🕵️‍♂️ Plagiarism Checker (DSA Project)

A compact demo that uses a native C++ core to compare two code/text blobs for similarity and a minimal Node.js web UI to run comparisons. The Express server forwards requests to the compiled C++ binary and returns the results.

Live demo (local): compile the C++ core, run npm start, then open the frontend in your browser.

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📋 Quick overview

• Backend core: C++ implementation (plagiarism_core.*) that performs code/text comparison.
• Server: server.js — Express bridge that accepts requests and invokes the compiled C++ binary.
• Frontend: public/ — minimal UI to submit two code snippets and view results (HTML, CSS, JS).

This README describes how to compile, run, and use the plagiarism checker with the files present in this repo.

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📁 Project structure

DSA-Project/
├── Backend/
│   ├── plagiarism_core.cpp
│   ├── plagiarism_core.hpp
│   └── plagiarism_core        # compiled binary
├── public/
│   ├── index.html
│   ├── style.css
│   └── script.js
├── package.json
├── server.js
├── README.md
└── node_modules/

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🛠️ Tech stack

• Backend core: C++ (plagiarism/comparison logic)
• Server layer: Node.js + Express (simple HTTP bridge)
• Frontend: HTML + vanilla JavaScript + CSS
• Data / I/O: binary stdin/stdout communication between server and C++ core

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🚀 Quick start (Linux / macOS)

1. Compile the C++ core

   Compile the C++ source into a binary named plagiarism_core placed in Backend/:

   cd Backend
   g++ -std=c++17 -O2 plagiarism_core.cpp -o plagiarism_core
   chmod +x plagiarism_core
   cd ..

2. Install Node.js dependencies

   npm install

3. Start the Express server

   npm start

   By default the server runs on http://localhost:5000 and serves the public/ folder.

4. Open the frontend

   Open your browser to:

   http://localhost:5000/
   

🚀 Quick start (Windows)

Option A — MSYS2 / MinGW (recommended if you have GNU toolchain):

1. Install MSYS2 and open the MinGW64 shell. Install the toolchain:

   pacman -Syu
   pacman -S mingw-w64-x86_64-toolchain

2. Compile the C++ core (inside the MinGW64 shell):

   cd /c/path/to/DSA-Project/Backend
   g++ -std=c++17 -O2 plagiarism_core.cpp -o plagiarism_core.exe
   cd ..

Option B — Visual Studio (MSVC):

1. Open "x64 Native Tools Command Prompt for VS" and compile with cl:

   cl /std:c++17 /O2 plagiarism_core.cpp /Fe:plagiarism_core.exe

Node.js & Express server (Windows)

1. Install Node.js dependencies (PowerShell):

   npm install

2. Run the server:

   npm start

3. Open the frontend:

   http://localhost:5000/
   

Notes:

• The server automatically detects .exe extension on Windows.
• Use the MinGW shell when running gcc-built binaries if you encounter runtime/locale issues.
• If your g++ doesn't support C++17, try C++11 instead: g++ -std=c++11 -O2 ...

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🔌 Server details

server.js is a small Express app that serves the frontend and forwards compare requests to the compiled C++ core.

• Static frontend directory: public/ (served at /) — visiting / returns index.html.
• Binary path (built-in): Backend/plagiarism_core — the binary should be named plagiarism_core (or plagiarism_core.exe on Windows) and placed in the Backend/ directory.

Endpoints implemented by server.js:

• GET / → serves public/index.html
• POST /compare
  • Expects a JSON body: { "codeA": "...", "codeB": "...", "window": <int> }
  • codeA and codeB are the two source texts to compare (strings).
  • window is optional and passed to the binary via the WINDOW environment variable.
  • The server builds a byte stream (header + code blobs) and runs the binary, returning its stdout as the HTTP response.
• GET /<filename> → serves static file from public/ (e.g., CSS, JS)

Example cURL:

curl -X POST http://localhost:5000/compare \
   -H "Content-Type: application/json" \
   -d '{"codeA":"print(1)","codeB":"print(2)","window":4}'

Note: server.js listens on http://localhost:5000 by default.

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📖 Usage guide (UI)

• Open the UI and paste or type the two code snippets you want to compare.
• Click the action button (Analyze) to send both snippets to the server.
• The server will return the C++ core's output (similarity/metrics) and the UI will display it.

Check the Express server console for incoming requests and for any stderr from the binary.

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⚙️ Notes on building and configuration

• The C++ binary should be compiled and placed in the Backend/ directory.
• On Windows, the binary should be named plagiarism_core.exe; on Linux/macOS, just plagiarism_core.
• If your backend requires a CSV dataset (e.g., dataset/users.csv), create that file under Backend/ and ensure the C++ binary reads from the correct path.

To customize the binary path in server.js:

const binaryPath = path.join(__dirname, "Backend", "plagiarism_core");

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🐛 Troubleshooting

• Server port in use: change the port in server.js (line with app.listen()) or stop the other process.
• Binary not found: compile the C++ sources and ensure the binary path matches the path used in server.js.
• Frontend fetches fail: ensure the server is running via npm start.
• Node modules missing: run npm install to install dependencies.

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🎓 Learning outcomes

• Native-code integration: calling a compiled C++ program from a Node.js server
• Text similarity and plagiarism detection heuristics (sliding-window comparisons, matching substrings)
• Building a minimal full-stack demo with a static frontend, Express bridge, and native core

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📝 License

MIT License — feel free to reuse and modify for coursework.