Add domain validation in source settings

app/src/main/java/org/koitharu/kotatsu/settings/DomainValidator.kt

@@ -0,0 +1,20 @@
+package org.koitharu.kotatsu.settings
+
+import okhttp3.internal.toCanonicalHost
+import org.koitharu.kotatsu.R
+import org.koitharu.kotatsu.utils.EditTextValidator
+
+class DomainValidator : EditTextValidator() {
+
+	override fun validate(text: String): ValidationResult {
+		if (text.isBlank()) {
+			return ValidationResult.Success
+		}
+		val host = text.trim().toCanonicalHost()
+		return if (host == null) {
+			ValidationResult.Failed(context.getString(R.string.invalid_domain_message))
+		} else {
+			ValidationResult.Success
+		}
+	}
+}

app/src/main/java/org/koitharu/kotatsu/settings/SourceSettingsExt.kt

@@ -28,6 +28,7 @@ fun PreferenceFragmentCompat.addPreferencesFromRepository(repository: RemoteMang
 						EditTextBindListener(
 							inputType = EditorInfo.TYPE_CLASS_TEXT or EditorInfo.TYPE_TEXT_VARIATION_URI,
 							hint = key.defaultValue,
+							validator = DomainValidator(),
 						)
 					)
 					setTitle(R.string.domain)

app/src/main/java/org/koitharu/kotatsu/settings/utils/EditTextBindListener.kt

@@ -2,14 +2,17 @@ package org.koitharu.kotatsu.settings.utils
 
 import android.widget.EditText
 import androidx.preference.EditTextPreference
+import org.koitharu.kotatsu.utils.EditTextValidator
 
 class EditTextBindListener(
 	private val inputType: Int,
-	private val hint: String
+	private val hint: String,
+	private val validator: EditTextValidator?,
 ) : EditTextPreference.OnBindEditTextListener {
 
 	override fun onBindEditText(editText: EditText) {
 		editText.inputType = inputType
 		editText.hint = hint
+		validator?.attachToEditText(editText)
 	}
 }

app/src/main/java/org/koitharu/kotatsu/utils/EditTextValidator.kt

@@ -0,0 +1,54 @@
+package org.koitharu.kotatsu.utils
+
+import android.content.Context
+import android.text.Editable
+import android.text.TextWatcher
+import android.widget.EditText
+import androidx.annotation.CallSuper
+import org.koitharu.kotatsu.utils.ext.getDisplayMessage
+import java.lang.ref.WeakReference
+
+abstract class EditTextValidator : TextWatcher {
+
+	private var editTextRef: WeakReference<EditText>? = null
+
+	protected val context: Context
+		get() = checkNotNull(editTextRef?.get()?.context) {
+			"EditTextValidator is not attached to EditText"
+		}
+
+	override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) = Unit
+
+	override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) = Unit
+
+	@CallSuper
+	override fun afterTextChanged(s: Editable?) {
+		val editText = editTextRef?.get() ?: return
+		val newText = s?.toString().orEmpty()
+		val result = runCatching {
+			validate(newText)
+		}.getOrElse { e ->
+			ValidationResult.Failed(e.getDisplayMessage(editText.resources))
+		}
+		editText.error = when (result) {
+			is ValidationResult.Failed -> result.message
+			ValidationResult.Success -> null
+		}
+	}
+
+	fun attachToEditText(editText: EditText) {
+		editTextRef = WeakReference(editText)
+		editText.removeTextChangedListener(this)
+		editText.addTextChangedListener(this)
+		afterTextChanged(editText.text)
+	}
+
+	abstract fun validate(text: String): ValidationResult
+
+	sealed class ValidationResult {
+
+		object Success : ValidationResult()
+
+		class Failed(val message: CharSequence) : ValidationResult()
+	}
+}

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

@@ -320,4 +320,5 @@
 	<string name="exclude_nsfw_from_history_summary">Manga marked as NSFW will never added to the history and your progress will not be saved</string>
 	<string name="clear_cookies_summary">Can help in case of some issues. All authorizations will be invalidated</string>
 	<string name="show_all">Show all</string>
+	<string name="invalid_domain_message">Invalid domain</string>
 </resources>