fix: make completions endpoint more close to OpenAI specification (#790)

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

api/openai/api.go

@@ -46,7 +46,7 @@ type OpenAIResponse struct {
 }
 
 type Choice struct {
-	Index        int      `json:"index,omitempty"`
+	Index        int      `json:"index"`
 	FinishReason string   `json:"finish_reason,omitempty"`
 	Message      *Message `json:"message,omitempty"`
 	Delta        *Message `json:"delta,omitempty"`

api/openai/chat.go

@@ -302,7 +302,7 @@ func ChatEndpoint(cm *config.ConfigLoader, o *options.Option) func(c *fiber.Ctx)
 
 				return
 			}
-			*c = append(*c, Choice{Message: &Message{Role: "assistant", Content: &s}})
+			*c = append(*c, Choice{FinishReason: "stop", Index: 0, Message: &Message{Role: "assistant", Content: &s}})
 		}, nil)
 		if err != nil {
 			return err

api/openai/completion.go

@@ -122,7 +122,7 @@ func CompletionEndpoint(cm *config.ConfigLoader, o *options.Option) func(c *fibe
 		}
 
 		var result []Choice
-		for _, i := range config.PromptStrings {
+		for k, i := range config.PromptStrings {
 			// A model can have a "file.bin.tmpl" file associated with a prompt template prefix
 			templatedInput, err := o.Loader.TemplatePrefix(templateFile, struct {
 				Input string
@@ -135,7 +135,7 @@ func CompletionEndpoint(cm *config.ConfigLoader, o *options.Option) func(c *fibe
 			}
 
 			r, err := ComputeChoices(i, input.N, config, o, o.Loader, func(s string, c *[]Choice) {
-				*c = append(*c, Choice{Text: s})
+				*c = append(*c, Choice{Text: s, FinishReason: "stop", Index: k})
 			}, nil)
 			if err != nil {
 				return err