bitforum-backend/Application/Features/Api/Crypto/Trade/GetRecent/Handler.cs

using Application.Abstractions.Messaging;
using Application.Abstractions.Cache;
using Application.Abstractions.Crypto;

namespace Application.Features.Api.Crypto.Trade.GetRecent;

public sealed class Handler(IUpbitClient upbit, ICacheService cache) : IQueryHandler<Query, Response>
{
    private static readonly TimeSpan _cacheExpiry = TimeSpan.FromSeconds(5);

    public async Task<Response> Handle(Query request, CancellationToken ct)
    {
        var count = Math.Clamp(request.Count, 1, 100);
        var market = $"KRW-{request.Symbol.ToUpper()}";
        var cacheKey = CacheKeys.CryptoTrades(request.Symbol);

        // 캐시 확인
        var cached = await cache.GetAsync<List<Response.TradeItem>>(cacheKey, ct);
        if (cached is { Count: > 0 })
        {
            return new Response(cached);
        }

        // Upbit REST API 호출
        var trades = await upbit.GetTradesAsync(market, count, ct);

        var items = trades
            .Select(t => new Response.TradeItem(
                t.Timestamp,
                t.TradePrice,
                t.TradeVolume,
                t.AskBid,
                t.SequentialId
            ))
            .ToList();

        // Redis 캐시 저장 (5초)
        if (items.Count > 0)
        {
            await cache.SetAsync(cacheKey, items, _cacheExpiry, ct);
        }

        return new Response(items);
    }
}