[Multiple-Profile]feat:profile name validation

AnkiDroid/src/main/java/com/ichi2/anki/multiprofile/ProfileManager.kt

@@ -76,7 +76,7 @@ class ProfileManager private constructor(
         val defaultId = ProfileId.DEFAULT
 
         val metadata =
-            ProfileMetadata(displayName = DEFAULT_PROFILE_DISPLAY_NAME)
+            ProfileMetadata(displayName = ProfileName.fromTrustedSource(DEFAULT_PROFILE_DISPLAY_NAME))
 
         profileRegistry.saveProfile(id = defaultId, metadata = metadata, isActive = true)
         profileRegistry.setLastActiveProfileId(defaultId)
@@ -96,14 +96,14 @@ class ProfileManager private constructor(
      *
      * @throws Exception if profile creation or persistence fails.
      */
-    fun createNewProfile(displayName: String): ProfileId {
+    fun createNewProfile(displayName: ProfileName): ProfileId {
         val newProfileId = generateUniqueProfileId()
 
         val metadata = ProfileMetadata(displayName = displayName)
 
         profileRegistry.saveProfile(newProfileId, metadata)
 
-        Timber.i("Created new profile: $displayName (${newProfileId.value})")
+        Timber.i("Created new profile: ${displayName.value} (${newProfileId.value})")
         return newProfileId
     }
 
@@ -232,19 +232,53 @@ class ProfileManager private constructor(
         return ProfileRestrictedDirectory(directoryFile)
     }
 
+    /**
+     * Renames an existing profile by updating its display name in
+     * the registry.
+     *
+     * All other metadata fields (version, creation timestamp) are
+     * preserved. The change is persisted immediately.
+     *
+     * @param profileId      The [ProfileId] of the profile to rename.
+     * @param newDisplayName  The new user-facing name.
+     *
+     * @throws IllegalArgumentException if [profileId] does not
+     *   exist in the registry.
+     */
+    fun renameProfile(
+        profileId: ProfileId,
+        newDisplayName: ProfileName,
+    ) {
+        Timber.d("ProfileManager::renameProfile called for $profileId")
+
+        val existing =
+            profileRegistry.getProfileMetadata(profileId)
+                ?: throw IllegalArgumentException("Profile $profileId not found")
+
+        if (existing.displayName == newDisplayName) {
+            Timber.d("Rename skipped: New name matches existing name for $profileId")
+            return
+        }
+
+        val updated = existing.copy(displayName = newDisplayName)
+        profileRegistry.saveProfile(profileId, updated)
+
+        Timber.d("Renamed profile $profileId to '$newDisplayName'")
+    }
+
     /**
      * Holds the meta-data for a profile.
      * Converted to JSON for storage to allow future extensibility (e.g. avatars, themes).
      */
     data class ProfileMetadata(
-        val displayName: String,
+        val displayName: ProfileName,
         val version: Int = 1,
         val createdTimestamp: String = getTimestamp(TimeManager.time),
     ) {
         fun toJson(): String =
             JSONObject()
                 .apply {
-                    put("displayName", displayName)
+                    put("displayName", displayName.value)
                     put("version", version)
                     put("created", createdTimestamp)
                 }.toString()
@@ -253,7 +287,7 @@ class ProfileManager private constructor(
             fun fromJson(jsonString: String): ProfileMetadata {
                 val json = JSONObject(jsonString)
                 return ProfileMetadata(
-                    displayName = json.optString("displayName", "Unknown"),
+                    displayName = ProfileName.fromTrustedSource(json.optString("displayName", "Unknown")),
                     version = json.optInt("version", 1),
                     createdTimestamp = json.optString("created", ""),
                 )

AnkiDroid/src/main/java/com/ichi2/anki/multiprofile/ProfileName.kt

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2026 Ashish Yadav <mailtoashish693@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3 of the License, or (at your option) any later
+ * version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.ichi2.anki.multiprofile
+
+/**
+ * A validated, user-facing profile display name.
+ *
+ * Values can only be obtained through [validate] (for user input) or
+ * [fromTrustedSource] (for persisted / hard-coded values). This makes invalid
+ * profile names unrepresentable in the domain layer.
+ */
+@JvmInline
+value class ProfileName private constructor(
+    val value: String,
+) {
+    override fun toString(): String = value
+
+    companion object {
+        const val MAX_LENGTH = 50
+
+        /**
+         * Validates raw user input. Trims leading and trailing whitespace
+         * before checking the rules; interior whitespace (including multiple
+         * spaces between words) is preserved as-is.
+         *
+         * Any non-whitespace character is permitted — including punctuation,
+         * emoji, and symbols — matching the desktop Anki behavior. Only
+         * length and emptiness are enforced here; uniqueness is checked at
+         * the registry layer.
+         *
+         * Returns a [ValidationResult] — never throws.
+         */
+        fun validate(raw: String): ValidationResult {
+            val cleaned = raw.trim()
+            return when {
+                cleaned.isEmpty() -> ValidationResult.Empty
+                cleaned.length > MAX_LENGTH ->
+                    ValidationResult.TooLong(cleaned.length)
+                else -> ValidationResult.Valid(ProfileName(cleaned))
+            }
+        }
+
+        /**
+         * Constructs a [ProfileName] from a value that has already been
+         * validated elsewhere (persisted metadata, hard-coded defaults).
+         *
+         * DO NOT use this for raw user input — use [validate] instead.
+         */
+        internal fun fromTrustedSource(value: String): ProfileName = ProfileName(value)
+    }
+
+    /** Outcome of validating a candidate profile name. */
+    sealed interface ValidationResult {
+        data class Valid(
+            val name: ProfileName,
+        ) : ValidationResult
+
+        data object Empty : ValidationResult
+
+        data class TooLong(
+            val actualLength: Int,
+        ) : ValidationResult
+    }
+}

AnkiDroid/src/test/java/com/ichi2/anki/multiprofile/ProfileManagerTest.kt

@@ -39,6 +39,7 @@ import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.junit.Before
 import org.junit.Test
+import org.junit.jupiter.api.Assertions.assertThrows
 import org.junit.runner.RunWith
 import org.robolectric.annotation.Config
 import java.io.File
@@ -162,7 +163,7 @@ class ProfileManagerTest {
     fun `ProfileMetadata JSON round-trip preserves all fields`() {
         val original =
             ProfileManager.ProfileMetadata(
-                displayName = "Test User",
+                displayName = ProfileName.fromTrustedSource("Test User"),
                 version = 5,
                 createdTimestamp = "2025-12-31T23:59:59Z",
             )
@@ -177,18 +178,18 @@ class ProfileManagerTest {
     fun `getAllProfiles returns all registered profiles`() {
         val manager = ProfileManager.create(context)
 
-        val profile1 = manager.createNewProfile("Work")
-        val profile2 = manager.createNewProfile("Personal")
+        val profile1 = manager.createNewProfile(ProfileName.fromTrustedSource("Work"))
+        val profile2 = manager.createNewProfile(ProfileName.fromTrustedSource("Personal"))
 
         val allProfiles = manager.getAllProfiles()
 
         assertEquals(3, allProfiles.size)
         assertTrue(allProfiles.containsKey(ProfileId.DEFAULT))
         assertTrue(allProfiles.containsKey(profile1))
         assertTrue(allProfiles.containsKey(profile2))
-        assertEquals("Default", allProfiles[ProfileId.DEFAULT]?.displayName)
-        assertEquals("Work", allProfiles[profile1]?.displayName)
-        assertEquals("Personal", allProfiles[profile2]?.displayName)
+        assertEquals("Default", allProfiles[ProfileId.DEFAULT]?.displayName?.value)
+        assertEquals("Work", allProfiles[profile1]?.displayName?.value)
+        assertEquals("Personal", allProfiles[profile2]?.displayName?.value)
     }
 
     @Test
@@ -200,4 +201,66 @@ class ProfileManagerTest {
         assertEquals(1, allProfiles.size)
         assertTrue(allProfiles.containsKey(ProfileId.DEFAULT))
     }
+
+    @Test
+    fun `renameProfile updates displayName in registry`() {
+        val manager = ProfileManager.create(context)
+        val profileId = manager.createNewProfile(ProfileName.fromTrustedSource("Original Name"))
+        val newName = ProfileName.fromTrustedSource("Updated Name")
+
+        manager.renameProfile(profileId, newName)
+
+        val json = prefs.getString(profileId.value, null)
+        val metadata = ProfileManager.ProfileMetadata.fromJson(json!!)
+
+        assertEquals(newName, metadata.displayName)
+    }
+
+    @Test
+    fun `renameProfile preserves version and createdTimestamp`() {
+        val manager = ProfileManager.create(context)
+        val profileId = manager.createNewProfile(ProfileName.fromTrustedSource("Original Name"))
+
+        val originalJson = prefs.getString(profileId.value, null)
+        val originalMetadata = ProfileManager.ProfileMetadata.fromJson(originalJson!!)
+
+        manager.renameProfile(profileId, ProfileName.fromTrustedSource("New Name"))
+
+        val updatedJson = prefs.getString(profileId.value, null)
+        val updatedMetadata = ProfileManager.ProfileMetadata.fromJson(updatedJson!!)
+
+        assertEquals("Version must be preserved", originalMetadata.version, updatedMetadata.version)
+        assertEquals(
+            "Timestamp must be preserved",
+            originalMetadata.createdTimestamp,
+            updatedMetadata.createdTimestamp,
+        )
+    }
+
+    @Test
+    fun `renameProfile does not write to disk if name is identical`() {
+        val manager = ProfileManager.create(context)
+        val name = ProfileName.fromTrustedSource("No Change")
+        val profileId = manager.createNewProfile(name)
+
+        val originalJson = prefs.getString(profileId.value, null)
+
+        manager.renameProfile(profileId, name)
+
+        val currentJson = prefs.getString(profileId.value, null)
+        assertEquals("No disk write should occur for identical names", originalJson, currentJson)
+    }
+
+    @Test
+    fun `renameProfile throws IllegalArgumentException for missing profile`() {
+        val manager = ProfileManager.create(context)
+        val fakeId = ProfileId("p_ghost")
+
+        val exception =
+            assertThrows(IllegalArgumentException::class.java) {
+                manager.renameProfile(fakeId, ProfileName.fromTrustedSource("New Name"))
+            }
+
+        assertTrue(exception.message!!.contains("not found"))
+    }
 }