feat(settings): split pasted dictionary URLs into separate fields

Pasting several URLs separated by spaces, newlines or commas into one
field now distributes them across separate fields when every token is a
valid source template. Previously the joined text passed validation as a
single URL and failed at download time.

app/src/main/java/com/example/research/ui/settings/components/DictionaryUrlInputContent.kt

@@ -66,6 +66,15 @@ private fun validateDictionaryUrl(context: UrlValidationContext): String? {
     }
 }
 
+private val urlSplitRegex = Regex("[\\s,;]+")
+
+private fun splitPastedUrls(text: String): List<String>? =
+    text.split(urlSplitRegex).filter { it.isNotEmpty() }.takeIf { tokens ->
+        tokens.size > 1 && tokens.all {
+            DictionarySource.validateTemplate(it) is DictionarySource.ValidationResult.Valid
+        }
+    }
+
 private val urlInputTransformation = InputTransformation {
     val text = toString()
     val filtered = text
@@ -92,6 +101,17 @@ fun DictionaryUrlInputContent(
     val scrollState = rememberScrollState()
     val focusManager = LocalFocusManager.current
 
+    LaunchedEffect(Unit) {
+        snapshotFlow { urls.map { it.text.toString() } }.collect { texts ->
+            val (index, tokens) = texts.withIndex().firstNotNullOfOrNull { (i, text) ->
+                splitPastedUrls(text)?.let { i to it }
+            } ?: return@collect
+            urls[index].edit { replace(0, length, tokens.first()) }
+            urls.addAll(index + 1, tokens.subList(1, tokens.size).map { TextFieldState(it) })
+            validationErrors.clear()
+        }
+    }
+
     val errorMessages = ErrorMessages(
         empty = stringResource(R.string.dictionary_source_url_empty),
         duplicateInForm = stringResource(R.string.dictionary_source_duplicate_in_form),