import type { CollectionStatus } from '../../shared/types.js';
import { database, databaseDialect, type QueryContext } from '../database.js';

export interface CollectionStatusResult {
  status: CollectionStatus;
  workCount: number;
  approvedCount: number;
  completedAt: string | null;
}

export function deriveCollectionStatus(workCount: number, approvedCount: number): Exclude<CollectionStatus, 'archived'> {
  if (workCount === 0) return 'draft';
  if (approvedCount === workCount) return 'completed';
  return 'reviewing';
}

export async function recalculateCollectionStatus(
  collectionId: number,
  tx: QueryContext = database,
): Promise<CollectionStatusResult | null> {
  const collection = await tx.one<{ status: CollectionStatus; completed_at: string | null }>(
    `SELECT status, completed_at FROM collections WHERE id = ?${databaseDialect === 'postgres' ? ' FOR NO KEY UPDATE' : ''}`,
    [collectionId],
  );
  if (!collection) return null;

  const counts = await tx.one<{ work_count: number | string; approved_count: number | string }>(
    `SELECT COUNT(*) AS work_count,
      SUM(CASE WHEN review_status = 'approved' THEN 1 ELSE 0 END) AS approved_count
    FROM notes WHERE collection_id = ? AND review_status != 'draft'`,
    [collectionId],
  );
  const workCount = Number(counts?.work_count ?? 0);
  const approvedCount = Number(counts?.approved_count ?? 0);

  if (collection.status === 'archived') {
    return { status: 'archived', workCount, approvedCount, completedAt: collection.completed_at };
  }

  const status = deriveCollectionStatus(workCount, approvedCount);
  const completedAt = status === 'completed'
    ? collection.completed_at ?? new Date().toISOString()
    : null;
  await tx.execute('UPDATE collections SET status = ?, completed_at = ? WHERE id = ?', [status, completedAt, collectionId]);
  return { status, workCount, approvedCount, completedAt };
}