refactor, Extract the logic to fetch models from the openrouter API i…

…nto a helper, so to it can be reused

Part of #296

provider/openrouter/openrouter.go

@@ -2,7 +2,11 @@ package openrouter
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
+	"io"
+	"net/http"
+	"net/url"
 	"strings"
 	"time"
 
@@ -81,16 +85,49 @@ type Pricing struct {
 
 // Models returns which models are available to be queried via this provider.
 func (p *Provider) Models() (models []model.Model, err error) {
-	client := p.client()
+	responseModels, err := p.fetchModels()
+	if err != nil {
+		return nil, err
+	}
+
+	models = make([]model.Model, len(responseModels.Models))
+	for i, model := range responseModels.Models {
+		models[i] = llm.NewModel(p, p.ID()+provider.ProviderModelSeparator+model.ID)
+	}
+
+	return models, nil
+}
+
+// fetchModels returns the list of models of the provider.
+func (p *Provider) fetchModels() (models ModelsList, err error) {
+	modelsURLPath, err := url.JoinPath(p.baseURL, "models")
+	if err != nil {
+		return ModelsList{}, pkgerrors.WithStack(err)
+	}
+	request, err := http.NewRequest("GET", modelsURLPath, nil)
+	if err != nil {
+		return ModelsList{}, pkgerrors.WithStack(err)
+	}
+	request.Header.Set("Accept", "application/json")
 
-	var responseModels openai.ModelsList
+	client := &http.Client{}
+	var responseBody []byte
 	if err := retry.Do( // Query available models with a retry logic cause "openrouter.ai" has failed us in the past.
 		func() error {
-			ms, err := client.ListModels(context.Background())
+			response, err := client.Do(request)
+			if err != nil {
+				return pkgerrors.WithStack(err)
+			}
+			defer response.Body.Close()
+
+			if response.StatusCode != http.StatusOK {
+				return pkgerrors.Errorf("received status code %d when querying provider models", response.StatusCode)
+			}
+
+			responseBody, err = io.ReadAll(response.Body)
 			if err != nil {
 				return pkgerrors.WithStack(err)
 			}
-			responseModels = ms
 
 			return nil
 		},
@@ -99,12 +136,11 @@ func (p *Provider) Models() (models []model.Model, err error) {
 		retry.DelayType(retry.BackOffDelay),
 		retry.LastErrorOnly(true),
 	); err != nil {
-		return nil, err
+		return ModelsList{}, err
 	}
 
-	models = make([]model.Model, len(responseModels.Models))
-	for i, model := range responseModels.Models {
-		models[i] = llm.NewModel(p, p.ID()+provider.ProviderModelSeparator+model.ID)
+	if err = json.Unmarshal(responseBody, &models); err != nil {
+		return ModelsList{}, pkgerrors.WithStack(err)
 	}
 
 	return models, nil