using System.Linq.Expressions;
using Microsoft.EntityFrameworkCore;

namespace General_Ledger_Service.Repositories
{
    // Shared boilerplate for the GetByIdAsync/ExistsAsync/AddAsync one-liners duplicated across
    // most repositories (01_Full_Development_Plan.md Section 10.4) - same shape as
    // RecursiveTreeQueries.cs: a parameterized static helper, not a generic repository base class
    // (CLAUDE.md Rule 2). Each repository keeps its own public interface/method names and calls
    // this internally only where its own method body is literally this one-line shape.
    internal static class RepositoryHelpers
    {
        public static async Task<T?> GetByIdAsync<T>(DbSet<T> set, params object[] keyValues) where T : class =>
            await set.FindAsync(keyValues);

        public static async Task<bool> ExistsAsync<T>(DbSet<T> set, Expression<Func<T, bool>> predicate) where T : class =>
            await set.AnyAsync(predicate);

        public static async Task<T> AddAsync<T>(DbSet<T> set, T entity) where T : class
        {
            await set.AddAsync(entity);
            return entity;
        }

        // Paging is only applied when the caller explicitly supplies both page and pageSize -
        // no invented defaults (e.g. page=1/pageSize=20) when either is omitted, so a caller that
        // doesn't need paging at a given moment gets the full matching result set back untouched.
        public static IQueryable<T> ApplyPaging<T>(IQueryable<T> query, int? page, int? pageSize)
        {
            if (page.HasValue && pageSize.HasValue)
            {
                query = query.Skip((page.Value - 1) * pageSize.Value).Take(pageSize.Value);
            }

            return query;
        }
    }
}