app.py

from fastapi import FastAPI, File, UploadFile, HTTPException, Form, Response
import uuid
import mimetypes
from datetime import datetime, timedelta

app = FastAPI()

# **In-Memory Storage (FOR DEMO ONLY)**
# Replace with Redis, NoSQL DB, or Cloud Storage for Production
data_storage = {}

@app.post("/upload/file")
async def upload_file(file: UploadFile = File(...)):
    upload_id = str(uuid.uuid4())
    data_storage[upload_id] = {
        'file_name': file.filename,
        'file_data': await file.read(),
       'mime_type': file.content_type,
        'upload_time': datetime.utcnow()
    }
    return {"upload_id": upload_id, "message": "File uploaded successfully"}

@app.post("/upload/custom")
async def upload_custom(file: UploadFile = File(...), download_link: str = Form(...)):
    if not download_link:
        raise HTTPException(status_code=400, detail="Download link is required")
    
    # Validate the download_link to be URL-safe
    if not download_link.isalnum() and not all(c in string.ascii_letters + string.digits + '-_' for c in download_link):
        raise HTTPException(status_code=400, detail="Invalid download link format")
    
    # Assign the custom download link
    data_storage[download_link] = {
        'file_name': file.filename,
        'file_data': await file.read(),
       'mime_type': file.content_type,
        'upload_time': datetime.utcnow()
    }
    return {"download_link": download_link, "message": "File uploaded successfully"}

@app.get("/download/{upload_id}")
async def download_file(upload_id: str):
    # Remove expired files
    expire_time = datetime.utcnow() - timedelta(minutes=5)
    keys_to_remove = [key for key, value in data_storage.items() if value['upload_time'] < expire_time]
    for key in keys_to_remove:
        del data_storage[key]
    
    if upload_id not in data_storage:
        raise HTTPException(status_code=404, detail="Upload not found")
    
    upload_data = data_storage[upload_id]
    file_name = upload_data['file_name']
    mime_type = upload_data['mime_type'] or mimetypes.guess_type(file_name)[0] or "application/octet-stream"
    
    return Response(content=upload_data['file_data'], media_type=mime_type, 
                    headers={"Content-Disposition": f"attachment; filename={file_name}"})

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8083)