentDate)) {
+                Toast.makeText(getContext(), "You cannot select future dates", Toast.LENGTH_SHORT).show();
+            } else {
+                updateMarkDoneButtonState(selectedDate);
+                if (!isCurrentDateMarked()) {
+                    showMarkAsDoneConfirmation();
+                } else {
+                    Toast.makeText(getContext(), "This day is already marked as done!", Toast.LENGTH_SHORT).show();
+                }
             }
         });
 
-        return view;
+        calendarView.setDate(today.getTimeInMillis(), false, true);
+        highlightDates();
+    }
+
+    private void setupMarkDoneButton() {
+        markDoneButton.setOnClickListener(v -> showMarkAsDoneConfirmation());
+        updateMarkDoneButtonState(Calendar.getInstance());
+    }
+
+    private void showPastDatePopup() {
+        new AlertDialog.Builder(requireContext())
+            .setTitle("Past Date")
+            .setMessage("You cannot select previous dates.")
+            .setPositiveButton("OK", null)
+            .show();
+    }
+
+    private void showMarkAsDoneConfirmation() {
+        new AlertDialog.Builder(requireContext())
+            .setTitle("Mark as Done")
+            .setMessage("Are you sure you want to mark this day as done? This action cannot be undone.")
+            .setPositiveButton("Yes", (dialog, which) -> markTodayAsDone())
+            .setNegativeButton("No", null)
+            .show();
+    }
+
+    private void markTodayAsDone() {
+        Calendar calendar = Calendar.getInstance();
+        String currentDate = formatDate(calendar);
+
+        if (!markedDays.contains(currentDate)) {
+            markedDays.add(currentDate);
+            SharedPreferences.Editor editor = sharedPreferences.edit();
+            editor.putStringSet("markedDays", markedDays);
+            editor.apply();
+
+            Toast.makeText(getContext(), "Marked as done!", Toast.LENGTH_SHORT).show();
+        }
+        updateMarkDoneButtonState(calendar);
+        updateStreak();
+        highlightDates();
+    }
+
+    private void updateMarkDoneButtonState(Calendar selectedDate) {
+        boolean isToday = isToday(selectedDate);
+        String currentDate = formatDate(selectedDate);
+        markDoneButton.setEnabled(isToday && !markedDays.contains(currentDate));
+    }
 
+    private String formatDate(Calendar calendar) {
+        return calendar.get(Calendar.DAY_OF_MONTH) + "/" +
+               (calendar.get(Calendar.MONTH) + 1) + "/" +
+               calendar.get(Calendar.YEAR);
     }
 
+    private boolean isToday(Calendar date) {
+        Calendar today = Calendar.getInstance();
+        return date.get(Calendar.YEAR) == today.get(Calendar.YEAR) &&
+               date.get(Calendar.MONTH) == today.get(Calendar.MONTH) &&
+               date.get(Calendar.DAY_OF_MONTH) == today.get(Calendar.DAY_OF_MONTH);
+    }
+
+    private boolean isCurrentDateMarked() {
+        Calendar calendar = Calendar.getInstance();
+        String currentDate = formatDate(calendar);
+        return markedDays.contains(currentDate);
+    }
+
+    private void updateStreak() {
+        int streak = calculateStreak();
+        streakTextView.setText("Current Streak: " + streak + " days");
+    }
+
+    private int calculateStreak() {
+        Calendar today = Calendar.getInstance();
+        int streak = 0;
+
+        while (markedDays.contains(formatDate(today))) {
+            streak++;
+            today.add(Calendar.DAY_OF_MONTH, -1);
+        }
+
+        return streak;
+    }
+
+    private View getDayViewByDate(long dateInMillis) {
+        // Implement the logic to get the day view by date
+        // This is a placeholder implementation and may need to be adjusted based on your CalendarView implementation
+        return calendarView.findViewWithTag(dateInMillis);
+    }
+
+    private void highlightDates() {
+        for (String date : markedDays) {
+            // Logic to highlight the marked dates
+            String[] parts = date.split("/");
+            int day = Integer.parseInt(parts[0]);
+            int month = Integer.parseInt(parts[1]) - 1; // Calendar months are 0-based
+            int year = Integer.parseInt(parts[2]);
+
+            Calendar calendar = Calendar.getInstance();
+            calendar.set(year, month, day);
+
+            long dateInMillis = calendar.getTimeInMillis();
+            calendarView.setDate(dateInMillis, false, true);
+
+            // Assuming you have a method to get the day view by date
+            View dayView = getDayViewByDate(dateInMillis);
+            if (dayView != null) {
+                dayView.setBackgroundResource(R.drawable.dark_red_circle);
+            }
+        }
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+        setupCalendarView();
+        updateMarkDoneButtonState(Calendar.getInstance());
+        updateStreak();
+    }
 }
diff --git a/app/src/main/res/drawable/dark_red_circle.xml b/app/src/main/res/drawable/dark_red_circle.xml
new file mode 100644
index 0000000..2fd16a2
--- /dev/null
+++ b/app/src/main/res/drawable/dark_red_circle.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <solid android:color="#8B0000"/> <!-- Dark Red Color -->
+    <stroke
+        android:width="2dp"
+        android:color="#8B0000"/> <!-- Dark Red Border -->
+    <corners android:radius="50dp"/>
+</shape>
diff --git a/app/src/main/res/layout/fragment_2day_rule.xml b/app/src/main/res/layout/fragment_2day_rule.xml
index 6068d0d..ecd9d39 100644
--- a/app/src/main/res/layout/fragment_2day_rule.xml
+++ b/app/src/main/res/layout/fragment_2day_rule.xml
@@ -1,5 +1,6 @@
 
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     xmlns:app="http://schemas.android.com/apk/res-auto"
@@ -11,15 +12,30 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginHorizontal="15dp"
-        android:layout_marginTop="7dp"
-        android:text="\n\nDon't let more than 2 days go by without doing the activity you're trying to make a habit!"
+        android:layout_marginTop="4dp"
+        android:paddingTop="7dp"
+        android:text="Don't let more than 2 days go by without doing the activity you're trying to make a habit!"
         android:textAlignment="center"
+        android:textColor="?attr/colorOnPrimary"
         android:textSize="18sp"
         android:textStyle="bold"
-        android:paddingTop="7dp"
         app:layout_constraintTop_toTopOf="parent"
-        android:textColor="?attr/colorOnPrimary"/>
+        tools:layout_editor_absoluteX="0dp" />
 
+    <TextView
+        android:id="@+id/streakTextView"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginHorizontal="15dp"
+        android:layout_marginTop="4dp"
+        android:paddingTop="7dp"
+        android:text="Current Streak: 0 days"
+        android:textAlignment="center"
+        android:textColor="?attr/colorOnPrimary"
+        android:textSize="18sp"
+        android:textStyle="bold"
+        app:layout_constraintTop_toBottomOf="@+id/textView"
+        tools:layout_editor_absoluteX="0dp" />
 
     <CalendarView
         android:id="@+id/calendarView"
@@ -29,22 +45,16 @@
         android:dateTextAppearance="@style/customCalendarTheme"
         android:weekDayTextAppearance="@style/customCalendarTheme"
         app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintTop_toTopOf="@+id/textView"
+        app:layout_constraintTop_toBottomOf="@+id/streakTextView"
         android:background="@drawable/rectangle"/>
 
-    <TextView
-        android:textStyle="bold"
-        android:id="@+id/textView2"
-        android:layout_width="match_parent"
+    <Button
+        android:id="@+id/markDoneButton"
+        android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:text="Stay on track and don't break the chain!"
-        android:textAlignment="center"
-        android:textSize="18sp"
-        android:layout_marginHorizontal="15dp"
-        app:layout_constraintBottom_toBottomOf="parent"
+        android:text="Mark as Done"
+        android:layout_marginTop="16dp"
         app:layout_constraintTop_toBottomOf="@+id/calendarView"
-        android:textColor="?attr/colorOnPrimary"/>
-
-
-
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"/>
 </androidx.constraintlayout.widget.ConstraintLayout>
diff --git a/app/src/main/res/layout/fragment_2priority_task_rule.xml b/app/src/main/res/layout/fragment_2priority_task_rule.xml
index a1b615c..b2b4782 100644
--- a/app/src/main/res/layout/fragment_2priority_task_rule.xml
+++ b/app/src/main/res/layout/fragment_2priority_task_rule.xml
@@ -12,4 +12,4 @@
         android:textAlignment="center"
         android:textSize="20sp"
         android:text="2-Priority Tasks for Today!\n(--To be Implemented--)" />
-</LinearLayout>
+</LinearLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/styles.xml b/app/src/main/res/values/styles.xml
index 35c826f..52779df 100644
--- a/app/src/main/res/values/styles.xml
+++ b/app/src/main/res/values/styles.xml
@@ -25,5 +25,19 @@
         <item name="colorControlHighlight">@color/white</item>
         <item name="android:textColor">@drawable/selector</item>
     </style>
+    <style name="MarkedDateStyle">
+        <item name="android:textColor">#FF0000</item> <!-- Red color for marked dates -->
+        <item name="android:textStyle">bold</item>
+    </style>
+    <style name="DarkRedCircle">
+        <item name="android:background">@drawable/dark_red_circle</item>
+    </style>
 
-</resources>
\ No newline at end of file
+    <style name="GrayOutDateStyle">
+        <item name="android:textColor">#A9A9A9</item> <!-- Gray color for upcoming dates -->
+    </style>
+
+    <style name="DefaultDateStyle">
+        <item name="android:textColor">#000000</item> <!-- Default color for other dates -->
+    </style>
+</resources>
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index f45e369..4ce0601 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,5 +1,5 @@
 [versions]
-agp = "8.7.0"
+agp = "8.7.1"
 junit = "4.13.2"
 junitVersion = "1.2.1"
 espressoCore = "3.6.1"