AI Code Assistant Backend

Spring Boot backend for analyzing code snippets and uploaded source files with OpenAI-backed bug finding and fallback local analysis.

Stack

• Java 17
• Spring Boot
• Maven Wrapper
• OpenAI Java SDK

What This Backend Does

• Accepts source code as JSON and returns bug analysis, fixes, explanations, edge cases, and complexity notes
• Accepts source files or zip uploads for analysis
• Uses OpenAI when OPENAI_API_KEY is configured
• Falls back to a local rule-based response when the API key is missing or the OpenAI call fails

Project Structure

• src/main/java/com/aibugfinder/backend/controller - REST API controllers
• src/main/java/com/aibugfinder/backend/service - analysis logic and OpenAI client integration
• src/main/java/com/aibugfinder/backend/dto - request and response DTOs
• src/main/resources/application.properties - app configuration

Requirements

• Java 17+
• Internet access for dependency download and OpenAI API calls

Run Locally

1. Set the OpenAI API key

PowerShell, current terminal only:

$env:OPENAI_API_KEY="your_real_key_here"

Permanent Windows user variable:

[System.Environment]::SetEnvironmentVariable("OPENAI_API_KEY", "your_real_key_here", "User")

Important:

• Do not commit the real API key into the repository
• If you set the key permanently, reopen your terminal or IDE before starting the app again

2. Start the backend

Windows:

.\mvnw.cmd spring-boot:run

macOS or Linux:

./mvnw spring-boot:run

The backend runs on:

http://localhost:8081

API Endpoints

Base path:

/api

POST /api/analyze

Analyze raw code sent in JSON.

Request body:

{
  "code": "public class Demo { public static void main(String[] args) {} }",
  "language": "java"
}

Sample response shape:

{
  "bugs": ["Possible misuse of '==' instead of equals()"],
  "fixedCode": "...",
  "explanation": "...",
  "edgeCasesToTest": ["..."],
  "timeComplexity": "...",
  "spaceComplexity": "...",
  "optimality": "...",
  "learningResources": ["..."]
}

POST /api/analyze/upload

Analyze an uploaded source file or zip archive.

Form fields:

• file - required multipart file
• language - optional language override

Example with PowerShell:

curl.exe -X POST "http://localhost:8081/api/analyze/upload?language=java" ^
  -F "file=@D:\path\to\BinarySearch.java"

Frontend Team Notes

• The frontend should call this backend only
• The OpenAI API key must stay on the backend or deployment environment
• Do not place the OpenAI API key in frontend code, .env frontend files, or client-side requests
• If the backend is deployed centrally, frontend developers do not need the OpenAI key at all

Configuration

Current app settings live in src/main/resources/application.properties:

spring.application.name=demo
openai.model=gpt-5-mini
openai.api-key=${OPENAI_API_KEY}
server.port=8081

Testing

Run tests with the Maven wrapper:

Windows:

.\mvnw.cmd test

macOS or Linux:

./mvnw test

Notes

• If OPENAI_API_KEY is invalid, the service returns fallback analysis instead of crashing
• Error messages are sanitized so API keys are not echoed back in responses
• CORS is enabled on the controller for frontend integration