Merge pull request #41 from SomeAnonimCoder/back_button

Back button

app/src/main/java/msu/ug/ChoiceFragment.kt

@@ -34,9 +34,9 @@ class ChoiceFragment(private val actContext: Context) : ListFragment() {
         super.onListItemClick(l, v, position, id)
         if (toIndices[position] == 0) {
             storage.appendPath(taxons[position])
-            storage.currentChoise = 1
+            storage.currentChoice = 1
         } else {
-            storage.currentChoise = toIndices[position]
+            storage.currentChoice = toIndices[position]
         }
 
     }
@@ -60,7 +60,7 @@ class ChoiceFragment(private val actContext: Context) : ListFragment() {
         if (path == "/") {
             path = ""
         }
-        val file =  path + storage.currentChoise.toString()
+        val file =  path + storage.currentChoice.toString()
 
         val arr = JSONArray(getPlainText(file))
         toIndices.clear()

app/src/main/java/msu/ug/Const.kt

@@ -2,7 +2,7 @@ package msu.ug
 
 class Const {
     companion object {
-        const val CUR_CHOICE_KEY = "current_choise"
+        const val STEPS_NUM_KEY = "steps_num"
         const val PATH_LEN_KEY = "path_len"
 
         const val DEFAULT_TAXON = "Nihil"
@@ -17,5 +17,9 @@ class Const {
         fun folderKey(folderIndex : Int) : String {
             return "folder_$folderIndex"
         }
+
+        fun stepKey(stepIndex : Int) : String {
+            return "step_$stepIndex"
+        }
     }
 }

app/src/main/java/msu/ug/IntroActivity.kt

@@ -16,15 +16,15 @@ class IntroActivity : AppCompatActivity() {
         requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
 
         setContentView(R.layout.activity_intro)
-        val context:Context = this
+
         val classButton = findViewById<Button>(R.id.button_classifier)
         classButton.setOnClickListener {
-            val intent =  Intent(context, MainActivity::class.java)
+            val intent =  Intent(this, MainActivity::class.java)
             startActivity(intent)
         }
         val aboutButton = findViewById<Button>(R.id.button_about)
         aboutButton.setOnClickListener {
-            val intent = Intent(context, AboutActivity::class.java)
+            val intent = Intent(this, AboutActivity::class.java)
             startActivity(intent)
         }
 

app/src/main/java/msu/ug/MainActivity.kt

@@ -3,11 +3,12 @@ package msu.ug
 import android.content.pm.ActivityInfo
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
-
+import android.view.View
+import android.widget.Button
+import android.widget.Toast
 
 
 class MainActivity : AppCompatActivity() {
-
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
@@ -16,5 +17,21 @@ class MainActivity : AppCompatActivity() {
         val transaction = supportFragmentManager.beginTransaction()
         transaction.replace(R.id.fragment_frame, ChoiceFragment(this))
         transaction.commit()
+
+        val storage = Storage(this)
+
+        val backButton = findViewById<Button>(R.id.back_button)
+
+        backButton.setOnClickListener {
+            if (!storage.goBack()) {
+                Toast.makeText(this, "Вы в начале", Toast.LENGTH_SHORT).show()
+            }
+        }
+
+        val toStartButton = findViewById<Button>(R.id.to_start_button)
+
+        toStartButton.setOnClickListener {
+            storage.toStart()
+        }
     }
 }

app/src/main/java/msu/ug/Storage.kt

@@ -5,23 +5,40 @@ import android.content.SharedPreferences
 
 class Storage (context : Context) {
     private val sp : SharedPreferences = context.getSharedPreferences(Const.SP_NAME, Context.MODE_PRIVATE)
-    private val switchListeners : ArrayList<() -> Unit> = ArrayList()
 
     fun addSwitchListener(listener : () -> Unit) {
-        switchListeners.add(listener)
+        sp.registerOnSharedPreferenceChangeListener { _, s ->
+            if (s == Const.STEPS_NUM_KEY) {
+                //important: UI updates only after stepsNum changes.
+                // That means, to get the proper UI you need first update pathLen and then update stepsNum
+                listener.invoke()
+            }
+        }
     }
 
-    var currentChoise : Int
+    private var stepsNum : Int
         set(value) {
-            if (value > 0) {
-                sp.edit().putInt(Const.CUR_CHOICE_KEY, value).apply()
-                switchListeners.forEach {
-                    it.invoke()
-                }
-            }
+            sp.edit().putInt(Const.STEPS_NUM_KEY, value).apply()
         }
         get() {
-            return sp.getInt(Const.CUR_CHOICE_KEY, 1)
+            return sp.getInt(Const.STEPS_NUM_KEY, 0)
+        }
+
+    private var pathLen : Int
+        set(value) {
+            sp.edit().putInt(Const.PATH_LEN_KEY, value).apply()
+        }
+        get() {
+            return sp.getInt(Const.PATH_LEN_KEY, 0)
+        }
+
+    var currentChoice : Int
+        set(value) {
+            sp.edit().putInt(Const.stepKey(stepsNum + 1), value).apply()
+            stepsNum += 1
+        }
+        get() {
+            return sp.getInt(Const.stepKey(stepsNum), 1)
         }
 
     fun getPath() : List<String> {
@@ -39,8 +56,26 @@ class Storage (context : Context) {
     }
 
     fun appendPath(folder : String) {
-        val len = sp.getInt(Const.PATH_LEN_KEY, 0)
-        sp.edit().putString(Const.folderKey(len), folder).apply()
-        sp.edit().putInt(Const.PATH_LEN_KEY, len + 1).apply()
+        sp.edit().putString(Const.folderKey(pathLen), folder).apply()
+        pathLen += 1
+    }
+
+    fun goBack() : Boolean {
+        return if (stepsNum > 0) {
+            if (currentChoice == 1) {
+                pathLen -= 1
+            }
+
+            stepsNum -= 1
+
+            true
+        } else {
+            false
+        }
+    }
+
+    fun toStart() {
+        pathLen = 0
+        stepsNum = 0
     }
 }

app/src/main/res/layout/activity_main.xml

@@ -1,13 +1,30 @@
 <?xml version="1.0" encoding="utf-8"?>
-<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"
-        tools:context=".MainActivity">
+<LinearLayout android:orientation="vertical"
+              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"
+              tools:context=".MainActivity">
     <FrameLayout android:layout_width="match_parent"
-                 android:layout_height="match_parent"
-                 android:id="@+id/fragment_frame" android:background="#4CAF50">
+                 android:layout_height="0dp"
+                 android:id="@+id/fragment_frame"
+                 android:background="#4CAF50"
+                 android:layout_weight="0.9">
 
     </FrameLayout>
-</androidx.constraintlayout.widget.ConstraintLayout>
+    <LinearLayout android:layout_width="match_parent"
+                  android:layout_height="wrap_content"
+                  android:layout_gravity="center">
+        <Button android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:text="@string/back"
+                android:id="@+id/back_button"
+                android:layout_weight="1"/>
+
+        <Button android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:text="@string/to_start"
+                android:id="@+id/to_start_button"
+                android:layout_weight="1"/>
+    </LinearLayout>
+</LinearLayout>

app/src/main/res/values/strings.xml

@@ -43,6 +43,8 @@
     <string name="name">The Big\nMayevsky</string>
     <string name="classifier_button">Определитель</string>
     <string name="about_button">О программе</string>
+    <string name="back">Назад</string>
+    <string name="to_start">К началу</string>
     <string name="copyrights">There will be copyright</string>
 
 </resources>