// Resume a cancelled/failed background job — POST /api/generate-classroom/[jobId]/resume
//
// Re-runs the job from its persisted input (the generation restarts from the
// beginning; server-side generation is atomic, so there is no partial state to
// continue from). Returns 409 when the job is not resumable.

import { type NextRequest } from 'next/server';
import { apiError, apiSuccess } from '@/lib/server/api-response';
import {
  isValidClassroomJobId,
  readClassroomGenerationJob,
} from '@/lib/server/classroom-job-store';
import { resumeClassroomGenerationJob } from '@/lib/server/classroom-job-runner';
import { buildRequestOrigin } from '@/lib/server/classroom-storage';
import { createLogger } from '@/lib/logger';
import {
  authorizeClassroomJobRequest,
  classroomJobAccessError,
} from '@/lib/server/authz/classroom-job-access';

const log = createLogger('ClassroomJobResume API');

export const dynamic = 'force-dynamic';

export async function POST(req: NextRequest, context: { params: Promise<{ jobId: string }> }) {
  try {
    const { jobId } = await context.params;
    if (!isValidClassroomJobId(jobId)) {
      return apiError('INVALID_REQUEST', 400, 'Invalid classroom generation job id');
    }
    const job = await readClassroomGenerationJob(jobId);
    if (!job) {
      return apiError('INVALID_REQUEST', 404, 'Classroom generation job not found');
    }
    const access = await authorizeClassroomJobRequest(req, job, 'resume');
    if (!access.allowed) return classroomJobAccessError(access);
    if (job.status === 'running' || job.status === 'queued') {
      return apiError('INVALID_REQUEST', 409, 'Job is already active');
    }
    const resumed = await resumeClassroomGenerationJob(jobId, buildRequestOrigin(req));
    if (!resumed) {
      return apiError('INVALID_REQUEST', 409, 'Job cannot be resumed (no persisted input)');
    }
    return apiSuccess({ jobId, status: 'queued' });
  } catch (error) {
    log.error('Classroom job resume failed:', error);
    return apiError(
      'INTERNAL_ERROR',
      500,
      'Failed to resume classroom generation job',
      error instanceof Error ? error.message : String(error),
    );
  }
}