Add gemini support

src/api/gemini.ts

@@ -0,0 +1,57 @@
+import { Anthropic } from "@anthropic-ai/sdk"
+import { FunctionCallingMode, GoogleGenerativeAI } from "@google/generative-ai"
+import { ApiHandler, ApiHandlerMessageResponse } from "."
+import { ApiHandlerOptions, geminiDefaultModelId, GeminiModelId, geminiModels, ModelInfo } from "../shared/api"
+import {
+	convertAnthropicMessageToGemini,
+	convertAnthropicToolToGemini,
+	convertGeminiResponseToAnthropic,
+} from "../utils/gemini-format"
+
+export class GeminiHandler implements ApiHandler {
+	private options: ApiHandlerOptions
+	private client: GoogleGenerativeAI
+
+	constructor(options: ApiHandlerOptions) {
+		if (!options.geminiApiKey) {
+			throw new Error("API key is required for Google Gemini")
+		}
+		this.options = options
+		this.client = new GoogleGenerativeAI(options.geminiApiKey)
+	}
+
+	async createMessage(
+		systemPrompt: string,
+		messages: Anthropic.Messages.MessageParam[],
+		tools: Anthropic.Messages.Tool[]
+	): Promise<ApiHandlerMessageResponse> {
+		const model = this.client.getGenerativeModel({
+			model: this.getModel().id,
+			systemInstruction: systemPrompt,
+			tools: [{ functionDeclarations: tools.map(convertAnthropicToolToGemini) }],
+			toolConfig: {
+				functionCallingConfig: {
+					mode: FunctionCallingMode.AUTO,
+				},
+			},
+		})
+		const result = await model.generateContent({
+			contents: messages.map(convertAnthropicMessageToGemini),
+			generationConfig: {
+				maxOutputTokens: this.getModel().info.maxTokens,
+			},
+		})
+		const message = convertGeminiResponseToAnthropic(result.response)
+
+		return { message }
+	}
+
+	getModel(): { id: GeminiModelId; info: ModelInfo } {
+		const modelId = this.options.apiModelId
+		if (modelId && modelId in geminiModels) {
+			const id = modelId as GeminiModelId
+			return { id, info: geminiModels[id] }
+		}
+		return { id: geminiDefaultModelId, info: geminiModels[geminiDefaultModelId] }
+	}
+}

src/api/index.ts

@@ -6,6 +6,7 @@ import { OpenRouterHandler } from "./openrouter"
 import { VertexHandler } from "./vertex"
 import { OpenAiHandler } from "./openai"
 import { OllamaHandler } from "./ollama"
+import { GeminiHandler } from "./gemini"
 
 export interface ApiHandlerMessageResponse {
 	message: Anthropic.Messages.Message
@@ -37,6 +38,8 @@ export function buildApiHandler(configuration: ApiConfiguration): ApiHandler {
 			return new OpenAiHandler(options)
 		case "ollama":
 			return new OllamaHandler(options)
+		case "gemini":
+			return new GeminiHandler(options)
 		default:
 			return new AnthropicHandler(options)
 	}