using Backend.DatabaseHandler;
using Backend.MarketDataRequest;
using Backend.Interface;
using IBApi;
using System.Globalization;

namespace Backend.ServiceHandler
{
	public sealed class MarketDataService
	{
		private readonly IBGatewayControl Gateway;
		private readonly IHistoricalMarketDataCache Cache;
		private int NextRequestId = 1;
		private readonly object Lock = new();

		public MarketDataService(IHistoricalMarketDataCache cache)
		{
			Cache = cache;

			Gateway = new IBGatewayControl();
			try
			{
				Gateway.Start("127.0.0.1", 4002, 1);
			}
			catch
			{
				Console.WriteLine("Invalid connection to IB Gateway. Please ensure gateway is running and connected.");
				Environment.Exit(1);
			}
		}

		private int GetNextRequestId()
		{
			lock (Lock)
			{
				return NextRequestId++;
			}
		}

		public LiveEquitySnapshot GetLiveQuote(string symbol)
		{
			var request = new LiveEquityRequest
			{
				RequestId = GetNextRequestId(),
				Symbol = symbol,
				SecType = "STK",
				Exchange = "SMART",
				PrimaryExchange = "NASDAQ",
				Currency = "USD",
				RegulatorySnapshot = false
			};

			return Gateway.RequestLiveEquityBlocking(request, TimeSpan.FromSeconds(10));
		}

		public async Task<List<object>> GetHistoricalAsync(
			string symbol,
			string endDateTime,
			string duration,
			HistoricalBarSize barSize,
			HistoricalWhatToShow whatToShow = HistoricalWhatToShow.Trades,
			bool useRth = true)
		{
			var bars = await GetHistoricalBarsAsync(
				symbol,
				endDateTime,
				duration,
				barSize,
				whatToShow,
				useRth);

			return bars.Select(b => new
			{
				timestamp = ToIsoUtcString(b.TimestampUtc),
				open = b.Open,
				high = b.High,
				low = b.Low,
				close = b.Close,
				volume = b.Volume
			}).Cast<object>().ToList();
		}

		public async Task<List<object>> GetHistoricalLineAsync(
			string symbol,
			string endDateTime,
			string duration,
			HistoricalBarSize barSize,
			HistoricalWhatToShow whatToShow = HistoricalWhatToShow.Trades,
			bool useRth = true)
		{
			var bars = await GetHistoricalBarsAsync(
				symbol,
				endDateTime,
				duration,
				barSize,
				whatToShow,
				useRth);

			return bars.Select(b => new
			{
				timestamp = ToIsoUtcString(b.TimestampUtc),
				price = b.Close,
				volume = b.Volume
			}).Cast<object>().ToList();
		}

		private async Task<List<HistoricalBarRecord>> GetHistoricalBarsAsync(
			string symbol,
			string endDateTimeIsoUtc,
			string duration,
			HistoricalBarSize barSize,
			HistoricalWhatToShow whatToShow,
			bool useRth)
		{
			var window = HistoricalRequestParser.BuildWindow(endDateTimeIsoUtc, duration, barSize);

			var cachedBars = await Cache.GetBarsAsync(
				symbol,
				barSize,
				whatToShow,
				useRth,
				window.StartUtc,
				window.EndUtc);

			if (cachedBars.Count >= window.ExpectedBarCountMin)
			{
				return cachedBars;
			}

			var request = new HistoricalEquityRequest
			{
				RequestId = GetNextRequestId(),
				Symbol = symbol,
				EndDateTime = ToIbHistoricalEndDateTime(window.EndUtc),
				Duration = NormalizeDuration(duration),
				BarSize = barSize,
				WhatToShow = whatToShow,
				UseRth = useRth,
				KeepUpToDate = false,
				FormatDate = 1
			};

			List<Bar> ibBars = Gateway.RequestHistoricalBlocking(request, TimeSpan.FromSeconds(20));

			var mappedBars = ibBars.Select(b => new HistoricalBarRecord
			{
				Symbol = symbol,
				BarSize = barSize.ToIbString(),
				WhatToShow = whatToShow.ToIbString(),
				UseRth = useRth,
				TimestampUtc = ParseIbBarTimeToUtc(b.Time),
				Open = b.Open,
				High = b.High,
				Low = b.Low,
				Close = b.Close,
				Volume = (long)b.Volume
			})
			.OrderBy(b => b.TimestampUtc)
			.ToList();

			await Cache.UpsertBarsAsync(mappedBars);

			return mappedBars
				.Where(b => b.TimestampUtc >= window.StartUtc && b.TimestampUtc <= window.EndUtc)
				.OrderBy(b => b.TimestampUtc)
				.ToList();
		}

		public (bool Found, string Message) CheckSymbol(string symbol)
	{
		var request = new SymbolLookupRequest
		{
			RequestId = GetNextRequestId(),
			Pattern = symbol
		};

		ContractDescription[] results = Gateway.RequestMatchingSymbolsBlocking(request, TimeSpan.FromSeconds(10));

		// Find exact symbol matches (IBKR pattern search may return partial matches)
		var exactMatches = results
			.Where(c => string.Equals(c.Contract.Symbol, symbol, StringComparison.OrdinalIgnoreCase))
			.ToList();

		bool isStockOrEtf = exactMatches.Any(c =>
			string.Equals(c.Contract.SecType, "STK", StringComparison.OrdinalIgnoreCase) ||
			string.Equals(c.Contract.SecType, "ETF", StringComparison.OrdinalIgnoreCase));

		if (!isStockOrEtf)
			return (false, "This symbol does not belong to any stock or ETF, please try again.");

		bool isNasdaq = exactMatches.Any(c =>
			(string.Equals(c.Contract.SecType, "STK", StringComparison.OrdinalIgnoreCase) ||
			 string.Equals(c.Contract.SecType, "ETF", StringComparison.OrdinalIgnoreCase)) &&
			c.Contract.PrimaryExch.Contains("NASDAQ", StringComparison.OrdinalIgnoreCase));

		if (!isNasdaq)
			return (false, "Unfortunately, this symbol is currently unsupported. We only support NASDAQ listed stocks.");

		return (true, "Symbol found.");
	}

	private static string NormalizeDuration(string duration)
		{
			return duration.Trim().Replace("+", " ");
		}

		private static string ToIsoUtcString(DateTime utc)
		{
			return utc.ToUniversalTime().ToString("yyyy-MM-ddTHH:mm:ssZ", CultureInfo.InvariantCulture);
		}

		private static string ToIbHistoricalEndDateTime(DateTime utc)
		{
			var eastern = GetEasternTimeZone();
			var easternTime = TimeZoneInfo.ConvertTimeFromUtc(utc.ToUniversalTime(), eastern);
			return easternTime.ToString("yyyyMMdd HH:mm:ss", CultureInfo.InvariantCulture) + " US/Eastern";
		}

		private static DateTime ParseIbBarTimeToUtc(string raw)
		{
			if (string.IsNullOrWhiteSpace(raw))
				throw new FormatException("IB bar time is empty.");

			raw = raw.Trim();

			const string easternSuffix = " US/Eastern";
			if (raw.EndsWith(easternSuffix, StringComparison.Ordinal))
			{
				string localPart = raw[..^easternSuffix.Length];

				if (!DateTime.TryParseExact(
						localPart,
						"yyyyMMdd HH:mm:ss",
						CultureInfo.InvariantCulture,
						DateTimeStyles.None,
						out var easternLocal))
				{
					throw new FormatException($"Unable to parse IB datetime portion: {localPart}");
				}

				return TimeZoneInfo.ConvertTimeToUtc(easternLocal, GetEasternTimeZone());
			}

			if (DateTime.TryParseExact(
					raw,
					"yyyyMMdd",
					CultureInfo.InvariantCulture,
					DateTimeStyles.None,
					out var dayOnly))
			{
				// Daily bars: treat as midnight UTC for storage consistency.
				return DateTime.SpecifyKind(dayOnly, DateTimeKind.Utc);
			}

			if (DateTimeOffset.TryParseExact(
					raw,
					new[] { "yyyy-MM-ddTHH:mm:ss'Z'", "O" },
					CultureInfo.InvariantCulture,
					DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal,
					out var iso))
			{
				return iso.UtcDateTime;
			}

			throw new FormatException($"Unable to parse IB bar time: {raw}");
		}

		private static TimeZoneInfo GetEasternTimeZone()
		{
			return TimeZoneInfo.FindSystemTimeZoneById(
				OperatingSystem.IsWindows() ? "Eastern Standard Time" : "America/New_York");
		}

		public void Dispose()
		{
			Gateway.Dispose();
		}

		public void Disconnect()
		{
			Gateway.Disconnect();
		}
	}
}