refactor: split PersonalizationService into enum with CohereService

- Refactor PersonalizationService as enum with Cohere and Uninitialized variants
- Create dedicated CohereService struct with rerank_search_results method
- Split constructor into cohere() and uninitialized() methods
- Move all Cohere logic into CohereService for better separation of concerns
- Update tests and lib.rs to use new API
- Improve code organization and maintainability

crates/meilisearch/src/lib.rs

@@ -624,9 +624,11 @@ pub fn configure_data(
     analytics: Data<Analytics>,
 ) {
     // Create personalization service with API key from options
-    let personalization_service = personalization::PersonalizationService::new(
-        index_scheduler.experimental_personalization_api_key().cloned(),
-    );
+    let personalization_service = index_scheduler
+        .experimental_personalization_api_key()
+        .cloned()
+        .map(personalization::PersonalizationService::cohere)
+        .unwrap_or_else(personalization::PersonalizationService::uninitialized);
     let http_payload_size_limit = opt.http_payload_size_limit.as_u64() as usize;
     config
         .app_data(index_scheduler)

crates/meilisearch/src/personalization/mod.rs

@@ -6,21 +6,14 @@ use cohere_rust::{
 use meilisearch_types::error::ResponseError;
 use tracing::{debug, error, info};
 
-pub struct PersonalizationService {
-    cohere: Option<Cohere>,
+pub struct CohereService {
+    cohere: Cohere,
 }
 
-impl PersonalizationService {
-    pub fn new(api_key: Option<String>) -> Self {
-        let cohere = api_key.map(|key| Cohere::new("https://api.cohere.ai", key));
-
-        if cohere.is_some() {
-            info!("Personalization service initialized with Cohere API");
-        } else {
-            debug!("Personalization service initialized without Cohere API key");
-        }
-
-        Self { cohere }
+impl CohereService {
+    pub fn new(api_key: String) -> Self {
+        info!("Personalization service initialized with Cohere API");
+        Self { cohere: Cohere::new("https://api.cohere.ai", api_key) }
     }
 
     pub async fn rerank_search_results(
@@ -29,9 +22,6 @@ impl PersonalizationService {
         personalize: Option<&Personalize>,
         query: Option<&str>,
     ) -> Result<SearchResult, ResponseError> {
-        // If no API key, return original results
-        let Some(cohere) = &self.cohere else { return Ok(search_result) };
-
         // Extract user context from personalization
         let user_context = personalize.and_then(|p| p.user_context.as_deref());
 
@@ -67,7 +57,7 @@ impl PersonalizationService {
         };
 
         // Call Cohere's rerank API
-        match cohere.rerank(&rerank_request).await {
+        match self.cohere.rerank(&rerank_request).await {
             Ok(rerank_response) => {
                 debug!("Cohere rerank successful, reordering {} results", search_result.hits.len());
 
@@ -94,6 +84,36 @@ impl PersonalizationService {
     }
 }
 
+pub enum PersonalizationService {
+    Cohere(CohereService),
+    Uninitialized,
+}
+
+impl PersonalizationService {
+    pub fn cohere(api_key: String) -> Self {
+        Self::Cohere(CohereService::new(api_key))
+    }
+
+    pub fn uninitialized() -> Self {
+        debug!("Personalization service uninitialized");
+        Self::Uninitialized
+    }
+
+    pub async fn rerank_search_results(
+        &self,
+        search_result: SearchResult,
+        personalize: Option<&Personalize>,
+        query: Option<&str>,
+    ) -> Result<SearchResult, ResponseError> {
+        match self {
+            Self::Cohere(cohere_service) => {
+                cohere_service.rerank_search_results(search_result, personalize, query).await
+            }
+            Self::Uninitialized => Ok(search_result),
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -101,7 +121,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_personalization_service_without_api_key() {
-        let service = PersonalizationService::new(None);
+        let service = PersonalizationService::uninitialized();
         let personalize = Personalize { user_context: Some("test user".to_string()) };
 
         let search_result = SearchResult {
@@ -134,7 +154,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_personalization_service_with_user_context_only() {
-        let service = PersonalizationService::new(Some("fake_key".to_string()));
+        let service = PersonalizationService::cohere("fake_key".to_string());
         let personalize = Personalize { user_context: Some("test user".to_string()) };
 
         let search_result = SearchResult {
@@ -166,7 +186,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_personalization_service_with_query_only() {
-        let service = PersonalizationService::new(Some("fake_key".to_string()));
+        let service = PersonalizationService::cohere("fake_key".to_string());
 
         let search_result = SearchResult {
             hits: vec![SearchHit {
@@ -196,7 +216,7 @@ mod tests {
 
     #[tokio::test]
     async fn test_personalization_service_both_none() {
-        let service = PersonalizationService::new(Some("fake_key".to_string()));
+        let service = PersonalizationService::cohere("fake_key".to_string());
 
         let search_result = SearchResult {
             hits: vec![SearchHit {