Enable confirmButton only when needed to respond to user input (#8848)

* Enable `confirmButton` when appropriate

* Show error in dialog instead

* Follow M3 guidelines

app/src/main/java/eu/kanade/presentation/more/settings/screen/SettingsAdvancedScreen.kt

@@ -275,10 +275,6 @@ object SettingsAdvancedScreen : SearchableSettings {
                     pref = userAgentPref,
                     title = stringResource(R.string.pref_user_agent_string),
                     onValueChanged = {
-                        if (it.isBlank()) {
-                            context.toast(R.string.error_user_agent_string_blank)
-                            return@EditTextPreference false
-                        }
                         try {
                             // OkHttp checks for valid values internally
                             Headers.Builder().add("User-Agent", it)

app/src/main/java/eu/kanade/presentation/more/settings/screen/SettingsLibraryScreen.kt

@@ -315,7 +315,10 @@ object SettingsLibraryScreen : SearchableSettings {
                 }
             },
             confirmButton = {
-                TextButton(onClick = { onValueChanged(portraitValue, landscapeValue) }) {
+                TextButton(
+                    enabled = portraitValue != initialPortrait || landscapeValue != initialLandscape,
+                    onClick = { onValueChanged(portraitValue, landscapeValue) },
+                ) {
                     Text(text = stringResource(android.R.string.ok))
                 }
             },

app/src/main/java/eu/kanade/presentation/more/settings/screen/SettingsTrackingScreen.kt

@@ -222,7 +222,7 @@ object SettingsTrackingScreen : SearchableSettings {
                         label = { Text(text = stringResource(uNameStringRes)) },
                         keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
                         singleLine = true,
-                        isError = inputError && username.text.isEmpty(),
+                        isError = inputError && !processing,
                     )
 
                     var hidePassword by remember { mutableStateOf(true) }
@@ -253,21 +253,16 @@ object SettingsTrackingScreen : SearchableSettings {
                             imeAction = ImeAction.Done,
                         ),
                         singleLine = true,
-                        isError = inputError && password.text.isEmpty(),
+                        isError = inputError && !processing,
                     )
                 }
             },
             confirmButton = {
                 Button(
                     modifier = Modifier.fillMaxWidth(),
-                    enabled = !processing,
+                    enabled = !processing && username.text.isNotBlank() && password.text.isNotBlank(),
                     onClick = {
-                        if (username.text.isEmpty() || password.text.isEmpty()) {
-                            inputError = true
-                            return@Button
-                        }
                         scope.launchIO {
-                            inputError = false
                             processing = true
                             val result = checkLogin(
                                 context = context,
@@ -275,6 +270,7 @@ object SettingsTrackingScreen : SearchableSettings {
                                 username = username.text,
                                 password = password.text,
                             )
+                            inputError = !result
                             if (result) onDismissRequest()
                             processing = false
                         }

app/src/main/java/eu/kanade/presentation/more/settings/widget/EditTextPreferenceWidget.kt

@@ -1,7 +1,12 @@
 package eu.kanade.presentation.more.settings.widget
 
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Cancel
+import androidx.compose.material.icons.filled.Error
 import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
 import androidx.compose.material3.OutlinedTextField
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
@@ -50,6 +55,16 @@ fun EditTextPreferenceWidget(
                 OutlinedTextField(
                     value = textFieldValue,
                     onValueChange = { textFieldValue = it },
+                    trailingIcon = {
+                        if (textFieldValue.text.isBlank()) {
+                            Icon(imageVector = Icons.Filled.Error, contentDescription = null)
+                        } else {
+                            IconButton(onClick = { textFieldValue = TextFieldValue("") }) {
+                                Icon(imageVector = Icons.Filled.Cancel, contentDescription = null)
+                            }
+                        }
+                    },
+                    isError = textFieldValue.text.isBlank(),
                     singleLine = true,
                     modifier = Modifier.fillMaxWidth(),
                 )
@@ -59,6 +74,7 @@ fun EditTextPreferenceWidget(
             ),
             confirmButton = {
                 TextButton(
+                    enabled = textFieldValue.text != value && textFieldValue.text.isNotBlank(),
                     onClick = {
                         scope.launch {
                             if (onConfirm(textFieldValue.text)) {