Popping can also cause back navigation between tabs when current stack is depleted

app/src/main/java/com/ncapdevi/sample/activities/BottomTabsActivity.java

@@ -7,6 +7,9 @@
 import android.view.MenuItem;
 
 import com.ncapdevi.fragnav.FragNavController;
+import com.ncapdevi.fragnav.FragNavSwitchController;
+import com.ncapdevi.fragnav.FragNavTransactionOptions;
+import com.ncapdevi.fragnav.tabhistory.FragNavTabHistoryController;
 import com.ncapdevi.sample.R;
 import com.ncapdevi.sample.fragments.BaseFragment;
 import com.ncapdevi.sample.fragments.FavoritesFragment;
@@ -32,15 +35,25 @@ protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(com.ncapdevi.sample.R.layout.activity_bottom_tabs);
 
-        BottomBar mBottomBar = findViewById(R.id.bottomBar);
-        mBottomBar.selectTabAtPosition(INDEX_NEARBY);
+        final BottomBar bottomBar = findViewById(R.id.bottomBar);
+        boolean initial = savedInstanceState == null;
+        if (initial) {
+            bottomBar.selectTabAtPosition(INDEX_NEARBY);
+        }
         mNavController = FragNavController.newBuilder(savedInstanceState, getSupportFragmentManager(), R.id.container)
                 .transactionListener(this)
                 .rootFragmentListener(this, 5)
+                .popStrategy(FragNavTabHistoryController.UNIQUE_TAB_HISTORY)
+                .switchController(new FragNavSwitchController() {
+                    @Override
+                    public void switchTab(int index, FragNavTransactionOptions transactionOptions) {
+                        bottomBar.selectTabAtPosition(index);
+                    }
+                })
                 .build();
 
 
-        mBottomBar.setOnTabSelectListener(new OnTabSelectListener() {
+        bottomBar.setOnTabSelectListener(new OnTabSelectListener() {
             @Override
             public void onTabSelected(@IdRes int tabId) {
                 switch (tabId) {
@@ -61,9 +74,9 @@ public void onTabSelected(@IdRes int tabId) {
                         break;
                 }
             }
-        });
+        }, initial);
 
-        mBottomBar.setOnTabReselectListener(new OnTabReselectListener() {
+        bottomBar.setOnTabReselectListener(new OnTabReselectListener() {
             @Override
             public void onTabReSelected(@IdRes int tabId) {
                 mNavController.clearStack();
@@ -74,9 +87,7 @@ public void onTabReSelected(@IdRes int tabId) {
 
     @Override
     public void onBackPressed() {
-        if (!mNavController.isRootFragment()) {
-            mNavController.popFragment();
-        } else {
+        if (!mNavController.popFragment()) {
             super.onBackPressed();
         }
     }

frag-nav/src/main/java/com/ncapdevi/fragnav/FragNavController.java

@@ -13,6 +13,11 @@
 import android.support.v4.util.Pair;
 import android.view.View;
 
+import com.ncapdevi.fragnav.tabhistory.CurrentTabHistoryController;
+import com.ncapdevi.fragnav.tabhistory.FragNavTabHistoryController;
+import com.ncapdevi.fragnav.tabhistory.UniqueTabHistoryController;
+import com.ncapdevi.fragnav.tabhistory.UnlimitedTabHistoryController;
+
 import org.json.JSONArray;
 
 import java.lang.annotation.Retention;
@@ -21,6 +26,10 @@
 import java.util.List;
 import java.util.Stack;
 
+import static com.ncapdevi.fragnav.tabhistory.FragNavTabHistoryController.CURRENT_TAB;
+import static com.ncapdevi.fragnav.tabhistory.FragNavTabHistoryController.UNIQUE_TAB_HISTORY;
+import static com.ncapdevi.fragnav.tabhistory.FragNavTabHistoryController.UNLIMITED_TAB_HISTORY;
+
 /**
  * The class is used to manage navigation through multiple stacks of fragments, as well as coordinate
  * fragments that may appear on screen
@@ -83,6 +92,9 @@ public class FragNavController {
     @Nullable
     private TransactionListener mTransactionListener;
     private boolean mExecutingTransaction;
+    private FragNavTabHistoryController mFragNavTabHistoryController;
+    @FragNavTabHistoryController.PopStrategy
+    private final int mPopStrategy;
 
     //region Construction and setup
 
@@ -94,6 +106,24 @@ private FragNavController(Builder builder, @Nullable Bundle savedInstanceState)
         mTransactionListener = builder.mTransactionListener;
         mDefaultTransactionOptions = builder.mDefaultTransactionOptions;
         mSelectedTabIndex = builder.mSelectedTabIndex;
+        mPopStrategy = builder.mPopStrategy;
+
+        DefaultFragNavPopController fragNavPopController = new DefaultFragNavPopController();
+        switch (mPopStrategy) {
+            case CURRENT_TAB:
+                mFragNavTabHistoryController = new CurrentTabHistoryController(fragNavPopController);
+                break;
+            case UNIQUE_TAB_HISTORY:
+                mFragNavTabHistoryController = new UniqueTabHistoryController(fragNavPopController,
+                        builder.fragNavSwitchController);
+                break;
+            case UNLIMITED_TAB_HISTORY:
+                mFragNavTabHistoryController = new UnlimitedTabHistoryController(fragNavPopController,
+                        builder.fragNavSwitchController);
+                break;
+        }
+
+        mFragNavTabHistoryController.switchTab(mSelectedTabIndex);
 
         //Attempt to restore from bundle, if not, initialize
         if (!restoreFromBundle(savedInstanceState, builder.mRootFragments)) {
@@ -107,6 +137,8 @@ private FragNavController(Builder builder, @Nullable Bundle savedInstanceState)
             }
 
             initialize(builder.mSelectedTabIndex);
+        } else {
+            mFragNavTabHistoryController.restoreFromBundle(savedInstanceState);
         }
     }
 
@@ -157,6 +189,10 @@ public void initialize(@TabIndex int index) {
      * @throws IndexOutOfBoundsException Thrown if trying to switch to an index outside given range
      */
     public void switchTab(@TabIndex int index, @Nullable FragNavTransactionOptions transactionOptions) throws IndexOutOfBoundsException {
+        switchTabInternal(index, transactionOptions);
+    }
+
+    private void switchTabInternal(@TabIndex int index, @Nullable FragNavTransactionOptions transactionOptions) throws IndexOutOfBoundsException {
         //Check to make sure the tab is within range
         if (index >= mFragmentStacks.size()) {
             throw new IndexOutOfBoundsException("Can't switch to a tab that hasn't been initialized, " +
@@ -165,6 +201,7 @@ public void switchTab(@TabIndex int index, @Nullable FragNavTransactionOptions t
         }
         if (mSelectedTabIndex != index) {
             mSelectedTabIndex = index;
+            mFragNavTabHistoryController.switchTab(index);
 
             FragmentTransaction ft = createTransactionWithOptions(transactionOptions, false);
 
@@ -185,9 +222,9 @@ public void switchTab(@TabIndex int index, @Nullable FragNavTransactionOptions t
                 }
             }
 
+
             mCurrentFrag = fragment;
             if (mTransactionListener != null) {
-
                 mTransactionListener.onTabTransaction(getCurrentFrag(), mSelectedTabIndex);
             }
         }
@@ -241,25 +278,30 @@ public void pushFragment(@Nullable Fragment fragment) {
      *
      * @param transactionOptions Transaction options to be displayed
      */
-    public void popFragment(@Nullable FragNavTransactionOptions transactionOptions) throws UnsupportedOperationException {
-        popFragments(1, transactionOptions);
+    public boolean popFragment(@Nullable FragNavTransactionOptions transactionOptions) throws UnsupportedOperationException {
+        return popFragments(1, transactionOptions);
     }
 
     /**
      * Pop the current fragment from the current tab
      */
-    public void popFragment() throws UnsupportedOperationException {
-        popFragment(null);
+    public boolean popFragment() throws UnsupportedOperationException {
+        return popFragment(null);
     }
 
     /**
      * Pop the current stack until a given tag is found. If the tag is not found, the stack will popFragment until it is at
      * the root fragment
      *
      * @param transactionOptions Transaction options to be displayed
+     * @return true if any any fragment has been popped
      */
-    public void popFragments(int popDepth, @Nullable FragNavTransactionOptions transactionOptions) throws UnsupportedOperationException {
-        if (isRootFragment()) {
+    public boolean popFragments(int popDepth, @Nullable FragNavTransactionOptions transactionOptions) throws UnsupportedOperationException {
+        return mFragNavTabHistoryController.popFragments(popDepth, transactionOptions);
+    }
+
+    private int tryPopFragmentsFromCurrentStack(int popDepth, @Nullable FragNavTransactionOptions transactionOptions) throws UnsupportedOperationException {
+        if (mPopStrategy == CURRENT_TAB && isRootFragment()) {
             throw new UnsupportedOperationException(
                     "You can not popFragment the rootFragment. If you need to change this fragment, use replaceFragment(fragment)");
         } else if (popDepth < 1) {
@@ -269,9 +311,10 @@ public void popFragments(int popDepth, @Nullable FragNavTransactionOptions trans
         }
 
         //If our popDepth is big enough that it would just clear the stack, then call that.
-        if (popDepth >= mFragmentStacks.get(mSelectedTabIndex).size() - 1) {
+        int poppableSize = mFragmentStacks.get(mSelectedTabIndex).size() - 1;
+        if (popDepth >= poppableSize) {
             clearStack(transactionOptions);
-            return;
+            return poppableSize;
         }
 
         Fragment fragment;
@@ -316,6 +359,7 @@ public void popFragments(int popDepth, @Nullable FragNavTransactionOptions trans
         if (mTransactionListener != null) {
             mTransactionListener.onFragmentTransaction(getCurrentFrag(), TransactionType.POP);
         }
+        return popDepth;
     }
 
     /**
@@ -697,7 +741,6 @@ private FragmentTransaction createTransactionWithOptions(@Nullable FragNavTransa
 
     /**
      * Helper function to commit fragment transaction with transaction option - allowStateLoss
-     * k
      *
      * @param fragmentTransaction
      * @param transactionOptions
@@ -734,7 +777,9 @@ public int getSize() {
     @CheckResult
     @Nullable
     public Stack<Fragment> getStack(@TabIndex int index) {
-        if (index == NO_TAB) return null;
+        if (index == NO_TAB) {
+            return null;
+        }
         if (index >= mFragmentStacks.size()) {
             throw new IndexOutOfBoundsException("Can't get an index that's larger than we've setup");
         }
@@ -826,6 +871,8 @@ public void onSaveInstanceState(@NonNull Bundle outState) {
         } catch (Throwable t) {
             // Nothing we can do
         }
+
+        mFragNavTabHistoryController.onSaveInstanceState(outState);
     }
 
     /**
@@ -937,6 +984,13 @@ public interface TransactionListener {
         void onFragmentTransaction(Fragment fragment, TransactionType transactionType);
     }
 
+    public class DefaultFragNavPopController implements com.ncapdevi.fragnav.FragNavPopController {
+        @Override
+        public int tryPopFragments(int popDepth, FragNavTransactionOptions transactionOptions) throws UnsupportedOperationException {
+            return FragNavController.this.tryPopFragmentsFromCurrentStack(popDepth, transactionOptions);
+        }
+    }
+
     public static final class Builder {
         private final int mContainerId;
         private FragmentManager mFragmentManager;
@@ -946,8 +1000,14 @@ public static final class Builder {
         private TransactionListener mTransactionListener;
         private FragNavTransactionOptions mDefaultTransactionOptions;
         private int mNumberOfTabs = 0;
+
+        @FragNavTabHistoryController.PopStrategy
+        private int mPopStrategy = CURRENT_TAB;
         private List<Fragment> mRootFragments;
         private Bundle mSavedInstanceState;
+
+        @Nullable
+        private FragNavSwitchController fragNavSwitchController;
 
         public Builder(@Nullable Bundle savedInstanceState, FragmentManager mFragmentManager, int mContainerId) {
             this.mSavedInstanceState = savedInstanceState;
@@ -1018,10 +1078,30 @@ public Builder transactionListener(TransactionListener val) {
             return this;
         }
 
+        /**
+         * @param popStrategy Switch between different approaches of handling tab history while popping fragments on current tab
+         */
+        public Builder popStrategy(@FragNavTabHistoryController.PopStrategy int popStrategy) {
+            mPopStrategy = popStrategy;
+            return this;
+        }
+
+        /**
+         * @param fragNavSwitchController Handles switch requests
+         */
+        public Builder switchController(FragNavSwitchController fragNavSwitchController) {
+            this.fragNavSwitchController = fragNavSwitchController;
+            return this;
+        }
+
         public FragNavController build() {
             if (mRootFragmentListener == null && mRootFragments == null) {
                 throw new IndexOutOfBoundsException("Either a root fragment(s) needs to be set, or a fragment listener");
             }
+            if ((mPopStrategy == UNIQUE_TAB_HISTORY || mPopStrategy == UNLIMITED_TAB_HISTORY) && fragNavSwitchController == null) {
+                throw new IllegalStateException(
+                        "Switch handler needs to be set for unique or unlimited tab history strategy");
+            }
             return new FragNavController(this, mSavedInstanceState);
         }
     }

frag-nav/src/main/java/com/ncapdevi/fragnav/FragNavPopController.java

@@ -0,0 +1,5 @@
+package com.ncapdevi.fragnav;
+
+public interface FragNavPopController {
+    int tryPopFragments(int popDepth, FragNavTransactionOptions transactionOptions) throws UnsupportedOperationException;
+}

frag-nav/src/main/java/com/ncapdevi/fragnav/FragNavSwitchController.java

@@ -0,0 +1,5 @@
+package com.ncapdevi.fragnav;
+
+public interface FragNavSwitchController {
+    void switchTab(@FragNavController.TabIndex int index, FragNavTransactionOptions transactionOptions);
+}

frag-nav/src/main/java/com/ncapdevi/fragnav/tabhistory/BaseFragNavTabHistoryController.java

@@ -0,0 +1,11 @@
+package com.ncapdevi.fragnav.tabhistory;
+
+import com.ncapdevi.fragnav.FragNavPopController;
+
+abstract class BaseFragNavTabHistoryController implements FragNavTabHistoryController {
+    FragNavPopController fragNavPopController;
+
+    BaseFragNavTabHistoryController(FragNavPopController fragNavPopController) {
+        this.fragNavPopController = fragNavPopController;
+    }
+}