add and implement open-router service

Author: Jawher Kallel

gateway/internal/config/config.go

@@ -13,6 +13,7 @@ type Config struct {
     HuggingFaceKey string
     GroqKey        string
     RedisAddr  string
+	OpenRouterKey string
 }
 
 func Load() *Config {
@@ -26,6 +27,7 @@ func Load() *Config {
 		OpenAIKey:      getEnv("OPENAI_API_KEY", ""),
 		HuggingFaceKey: getEnv("HF_API_KEY", ""),
 		GroqKey:       getEnv("GROQ_API_KEY", ""),
+		OpenRouterKey: getEnv("OPENROUTER_API_KEY", ""),
 		RedisAddr:      getEnv("REDIS_ADDR", "localhost:6379"),
 	}
 	if cfg.OpenAIKey == "" {

gateway/internal/handlers/query.go

@@ -46,6 +46,8 @@ func QueryHandler(cfg *config.Config, cache *cache.Cache) gin.HandlerFunc {
             response, err = services.QueryHuggingFace(cfg.HuggingFaceKey, req.Prompt)
         case "groq":
             response, err = services.QueryGroq(cfg.GroqKey, req.Prompt)
+        case "openrouter":
+            response, err = services.QueryOpenRouter(cfg.OpenRouterKey, req.Prompt)
         default:
             c.JSON(http.StatusBadRequest, gin.H{"error": "Unsupported provider"})
             return

gateway/internal/services/openrouter.go

@@ -0,0 +1,67 @@
+package services
+
+import (
+    "bytes"
+    "encoding/json"
+    "fmt"
+    "io"
+    "net/http"
+)
+
+type OpenRouterRequest struct {
+    Model    string              `json:"model"`
+    Messages []map[string]string `json:"messages"`
+}
+
+type OpenRouterResponse struct {
+    Choices []struct {
+        Message struct {
+            Content string `json:"content"`
+        } `json:"message"`
+    } `json:"choices"`
+    Error struct {
+        Message string `json:"message"`
+    } `json:"error"`
+}
+
+func QueryOpenRouter(apiKey, prompt string) (string, error) {
+    reqBody := OpenRouterRequest{
+        Model: "openai/gpt-4o-mini",
+        Messages: []map[string]string{
+            {"role": "system", "content": "You are a helpful assistant."},
+            {"role": "user", "content": prompt},
+        },
+    }
+    jsonData, _ := json.Marshal(reqBody)
+
+    req, _ := http.NewRequest("POST", "https://openrouter.ai/api/v1/chat/completions", bytes.NewBuffer(jsonData))
+    req.Header.Set("Authorization", "Bearer "+apiKey)
+    req.Header.Set("Content-Type", "application/json")
+
+    client := &http.Client{}
+    resp, err := client.Do(req)
+    if err != nil {
+        return "", err
+    }
+    defer resp.Body.Close()
+
+    bodyBytes, _ := io.ReadAll(resp.Body)
+    if resp.StatusCode != http.StatusOK {
+        var errResp OpenRouterResponse
+        json.Unmarshal(bodyBytes, &errResp)
+        if errResp.Error.Message != "" {
+            return "", fmt.Errorf("OpenRouter error: %s", errResp.Error.Message)
+        }
+        return "", fmt.Errorf("OpenRouter API error: %s", string(bodyBytes))
+    }
+
+    var result OpenRouterResponse
+    if err := json.Unmarshal(bodyBytes, &result); err != nil {
+        return "", fmt.Errorf("failed to parse OpenRouter response: %w", err)
+    }
+
+    if len(result.Choices) > 0 {
+        return result.Choices[0].Message.Content, nil
+    }
+    return "", fmt.Errorf("no choices returned from OpenRouter: %s", string(bodyBytes))
+}