private fun pickImageFromGallery() {
       //Intent to pick image
       val intent = Intent(Intent.ACTION_PICK)
       intent.type = "image/*"
       startActivityForResult(intent, IMAGE_PICK_CODE)
   }

    override fun onCreate(savedInstanceState: Bundle?) {
       super.onCreate(savedInstanceState)
       setContentView(R.layout.activity_main)

       //BUTTON CLICK
       img_pick_btn.setOnClickListener {
           //check runtime permission
           if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
               if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_DENIED) {
                   //permission denied
                   val permissions = arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE);
                   //show popup to request runtime permission
                   requestPermissions(permissions, PERMISSION_CODE);
               } else {
                   //permission already granted
                   pickImageFromGallery();
               }
           } else {
               //system OS is < Marshmallow
               pickImageFromGallery();
           }
       }
   }
   

 fun selectImage(v: View) {
       val intent = Intent()
       intent.type = "image/*"
       intent.action = Intent.ACTION_GET_CONTENT
       startActivityForResult(Intent.createChooser(intent, "Select Picture"), 1)
   }

 fun startRecognizing(v: View) {
        if (imageView.drawable != null) {
            editText.setText("")
            v.isEnabled = false
            val bitmap = (imageView.drawable as BitmapDrawable).bitmap
            val image = FirebaseVisionImage.fromBitmap(bitmap)
            val detector = FirebaseVision.getInstance().onDeviceTextRecognizer

            detector.processImage(image)
                .addOnSuccessListener { firebaseVisionText ->
                    v.isEnabled = true
                    processResultText(firebaseVisionText)

                    var toCheckList: List<String?>  // list to send to checklist activity
                    toCheckList = ArrayList(50)

                    var products: List<Pair<Double, String>>  // auxiliary list to make tochecklist
                    products = processResultText(firebaseVisionText)

                    for (x in products)
                        toCheckList.add(x.first.toString() + ',' + x.second)
                    // pass the products array to checklist for merging
                    val Checklist = Intent(this, ChecklistActivity::class.java)
                    Checklist.putExtra("Products", toCheckList)
                    startActivity(Checklist)

                }
                .addOnFailureListener {
                    v.isEnabled = true
                    editText.setText("Failed")
                }
        } else {
            Toast.makeText(this, "Select an Image First", Toast.LENGTH_LONG).show()
        }
    }

    private fun processResultText(resultText: FirebaseVisionText): List<Pair<Double, String>> {

        var products: List<Pair<Double, String>>
        products = ArrayList(50)

        if (resultText.textBlocks.size == 0) {
            editText.setText("No Text Found")
            return products
        }

        for (block in resultText.textBlocks) {
            val blockText = block.text
            editText.append(blockText + "\n")
        }

        val tuples = getTuples(editText.text.toString())
        products = getTuples(editText.text.toString())
        editText.setText("")
        for (t in tuples) {
            editText.append(t.toString() + "\n")
        }
        return products
    }  

  // returns a list of pairs (price, product_name), given the text of the receipt
    fun getTuples(text: String): List<Pair<Double, String>> {
        var products = mutableListOf<Pair<Double, String>>()
        var produs_crt = 0
        var pret_crt = 0
        var nume_crt = 0
        var started =
            false  // all the text from the upper part of the receipt is unnecessary and it should be skipped
        val lines = text.split("\n")
        for (line in lines) {
            if ("total" == line.toLowerCase(Locale.getDefault())
                || "*" in line.toLowerCase(Locale.getDefault())
            ) {
                break
            }

            if ("x " in line.toLowerCase(Locale.getDefault())) {
                val trimmedLine = line.drop(line.toLowerCase(Locale.getDefault()).indexOf("x ") + 2)
                if (trimmedLine.isEmpty()) {
                    continue
                }
                val words = trimmedLine.split(' ')
                if (words.isNotEmpty()) {
                    if (words[0].toDoubleOrNull() != null) {
                        val nr = words[0].toDouble()
                        if (pret_crt == produs_crt) {
                            products.add(Pair(nr, ""))
                            produs_crt += 1
                            pret_crt += 1
                        } else {
                            products[pret_crt] = Pair(nr, products[pret_crt].second)
                            pret_crt += 1
                        }
                        started = true
                    }
                }
            } else if (started
                && !line[0].isDigit()
                && "discount" !in line.toLowerCase(Locale.getDefault())
                && "total" !in line.toLowerCase(Locale.getDefault())
                && "lei" != line.toLowerCase(Locale.getDefault())
                && "lel" != line.toLowerCase(Locale.getDefault())
            ) {  // the text recognizer might confuse i for l

                if (nume_crt == produs_crt) {
                    products.add(Pair(0.toDouble(), line))
                    produs_crt += 1
                    nume_crt += 1
                } else {
                    products[nume_crt] = Pair(products[nume_crt].first, line)
                    nume_crt += 1
                }
            }
        }
        return products
    }
    

   // Adding the items to the list when the add button is pressed
  add.setOnClickListener {
           addRow()
       }

  // Adding a new row to the CheckList
  fun addRow() {
      // Create product with name and prace
      val name = editText.text.toString()
      val price = et_price.text.toString().toDouble()
      val p = Product(name, price)

      // Add product to the list of Products
      itemList.add(p)

      // Notify the attached observers that the underlying data has been changed and
      // the listView should refresh itself
      (listView.adapter as ProductAdapter).notifyDataSetChanged()

      // After adding the item, the edit texts for name and for price will be cleared
      editText.text.clear()
      et_price.text.clear()
  }

    // Delete the all rows form the listView
    clear.setOnClickListener {
            clearRows()
        }

   // Delete the all rows form the listView
   fun clearRows() {
       itemList.clear()

       // Notify the attached observers that the underlying data has been changed and
       // the listView should refresh itself
       (listView.adapter as ProductAdapter).notifyDataSetChanged()
   }

    // Selecting and Deleting the items from the list when the delete button is pressed    
    delete.setOnClickListener {
         deleteRow()
        }

    // Delete the selected rows form the listView
    fun deleteRow() {
        val position: SparseBooleanArray =
            listView.checkedItemPositions // Map with indices of the items from listView
        // and true/false if the item is checked/ is not checked
        val count = listView.count // size of the listView
        var item = count - 1 // index for the list

        // Removing the selected items
        while (item >= 0) {
            if (position.get(item)) {
                itemList.removeAt(item)
            }
            item--
        }
        position.clear()

        // Notify the attached observers that the underlying data has been changed and
        // the listView should refresh itself
        (listView.adapter as ProductAdapter).notifyDataSetChanged()
    }

       // Calculate how much has the person to pay
       calculate.setOnClickListener {
           var sum = calculatePriceToPay()
           // Show a text with the sum
           android.widget.Toast.makeText(
               this,
               "You have to pay $sum",
               android.widget.Toast.LENGTH_SHORT
           ).show()
       }

    // Calculate how much the user has to pay
    fun calculatePriceToPay(): Double {
        val position: SparseBooleanArray =
            listView.checkedItemPositions // Map with indices of the items from listView
        // and true/false if the item is checked/ is not checked
        val count = listView.count // Size of the listView

        var pricesOfProducts: ArrayList<Double> = ArrayList<Double>()

        // Select the products that are checked
        var item = count - 1
        while (item >= 0) {
            if (position.get(item)) {
                pricesOfProducts.add(itemList[item].price)
            }
            item--
        }

        // Calculate the sum of the selected products
        return sumAux(pricesOfProducts)
    }

@Test
    fun user_add_product_correct() {
        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText("mere"))
        onView(withId(R.id.et_price)).perform(typeText("4.5"))

        var sizeBeforeAdd =
            rule.activity.getItemListSize() // Size of the Checklist before inserting a new element

        // Click on add button
        onView(withId(R.id.add)).perform(click())

        var sizeAfterAdd =
            rule.activity.getItemListSize() // Size of the Checklist after inserting a new element

        // Check if the product was added, the size after add should be equal with the initial size + one
        Assert.assertEquals(
            "The product was not insert in the CheckList",
            (sizeBeforeAdd + 1).toDouble(), sizeAfterAdd.toDouble(), 0.0
        )
    }

@Test
    fun user_add_product_wrong() {
        // Product name and price
        var nameProduct = "mere"
        var priceProduct = "ciocolata"

        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText(nameProduct))
        onView(withId(R.id.et_price)).perform(typeText(priceProduct))

        var ok: Boolean = true // Check whether the input was correct or not
        if (priceProduct.toDoubleOrNull() == null) // if price is not double
            ok = false

        if (priceProduct == "" || nameProduct == "") // if price or name is not written
            ok = false

        // Check if the product was added, the size after add should be equal with the initial size + one
        Assert.assertTrue("The product was not insert in the CheckList", ok)
    }

@Test
    fun user_add_and_delete_product_correct() {
        // Add 2 products to the CheckList
        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText("mere"))
        onView(withId(R.id.et_price)).perform(typeText("4.5"))
        // Click on add button
        onView(withId(R.id.add)).perform(click())
        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText("pere"))
        onView(withId(R.id.et_price)).perform(typeText("5.0"))
        // Click on add button
        onView(withId(R.id.add)).perform(click())

        var sizeBeforeDelete =
            rule.activity.getItemListSize() // Size of the Checklist before deleting an element

        // Select "mere" from list
        onView(withText("mere")).perform(click())

        // Delete selected products from CheckList
        onView(withId(R.id.delete)).perform(click())

        var sizeAfterDelete =
            rule.activity.getItemListSize() // Size of the Checklist after deleting an element

        // Check if the product was added, the size after add should be equal with the initial size + one
        Assert.assertEquals(
            "The product was not deleted from the CheckList",
            (sizeBeforeDelete - 1).toDouble(), sizeAfterDelete.toDouble(), 0.0
        )
    }

@Test
    fun user_add_and_clear_product_correct() {
        // Add 2 products to the CheckList
        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText("mere"))
        onView(withId(R.id.et_price)).perform(typeText("4.5"))
        // Click on add button
        onView(withId(R.id.add)).perform(click())
        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText("pere"))
        onView(withId(R.id.et_price)).perform(typeText("5.0"))
        // Click on add button
        onView(withId(R.id.add)).perform(click())

        // Click on clear button
        onView(withId(R.id.clear)).perform(click())

        var sizeAfterClear =
            rule.activity.getItemListSize() // Size of the Checklist after deleting an element

        // Check if the product was added, the size after add should be equal with the initial size + one
        Assert.assertEquals(
            "The product was not deleted from the CheckList",
            0.0, sizeAfterClear.toDouble(), 0.0
        )
    }

@Test
    fun user_calculate_correct() {
        // Add 2 products to the CheckList
        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText("mere"))
        onView(withId(R.id.et_price)).perform(typeText("4.5"))
        // Click on add button
        onView(withId(R.id.add)).perform(click())
        // Write product information in typeTexts
        onView(withId(R.id.editText)).perform(typeText("pere"))
        onView(withId(R.id.et_price)).perform(typeText("5.0"))
        // Click on add button
        onView(withId(R.id.add)).perform(click())

        // Select "mere" from list
        onView(withText("mere")).perform(click())
        // Select "pere" from list
        onView(withText("pere")).perform(click())

        var correctSum: Double = 4.5 + 5.0

        // How much has the user to pay for selected items
        var sum = rule.activity.calculatePriceToPay()

        // Check if the product was added, the size after add should be equal with the initial size + one
        Assert.assertEquals(
            "The sum is wrong",
            correctSum, sum, 0.0
        )
    }