// Large-course mode API — course detail (ops side).
//
//   GET /api/courses/:courseId
//
// Returns the full course record (reconciled against classroom jobs) plus
// per-module publish annotations from the L2 courseware repo. Modules that are
// currently generating carry the live progress of their classroom job so the
// builder page can show real-time progress.

import { type NextRequest } from 'next/server';
import { apiError, apiSuccess, API_ERROR_CODES } from '@/lib/server/api-response';
import { createLogger } from '@/lib/logger';
import { isValidCourseId, readCourseRecordReconciled } from '@/lib/course-framework/store';
import { readClassroomGenerationJob } from '@/lib/server/classroom-job-store';
import { COURSEWARES_DIR, createFileCoursewareRepo } from '@/lib/courseware-repo/store';
import type { CourseDetail, CourseModuleView } from '@/lib/course-framework/types';
import { courseModuleCoursewareId } from '@/lib/course-framework/publish-identity';
import { requireOpsAccess } from '@/lib/server/ops-access';
import { readClassroom } from '@/lib/server/classroom-storage';
import { computeClassroomSourceRevisionHash } from '@/lib/course-framework/module-digest';

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

export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ courseId: string }> },
) {
  const denied = await requireOpsAccess(request);
  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}`);
    }

    // Annotate each generated module with its published state. Learner-facing
    // ids are derived from course + module and deliberately differ from the
    // mutable operations-side classroom id.
    const coursewareRepo = createFileCoursewareRepo(COURSEWARES_DIR);
    const modules: CourseModuleView[] = [];
    for (const moduleRec of record.modules) {
      let published = false;
      let publishedCoursewareId: string | undefined;
      if (record.externalPublication?.status === 'published') {
        published = true;
        publishedCoursewareId = `${record.externalPublication.courseId}_m${moduleRec.index}`;
      }
      if (moduleRec.classroomId) {
        const coursewareId = courseModuleCoursewareId(courseId, moduleRec.index);
        const receipt = record.publication?.modules.find(
          (entry) => entry.index === moduleRec.index,
        );
        const currentClassroom = receipt
          ? await readClassroom(moduleRec.classroomId).catch(() => null)
          : null;
        const currentSourceRevisionHash = currentClassroom
          ? computeClassroomSourceRevisionHash(currentClassroom)
          : undefined;
        published = published || Boolean(
          receipt &&
          receipt.coursewareId === coursewareId &&
          receipt.sourceClassroomId === moduleRec.classroomId &&
          receipt.sourceRevisionHash === moduleRec.outputDigest?.sourceRevisionHash &&
          receipt.sourceRevisionHash === currentSourceRevisionHash &&
          receipt.sourceSemanticHash === moduleRec.outputDigest?.semanticHash,
        );
        // A receipt is authoritative and must fail closed if the mutable
        // source/digest has drifted. The registry fallback is legacy-only.
        if (!published && !record.publication) {
          const latest = await coursewareRepo
            .getLatestRecord(coursewareId, { status: 'published' })
            .catch(() => null);
          published = latest?.sourceClassroomId === moduleRec.classroomId;
        }
        if (published) publishedCoursewareId = coursewareId;
      }
      let jobProgress: number | undefined;
      let jobMessage: string | undefined;
      let scenesGenerated: number | undefined;
      let totalScenes: number | undefined;
      if (moduleRec.status === 'generating' && moduleRec.jobId) {
        const job = await readClassroomGenerationJob(moduleRec.jobId).catch(() => null);
        if (job) {
          jobProgress = job.progress;
          jobMessage = job.message;
          scenesGenerated = job.scenesGenerated;
          totalScenes = job.totalScenes;
        }
      }
      modules.push({
        ...moduleRec,
        published,
        publishedCoursewareId,
        jobProgress,
        jobMessage,
        scenesGenerated,
        totalScenes,
      });
    }

    const detail: CourseDetail = {
      ...record,
      modules,
      frameworkTitle: record.framework?.courseTitle,
      counts: {
        total: modules.length,
        succeeded: modules.filter((m) => m.status === 'succeeded').length,
        failed: modules.filter((m) => m.status === 'failed').length,
        generating: modules.filter((m) => m.status === 'generating').length,
        pending: modules.filter((m) => m.status === 'pending').length,
        published: modules.filter((m) => m.published).length,
      },
    };

    return apiSuccess({ course: detail });
  } catch (error) {
    log.error('Course detail failed:', error);
    return apiError(API_ERROR_CODES.INTERNAL_ERROR, 500, 'Failed to load course');
  }
}