Fix/recovery password copies linebreak (#909)

* Filtered any control characters or double-spaces from copied recovery password mnemonic

* Fix typo in comment

* Single char comment alignment adjustment

---------

Co-authored-by: alansley <aclansley@gmail.com>

app/src/main/java/org/thoughtcrime/securesms/recoverypassword/RecoveryPasswordViewModel.kt

@@ -27,14 +27,33 @@ class RecoveryPasswordViewModel @Inject constructor(
 ): AndroidViewModel(application) {
     val prefs = AppTextSecurePreferences(application)
 
+    // Regex to remove any spurious characters from our recovery password mnemonic.
+    // The regex matches are:
+    //   - "\r"      - carriage return,
+    //   - "\n"      - newline,
+    //   - "\u2028"  - unicode line separator,
+    //   - "\u2029"  - unicode paragraph separator,
+    //   - "|\s{2,}" - two or more consecutive spaces.
+    val linebreakRemovalRegex = Regex("""[\r\n\u2028\u2029]+|\s{2,}""")
+
     val seed = MutableStateFlow<String?>(null)
     val mnemonic = seed.filterNotNull()
-        .map { MnemonicCodec { MnemonicUtilities.loadFileContents(application, it) }.encode(it, MnemonicCodec.Language.Configuration.english) }
+        .map {
+            MnemonicCodec {
+                MnemonicUtilities.loadFileContents(application, it)
+            }
+            .encode(it, MnemonicCodec.Language.Configuration.english)
+            .trim() // Remove any leading or trailing whitespace
+        }
         .stateIn(viewModelScope, SharingStarted.Eagerly, "")
 
     fun copyMnemonic() {
         prefs.setHasViewedSeed(true)
-        ClipData.newPlainText("Seed", mnemonic.value)
+
+        // Ensure that our mnemonic words are separated by single spaces only without any control characters
+        val normalisedMnemonic = mnemonic.value.replace(linebreakRemovalRegex, " ")
+
+        ClipData.newPlainText("Seed", normalisedMnemonic)
             .let(application.clipboard::setPrimaryClip)
     }