Show dedicated UI with instruction when NFC is lost

app/src/main/java/pl/lebihan/authnkey/CredentialBottomSheet.kt

@@ -3,6 +3,7 @@ package pl.lebihan.authnkey
 import android.animation.ObjectAnimator
 import android.content.Context
 import android.content.DialogInterface
+import android.content.res.ColorStateList
 import android.os.Bundle
 import android.text.InputType
 import android.view.LayoutInflater
@@ -14,6 +15,7 @@ import android.view.inputmethod.InputMethodManager
 import android.widget.ImageView
 import android.widget.ProgressBar
 import android.widget.TextView
+import androidx.core.content.ContextCompat
 import androidx.core.content.edit
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
@@ -33,6 +35,7 @@ class CredentialBottomSheet : BottomSheetDialogFragment() {
         PIN,
         ACCOUNT_SELECT,
         SUCCESS,
+        TAG_LOST,
         ERROR
     }
 
@@ -221,20 +224,28 @@ class CredentialBottomSheet : BottomSheetDialogFragment() {
             State.PIN -> R.drawable.lock_24
             State.ACCOUNT_SELECT -> R.drawable.account_circle_24
             State.SUCCESS -> R.drawable.check_circle_24
+            State.TAG_LOST -> R.drawable.sensors_24
             State.ERROR -> R.drawable.error_24
         }
 
         iconStatus.setImageResource(iconRes)
+        iconBackground.backgroundTintList = null
 
         when (state) {
             State.WAITING, State.TOUCH -> startPulse()
+            State.TAG_LOST -> {
+                iconBackground.backgroundTintList = ColorStateList.valueOf(
+                    ContextCompat.getColor(requireContext(), R.color.warning_container)
+                )
+                startPulse(750)
+            }
             else -> {}
         }
     }
 
-    private fun startPulse() {
+    private fun startPulse(durationMs: Long = 1000) {
         pulseAnimator = ObjectAnimator.ofFloat(iconBackground, View.ALPHA, 1f, 0.3f).apply {
-            duration = 1000
+            duration = durationMs
             repeatCount = ObjectAnimator.INFINITE
             repeatMode = ObjectAnimator.REVERSE
             interpolator = AccelerateDecelerateInterpolator()

app/src/main/java/pl/lebihan/authnkey/CredentialProviderActivity.kt

@@ -387,9 +387,14 @@ class CredentialProviderActivity : AppCompatActivity() {
 
             } catch (e: Exception) {
                 Log.e(TAG, "NFC error", e)
-                setInstruction(getString(R.string.error_retry_format, e.toUserMessage(this@CredentialProviderActivity)))
-                setState(CredentialBottomSheet.State.ERROR)
                 showProgress(false)
+                if (e is android.nfc.TagLostException) {
+                    setInstruction(getString(R.string.instruction_tag_lost))
+                    setState(CredentialBottomSheet.State.TAG_LOST)
+                } else {
+                    setInstruction(getString(R.string.error_retry_format, e.toUserMessage(this@CredentialProviderActivity)))
+                    setState(CredentialBottomSheet.State.ERROR)
+                }
             }
         }
     }
@@ -1074,8 +1079,13 @@ class CredentialProviderActivity : AppCompatActivity() {
     private fun handleError(e: Exception) {
         runOnUiThread {
             showProgress(false)
-            setInstruction(getString(R.string.error_format, e.toUserMessage(this)))
-            setState(CredentialBottomSheet.State.ERROR)
+            if (e is android.nfc.TagLostException) {
+                setInstruction(getString(R.string.instruction_tag_lost))
+                setState(CredentialBottomSheet.State.TAG_LOST)
+            } else {
+                setInstruction(getString(R.string.error_format, e.toUserMessage(this)))
+                setState(CredentialBottomSheet.State.ERROR)
+            }
         }
     }
 

app/src/main/res/values-night/colors.xml

@@ -7,4 +7,7 @@
     <!-- Provider status - not enabled (dark theme) -->
     <color name="provider_not_enabled_background">#BF360C</color>
     <color name="provider_not_enabled_text">#FFCC80</color>
+    
+    <!-- Tag lost warning state -->
+    <color name="warning_container">#7C2D12</color>
 </resources>

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

@@ -7,4 +7,7 @@
     <!-- Provider status - not enabled (light theme) -->
     <color name="provider_not_enabled_background">#FFF3E0</color>
     <color name="provider_not_enabled_text">#E65100</color>
+    
+    <!-- Tag lost warning state -->
+    <color name="warning_container">#FED7AA</color>
 </resources>

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

@@ -27,6 +27,7 @@
     <string name="instruction_initializing">Initializing…</string>
     <string name="instruction_verifying">Verifying…</string>
     <string name="instruction_verifying_pin">Verifying PIN…</string>
+    <string name="instruction_tag_lost">Lost contact with the security key\n\nReposition and hold until completion</string>
 
     <!-- PIN Dialog -->
     <string name="pin_dialog_title">Security Key PIN</string>