using System.Collections.Concurrent;
using System.Text.RegularExpressions;
using Npgsql;

namespace FinlyticCore.Utils;

/// <summary>
/// Resolves the crypto subtitle/ticker (e.g. "BTC", "ETH", "SOL") for Trade Republic internal ISINs starting with 'X'.
/// </summary>
public static class CryptoSubtitleResolver
{
    private static readonly ConcurrentDictionary<string, (string Subtitle, string? Name)> _cache = new();

    /// <summary>
    /// Checks if an ISIN is a Trade Republic internal crypto ISIN (starts with 'X') and resolves its Subtitle from DB or heuristic.
    /// </summary>
    public static async Task<(string? Subtitle, string? Name)> ResolveCryptoInfoAsync(
        string isin,
        string? defaultConnectionString = null,
        CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(isin)) return (null, null);

        var cleanIsin = isin.Trim().ToUpperInvariant();
        if (!cleanIsin.StartsWith("X", StringComparison.OrdinalIgnoreCase))
        {
            return (null, null);
        }

        if (_cache.TryGetValue(cleanIsin, out var cached))
        {
            return (cached.Subtitle, cached.Name);
        }

        // 1. Try querying PostgreSQL database (finlytic_assets)
        if (!string.IsNullOrWhiteSpace(defaultConnectionString))
        {
            try
            {
                var assetsConnStr = Regex.Replace(defaultConnectionString, @"Database=[^;]+", "Database=finlytic_assets", RegexOptions.IgnoreCase);
                await using var conn = new NpgsqlConnection(assetsConnStr);
                await conn.OpenAsync(cancellationToken);

                await using var cmd = new NpgsqlCommand(
                    "SELECT \"Subtitle\", \"SearchSubtitle\", \"Name\" FROM \"TradeRepublicAssets\" " +
                    "WHERE \"Isin\" = @isin AND (\"AssetType\" = 'Crypto' OR \"InstrumentCategory\" = 'crypto' OR \"Subtitle\" IS NOT NULL) " +
                    "LIMIT 1",
                    conn);
                cmd.Parameters.AddWithValue("isin", cleanIsin);

                await using var reader = await cmd.ExecuteReaderAsync(cancellationToken);
                if (await reader.ReadAsync(cancellationToken))
                {
                    string? sub = reader.IsDBNull(0) ? null : reader.GetString(0);
                    if (string.IsNullOrWhiteSpace(sub) && !reader.IsDBNull(1))
                    {
                        sub = reader.GetString(1);
                    }

                    string? name = reader.IsDBNull(2) ? null : reader.GetString(2);

                    if (!string.IsNullOrWhiteSpace(sub))
                    {
                        var cleanSub = sub.Trim().ToUpperInvariant();
                        _cache[cleanIsin] = (cleanSub, name);
                        return (cleanSub, name);
                    }
                }
            }
            catch
            {
                // Fall through to heuristic if DB unreachable or different server
            }
        }

        // 2. Heuristic fallback for Trade Republic internal ISIN patterns (e.g. XF000BTC0017 -> BTC)
        var match = Regex.Match(cleanIsin, @"^X[A-Z0-9]*?000([A-Z0-9]{3,6})\d*$");
        if (match.Success)
        {
            var extracted = match.Groups[1].Value;
            _cache[cleanIsin] = (extracted, null);
            return (extracted, null);
        }

        return (null, null);
    }

    /// <summary>
    /// Convenience method returning just the crypto subtitle (e.g. "BTC").
    /// </summary>
    public static async Task<string?> ResolveCryptoSubtitleAsync(
        string isin,
        string? defaultConnectionString = null,
        CancellationToken cancellationToken = default)
    {
        var (sub, _) = await ResolveCryptoInfoAsync(isin, defaultConnectionString, cancellationToken);
        return sub;
    }
}