ANTOOZA-BACKEND/Infrastructure/StockData/KosisHttp.cs

using System.Net.Http.Headers;
using Microsoft.Extensions.Logging;

namespace Infrastructure.StockData;

/// <summary>
/// KOSIS(kosis.kr) OpenAPI 호출 공통 — 인증은 URL query param apiKey (헤더 아님, koreaexim/OpenDART 와 동일 방식).
/// 호출부가 apiKey 를 포함한 완성 URL 을 넘기며, 여기선 Accept json + 간단 3회 재시도(2s/4s 백오프) + 로그 시 키 마스킹만 담당.
/// </summary>
internal static class KosisHttp
{
    public const string ClientName = "Kosis";

    private const int MaxAttempts = 3;

    public static async Task<string> GetStringWithRetryAsync(HttpClient client, string url, ILogger logger, CancellationToken ct)
    {
        for (var attempt = 1; ; attempt++)
        {
            try
            {
                using var request = new HttpRequestMessage(HttpMethod.Get, url);
                request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

                using var response = await client.SendAsync(request, ct);
                response.EnsureSuccessStatusCode();
                return await response.Content.ReadAsStringAsync(ct);
            }
            catch (Exception ex) when (ex is not OperationCanceledException && attempt < MaxAttempts)
            {
                logger.LogWarning(ex, "[Kosis] HTTP 실패 — 재시도 {Attempt}/{Max} (url={Url})", attempt, MaxAttempts, Mask(url));
                await Task.Delay(TimeSpan.FromSeconds(2 * attempt), ct);
            }
        }
    }

    /// <summary>로그용 URL 에서 apiKey 값을 가린다.</summary>
    public static string Mask(string url)
    {
        var idx = url.IndexOf("apiKey=", StringComparison.OrdinalIgnoreCase);

        if (idx < 0)
        {
            return url;
        }

        var start = idx + "apiKey=".Length;
        var end = url.IndexOf('&', start);

        if (end < 0)
        {
            end = url.Length;
        }

        return string.Concat(url.AsSpan(0, start), "***", url.AsSpan(end));
    }
}