using Microsoft.Win32;
using Microsoft.Extensions.Logging;

namespace CredentialManager.Services;

/// <summary>
/// Informazioni su un DSN ODBC
/// </summary>
public class OdbcDsnInfo
{
    public string Name { get; set; } = string.Empty;
    public string Driver { get; set; } = string.Empty;
    public string? Description { get; set; }
    public bool IsUserDsn { get; set; } // true = User DSN, false = System DSN
    public Dictionary<string, string> Properties { get; set; } = new();
}

/// <summary>
/// Interfaccia per il servizio di discovery DSN ODBC
/// </summary>
public interface IOdbcDsnDiscoveryService
{
    /// <summary>
    /// Ottiene tutti i DSN ODBC configurati (sia User che System)
    /// </summary>
    List<OdbcDsnInfo> GetAllDsn();
    
    /// <summary>
    /// Ottiene solo i DSN utente
    /// </summary>
    List<OdbcDsnInfo> GetUserDsn();
    
    /// <summary>
    /// Ottiene solo i DSN di sistema
    /// </summary>
    List<OdbcDsnInfo> GetSystemDsn();
    
    /// <summary>
    /// Ottiene i dettagli di un DSN specifico
    /// </summary>
    OdbcDsnInfo? GetDsnDetails(string dsnName, bool isUserDsn = true);
    
    /// <summary>
    /// Ottiene la lista dei driver ODBC installati
    /// </summary>
    List<string> GetInstalledDrivers();
}

/// <summary>
/// Servizio per la scoperta e lettura dei DSN ODBC configurati sul sistema
/// </summary>
public class OdbcDsnDiscoveryService : IOdbcDsnDiscoveryService
{
    private readonly ILogger<OdbcDsnDiscoveryService> _logger;

    // Percorsi del registro di Windows per ODBC
    private const string USER_DSN_PATH = @"SOFTWARE\ODBC\ODBC.INI\ODBC Data Sources";
    private const string SYSTEM_DSN_PATH = @"SOFTWARE\ODBC\ODBC.INI\ODBC Data Sources";
    private const string USER_DSN_DETAILS_PATH = @"SOFTWARE\ODBC\ODBC.INI\";
    private const string SYSTEM_DSN_DETAILS_PATH = @"SOFTWARE\ODBC\ODBC.INI\";
    private const string DRIVERS_PATH = @"SOFTWARE\ODBC\ODBCINST.INI\ODBC Drivers";

    public OdbcDsnDiscoveryService(ILogger<OdbcDsnDiscoveryService> logger)
    {
        _logger = logger;
    }

    public List<OdbcDsnInfo> GetAllDsn()
    {
        var allDsn = new List<OdbcDsnInfo>();
        allDsn.AddRange(GetUserDsn());
        allDsn.AddRange(GetSystemDsn());
        return allDsn;
    }

    public List<OdbcDsnInfo> GetUserDsn()
    {
        return GetDsnFromRegistry(Registry.CurrentUser, USER_DSN_PATH, USER_DSN_DETAILS_PATH, true);
    }

    public List<OdbcDsnInfo> GetSystemDsn()
    {
        return GetDsnFromRegistry(Registry.LocalMachine, SYSTEM_DSN_PATH, SYSTEM_DSN_DETAILS_PATH, false);
    }

    public OdbcDsnInfo? GetDsnDetails(string dsnName, bool isUserDsn = true)
    {
        var allDsn = isUserDsn ? GetUserDsn() : GetSystemDsn();
        return allDsn.FirstOrDefault(d => d.Name.Equals(dsnName, StringComparison.OrdinalIgnoreCase));
    }

    public List<string> GetInstalledDrivers()
    {
        var drivers = new List<string>();

        try
        {
            using var key = Registry.LocalMachine.OpenSubKey(DRIVERS_PATH);
            if (key != null)
            {
                foreach (var driverName in key.GetValueNames())
                {
                    var value = key.GetValue(driverName)?.ToString();
                    if (value == "Installed")
                    {
                        drivers.Add(driverName);
                    }
                }
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Errore nella lettura dei driver ODBC dal registro");
        }

        return drivers.OrderBy(d => d).ToList();
    }

    private List<OdbcDsnInfo> GetDsnFromRegistry(RegistryKey rootKey, string dsnPath, string detailsPath, bool isUserDsn)
    {
        var dsnList = new List<OdbcDsnInfo>();

        try
        {
            using var dsnKey = rootKey.OpenSubKey(dsnPath);
            if (dsnKey == null)
            {
                _logger.LogWarning("Chiave registro ODBC non trovata: {Path}", dsnPath);
                return dsnList;
            }

            foreach (var dsnName in dsnKey.GetValueNames())
            {
                try
                {
                    var driver = dsnKey.GetValue(dsnName)?.ToString();
                    if (string.IsNullOrEmpty(driver))
                        continue;

                    var dsnInfo = new OdbcDsnInfo
                    {
                        Name = dsnName,
                        Driver = driver,
                        IsUserDsn = isUserDsn
                    };

                    // Leggi i dettagli del DSN
                    using var detailKey = rootKey.OpenSubKey(detailsPath + dsnName);
                    if (detailKey != null)
                    {
                        foreach (var valueName in detailKey.GetValueNames())
                        {
                            var value = detailKey.GetValue(valueName)?.ToString();
                            if (!string.IsNullOrEmpty(value))
                            {
                                dsnInfo.Properties[valueName] = value;

                                // Popola proprietà comuni
                                if (valueName.Equals("Description", StringComparison.OrdinalIgnoreCase))
                                    dsnInfo.Description = value;
                            }
                        }
                    }

                    dsnList.Add(dsnInfo);
                    _logger.LogDebug("DSN trovato: {Name} ({Driver}) - Type: {Type}", 
                        dsnName, driver, isUserDsn ? "User" : "System");
                }
                catch (Exception ex)
                {
                    _logger.LogWarning(ex, "Errore nella lettura del DSN: {DsnName}", dsnName);
                }
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Errore nella lettura dei DSN ODBC dal registro");
        }

        return dsnList;
    }
}