backend: initial full working logic with gemini 3.0 flash model addded

Author: dineshsutihar

backend/src/index.ts

@@ -0,0 +1,57 @@
+import { GoogleGenerativeAI } from '@google/generative-ai';
+
+export interface Env {
+	GEMINI_API_KEY: string;
+}
+
+export default {
+	async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
+		const corsHeaders = {
+			'Access-Control-Allow-Origin': '*',
+			'Access-Control-Allow-Methods': 'POST, OPTIONS',
+			'Access-Control-Allow-Headers': 'Content-Type',
+		};
+
+		if (request.method === 'OPTIONS') {
+			return new Response(null, { headers: corsHeaders });
+		}
+
+		try {
+			const { code, targetLanguage } = await request.json<{ code: string; targetLanguage: string }>();
+
+			if (!code || !targetLanguage) {
+				return new Response(JSON.stringify({ error: "Missing 'code' or 'targetLanguage' in request body." }), {
+					status: 400,
+					headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+				});
+			}
+
+			const genAI = new GoogleGenerativeAI(env.GEMINI_API_KEY);
+
+			const model = genAI.getGenerativeModel({ model: 'gemini-2.0-flash' });
+
+			const prompt = `Translate the following code snippet to ${targetLanguage}.
+Do not add any explanation, commentary, or markdown formatting like \`\`\` around the code.
+**IMPORTANT: Preserve all original comments and their exact placement in the translated code. do not add extra spaces in between.**
+Only provide the raw, translated code itself.
+
+Original Code:
+${code}`;
+
+			const result = await model.generateContent(prompt);
+			const geminiResponse = result.response;
+			const translatedCode = geminiResponse.text();
+
+			return new Response(JSON.stringify({ translation: translatedCode }), {
+				status: 200,
+				headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+			});
+		} catch (error) {
+			console.error('Error during translation:', error);
+			return new Response(JSON.stringify({ error: 'An error occurred while translating the code.' }), {
+				status: 500,
+				headers: { ...corsHeaders, 'Content-Type': 'application/json' },
+			});
+		}
+	},
+};