feat: support perplexity

relay/channel/perplexity/relay-perplexity.go

@@ -0,0 +1,21 @@
+package perplexity
+
+import "one-api/dto"
+
+func requestOpenAI2Perplexity(request dto.GeneralOpenAIRequest) *dto.GeneralOpenAIRequest {
+	messages := make([]dto.Message, 0, len(request.Messages))
+	for _, message := range request.Messages {
+		messages = append(messages, dto.Message{
+			Role:    message.Role,
+			Content: message.Content,
+		})
+	}
+	return &dto.GeneralOpenAIRequest{
+		Model:       request.Model,
+		Stream:      request.Stream,
+		Messages:    messages,
+		Temperature: request.Temperature,
+		TopP:        request.TopP,
+		MaxTokens:   request.MaxTokens,
+	}
+}