refactor: Simplify model mapping and pricing logic across relay modules

relay/helper/model_mapped.go

@@ -0,0 +1,25 @@
+package helper
+
+import (
+	"encoding/json"
+	"fmt"
+	"github.com/gin-gonic/gin"
+	"one-api/relay/common"
+)
+
+func ModelMappedHelper(c *gin.Context, info *common.RelayInfo) error {
+	// map model name
+	modelMapping := c.GetString("model_mapping")
+	if modelMapping != "" && modelMapping != "{}" {
+		modelMap := make(map[string]string)
+		err := json.Unmarshal([]byte(modelMapping), &modelMap)
+		if err != nil {
+			return fmt.Errorf("unmarshal_model_mapping_failed")
+		}
+		if modelMap[info.OriginModelName] != "" {
+			info.UpstreamModelName = modelMap[info.OriginModelName]
+			info.IsModelMapped = true
+		}
+	}
+	return nil
+}