Android Fragment Manager Classes

FragmentBackStackManagement

Add base fragment : backStackManager?.addBaseFragment(showcaseFragment, R.id.home)

Add subFragment   : backStackManager?.loadFragmentAndAddToBackStack(fragment = event.fragment)
                    backStackManager?.loadFragmentAndAddToBackStack(fragment = event.fragment,menuId = event.menuId)
                    
Pop Backstack     : backStackManager?.popFragmentBackStack(activeMenuId)
                    
                    
Switch Menu       : private fun switchMenu(activeMenuId: Int,targetMenuId: Int) { //Should invoke in navigationViewSelectedListener.
        Logger.d(TAG, "Menu Switched -> $activeMenuId -> $targetMenuId")
        backStackManager?.handleMenuSwitch(activeMenuId, targetMenuId)
        backStackManager?.updateMenuStackCount(targetMenuId)
    }
    
    
private fun setSelectedNavigationViewItem(itemId: Int) { //Should invoke in navigationViewSelectedListener.
        binding.bottomNavigationView.menu.findItem(itemId).isChecked = true
    }



class BackStack {
    private val TAG = this.javaClass.simpleName
    private val homeStack = Stack<Fragment>()
    private val categoriesStack = Stack<Fragment>()
    private val favoritesStack = Stack<Fragment>()
    private val basketStack = Stack<Fragment>()
    private val profileStack = Stack<Fragment>()

    private val menuStack = Stack<Int>()

    fun getMenuStack(): Stack<Int> {
        return menuStack
    }

    val menuStackCount: Int
        get() = menuStack.size


    fun getFragmentStack(menuId: Int): Stack<Fragment>? {
        Logger.d(TAG,"homeStack : ${homeStack.size}")
        Logger.d(TAG,"categoriesStack : ${categoriesStack.size}")
        Logger.d(TAG,"favoritesStack : ${favoritesStack.size}")
        Logger.d(TAG,"basketStack : ${basketStack.size}")
        Logger.d(TAG,"profileStack : ${profileStack.size}")
        Logger.d(TAG,"menuStack : ${menuStack.size}\n\n")
        return when (menuId) {
            R.id.home -> homeStack
            R.id.categories -> categoriesStack
            R.id.favorites -> favoritesStack
            R.id.basket -> basketStack
            R.id.profile -> profileStack
            else -> null
        }
    }

    fun getFragmentStackCount(menuId: Int): Int {
        return getFragmentStack(menuId)!!.size
    }

    fun pushFragmentToStack(menuId: Int, fragment: Fragment) {
        if (getFragmentStack(menuId) != null) {
            getFragmentStack(menuId)!!.push(fragment)
        }
    }

    fun popFragmentBackStack(menuId: Int, fragmentManager: FragmentManager): Boolean {

        if (getFragmentStack(menuId) != null) {

            if (getFragmentStack(menuId)!!.size > 1) {

                try {
                    fragmentManager.beginTransaction()
                        .remove(getFragmentStack(menuId)!!.pop())
                        .commit()
                } catch (e: Exception) {
                }

                return true
            }

        }

        return false
    }


    private fun isHaveSameItem(menuId: Int): Boolean {
        return menuStack.contains(menuId)
    }

    fun updateMenuStack(menuId: Int) {
        Logger.d(TAG,"updateMenuStack : $menuId")
        if (!isHaveSameItem(menuId)) {
            menuStack.push(menuId)
        }
    }

    fun popMenuBackStack(): Int {
        val stackSize = menuStack.size
        Logger.d(TAG,"menuStackSize -> $stackSize")
        if (stackSize > 1) {
            menuStack.pop()
            return menuStack.peek()
        }

        return menuStack.peek()
    }

    fun clearBackStackHistories() {
        homeStack.clear()
        categoriesStack.clear()
        favoritesStack.clear()
        basketStack.clear()
        profileStack.clear()
        menuStack.clear()
    }
}


class BackStackManager(private val fragmentManager: FragmentManager) {
    private val backStack = BackStack()

    fun getBackStack(): BackStack {
        return backStack
    }

    val menuStackCount: Int
        get() = backStack.menuStackCount


    fun loadFragmentAndAddToBackStack(fragment: Fragment, menuId: Int = Config.lastSelectedNavigationItemId, containerId: Int = R.id.fragment_in_main) {
        addFragmentAndBackStack(containerId, fragment, menuId)
    }

    private fun addFragmentAndBackStack(containerId: Int, fragment: Fragment, menuId: Int) {
        addFragment(containerId, fragment)
        backStack.pushFragmentToStack(menuId, fragment)
    }

    private fun addFragment(containerId: Int, fragment: Fragment) {
        val a = fragmentManager.beginTransaction()
        if (containerId == R.id.fragment_in_main) {
            a.setCustomAnimations(
                    android.R.anim.fade_in,
                    android.R.anim.fade_out,
                    android.R.anim.fade_in,
                    android.R.anim.fade_out
            )
        }
        a.add(containerId, fragment)
        a.commit()
    }

    fun addBaseFragment(fragment: Fragment, menuId: Int) {
        fragmentManager.beginTransaction()
                .add(R.id.fragment_in_main, fragment, fragment.javaClass.simpleName)
                .commit()
        backStack.pushFragmentToStack(menuId, fragment)
    }

    fun getFragmentStackCount(menuId: Int): Int {
        return backStack.getFragmentStackCount(menuId)
    }

    fun popFragmentBackStack(menuId: Int): Boolean {
        // RxBus.publish(Events.RemoveBackStackListener(menuId))
        return backStack.popFragmentBackStack(menuId, fragmentManager)
    }

    fun updateMenuStackCount(menuId: Int) {
        backStack.updateMenuStack(menuId)
    }

    fun popMenuStack(): Int {
        return backStack.popMenuBackStack()
    }

    fun handleMenuSwitch(activeMenuId: Int, targetMenuId: Int) {
        try {
            if (activeMenuId != targetMenuId) {
                val targetFragments = backStack.getFragmentStack(targetMenuId)
                if (targetFragments != null) {
                    for (fragment in targetFragments) {
                        fragmentManager.beginTransaction().show(fragment).commit()
                    }
                }

                val activeFragments = backStack.getFragmentStack(activeMenuId)
                if (activeFragments != null) {
                    for (fragment in activeFragments) {
                        fragmentManager.beginTransaction().hide(fragment).commit()
                    }
                }

            }
        } catch (e: Exception) {

        }
    }

    fun clearBackStackHistory() {
        backStack.clearBackStackHistories()
    }
}