feat: replaced ollama with litellm (#18)

Co-authored-by: Sharang Parnerkar <parnerkarsharang@gmail.com>
Reviewed-on: https://gitea.meghsakha.com/sharang/certifai/pulls/18

src/infrastructure/provider_client.rs

@@ -1,6 +1,6 @@
 //! Unified LLM provider dispatch.
 //!
-//! Routes chat completion requests to Ollama, OpenAI, Anthropic, or
+//! Routes chat completion requests to LiteLLM, OpenAI, Anthropic, or
 //! HuggingFace based on the session's provider setting. All providers
 //! except Anthropic use the OpenAI-compatible chat completions format.
 
@@ -20,11 +20,11 @@ pub struct ProviderMessage {
 ///
 /// # Arguments
 ///
-/// * `state` - Server state (for default Ollama URL/model)
-/// * `provider` - Provider name (`"ollama"`, `"openai"`, `"anthropic"`, `"huggingface"`)
+/// * `state` - Server state (for default LiteLLM URL/model)
+/// * `provider` - Provider name (`"litellm"`, `"openai"`, `"anthropic"`, `"huggingface"`)
 /// * `model` - Model ID
 /// * `messages` - Conversation history
-/// * `api_key` - API key (required for non-Ollama providers)
+/// * `api_key` - API key (required for non-LiteLLM providers; LiteLLM uses server config)
 /// * `stream` - Whether to request streaming
 ///
 /// # Returns
@@ -123,11 +123,11 @@ pub async fn send_chat_request(
                 .send()
                 .await
         }
-        // Default: Ollama (OpenAI-compatible endpoint)
+        // Default: LiteLLM proxy (OpenAI-compatible endpoint)
         _ => {
-            let base_url = &state.services.ollama_url;
+            let base_url = &state.services.litellm_url;
             let resolved_model = if model.is_empty() {
-                &state.services.ollama_model
+                &state.services.litellm_model
             } else {
                 model
             };
@@ -137,12 +137,15 @@ pub async fn send_chat_request(
                 "messages": messages,
                 "stream": stream,
             });
-            client
+            let litellm_key = &state.services.litellm_api_key;
+            let mut request = client
                 .post(&url)
                 .header("content-type", "application/json")
-                .json(&body)
-                .send()
-                .await
+                .json(&body);
+            if !litellm_key.is_empty() {
+                request = request.header("Authorization", format!("Bearer {litellm_key}"));
+            }
+            request.send().await
         }
     }
 }