Implemented catching Flickercode decoding errors and displaying them in UI

fints4javaAndroidApp/src/main/java/net/dankito/banking/fints4java/android/ui/dialogs/EnterTanDialog.kt

@@ -26,7 +26,6 @@ import net.dankito.banking.ui.model.TanMediumStatus
 import net.dankito.fints.messages.datenelemente.implementierte.tan.TanGeneratorTanMedium
 import net.dankito.fints.model.*
 import net.dankito.fints.response.client.FinTsClientResponse
-import net.dankito.fints.tan.TanImage
 
 
 open class EnterTanDialog : DialogFragment() {
@@ -136,7 +135,14 @@ open class EnterTanDialog : DialogFragment() {
             if (tanChallenge is FlickercodeTanChallenge) {
                 val flickerCodeView = rootView.flickerCodeView
                 flickerCodeView.visibility = View.VISIBLE
-                flickerCodeView.setCode((tanChallenge as FlickercodeTanChallenge).flickercode)
+
+                val flickercode = (tanChallenge as FlickercodeTanChallenge).flickercode
+                if (flickercode.decodingSuccessful) {
+                    flickerCodeView.setCode(flickercode)
+                }
+                else {
+                    showDecodingTanChallengeFailedErrorDelayed(flickercode.error)
+                }
             }
             else if (tanChallenge is ImageTanChallenge) {
                 rootView.tanImageView.visibility = View.VISIBLE
@@ -147,7 +153,7 @@ open class EnterTanDialog : DialogFragment() {
                     rootView.imgTanImageView.setImageBitmap(bitmap)
                 }
                 else {
-                    showDecodingTanImageFailedErrorDelayed(decodedImage) // this method gets called right on start up before dialog is shown -> Alert would get displayed before dialog and therefore covered by dialog if we don't delay displaying dialog
+                    showDecodingTanChallengeFailedErrorDelayed(decodedImage.error)
                 }
             }
 
@@ -156,16 +162,20 @@ open class EnterTanDialog : DialogFragment() {
     }
 
 
-    protected open fun showDecodingTanImageFailedErrorDelayed(decodedImage: TanImage) {
+    /**
+     * This method gets called right on start up before dialog is shown -> Alert would get displayed before dialog and
+     * therefore covered by dialog -> delay displaying alert.
+     */
+    protected open fun showDecodingTanChallengeFailedErrorDelayed(error: Exception?) {
         val handler = Handler()
 
-        handler.postDelayed({ showDecodingTanImageFailedError(decodedImage) }, 500)
+        handler.postDelayed({ showDecodingTanChallengeFailedError(error) }, 500)
     }
 
-    protected open fun showDecodingTanImageFailedError(decodedImage: TanImage) {
+    protected open fun showDecodingTanChallengeFailedError(error: Exception?) {
         activity?.let { context ->
             AlertDialog.Builder(context)
-                .setMessage(context.getString(R.string.dialog_enter_tan_error_could_not_decode_tan_image, decodedImage.error?.localizedMessage))
+                .setMessage(context.getString(R.string.dialog_enter_tan_error_could_not_decode_tan_image, error?.localizedMessage))
                 .setPositiveButton(android.R.string.ok) { dialog, _ -> dialog.dismiss() }
                 .show()
         }

fints4javaLib/src/main/kotlin/net/dankito/fints/tan/Flickercode.kt

@@ -3,5 +3,20 @@ package net.dankito.fints.tan
 
 open class Flickercode(
     val challengeHHD_UC: String,
-    val parsedDataSet: String
+    val parsedDataSet: String,
-)
+    val error: Exception? = null
+) {
+
+    val decodingSuccessful: Boolean
+        get() = error == null
+
+
+    override fun toString(): String {
+        if (decodingSuccessful == false) {
+            return "Decoding error: $error"
+        }
+
+        return "Parsed $challengeHHD_UC to $parsedDataSet"
+    }
+
+}

fints4javaLib/src/main/kotlin/net/dankito/fints/tan/FlickercodeDecoder.kt

@@ -1,5 +1,6 @@
 package net.dankito.fints.tan
 
+import org.slf4j.LoggerFactory
 import java.util.regex.Pattern
 
 
@@ -7,10 +8,13 @@ open class FlickercodeDecoder {
 
     companion object {
         val ContainsOtherSymbolsThanFiguresPattern: Pattern = Pattern.compile("\\D")
+
+        private val log = LoggerFactory.getLogger(FlickercodeDecoder::class.java)
     }
 
 
     open fun decodeChallenge(challengeHHD_UC: String): Flickercode {
+        try {
             val challengeLength = parseIntToHex(challengeHHD_UC.substring(0, 2))
 
             val startCode = parseStartCode(challengeHHD_UC, 2)
@@ -37,6 +41,11 @@ open class FlickercodeDecoder {
             val parsedDataSet = dataWithoutChecksum + luhnChecksum + xorChecksumString
 
             return Flickercode(challengeHHD_UC, parsedDataSet)
+        } catch (e: Exception) {
+            log.error("Could not decode challenge $challengeHHD_UC")
+
+            return Flickercode(challengeHHD_UC, "", e)
+        }
     }
 
     protected fun parseStartCode(challengeHHD_UC: String, startIndex: Int): FlickercodeDatenelement {

fints4javaLib/src/main/kotlin/net/dankito/fints/tan/TanImage.kt

@@ -12,6 +12,10 @@ open class TanImage(
 
 
     override fun toString(): String {
+        if (decodingSuccessful == false) {
+            return "Decoding error: $error"
+        }
+
         return "$mimeType ${imageBytes.size} bytes"
     }