professor/lib/pistonClient.ts

import type { ExecutionResult } from '@/types';

// Wandbox — free public code execution API, no auth required
// https://github.com/melpon/wandbox
const WANDBOX_API = 'https://wandbox.org/api/compile.json';
const TIMEOUT_MS = 15_000;

export async function executePython(code: string, stdin = ''): Promise<ExecutionResult> {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), TIMEOUT_MS);

  try {
    const res = await fetch(WANDBOX_API, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      signal: controller.signal,
      body: JSON.stringify({
        compiler: 'cpython-3.12.7',
        code,
        stdin,
      }),
    });

    if (!res.ok) {
      throw new Error(`Execution service error: ${res.status}`);
    }

    const data = await res.json();
    const exitCode = parseInt(data.status ?? '0', 10);

    // Wandbox separates compiler errors from runtime errors
    const stderr = [data.program_error, data.compiler_error]
      .filter(Boolean)
      .join('\n')
      .trim();

    return {
      stdout: data.program_output ?? '',
      stderr,
      exitCode,
      timedOut: !!data.signal,
    };
  } catch (err: unknown) {
    if (err instanceof Error && err.name === 'AbortError') {
      return { stdout: '', stderr: '', exitCode: -1, timedOut: true, error: 'Execution timed out after 15 seconds.' };
    }
    return {
      stdout: '',
      stderr: '',
      exitCode: -1,
      timedOut: false,
      error: err instanceof Error ? err.message : 'Unknown execution error',
    };
  } finally {
    clearTimeout(timer);
  }
}