feat: add function and tools support for Gemini (#1358)

* Update model.go

* Support Gemini tool_calls.

* Fix gemini tool calls (also keep support functions).

* Fixed the problem of arguments not being stringified.

Fix panic: candidate.Content.Parts out of range

relay/adaptor/gemini/main.go

@@ -4,6 +4,10 @@ import (
 	"bufio"
 	"encoding/json"
 	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
 	"github.com/songquanpeng/one-api/common"
 	"github.com/songquanpeng/one-api/common/config"
 	"github.com/songquanpeng/one-api/common/helper"
@@ -13,9 +17,6 @@ import (
 	"github.com/songquanpeng/one-api/relay/adaptor/openai"
 	"github.com/songquanpeng/one-api/relay/constant"
 	"github.com/songquanpeng/one-api/relay/model"
-	"io"
-	"net/http"
-	"strings"
 
 	"github.com/gin-gonic/gin"
 )
@@ -54,7 +55,17 @@ func ConvertRequest(textRequest model.GeneralOpenAIRequest) *ChatRequest {
 			MaxOutputTokens: textRequest.MaxTokens,
 		},
 	}
-	if textRequest.Functions != nil {
+	if textRequest.Tools != nil {
+		functions := make([]model.Function, 0, len(textRequest.Tools))
+		for _, tool := range textRequest.Tools {
+			functions = append(functions, tool.Function)
+		}
+		geminiRequest.Tools = []ChatTools{
+			{
+				FunctionDeclarations: functions,
+			},
+		}
+	} else if textRequest.Functions != nil {
 		geminiRequest.Tools = []ChatTools{
 			{
 				FunctionDeclarations: textRequest.Functions,
@@ -154,6 +165,30 @@ type ChatPromptFeedback struct {
 	SafetyRatings []ChatSafetyRating `json:"safetyRatings"`
 }
 
+func getToolCalls(candidate *ChatCandidate) []model.Tool {
+	var toolCalls []model.Tool
+
+	item := candidate.Content.Parts[0]
+	if item.FunctionCall == nil {
+		return toolCalls
+	}
+	argsBytes, err := json.Marshal(item.FunctionCall.Arguments)
+	if err != nil {
+		logger.FatalLog("getToolCalls failed: " + err.Error())
+		return toolCalls
+	}
+	toolCall := model.Tool{
+		Id:   fmt.Sprintf("call_%s", random.GetUUID()),
+		Type: "function",
+		Function: model.Function{
+			Arguments: string(argsBytes),
+			Name:      item.FunctionCall.FunctionName,
+		},
+	}
+	toolCalls = append(toolCalls, toolCall)
+	return toolCalls
+}
+
 func responseGeminiChat2OpenAI(response *ChatResponse) *openai.TextResponse {
 	fullTextResponse := openai.TextResponse{
 		Id:      fmt.Sprintf("chatcmpl-%s", random.GetUUID()),
@@ -165,13 +200,19 @@ func responseGeminiChat2OpenAI(response *ChatResponse) *openai.TextResponse {
 		choice := openai.TextResponseChoice{
 			Index: i,
 			Message: model.Message{
-				Role:    "assistant",
+				Role: "assistant",
-				Content: "",
 			},
 			FinishReason: constant.StopFinishReason,
 		}
 		if len(candidate.Content.Parts) > 0 {
-			choice.Message.Content = candidate.Content.Parts[0].Text
+			if candidate.Content.Parts[0].FunctionCall != nil {
+				choice.Message.ToolCalls = getToolCalls(&candidate)
+			} else {
+				choice.Message.Content = candidate.Content.Parts[0].Text
+			}
+		} else {
+			choice.Message.Content = ""
+			choice.FinishReason = candidate.FinishReason
 		}
 		fullTextResponse.Choices = append(fullTextResponse.Choices, choice)
 	}

relay/adaptor/gemini/model.go

@@ -12,9 +12,15 @@ type InlineData struct {
 	Data     string `json:"data"`
 }
 
+type FunctionCall struct {
+	FunctionName string `json:"name"`
+	Arguments    any    `json:"args"`
+}
+
 type Part struct {
-	Text       string      `json:"text,omitempty"`
+	Text         string        `json:"text,omitempty"`
-	InlineData *InlineData `json:"inlineData,omitempty"`
+	InlineData   *InlineData   `json:"inlineData,omitempty"`
+	FunctionCall *FunctionCall `json:"functionCall,omitempty"`
 }
 
 type ChatContent struct {
@@ -28,7 +34,7 @@ type ChatSafetySettings struct {
 }
 
 type ChatTools struct {
-	FunctionDeclarations any `json:"functionDeclarations,omitempty"`
+	FunctionDeclarations any `json:"function_declarations,omitempty"`
 }
 
 type ChatGenerationConfig struct {