feat: support gemini-2.0-flash

- Enhance model support by adding new entries and refining checks for system instruction compatibility.
- Update logging display behavior and adjust default quotas for better user experience.
- Revamp pricing structures in the billing system to reflect current model values and deprecate outdated entries.
- Streamline code by replacing hardcoded values with configurations for maintainability.

relay/adaptor/gemini/adaptor.go

@@ -5,8 +5,10 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strings"
 
 	"github.com/gin-gonic/gin"
+	"github.com/songquanpeng/one-api/common/config"
 	"github.com/songquanpeng/one-api/common/helper"
 	channelhelper "github.com/songquanpeng/one-api/relay/adaptor"
 	"github.com/songquanpeng/one-api/relay/adaptor/openai"
@@ -19,15 +21,11 @@ type Adaptor struct {
 }
 
 func (a *Adaptor) Init(meta *meta.Meta) {
-
 }
 
 func (a *Adaptor) GetRequestURL(meta *meta.Meta) (string, error) {
-	var defaultVersion string
-	switch meta.ActualModelName {
-	case "gemini-2.0-flash-exp",
-		"gemini-2.0-flash-thinking-exp",
-		"gemini-2.0-flash-thinking-exp-01-21":
+	defaultVersion := config.GeminiVersion
+	if strings.Contains(meta.ActualModelName, "-2.0") {
 		defaultVersion = "v1beta"
 	}
 

relay/adaptor/gemini/constants.go

@@ -4,8 +4,38 @@ package gemini
 
 var ModelList = []string{
 	"gemini-pro", "gemini-1.0-pro",
-	"gemini-1.5-flash", "gemini-1.5-pro",
+	// "gemma-2-2b-it", "gemma-2-9b-it", "gemma-2-27b-it",
+	"gemini-1.5-flash", "gemini-1.5-flash-8b",
+	"gemini-1.5-pro", "gemini-1.5-pro-experimental",
 	"text-embedding-004", "aqa",
-	"gemini-2.0-flash-exp",
-	"gemini-2.0-flash-thinking-exp", "gemini-2.0-flash-thinking-exp-01-21",
+	"gemini-2.0-flash", "gemini-2.0-flash-exp",
+	"gemini-2.0-flash-lite-preview-02-05",
+	"gemini-2.0-flash-thinking-exp-01-21",
+	"gemini-2.0-pro-exp-02-05",
+}
+
+// ModelsSupportSystemInstruction is the list of models that support system instruction.
+//
+// https://cloud.google.com/vertex-ai/generative-ai/docs/learn/prompts/system-instructions
+var ModelsSupportSystemInstruction = []string{
+	// "gemini-1.0-pro-002",
+	// "gemini-1.5-flash", "gemini-1.5-flash-001", "gemini-1.5-flash-002",
+	// "gemini-1.5-flash-8b",
+	// "gemini-1.5-pro", "gemini-1.5-pro-001", "gemini-1.5-pro-002",
+	// "gemini-1.5-pro-experimental",
+	"gemini-2.0-flash", "gemini-2.0-flash-exp",
+	"gemini-2.0-flash-thinking-exp-01-21",
+}
+
+// IsModelSupportSystemInstruction check if the model support system instruction.
+//
+// Because the main version of Go is 1.20, slice.Contains cannot be used
+func IsModelSupportSystemInstruction(model string) bool {
+	for _, m := range ModelsSupportSystemInstruction {
+		if m == model {
+			return true
+		}
+	}
+
+	return false
 }

relay/adaptor/gemini/main.go

@@ -132,9 +132,16 @@ func ConvertRequest(textRequest model.GeneralOpenAIRequest) *ChatRequest {
 		}
 		// Converting system prompt to prompt from user for the same reason
 		if content.Role == "system" {
-			content.Role = "user"
 			shouldAddDummyModelMessage = true
+			if IsModelSupportSystemInstruction(textRequest.Model) {
+				geminiRequest.SystemInstruction = &content
+				geminiRequest.SystemInstruction.Role = ""
+				continue
+			} else {
+				content.Role = "user"
+			}
 		}
+
 		geminiRequest.Contents = append(geminiRequest.Contents, content)
 
 		// If a system message is the last message, we need to add a dummy model message to make gemini happy

relay/adaptor/gemini/model.go

@@ -1,10 +1,11 @@
 package gemini
 
 type ChatRequest struct {
-	Contents         []ChatContent        `json:"contents"`
-	SafetySettings   []ChatSafetySettings `json:"safety_settings,omitempty"`
-	GenerationConfig ChatGenerationConfig `json:"generation_config,omitempty"`
-	Tools            []ChatTools          `json:"tools,omitempty"`
+	Contents          []ChatContent        `json:"contents"`
+	SafetySettings    []ChatSafetySettings `json:"safety_settings,omitempty"`
+	GenerationConfig  ChatGenerationConfig `json:"generation_config,omitempty"`
+	Tools             []ChatTools          `json:"tools,omitempty"`
+	SystemInstruction *ChatContent         `json:"system_instruction,omitempty"`
 }
 
 type EmbeddingRequest struct {