// Large-course mode API — resume course generation.
//
//   POST /api/courses/:courseId/resume
//
// Continues whatever is unfinished: generates the framework when it does not
// exist yet, otherwise runs the module pipeline (skipping succeeded modules).
// No-op when everything already succeeded.

import { after, type NextRequest } from 'next/server';
import { apiError, apiSuccess, API_ERROR_CODES } from '@/lib/server/api-response';
import { buildRequestOrigin } from '@/lib/server/classroom-storage';
import { createLogger } from '@/lib/logger';
import { isValidCourseId, readCourseRecordReconciled } from '@/lib/course-framework/store';
import {
  isCourseGenerationRunning,
  runCourseFrameworkGeneration,
  runCourseModuleGeneration,
} from '@/lib/course-framework/runner';
import { requireOpsAccess } from '@/lib/server/ops-access';
import {
  CourseMutationInProgressError,
  isCoursePublishing,
} from '@/lib/course-framework/publish-state';
import { proxyLargeCourseControlToEngine } from '@/lib/makelore-runtime/ops-engine-control';
import {
  assertLearningCourseMutable,
  FrozenLearningCourseMutationError,
} from '@/lib/makelore-course/immutability';

const log = createLogger('Course Resume API');

export async function POST(
  req: NextRequest,
  { params }: { params: Promise<{ courseId: string }> },
) {
  const denied = await requireOpsAccess(req);
  if (denied) return denied;

  try {
    const { courseId } = await params;
    if (!isValidCourseId(courseId)) {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 400, `Invalid course id: ${courseId}`);
    }
    const record = await readCourseRecordReconciled(courseId);
    if (!record) {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 404, `Course not found: ${courseId}`);
    }
    const proxied = await proxyLargeCourseControlToEngine({
      request: req,
      course: record,
      action: 'resume',
    });
    if (proxied) return proxied;
    await assertLearningCourseMutable(courseId, record);
    if (record.status === 'completed') {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 409, 'Course is already completed');
    }
    if (isCourseGenerationRunning(courseId) || isCoursePublishing(courseId)) {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 409, '该课程已有生成任务正在运行');
    }

    const baseUrl = buildRequestOrigin(req);
    const hasFramework = !!record.framework;
    const run = hasFramework
      ? runCourseModuleGeneration(courseId, baseUrl)
      : runCourseFrameworkGeneration(courseId, baseUrl);
    after(() => run);

    return apiSuccess({
      courseId,
      status: hasFramework ? 'generating' : 'framework_generating',
      message: hasFramework ? '模块生成已继续' : '框架生成已继续',
      detailUrl: `${baseUrl}/api/courses/${courseId}`,
    });
  } catch (error) {
    if (error instanceof FrozenLearningCourseMutationError) {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 409, error.message);
    }
    if (error instanceof CourseMutationInProgressError) {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 409, error.message);
    }
    log.error('Course resume failed:', error);
    return apiError(API_ERROR_CODES.INTERNAL_ERROR, 500, 'Failed to resume course');
  }
}