using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using Microsoft.EntityFrameworkCore;

namespace Application.Features.Api.Ranking.GetMyRank;

internal sealed class Handler(IAppDbContext db) : IQueryHandler<Query, Response>
{
    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var category = string.IsNullOrWhiteSpace(request.Category) || request.Category == "all" ? null : request.Category;

        var query = db.RankingSnapshot.AsNoTracking()
            .Where(r => r.Type == request.Type && r.Period == request.Period && r.MemberID == request.MemberID);

        query = category == null
            ? query.Where(r => r.Category == null)
            : query.Where(r => r.Category == category);

        var mine = await query.OrderByDescending(r => r.SnapshotAt).FirstOrDefaultAsync(ct);

        if (mine == null)
        {
            return new Response(null, null, null, 0, 0, 0, null);
        }

        int? change = mine.PreviousRank.HasValue ? mine.PreviousRank.Value - mine.Rank : null;

        return new Response(mine.Rank, mine.PreviousRank, change, mine.Score, mine.MoneyAmount, mine.DonorCount, mine.SnapshotAt);
    }
}