lambda_function.py

import os
import requests
import time
import json
import base64

def lambda_handler(event, context):
    print("DEBUG: Lambda invoked with event:", event)

    # RapidAPI configuration
    RAPIDAPI_ENDPOINT = "https://judge0-ce.p.rapidapi.com"
    RAPIDAPI_HOST = "judge0-ce.p.rapidapi.com"
    RAPIDAPI_KEY = os.environ.get("RAPIDAPI_KEY")
    if not RAPIDAPI_KEY:
        raise Exception("Missing RAPIDAPI_KEY in environment variables")

    headers = {
        "Content-Type": "application/json",
        "X-RapidAPI-Host": RAPIDAPI_HOST,
        "X-RapidAPI-Key": RAPIDAPI_KEY,
    }

    # Parse event body
    body = event.get("body")
    if body and isinstance(body, str):
        try:
            body = json.loads(body)
        except json.JSONDecodeError:
            body = {}
    else:
        body = {}

    # Get code submission details from event
    source_code = body.get("source_code", "print('Hello, World!')")
    language_id = body.get("language_id", 71)
    stdin = body.get("stdin", "")

    # Check if stdin is empty and handle accordingly
    if stdin == "":
        stdin = None  # Ensure we don't send empty stdin, as some languages fail with empty input.

    submission_data = {
        "language_id": language_id,
        "source_code": source_code,
        "stdin": stdin
    }

    print("DEBUG: Submitting code to RapidAPI:", submission_data)

    # Submit code to Judge0 API
    submit_response = requests.post(
        f"{RAPIDAPI_ENDPOINT}/submissions?base64_encoded=true&wait=false",
        headers=headers,
        json=submission_data,
        timeout=30,
    )

    print("DEBUG: Submission response:", submit_response.status_code, submit_response.text)

    if submit_response.status_code != 201:
        return {
            "statusCode": submit_response.status_code,
            "body": json.dumps({"error": submit_response.text})
        }

    token = submit_response.json().get("token")
    if not token:
        print("No token received")
        return {
            "statusCode": 500,
            "body": json.dumps({"error": "No token received from submission"})
        }

    # Poll for result (up to 30 seconds)
    for _ in range(30):
        get_response = requests.get(
            f"{RAPIDAPI_ENDPOINT}/submissions/{token}?base64_encoded=true",
            headers=headers,
            timeout=10,
        )
        result = get_response.json()
        status_id = result.get("status", {}).get("id")
        print("DEBUG: Current status:", result.get("status"))

        if status_id not in [1, 2]:  # 1: Pending, 2: Running
            print("DEBUG: Execution finished with result:", result)

            # Decode the base64-encoded stderr and compile_output
            stderr = result.get("stderr", "")
            compile_output = result.get("compile_output", "")

            if stderr:
                decoded_stderr = base64.b64decode(stderr).decode('utf-8')
                print("DEBUG: stderr decoded:", decoded_stderr)
            if compile_output:
                decoded_compile_output = base64.b64decode(compile_output).decode('utf-8')
                print("DEBUG: compile_output decoded:", decoded_compile_output)

            return {
                "statusCode": 200,
                "body": json.dumps(result)
            }

        time.sleep(1)

    print("Execution timeout")
    return {
        "statusCode": 408,
        "body": json.dumps({"error": "Execution timeout"})
    }