feat: add clean errors + completion endpoint

src/providers/ollama.rs

@@ -1,5 +1,7 @@
 use reqwest::Client;
-use serde_json::Value;
+use serde_json::{Value, json};
+
+use crate::errors::OllamaError;
 
 #[derive(Clone)]
 pub struct OllamaProvider {
@@ -15,11 +17,82 @@ impl OllamaProvider {
         }
     }
 
-    pub async fn list_models(&self) -> Result<Value, reqwest::Error> {
+    pub async fn list_models(&self) -> Result<Value, OllamaError> {
         let url = format!("{}/api/tags", self.base_url);
 
         let res = self.client.get(url).send().await?.json::<Value>().await?;
 
         Ok(res)
     }
+
+    pub async fn completions(&self, body: Value) -> Result<Value, OllamaError> {
+        // Validate prompt
+        let prompt = body
+            .get("prompt")
+            .and_then(|v| v.as_str())
+            .filter(|s| !s.trim().is_empty())
+            .ok_or(OllamaError::MissingPrompt)?;
+
+        let model = body
+            .get("model")
+            .and_then(|v| v.as_str())
+            .unwrap_or("llama3");
+
+        // Validate model availability
+        let available = self.list_models().await?; // Http error auto-converts via #[from]
+        let model_exists = available
+            .get("models")
+            .and_then(|m| m.as_array())
+            .map(|arr| {
+                arr.iter()
+                    .any(|m| m.get("name").and_then(|n| n.as_str()) == Some(model))
+            })
+            .unwrap_or(false);
+
+        if !model_exists {
+            return Err(OllamaError::ModelNotFound(model.to_string()));
+        }
+
+        // Build payload (now using validated locals)
+        let ollama_payload = json!({
+            "model":  model,
+            "prompt": prompt,
+            "stream": false,
+            "options": {
+                "temperature": body.get("temperature"),
+                "top_p":       body.get("top_p"),
+                "num_predict": body.get("max_tokens"),
+            }
+        });
+
+        let url = format!("{}/api/generate", self.base_url);
+        let res = self
+            .client
+            .post(&url)
+            .json(&ollama_payload)
+            .send()
+            .await?
+            .json::<Value>()
+            .await?;
+
+        Ok(json!({
+            "id":      "cmpl-ollama",
+            "object":  "text_completion",
+            "model":   res.get("model"),
+            "choices": [{
+                "text":          res.get("response"),
+                "index":         0,
+                "finish_reason": if res.get("done").and_then(|v| v.as_bool()).unwrap_or(false) {
+                    "stop"
+                } else {
+                    "length"
+                },
+            }],
+            "usage": {
+                "prompt_tokens":     res.get("prompt_eval_count"),
+                "completion_tokens": res.get("eval_count"),
+                "total_tokens":      null,
+            }
+        }))
+    }
 }