backend/api/api.py

from ninja import NinjaAPI, File
from ninja.files import UploadedFile
from django.http import HttpResponse
from .midi_utils import process_midi # Import from the same directory

api = NinjaAPI(
    title="MIDI Processor API (Django Ninja)",
    version="2.0.0",
    description="A robust MIDI processing API built with Django Ninja."
)

@api.get("/")
def home(request):
    """
    A simple welcome endpoint.
    The interactive docs will be at /api/docs
    """
    return {"message": "Welcome to the Django Ninja MIDI API!", "docs_url": "/api/docs"}


@api.post("/process-midi")
def process_midi_file(request, file: UploadedFile = File(...)):
    """
    Receives a MIDI file, transposes it, and returns the processed file.
    """
    try:
        # Check filename
        if not file.name.lower().endswith(('.mid', '.midi')):
            return api.create_response(request, {"error": "Invalid file type"}, status=400)

        # Read file bytes
        midi_bytes = file.read()

        # Process the midi data
        processed_buffer = process_midi(midi_bytes)

        # Create an HTTP response with the processed file
        response = HttpResponse(
            processed_buffer.getvalue(),
            content_type='audio/midi'
        )
        response['Content-Disposition'] = f'attachment; filename="processed_{file.name}"'
        return response

    except Exception as e:
        return api.create_response(request, {"error": str(e)}, status=500)