using System.Text.Json;
using PineScriptV6;
using Serilog;

namespace Buyer
{
    /// <summary>
    /// Bitget REST API — 캔들 데이터 조회.
    /// GET /api/v2/mix/market/candles
    /// </summary>
    public class BitgetRestClient : IDisposable
    {
        private readonly HttpClient   _http;
        private readonly BitgetConfig _cfg;

        public BitgetRestClient(BitgetConfig cfg)
        {
            _cfg  = cfg;
            _http = new HttpClient
            {
                BaseAddress = new Uri(cfg.RestBaseUrl),
                Timeout     = TimeSpan.FromSeconds(cfg.RestTimeoutSec)
            };
            _http.DefaultRequestHeaders.Add("User-Agent", "Buyer/1.0");
        }

        /// <summary>
        /// 최근 <paramref name="limit"/>개 봉을 가져옵니다.
        /// 반환값은 과거→현재 오름차순으로 정렬됩니다.
        /// </summary>
        public async Task<List<CandleData>> GetCandlesAsync(int limit = 500)
        {
            int safeLimit = Math.Min(limit, 1000);

            // 기존 동작 확인된 파라미터 순서: symbol, granularity, limit, productType
            string url = "/api/v2/mix/market/candles"
                       + $"?symbol={_cfg.Symbol}"
                       + $"&granularity={_cfg.RestGranularity}"
                       + $"&limit={safeLimit}"
                       + $"&productType={_cfg.ProductType}";

            Log.Debug("[REST] 요청: {Url}", url);

            // GetStringAsync는 4xx/5xx 시 본문 없이 예외 → GetAsync로 변경하여 본문 확인
            HttpResponseMessage response;
            string body;
            try
            {
                response = await _http.GetAsync(url);
                body     = await response.Content.ReadAsStringAsync();
            }
            catch (Exception ex)
            {
                Log.Error(ex, "[REST] HTTP 요청 자체 실패 (네트워크 오류)");
                throw;
            }

            // HTTP 오류 시 응답 본문을 로그에 찍고 예외
            if (!response.IsSuccessStatusCode)
            {
                Log.Error("[REST] HTTP {Status} — 응답 본문: {Body}",
                    (int)response.StatusCode, body);
                throw new HttpRequestException(
                    $"HTTP {(int)response.StatusCode}: {body}");
            }

            // JSON 파싱
            using var doc  = JsonDocument.Parse(body);
            var       root = doc.RootElement;

            string code = root.TryGetProperty("code", out var codeEl)
                ? codeEl.GetString() ?? "" : "";

            if (code != "00000")
            {
                string msg = root.TryGetProperty("msg", out var msgEl)
                    ? msgEl.GetString() ?? "" : "";
                Log.Error("[REST] API 오류 code={Code} msg={Msg}  body={Body}",
                    code, msg, body);
                throw new Exception($"Bitget API 오류 code={code} msg={msg}");
            }

            var candles = new List<CandleData>();

            foreach (var item in root.GetProperty("data").EnumerateArray())
            {
                var arr = item.EnumerateArray().ToList();
                if (arr.Count < 6) continue;

                long    ts  = long.Parse(arr[0].GetString()!);
                decimal o   = decimal.Parse(arr[1].GetString()!,
                                System.Globalization.CultureInfo.InvariantCulture);
                decimal h   = decimal.Parse(arr[2].GetString()!,
                                System.Globalization.CultureInfo.InvariantCulture);
                decimal l   = decimal.Parse(arr[3].GetString()!,
                                System.Globalization.CultureInfo.InvariantCulture);
                decimal c   = decimal.Parse(arr[4].GetString()!,
                                System.Globalization.CultureInfo.InvariantCulture);
                decimal vol = decimal.Parse(arr[5].GetString()!,
                                System.Globalization.CultureInfo.InvariantCulture);

                candles.Add(new CandleData
                {
                    Time   = DateTimeOffset.FromUnixTimeMilliseconds(ts),
                    Open   = o,
                    High   = h,
                    Low    = l,
                    Close  = c,
                    Volume = vol
                });
            }

            // Bitget은 최신→과거 순으로 반환 → 오름차순 정렬
            candles.Sort((a, b) => a.Time.CompareTo(b.Time));

            Log.Debug("[REST] 수신 {Count}봉  {From} ~ {To}",
                candles.Count,
                candles.FirstOrDefault()?.Time.ToLocalTime().ToString("yyyy-MM-dd HH:mm") ?? "-",
                candles.LastOrDefault() ?.Time.ToLocalTime().ToString("yyyy-MM-dd HH:mm") ?? "-");

            return candles;
        }

        public void Dispose() => _http.Dispose();
    }
}