using Microsoft.EntityFrameworkCore;
using PnvPanel.Application.Common.Interfaces;
using PnvPanel.Application.Common.Messaging;
using PnvPanel.Application.Common.Models;

namespace PnvPanel.Application.Admin.Billing;

public sealed class ListPaymentRequestsQueryHandler(
    IAppDbContext dbContext,
    IIdentityService identityService
) : IQueryHandler<ListPaymentRequestsQuery, Result<PagedList<AdminPaymentRequestDto>>>
{
    public async Task<Result<PagedList<AdminPaymentRequestDto>>> Handle(
        ListPaymentRequestsQuery query,
        CancellationToken cancellationToken
    )
    {
        var page = query.Page <= 0 ? 1 : query.Page;
        var pageSize = query.PageSize is <= 0 or > 100 ? 20 : query.PageSize;

        var requestsQuery = dbContext.PaymentRequests.AsNoTracking();
        if (query.StatusFilter is { } status)
            requestsQuery = requestsQuery.Where(r => r.Status == status);
        if (query.KindFilter is { } kind)
            requestsQuery = requestsQuery.Where(r => r.Kind == kind);
        if (!string.IsNullOrWhiteSpace(query.Search))
        {
            // PaymentRequest хранит только UserId — резолвим совпадающих пользователей ДО пагинации
            // (иначе "поиск по имени" фильтровал бы уже отобранную страницу, а не весь набор).
            var matchingUserIds = await identityService.FindUserIdsByUserNameAsync(
                query.Search.Trim(),
                cancellationToken
            );
            requestsQuery = requestsQuery.Where(r => matchingUserIds.Contains(r.UserId));
        }

        var page1 = await requestsQuery
            .OrderByDescending(r => r.CreatedAt)
            .ToPagedListAsync(page, pageSize, cancellationToken);

        var userNames = await identityService.GetUserNamesAsync(
            page1.Items.Select(r => r.UserId).Distinct().ToList(),
            cancellationToken
        );

        var items = page1
            .Items.Select(r => new AdminPaymentRequestDto(
                r.Id,
                r.UserId,
                userNames.GetValueOrDefault(r.UserId, "?"),
                r.Kind,
                r.Period,
                r.AmountSnapshot,
                r.Status,
                r.CreatedAt
            ))
            .ToList();

        return Result.Success(
            new PagedList<AdminPaymentRequestDto>(items, page1.Total, page1.Page, page1.PageSize)
        );
    }
}