// Courseware detail — GET /api/coursewares/[id]
//
// Returns the latest published record for one courseware (or a specific
// version via `?version=N`). Public read path for the learner player.

import { type NextRequest } from 'next/server';
import { apiError, apiSuccess, API_ERROR_CODES } from '@/lib/server/api-response';
import { COURSEWARES_DIR, createFileCoursewareRepo } from '@/lib/courseware-repo/store';
import { toSummary } from '@/lib/courseware-repo';
import {
  filterLearnerVisibleCoursewares,
  isCoursewareLearnerVisible,
} from '@/lib/courseware-repo/learner-visibility';
import { createLogger } from '@/lib/logger';

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

export async function GET(request: NextRequest, context: { params: Promise<{ id: string }> }) {
  try {
    const { id } = await context.params;
    if (!/^[a-zA-Z0-9_-]+$/.test(id)) {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 400, 'Invalid courseware id');
    }
    const repo = createFileCoursewareRepo(COURSEWARES_DIR);
    const versionParam = new URL(request.url).searchParams.get('version');
    let record;
    if (versionParam) {
      const version = Number(versionParam);
      if (!Number.isInteger(version) || version < 1) {
        return apiError(API_ERROR_CODES.INVALID_REQUEST, 400, 'Invalid version');
      }
      record = await repo.getRecord(id, version);
      if (record && !(await isCoursewareLearnerVisible(record))) record = null;
    } else {
      const candidates = (await repo.listRecords({ status: 'published' })).filter(
        (candidate) => candidate.coursewareId === id,
      );
      const visible = await filterLearnerVisibleCoursewares(candidates);
      record = visible.sort((a, b) => b.version - a.version)[0] ?? null;
    }
    if (!record || record.status !== 'published') {
      return apiError(API_ERROR_CODES.INVALID_REQUEST, 404, 'Courseware not found');
    }
    return apiSuccess({ courseware: toSummary(record) });
  } catch (error) {
    log.error('Courseware detail failed:', error);
    return apiError(API_ERROR_CODES.INTERNAL_ERROR, 500, 'Courseware detail failed');
  }
}