using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using UtopiaCanteenSystem.Data;

namespace UtopiaCanteenSystem.Services;

/// <summary>
/// JSON-backed configuration (including remember-me credentials) stored under
/// LocalApplicationData so it survives app updates when deployed from a file server.
/// </summary>
public class ConfigService : IConfigService
{
    private readonly string _configPath;
    private AppConfig _config;

    public ConfigService()
    {
        _configPath = DatabasePath.GetConfigPath();
        _config = LoadConfig();
    }

    public string GetSyncApiEndpoint() => _config.SyncApiEndpoint ?? string.Empty;

    public void SetSyncApiEndpoint(string endpoint)
    {
        _config.SyncApiEndpoint = endpoint ?? string.Empty;
        SaveConfig();
    }

    public bool GetScannerConnected() => _config.ScannerConnected;

    public void SetScannerConnected(bool connected)
    {
        _config.ScannerConnected = connected;
        SaveConfig();
    }

    private const int ScanIntervalDaysMax = 365;
    private const int ScanIntervalHoursMax = 23;
    private const int ScanIntervalMinutesMax = 59;
    private const int ScanIntervalSecondsMax = 59;
    private static readonly TimeSpan ScanIntervalFallback = TimeSpan.FromMinutes(1);

    public int GetScanIntervalDays() => Math.Clamp(_config.ScanIntervalDays, 0, ScanIntervalDaysMax);
    public void SetScanIntervalDays(int value)
    {
        _config.ScanIntervalDays = Math.Clamp(value, 0, ScanIntervalDaysMax);
        SaveConfig();
    }

    public int GetScanIntervalHours() => Math.Clamp(_config.ScanIntervalHours, 0, ScanIntervalHoursMax);
    public void SetScanIntervalHours(int value)
    {
        _config.ScanIntervalHours = Math.Clamp(value, 0, ScanIntervalHoursMax);
        SaveConfig();
    }

    public int GetScanIntervalMinutes() => Math.Clamp(_config.ScanIntervalMinutes, 0, ScanIntervalMinutesMax);
    public void SetScanIntervalMinutes(int value)
    {
        _config.ScanIntervalMinutes = Math.Clamp(value, 0, ScanIntervalMinutesMax);
        SaveConfig();
    }

    public int GetScanIntervalSeconds() => Math.Clamp(_config.ScanIntervalSeconds, 0, ScanIntervalSecondsMax);
    public void SetScanIntervalSeconds(int value)
    {
        _config.ScanIntervalSeconds = Math.Clamp(value, 0, ScanIntervalSecondsMax);
        SaveConfig();
    }

    public TimeSpan GetScanInterval()
    {
        var days = Math.Clamp(_config.ScanIntervalDays, 0, ScanIntervalDaysMax);
        var hours = Math.Clamp(_config.ScanIntervalHours, 0, ScanIntervalHoursMax);
        var minutes = Math.Clamp(_config.ScanIntervalMinutes, 0, ScanIntervalMinutesMax);
        var seconds = Math.Clamp(_config.ScanIntervalSeconds, 0, ScanIntervalSecondsMax);
        var ts = TimeSpan.FromDays(days) + TimeSpan.FromHours(hours) + TimeSpan.FromMinutes(minutes) + TimeSpan.FromSeconds(seconds);
        return ts > TimeSpan.Zero ? ts : ScanIntervalFallback;
    }

    public string GetAdminCardId() => _config.AdminCardId ?? string.Empty;

    public void SetAdminCardId(string cardId)
    {
        _config.AdminCardId = cardId ?? string.Empty;
        SaveConfig();
    }

    public string GetSiteId()
    {
        // Return the configured SiteId as-is. No normalization.
        // Returns empty string if not configured.
       return _config.SiteId ?? string.Empty;
    }

   public void SetSiteId(string siteId)
    {
        // Store the SiteId exactly as provided. No automatic normalization.
        // Caller is responsible for formatting.
        _config.SiteId = siteId ?? string.Empty;
        SaveConfig();
    }

    public void ApplyLocationSiteIdFromAuth(string? locationSiteId)
    {
        if (string.IsNullOrWhiteSpace(locationSiteId))
            return;
        var digits = new string(locationSiteId.Where(char.IsDigit).ToArray());
        if (string.IsNullOrEmpty(digits))
            return;
        SetSiteId("SITE : " + digits);
    }

    public string GetDeviceId()
    {
        //var id = _config.DeviceId ?? string.Empty;
        var id = Environment.MachineName;
        if (string.IsNullOrWhiteSpace(id))
        {
            id = Guid.NewGuid().ToString("N");
            _config.DeviceId = id;
            SaveConfig();
        }
        return id;
    }

    public void SetDeviceId(string deviceId)
    {
        _config.DeviceId = deviceId ?? string.Empty;
        SaveConfig();
    }

    public bool GetRememberAdminCredentials() => _config.RememberAdminCredentials;

    public void SetRememberAdminCredentials(bool remember)
    {
        _config.RememberAdminCredentials = remember;
        SaveConfig();
    }

    public string GetSavedAdminUsername() => _config.SavedAdminUsername ?? string.Empty;

    public void SetSavedAdminUsername(string username)
    {
        _config.SavedAdminUsername = username ?? string.Empty;
        SaveConfig();
    }

    public string GetSavedAdminPassword()
    {
        if (!_config.RememberAdminCredentials)
            return string.Empty;

        var protectedValue = _config.SavedAdminPasswordProtected ?? string.Empty;
        if (string.IsNullOrWhiteSpace(protectedValue))
            return string.Empty;

        try
        {
            var bytes = Convert.FromBase64String(protectedValue);
            var clear = ProtectedData.Unprotect(bytes, null, DataProtectionScope.CurrentUser);
            return Encoding.UTF8.GetString(clear);
        }
        catch
        {
            return string.Empty;
        }
    }

    public void SetSavedAdminPassword(string password)
    {
        if (!_config.RememberAdminCredentials)
        {
            _config.SavedAdminPasswordProtected = string.Empty;
            SaveConfig();
            return;
        }

        try
        {
            var clear = Encoding.UTF8.GetBytes(password ?? string.Empty);
            var protectedBytes = ProtectedData.Protect(clear, null, DataProtectionScope.CurrentUser);
            _config.SavedAdminPasswordProtected = Convert.ToBase64String(protectedBytes);
        }
        catch
        {
            _config.SavedAdminPasswordProtected = string.Empty;
        }

        SaveConfig();
    }

    /// <summary>
    /// Returns MySQL connection string for sync. Set via appsettings.json (copy from appsettings.example.json).
    /// No default credentials; returns empty if not configured.
    /// </summary>
    public string GetMySqlConnectionString() => (_config.MySqlConnectionString ?? string.Empty).Trim();

    public void SetMySqlConnectionString(string connectionString)
    {
        _config.MySqlConnectionString = connectionString ?? string.Empty;
        SaveConfig();
    }

    //public string GetHrmsLookupConnectionString() => (_config.HrmsLookupConnectionString ?? string.Empty).Trim();

    public string GetHrmsLookupConnectionString()
    {
        var hrms = (_config.HrmsLookupConnectionString ?? string.Empty).Trim();
        if (!string.IsNullOrWhiteSpace(hrms))
            return hrms;

        // fallback to production/AWS connection string
        return GetMySqlConnectionString();
    }

    public void SetHrmsLookupConnectionString(string connectionString)
    {
        _config.HrmsLookupConnectionString = connectionString ?? string.Empty;
        SaveConfig();
    }

    private AppConfig LoadConfig()
    {
        try
        {
           if (!File.Exists(_configPath))
            {
                System.Diagnostics.Debug.WriteLine("[ConfigService] Config file not found. Creating with defaults.");
               var defaults = new AppConfig();
                SaveConfig(defaults);
               return defaults;
            }

           var json = File.ReadAllText(_configPath);
           var config = JsonSerializer.Deserialize<AppConfig>(json);
           config ??= new AppConfig();
            MigrateScanIntervalFromSecondsIfNeeded(config);
            
            System.Diagnostics.Debug.WriteLine($"[ConfigService] Config loaded from {_configPath}");
            System.Diagnostics.Debug.WriteLine($"[ConfigService] SiteId: '{config.SiteId}' (empty=not configured)");
            System.Diagnostics.Debug.WriteLine($"[ConfigService] MySqlConnectionString: {(string.IsNullOrWhiteSpace(config.MySqlConnectionString) ? "NOT CONFIGURED" : MaskConnectionString(config.MySqlConnectionString))}");
            System.Diagnostics.Debug.WriteLine($"[ConfigService] HrmsLookupConnectionString: {(string.IsNullOrWhiteSpace(config.HrmsLookupConnectionString) ? "NOT CONFIGURED" : MaskConnectionString(config.HrmsLookupConnectionString))}");
            
           return config;
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine($"[ConfigService] ERROR loading config: {ex.Message}");
           return new AppConfig();
        }
    }

    /// <summary>
    /// One-time migration: if old ScanTimeoutSeconds is set and new D/H/M are all zero, convert and persist.
    /// </summary>
    private void MigrateScanIntervalFromSecondsIfNeeded(AppConfig config)
    {
        var legacySeconds = config.ScanTimeoutSeconds;
        if (legacySeconds <= 0)
            return;
        var d = config.ScanIntervalDays;
        var h = config.ScanIntervalHours;
        var m = config.ScanIntervalMinutes;
        var s = config.ScanIntervalSeconds;
        if (d != 0 || h != 0 || m != 0 || s != 0)
            return; // Already using new format

        var totalSeconds = Math.Max(0, legacySeconds);
        var days = Math.Min(totalSeconds / 86400, ScanIntervalDaysMax);
        var remainder = totalSeconds % 86400;
        var hours = Math.Min(remainder / 3600, ScanIntervalHoursMax);
        remainder %= 3600;
        var minutes = Math.Min(remainder / 60, ScanIntervalMinutesMax);
        var seconds = Math.Min(remainder % 60, ScanIntervalSecondsMax);
        if (days == 0 && hours == 0 && minutes == 0 && seconds == 0)
            seconds = 1;

        config.ScanIntervalDays = days;
        config.ScanIntervalHours = hours;
        config.ScanIntervalMinutes = minutes;
        config.ScanIntervalSeconds = seconds;
        config.ScanTimeoutSeconds = 0;
        _config = config;
        SaveConfig(config);
    }

    private void SaveConfig()
    {
        SaveConfig(_config);
    }

    private void SaveConfig(AppConfig config)
    {
        try
        {
            // Log what's being saved
            System.Diagnostics.Debug.WriteLine($"[ConfigService] Saving config...");
            System.Diagnostics.Debug.WriteLine($"[ConfigService]   SiteId: '{_config.SiteId}'");
            System.Diagnostics.Debug.WriteLine($"[ConfigService]   MySqlConnectionString: {(string.IsNullOrWhiteSpace(_config.MySqlConnectionString) ? "NOT CONFIGURED" : MaskConnectionString(_config.MySqlConnectionString))}");
            System.Diagnostics.Debug.WriteLine($"[ConfigService]   HrmsLookupConnectionString: {(string.IsNullOrWhiteSpace(_config.HrmsLookupConnectionString) ? "NOT CONFIGURED" : MaskConnectionString(_config.HrmsLookupConnectionString))}");
            
           var json = JsonSerializer.Serialize(config, new JsonSerializerOptions
            {
                WriteIndented = true
            });
            File.WriteAllText(_configPath, json);
            System.Diagnostics.Debug.WriteLine($"[ConfigService] Config saved to {_configPath}");
        }
        catch (Exception ex)
        {
            System.Diagnostics.Debug.WriteLine($"[ConfigService] ERROR saving config: {ex.Message}");
        }
    }

    /// <summary>
    /// Masks sensitive connection string values for logging.
    /// Shows server and database but hides password.
    /// </summary>
    private static string MaskConnectionString(string connectionString)
    {
       if (string.IsNullOrWhiteSpace(connectionString))
           return string.Empty;

        // Simple masking: show everything before 'Password=' and mask the rest
       var passwordIndex = connectionString.IndexOf("Password=", StringComparison.OrdinalIgnoreCase);
       if (passwordIndex >= 0)
        {
           var semicolonAfterPassword = connectionString.IndexOf(';', passwordIndex);
           if (semicolonAfterPassword >= 0)
            {
               return connectionString.Substring(0, passwordIndex) + "Password=***" + connectionString.Substring(semicolonAfterPassword);
            }
           return connectionString.Substring(0, passwordIndex) + "Password=***";
        }

       return connectionString; // No password found, return as-is
    }

    private sealed class AppConfig
    {
        public string SyncApiEndpoint { get; set; } = "https://api.example.com/uind/sync";
        public bool ScannerConnected { get; set; } = false;
        /// <summary>Legacy: migrated to ScanIntervalDays/Hours/Minutes on first load. Kept for JSON deserialization.</summary>
        public int ScanTimeoutSeconds { get; set; } = 0;
        public int ScanIntervalDays { get; set; } = 0;
        public int ScanIntervalHours { get; set; } = 0;
        public int ScanIntervalMinutes { get; set; } = 0;
        public int ScanIntervalSeconds { get; set; } = 2;
        public string AdminCardId { get; set; } = "ADMIN";
        public string SiteId { get; set; } = string.Empty; // No default - must be explicitly configured
        public string DeviceId { get; set; } = string.Empty;

        // Admin credential persistence (optional).
        public bool RememberAdminCredentials { get; set; } = false;
        public string SavedAdminUsername { get; set; } = string.Empty;
        public string SavedAdminPasswordProtected { get; set; } = string.Empty;

        // MySQL connection string for sync. Set in appsettings.json (see appsettings.example.json). No default.
        public string MySqlConnectionString { get; set; } = string.Empty;

        // Local HRMS MySQL for employee lookup by RFID. Separate from production sync.
        public string HrmsLookupConnectionString { get; set; } = string.Empty;
    }
}