add comments

app/src/main/java/com/avs/rates/currency/BaseCurrency.kt

@@ -3,6 +3,9 @@ package com.avs.rates.currency
 import com.avs.rates.DEFAULT_RATE_VALUE
 import com.avs.rates.R
 
+/**
+ * Base class for every currency. Holds common data and methods.
+ */
 abstract class BaseCurrency {
 
     var rate: Double = DEFAULT_RATE_VALUE

app/src/main/java/com/avs/rates/ui/BaseActivity.kt

@@ -7,7 +7,7 @@ import com.avs.rates.di.ViewModelFactory
 
 /**
  * A class which serve as a parent to all activities classes in the app.
- * Contains common data and methods
+ * Contains common data and methods.
  */
 abstract class BaseActivity : AppCompatActivity() {
 

app/src/main/java/com/avs/rates/ui/main/CurrenciesAdapter.kt

@@ -7,16 +7,18 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.recyclerview.widget.RecyclerView
+import com.avs.rates.R
 import com.avs.rates.currency.BaseCurrency
 import com.avs.rates.databinding.RateItemListBinding
 import com.avs.rates.utils.CircleTransform
 import com.avs.rates.utils.formatNumber
+import com.avs.rates.utils.getSelectionIndex
 import com.squareup.picasso.Picasso
 import java.util.*
 
 interface RatesListener {
     fun onListItemClick(newBaseCurrency: BaseCurrency)
-    fun onEditTextChanged(text: String)
+    fun onEditTextChanged(stringValue: String)
 }
 
 class CurrenciesAdapter(
@@ -29,6 +31,10 @@ class CurrenciesAdapter(
     private var textWatcher = getTextWatcher()
     private var currencies: LinkedList<BaseCurrency>? = currencyList
 
+    /**
+     * Updates currencies list
+     * @param currencies - updated list of currencies
+     */
     fun setCurrencies(currencies: LinkedList<BaseCurrency>?) {
         this.currencies = currencies
         notifyItemRangeChanged(1, (this.currencies?.size?.minus(1) ?: 0))
@@ -50,6 +56,9 @@ class CurrenciesAdapter(
         }
     }
 
+    /**
+     * Update first two top items after base currency has changed
+     */
     fun updateTopItems() {
         if (itemCount != 0) notifyItemChanged(0)
         if (itemCount > 0) notifyItemChanged(1)
@@ -58,9 +67,12 @@ class CurrenciesAdapter(
     inner class RatesViewHolder(private val binding: RateItemListBinding) :
         RecyclerView.ViewHolder(binding.root), View.OnClickListener {
 
+        private val editTextMaxLength : Int
+
         init {
             binding.root.setOnClickListener(this)
             binding.editText.setOnClickListener(this)
+            editTextMaxLength = context.resources.getInteger(R.integer.edit_text_max_length)
         }
 
         fun bind(item: BaseCurrency, context: Context) {
@@ -70,14 +82,27 @@ class CurrenciesAdapter(
             bindFlagImage(item.getImagePath())
         }
 
+        /**
+         * Sets short currency name to a corresponding text view
+         * @param name - short name of currency
+         */
         private fun bindCurrencyShortName(name: String?) {
             if (name != null) binding.tvCurrencyShortName.text = name
         }
 
+        /**
+         * Sets full currency name to a corresponding text view
+         * @param name - full name of currency
+         */
         private fun bindCurrencyFullName(name: String?) {
             if (name != null) binding.tvCurrencyFullName.text = name
         }
 
+        /**
+         * Disables all the edit texts in the recycler view except for the top one.
+         * Sets rate value.
+         * @param value - a rate value
+         */
         private fun bindRate(value: String) {
             binding.editText.removeTextChangedListener(textWatcher)
             binding.editText.isEnabled = adapterPosition == 0
@@ -86,9 +111,14 @@ class CurrenciesAdapter(
                 binding.editText.addTextChangedListener(textWatcher)
                 itemClickListener.onEditTextChanged(binding.editText.text.toString())
                 binding.editText.requestFocus()
+                binding.editText.setSelection(getSelectionIndex(value.length, editTextMaxLength))
             }
         }
 
+        /**
+         * Loads image url into a image view using custom circle transformation
+         * @param imageUrl - country flag url
+         */
         private fun bindFlagImage(imageUrl: String?) {
             Picasso.get()
                 .load(imageUrl)
@@ -97,6 +127,10 @@ class CurrenciesAdapter(
                 .into(binding.ivFlagImage)
         }
 
+        /**
+         * Changes base currency to appear on the top, if not a first item was clicked
+         * @param view - recycler view item
+         */
         override fun onClick(view: View?) {
             val clickedPosition = adapterPosition
             if (clickedPosition != 0 && !currencies.isNullOrEmpty()) {
@@ -112,6 +146,10 @@ class CurrenciesAdapter(
         }
     }
 
+    /**
+     * Listens to a rate changing of a base currency
+     * @return
+     */
     private fun getTextWatcher(): TextWatcher {
         return object : TextWatcher {
 

app/src/main/java/com/avs/rates/ui/main/MainActivity.kt

@@ -15,7 +15,6 @@ import com.avs.rates.ui.BaseActivity
 import java.util.*
 import javax.inject.Inject
 
-
 class MainActivity : BaseActivity(), RatesListener {
 
     @Inject
@@ -55,18 +54,30 @@ class MainActivity : BaseActivity(), RatesListener {
         })
     }
 
+    /**
+     * Triggered when used has selected new base currency
+     * @param newBaseCurrency - new base currency
+     */
     override fun onListItemClick(newBaseCurrency: BaseCurrency) {
         binding.recyclerView.itemAnimator = defaultItemAnimator
         viewModel.handleUserInteraction(newBaseCurrency)
         binding.recyclerView.layoutManager?.scrollToPosition(0)
     }
 
-    override fun onEditTextChanged(text: String) {
-        viewModel.updateBaseCurrencyValue(text)
+    /**
+     * Triggered when used has changed a rate of a base currency
+     * @param stringValue - updated rate value of a base currency
+     */
+    override fun onEditTextChanged(stringValue: String) {
+        viewModel.updateBaseCurrencyValue(stringValue)
     }
 
-    private fun handleErrorItemsAppearance(it: ErrorType?) {
-        when (it) {
+    /**
+     * Manages UI items visibility in a case when network error has occurred before recycler view was shown
+     * @param errorType - network related type of error
+     */
+    private fun handleErrorItemsAppearance(errorType: ErrorType?) {
+        when (errorType) {
             null -> {
                 binding.ivCloud.visibility = View.INVISIBLE
                 binding.ivMessage.visibility = View.INVISIBLE

app/src/main/java/com/avs/rates/ui/main/MainViewModel.kt

@@ -168,6 +168,7 @@ class MainViewModel @Inject constructor(
      */
     fun updateBaseCurrencyValue(text: String) {
         baseCurrencyValue = text.toDoubleOrNull() ?: -1.0
+        currenciesList.first.rate = baseCurrencyValue
     }
 
     /**

app/src/main/java/com/avs/rates/utils/Format.kt

@@ -34,4 +34,14 @@ fun round(value: Double, decimalPlace: Int): Double {
     var number = BigDecimal(value.toString())
     number = number.setScale(decimalPlace, BigDecimal.ROUND_HALF_UP)
     return number.toDouble()
+}
+
+/**
+ *
+ * @param rateValueLength - rate value length
+ * @param maxLength - max allowed length of tne elements to be inserted in an edit text
+ * @return cursor position
+ */
+fun getSelectionIndex(rateValueLength: Int, maxLength: Int) : Int {
+    return if (rateValueLength > maxLength) maxLength else rateValueLength
 }

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

@@ -67,7 +67,7 @@
             android:hint="@string/edit_text_hint"
             android:inputType="numberDecimal"
             android:maxEms="7"
-            android:maxLength="12"
+            android:maxLength="@integer/edit_text_max_length"
             android:minEms="2"
             android:textAlignment="textEnd"
             android:textColor="@color/colorBlack"

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

@@ -8,4 +8,5 @@
     <dimen name="dimen_16dp">16dp</dimen>
     <dimen name="dimen_32dp">32dp</dimen>
     <dimen name="dimen_56dp">56dp</dimen>
+    <integer name="edit_text_max_length">18</integer>
 </resources>

app/src/test/java/com/avs/rates/utils/FormatKtTest.kt

@@ -36,4 +36,15 @@ class FormatKtTest {
         assertEquals(round(value, 2), 1234.01, delta)
         assertEquals(round(value, 3), 1234.01, delta)
     }
+
+    @Test
+    fun getSelectionIndexTest() {
+        var valueLength = 10
+        val maxLength = 18
+        assertEquals(getSelectionIndex(valueLength, maxLength), valueLength)
+        valueLength = 22
+        assertEquals(getSelectionIndex(valueLength, maxLength), maxLength)
+        valueLength = 18
+        assertEquals(getSelectionIndex(valueLength, maxLength), valueLength)
+    }
 }