refactor: refactor relay part (#957)

* refactor: refactor relay part

* refactor: refactor config part

relay/util/validation.go

@@ -0,0 +1,37 @@
+package util
+
+import (
+	"errors"
+	"math"
+	"one-api/relay/channel/openai"
+	"one-api/relay/constant"
+)
+
+func ValidateTextRequest(textRequest *openai.GeneralOpenAIRequest, relayMode int) error {
+	if textRequest.MaxTokens < 0 || textRequest.MaxTokens > math.MaxInt32/2 {
+		return errors.New("max_tokens is invalid")
+	}
+	if textRequest.Model == "" {
+		return errors.New("model is required")
+	}
+	switch relayMode {
+	case constant.RelayModeCompletions:
+		if textRequest.Prompt == "" {
+			return errors.New("field prompt is required")
+		}
+	case constant.RelayModeChatCompletions:
+		if textRequest.Messages == nil || len(textRequest.Messages) == 0 {
+			return errors.New("field messages is required")
+		}
+	case constant.RelayModeEmbeddings:
+	case constant.RelayModeModerations:
+		if textRequest.Input == "" {
+			return errors.New("field input is required")
+		}
+	case constant.RelayModeEdits:
+		if textRequest.Instruction == "" {
+			return errors.New("field instruction is required")
+		}
+	}
+	return nil
+}