using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.Threading;
using System.Threading.Tasks;
using System.ServiceProcess;

namespace HikvisionAttendanceService;

public sealed class HikvisionAttendanceWindowsService : ServiceBase
{
    private CancellationTokenSource? _cts;
    private Task? _mainTask;
    private HikvisionAttendanceManager? _manager;

    public HikvisionAttendanceWindowsService()
    {
        ServiceName = "HikvisionAttendanceService";
        CanStop = true;
        CanPauseAndContinue = false;
        AutoLog = false; // we use our own file logger
    }

    protected override void OnStart(string[] args)
    {
        _cts = new CancellationTokenSource();
        Environment.CurrentDirectory = AppContext.BaseDirectory;

        var baseDir = AppContext.BaseDirectory;
        var configPath = Path.Combine(baseDir, "serviceconfig.json");
        if (!File.Exists(configPath))
        {
            // Fallback to appsettings.json (developer convenience).
            configPath = Path.Combine(baseDir, "appsettings.json");
        }

        var config = HikvisionServiceConfig.Load(configPath);
        var logger = new FileLogger(config.LogDirectory);
        logger.Ops(OpsMarkers.Service, "WINDOWS SERVICE OnStart time=" + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") +
            " config=\"" + configPath + "\"");

        _manager = new HikvisionAttendanceManager(config, logger);
        _mainTask = _manager.RunAsync(_cts.Token);
    }

    protected override void OnStop()
    {
        if (_cts is null)
        {
            return;
        }

        try
        {
            _cts.Cancel();
        }
        catch
        {
            // ignore
        }

        if (_mainTask is not null)
        {
            try { _mainTask.Wait(TimeSpan.FromSeconds(20)); } catch { /* ignore */ }
        }

        _manager?.Dispose();
        _manager = null;
    }

    [DataContract]
    internal sealed class HikvisionServiceConfig
    {
        [DataMember]
        public string LogDirectory { get; set; } = @"C:\Users\Public\HikvisionAttendanceService";

        [DataMember]
        public string SqlConnectionString { get; set; } = "";

        [DataMember]
        public bool EnableDbIntegration { get; set; }

        [DataMember]
        public bool EnableDbMachineLoading { get; set; }

        [DataMember]
        public bool PreferDbMachinesOverConfig { get; set; }

        [DataMember]
        public bool EnableAttendanceDbPersistence { get; set; }

        [DataMember]
        public bool EnableTemplateDbPersistence { get; set; }

        /// <summary>When true, pull face templates from device and save to DB (DEVICE -&gt; DATABASE). Prefer only one template direction enabled at a time.</summary>
        [DataMember]
        public bool EnableTemplateDeviceToDbSync { get; set; }

        /// <summary>When true, push face templates from DB to device (DATABASE -&gt; DEVICE). Prefer only one template direction enabled at a time.</summary>
        [DataMember]
        public bool EnableTemplateDbToDeviceSync { get; set; }

        [DataMember]
        public bool KeepAttendanceFileExport { get; set; } = true;

        [DataMember]
        public bool KeepTemplateFiles { get; set; } = true;

        [DataMember]
        public string DbHost { get; set; } = "";

        [DataMember]
        public int DbPort { get; set; } = 3306;

        [DataMember]
        public string DbName { get; set; } = "hrms";

        [DataMember]
        public string DbUsername { get; set; } = "";

        [DataMember]
        public string DbPassword { get; set; } = "";

        [DataMember]
        public string DbConnectionString { get; set; } = "";

        /// <summary>When true and SqlConnectionString is set, attendance rows are INSERTed. Default false until schema is finalized.</summary>
        [DataMember]
        public bool EnableDatabasePersistence { get; set; }

        /// <summary>Plain-text attendance log. Empty = LogDirectory\attendance_records.txt</summary>
        [DataMember]
        public string AttendanceTextFilePath { get; set; } = "";

        [DataMember]
        public string AttendanceTableName { get; set; } = "dbo.HikvisionAttendanceEvents";

        [DataMember]
        public string HrExportPath { get; set; } = "";

        [DataMember]
        public bool AutoDoorControlOnSuccess { get; set; } = true;

        [DataMember]
        public int AutoDoorCloseDelaySeconds { get; set; } = 3;

        [DataMember]
        public List<DeviceConfig> Devices { get; set; } = new List<DeviceConfig>();

        /// <summary>0 = all majors (per GetACSEvent demo).</summary>
        [DataMember]
        public uint AcsHistoryMajor { get; set; }

        /// <summary>0 = all minors.</summary>
        [DataMember]
        public uint AcsHistoryMinor { get; set; }

        /// <summary>0 = disabled. Otherwise interval in minutes for NET_DVR_GET_ACS_EVENT sync.</summary>
        [DataMember]
        public int HistoricalFetchIntervalMinutes { get; set; }

        [DataMember]
        public int HistoricalFetchLookbackMinutes { get; set; } = 1440;

        /// <summary>Enable/disable scheduled attendance historical sync job.</summary>
        [DataMember]
        public bool EnableAttendanceSync { get; set; } = true;

        /// <summary>Scheduled attendance sync interval in minutes (default 5).</summary>
        [DataMember]
        public int AttendanceSyncIntervalMinutes { get; set; } = 5;

        /// <summary>
        /// When true, user-info/faceURL lookups use direct ISAPI HTTP (Digest auth) instead of SDK STDXML wrappers.
        /// Default true because some terminals return richer UserInfo fields (e.g. faceURL) over HTTP.
        /// </summary>
        [DataMember]
        public bool UseIsapiHttpForUserInfo { get; set; } = true;

        /// <summary>HTTP port for direct ISAPI calls. 80 by default.</summary>
        [DataMember]
        public int IsapiHttpPort { get; set; } = 80;

        /// <summary>When true, periodically syncs users and face images from <see cref="SourceDeviceId"/> to <see cref="TargetDeviceIds"/> via ISAPI HTTP (Digest).</summary>
        [DataMember]
        public bool EnableUserSync { get; set; }

        /// <summary>Interval between user/face sync cycles. Ignored if &lt;= 0 or sync is disabled.</summary>
        [DataMember]
        public int SyncIntervalMinutes { get; set; } = 60;

        /// <summary>Enable/disable scheduled face/fingerprint template export/fetch job.</summary>
        [DataMember]
        public bool EnableTemplateFetch { get; set; }

        /// <summary>Template fetch interval in hours (default 4).</summary>
        [DataMember]
        public int TemplateFetchIntervalHours { get; set; } = 4;

        [DataMember]
        public string MachineScopeMode { get; set; } = "CENTRAL";

        [DataMember]
        public List<string> ScopedMachineIps { get; set; } = new List<string>();

        /// <summary>DeviceId (from <see cref="DeviceConfig.DeviceId"/>) to treat as the authoritative user source.</summary>
        [DataMember]
        public string SourceDeviceId { get; set; } = "";

        [DataMember]
        public string SourceMachineIp { get; set; } = "";

        /// <summary>DeviceIds to push missing users/faces onto.</summary>
        [DataMember]
        public List<string> TargetDeviceIds { get; set; } = new List<string>();

        [DataMember]
        public List<string> TargetMachineIps { get; set; } = new List<string>();

        [DataMember]
        public List<string> SyncEmployeeIds { get; set; } = new List<string>();

        /// <summary>Optional directory to persist downloaded source face images for auditing or re-upload. Empty = skip file save.</summary>
        [DataMember]
        public string UserSyncFaceCacheDirectory { get; set; } = "";

        [DataMember]
        public UserSyncPoliciesConfig SyncPolicies { get; set; } = new UserSyncPoliciesConfig();

        public static HikvisionServiceConfig Load(string configPath)
        {
            // Minimal JSON config loader (no external packages).
            try
            {
                if (!File.Exists(configPath))
                {
                    var missingCfg = new HikvisionServiceConfig
                    {
                        LogDirectory = @"C:\Users\Public\HikvisionAttendanceService",
                        SqlConnectionString = "",
                        EnableDbIntegration = false,
                        EnableDbMachineLoading = false,
                        PreferDbMachinesOverConfig = false,
                        EnableAttendanceDbPersistence = false,
                        EnableTemplateDbPersistence = false,
                        EnableTemplateDeviceToDbSync = false,
                        EnableTemplateDbToDeviceSync = false,
                        KeepAttendanceFileExport = true,
                        KeepTemplateFiles = true,
                        DbHost = "",
                        DbPort = 3306,
                        DbName = "hrms",
                        DbUsername = "",
                        DbPassword = "",
                        DbConnectionString = "",
                        EnableDatabasePersistence = false,
                        AttendanceTextFilePath = "",
                        AttendanceTableName = "dbo.HikvisionAttendanceEvents",
                        HrExportPath = "",
                        AutoDoorControlOnSuccess = true,
                        AutoDoorCloseDelaySeconds = 3,
                        AcsHistoryMajor = 0,
                        AcsHistoryMinor = 0,
                        HistoricalFetchIntervalMinutes = 0,
                        HistoricalFetchLookbackMinutes = 1440,
                        EnableAttendanceSync = true,
                        AttendanceSyncIntervalMinutes = 5,
                        UseIsapiHttpForUserInfo = true,
                        IsapiHttpPort = 8000,
                        EnableTemplateFetch = false,
                        TemplateFetchIntervalHours = 4,
                        MachineScopeMode = "CENTRAL",
                        ScopedMachineIps = new List<string>(),
                        EnableUserSync = false,
                        SyncIntervalMinutes = 60,
                        SourceDeviceId = "",
                        SourceMachineIp = "",
                        TargetDeviceIds = new List<string>(),
                        TargetMachineIps = new List<string>(),
                        SyncEmployeeIds = new List<string>(),
                        UserSyncFaceCacheDirectory = "",
                        SyncPolicies = new UserSyncPoliciesConfig()
                    };
                    ApplyDeviceSettingsOverlay(missingCfg, configPath);
                    NormalizeLoadedDeviceConfig(missingCfg);
                    return missingCfg;
                }

                var raw = File.ReadAllText(configPath);
                var serializer = new DataContractJsonSerializer(typeof(HikvisionServiceConfig));

                // First attempt: strict JSON.
                try
                {
                    using (var ms = new MemoryStream(Encoding.UTF8.GetBytes(raw)))
                    {
                        var cfg = (HikvisionServiceConfig)serializer.ReadObject(ms);
                        ApplyEnvironmentOverrides(cfg);
                        ApplyDeviceSettingsOverlay(cfg, configPath);
                        NormalizeLoadedDeviceConfig(cfg);
                        return cfg;
                    }
                }
                catch
                {
                    // Second attempt: tolerate // and /* */ comments (your serviceconfig.json includes them).
                    var sanitized = StripJsonComments(raw);
                    using (var ms = new MemoryStream(Encoding.UTF8.GetBytes(sanitized)))
                    {
                        var cfg = (HikvisionServiceConfig)serializer.ReadObject(ms);
                        ApplyEnvironmentOverrides(cfg);
                        ApplyDeviceSettingsOverlay(cfg, configPath);
                        NormalizeLoadedDeviceConfig(cfg);
                        return cfg;
                    }
                }
            }
            catch
            {
                var fallbackCfg = new HikvisionServiceConfig
                {
                    LogDirectory = @"C:\Users\Public\HikvisionAttendanceService",
                    SqlConnectionString = "",
                    EnableDbIntegration = false,
                    EnableDbMachineLoading = false,
                    PreferDbMachinesOverConfig = false,
                    EnableAttendanceDbPersistence = false,
                    EnableTemplateDbPersistence = false,
                    EnableTemplateDeviceToDbSync = false,
                    EnableTemplateDbToDeviceSync = false,
                    KeepAttendanceFileExport = true,
                    KeepTemplateFiles = true,
                    DbHost = "",
                    DbPort = 3306,
                    DbName = "hrms",
                    DbUsername = "",
                    DbPassword = "",
                    DbConnectionString = "",
                    EnableDatabasePersistence = false,
                    AttendanceTextFilePath = "",
                    AttendanceTableName = "dbo.HikvisionAttendanceEvents",
                    HrExportPath = "",
                    AutoDoorControlOnSuccess = true,
                    AutoDoorCloseDelaySeconds = 3,
                    AcsHistoryMajor = 0,
                    AcsHistoryMinor = 0,
                    HistoricalFetchIntervalMinutes = 0,
                    HistoricalFetchLookbackMinutes = 1440,
                    EnableAttendanceSync = true,
                    AttendanceSyncIntervalMinutes = 5,
                    UseIsapiHttpForUserInfo = true,
                    IsapiHttpPort = 80,
                    EnableTemplateFetch = false,
                    TemplateFetchIntervalHours = 4,
                    MachineScopeMode = "CENTRAL",
                    ScopedMachineIps = new List<string>(),
                    EnableUserSync = false,
                    SyncIntervalMinutes = 60,
                    SourceDeviceId = "",
                    SourceMachineIp = "",
                    TargetDeviceIds = new List<string>(),
                    TargetMachineIps = new List<string>(),
                    SyncEmployeeIds = new List<string>(),
                    UserSyncFaceCacheDirectory = "",
                    SyncPolicies = new UserSyncPoliciesConfig()
                };
                ApplyDeviceSettingsOverlay(fallbackCfg, configPath);
                NormalizeLoadedDeviceConfig(fallbackCfg);
                return fallbackCfg;
            }
        }

        private static string StripJsonComments(string input)
        {
            if (string.IsNullOrEmpty(input))
                return input;

            var sb = new StringBuilder(input.Length);
            bool inString = false;
            char stringQuote = '\0';
            bool escape = false;

            for (int i = 0; i < input.Length; i++)
            {
                char c = input[i];

                if (inString)
                {
                    sb.Append(c);
                    if (escape)
                    {
                        escape = false;
                        continue;
                    }

                    if (c == '\\')
                    {
                        escape = true;
                        continue;
                    }

                    if (c == stringQuote)
                    {
                        inString = false;
                        stringQuote = '\0';
                    }

                    continue;
                }

                // Not in a string
                if (c == '"' || c == '\'')
                {
                    // JSON strings are double-quoted; single-quote is not valid JSON,
                    // but supporting it here doesn't hurt for comment stripping.
                    inString = true;
                    stringQuote = c;
                    sb.Append(c);
                    continue;
                }

                // Line comment //
                if (c == '/' && i + 1 < input.Length && input[i + 1] == '/')
                {
                    i += 1; // consume second '/'
                    // skip until newline or end
                    while (i + 1 < input.Length)
                    {
                        i += 1;
                        if (input[i] == '\r' || input[i] == '\n')
                        {
                            sb.Append(input[i]);
                            break;
                        }
                    }
                    continue;
                }

                // Block comment /* ... */
                if (c == '/' && i + 1 < input.Length && input[i + 1] == '*')
                {
                    i += 1; // consume '*'
                    while (i + 1 < input.Length)
                    {
                        i += 1;
                        if (input[i] == '*' && i + 1 < input.Length && input[i + 1] == '/')
                        {
                            i += 1; // consume '/'
                            break;
                        }
                    }
                    continue;
                }

                sb.Append(c);
            }

            return sb.ToString();
        }

        private static void ApplyEnvironmentOverrides(HikvisionServiceConfig cfg)
        {
            if (cfg == null)
                return;

            string ReadEnv(string key) => Environment.GetEnvironmentVariable(key) ?? "";

            var cs = ReadEnv("HIKVISION_DB_CONNECTION_STRING");
            var host = ReadEnv("HIKVISION_DB_HOST");
            var user = ReadEnv("HIKVISION_DB_USERNAME");
            var pass = ReadEnv("HIKVISION_DB_PASSWORD");
            var dbName = ReadEnv("HIKVISION_DB_NAME");
            var dbPort = ReadEnv("HIKVISION_DB_PORT");

            if (!string.IsNullOrWhiteSpace(cs))
                cfg.DbConnectionString = cs.Trim();
            if (!string.IsNullOrWhiteSpace(host))
                cfg.DbHost = host.Trim();
            if (!string.IsNullOrWhiteSpace(user))
                cfg.DbUsername = user.Trim();
            if (!string.IsNullOrWhiteSpace(pass))
                cfg.DbPassword = pass;
            if (!string.IsNullOrWhiteSpace(dbName))
                cfg.DbName = dbName.Trim();
            if (int.TryParse(dbPort, out var parsedPort) && parsedPort > 0)
                cfg.DbPort = parsedPort;
        }

        /// <summary>
        /// Overlays device-scope / template-direction settings from DeviceSettings.config
        /// (same folder as serviceconfig.json). Property names and behavior are unchanged.
        /// </summary>
        private static void ApplyDeviceSettingsOverlay(HikvisionServiceConfig cfg, string serviceConfigPath)
        {
            if (cfg == null)
                return;

            string dir;
            try
            {
                dir = Path.GetDirectoryName(Path.GetFullPath(serviceConfigPath ?? "")) ?? "";
            }
            catch
            {
                dir = "";
            }
            if (string.IsNullOrWhiteSpace(dir))
                dir = AppContext.BaseDirectory;

            var path = Path.Combine(dir, "DeviceSettings.config");
            if (!File.Exists(path))
                return;

            try
            {
                var raw = File.ReadAllText(path);
                var serializer = new DataContractJsonSerializer(typeof(DeviceSettingsFile));
                DeviceSettingsFile? overlay;
                using (var ms = new MemoryStream(Encoding.UTF8.GetBytes(raw)))
                    overlay = serializer.ReadObject(ms) as DeviceSettingsFile;
                if (overlay == null)
                    return;

                if (!string.IsNullOrWhiteSpace(overlay.MachineScopeMode))
                    cfg.MachineScopeMode = overlay.MachineScopeMode;
                if (overlay.ScopedMachineIps != null)
                    cfg.ScopedMachineIps = new List<string>(overlay.ScopedMachineIps);
                cfg.EnableTemplateDeviceToDbSync = overlay.EnableTemplateDeviceToDbSync;
                cfg.EnableTemplateDbToDeviceSync = overlay.EnableTemplateDbToDeviceSync;
                if (overlay.SourceMachineIp != null)
                    cfg.SourceMachineIp = overlay.SourceMachineIp;
                if (overlay.TargetMachineIps != null)
                    cfg.TargetMachineIps = new List<string>(overlay.TargetMachineIps);
                if (overlay.SyncEmployeeIds != null)
                    cfg.SyncEmployeeIds = new List<string>(overlay.SyncEmployeeIds);
            }
            catch
            {
                // Keep serviceconfig / defaults if DeviceSettings.config cannot be parsed.
            }
        }

        private static void NormalizeLoadedDeviceConfig(HikvisionServiceConfig? cfg)
        {
            if (cfg == null)
                return;

            cfg.MachineScopeMode = string.IsNullOrWhiteSpace(cfg.MachineScopeMode)
                ? "CENTRAL"
                : cfg.MachineScopeMode.Trim().ToUpperInvariant();
            cfg.SourceDeviceId = DeviceIdentity.NormalizeConfigured(cfg.SourceDeviceId);
            cfg.SourceMachineIp = string.IsNullOrWhiteSpace(cfg.SourceMachineIp) ? "" : cfg.SourceMachineIp.Trim();
            cfg.UserSyncFaceCacheDirectory = string.IsNullOrWhiteSpace(cfg.UserSyncFaceCacheDirectory)
                ? ""
                : cfg.UserSyncFaceCacheDirectory.Trim();
            cfg.SyncPolicies ??= new UserSyncPoliciesConfig();
            cfg.ScopedMachineIps ??= new List<string>();
            for (int i = 0; i < cfg.ScopedMachineIps.Count; i++)
                cfg.ScopedMachineIps[i] = (cfg.ScopedMachineIps[i] ?? "").Trim();
            if (cfg.TargetDeviceIds == null)
                cfg.TargetDeviceIds = new List<string>();
            else
            {
                for (int i = 0; i < cfg.TargetDeviceIds.Count; i++)
                    cfg.TargetDeviceIds[i] = DeviceIdentity.NormalizeConfigured(cfg.TargetDeviceIds[i]);
            }
            cfg.TargetMachineIps ??= new List<string>();
            for (int i = 0; i < cfg.TargetMachineIps.Count; i++)
                cfg.TargetMachineIps[i] = (cfg.TargetMachineIps[i] ?? "").Trim();
            cfg.SyncEmployeeIds ??= new List<string>();
            for (int i = 0; i < cfg.SyncEmployeeIds.Count; i++)
                cfg.SyncEmployeeIds[i] = (cfg.SyncEmployeeIds[i] ?? "").Trim();

            if (cfg.Devices == null)
                return;

            foreach (var d in cfg.Devices)
            {
                d.DeviceId = DeviceIdentity.NormalizeConfigured(d.DeviceId);
                if (!string.IsNullOrWhiteSpace(d.Ip))
                    d.Ip = d.Ip.Trim();
            }
        }
    }

    /// <summary>Device-scope and template-direction settings loaded from DeviceSettings.config.</summary>
    [DataContract]
    internal sealed class DeviceSettingsFile
    {
        [DataMember]
        public string MachineScopeMode { get; set; } = "CENTRAL";

        [DataMember]
        public List<string> ScopedMachineIps { get; set; } = new List<string>();

        [DataMember]
        public bool EnableTemplateDeviceToDbSync { get; set; }

        [DataMember]
        public bool EnableTemplateDbToDeviceSync { get; set; }

        [DataMember]
        public string SourceMachineIp { get; set; } = "";

        [DataMember]
        public List<string> TargetMachineIps { get; set; } = new List<string>();

        [DataMember]
        public List<string> SyncEmployeeIds { get; set; } = new List<string>();
    }

    /// <summary>Policies for multi-device user/face sync (ISAPI). Loaded from service JSON only.</summary>
    [DataContract]
    internal sealed class UserSyncPoliciesConfig
    {
        /// <summary>When true, attempts UserInfo/Modify on targets when name or validity differs from source.</summary>
        [DataMember]
        public bool UpdateExistingUserFields { get; set; }

        /// <summary>When true (default), face upload runs only if target has no enrolled face (numOfFace == 0).</summary>
        [DataMember]
        public bool UploadFaceIfMissingOnly { get; set; } = true;

        /// <summary>When true, deletes users on targets that are not present on the source (destructive).</summary>
        [DataMember]
        public bool DeleteOnTargetIfMissingInSource { get; set; }

        /// <summary>Face library type for FaceDataRecord upload (device-specific; Pro Series often uses blackFD).</summary>
        [DataMember]
        public string FaceLibType { get; set; } = "blackFD";

        /// <summary>Face library ID for FaceDataRecord upload.</summary>
        [DataMember]
        public string FaceLibraryFdId { get; set; } = "1";

        /// <summary>Max retries per HTTP call (exponential backoff between attempts).</summary>
        [DataMember]
        public int HttpMaxRetries { get; set; } = 3;
    }

    [DataContract]
    internal sealed class DeviceConfig
    {
        [DataMember]
        public string DeviceId { get; set; } = "";

        [DataMember]
        public string Ip { get; set; } = "";

        [DataMember]
        public int Port { get; set; } = 8000;

        [DataMember]
        public string Username { get; set; } = "";

        [DataMember]
        public string Password { get; set; } = "";

        // Door index used by NET_DVR_ControlGateway for manual open/close.
        [DataMember]
        public int GatewayDoorIndex { get; set; } = 1;

        // For template enrollment/sync (optional).
        [DataMember]
        public int FingerPrintReaderNo { get; set; } = 1;

        [DataMember]
        public int FaceReaderNo { get; set; } = 1;

        /// <summary>Optional: documented in JSON for support logs (not sent to SDK).</summary>
        [DataMember]
        public string Model { get; set; } = "";

        [DataMember]
        public string SerialNumber { get; set; } = "";

        [DataMember]
        public string FirmwareVersion { get; set; } = "";

        [DataMember]
        public string SubnetMask { get; set; } = "";

        [DataMember]
        public string DefaultGateway { get; set; } = "";
    }

    internal sealed class FileLogger : IDisposable
    {
        private readonly string _directory;
        private readonly string _internalLogsDirectory;
        private readonly string _attendanceBizDirectory;
        private readonly string _templateBizDirectory;
        private readonly string _userSyncBizDirectory;
        private readonly string _unreachableBizDirectory;
        private readonly object _sync = new();
        public readonly BizSessionTotals Totals = new BizSessionTotals();

        public FileLogger(string directory)
        {
            _directory = directory;
            Directory.CreateDirectory(_directory);
            var logsRoot = Path.Combine(_directory, "logs");
            _internalLogsDirectory = Path.Combine(_directory, "internal_logs");
            _attendanceBizDirectory = Path.Combine(logsRoot, "attendance_logs");
            _templateBizDirectory = Path.Combine(logsRoot, "template_fetching_logs");
            _userSyncBizDirectory = Path.Combine(logsRoot, "user_sync_logs");
            _unreachableBizDirectory = Path.Combine(_internalLogsDirectory, "unreachable_devices");
            Directory.CreateDirectory(_internalLogsDirectory);
            Directory.CreateDirectory(_attendanceBizDirectory);
            Directory.CreateDirectory(_templateBizDirectory);
            Directory.CreateDirectory(_userSyncBizDirectory);
            Directory.CreateDirectory(_unreachableBizDirectory);
        }

        public string LogDirectory => _directory;

        public void Info(string message) => WriteInternal("INFO", message);
        public void Warn(string message) => WriteInternal("WARN", message);
        public void Error(string message, Exception? ex = null) =>
            WriteInternal("ERROR", message + (ex is null ? "" : $" | {ex}"));

        /// <summary>Technical diagnostics only — never written to business logs/.</summary>
        public void JobInfo(string jobName, string message) => WriteInternalDiag(jobName, "INFO", message);
        public void JobWarn(string jobName, string message) => WriteInternalDiag(jobName, "WARN", message);
        public void JobError(string jobName, string message) => WriteInternalDiag(jobName, "ERROR", message);
        public void Diag(string jobName, string message) => WriteInternalDiag(jobName, "INFO", message);

        public void Ops(string marker, string message) =>
            WriteInternal("INFO", "[" + (marker ?? "OPS") + "] " + (message ?? ""));
        public void OpsWarn(string marker, string message) =>
            WriteInternal("WARN", "[" + (marker ?? "OPS") + "] " + (message ?? ""));
        public void OpsError(string marker, string message) =>
            WriteInternal("ERROR", "[" + (marker ?? "OPS") + "] " + (message ?? ""));

        public void Banner(params string[] lines)
        {
            if (lines == null || lines.Length == 0)
                return;
            lock (_sync)
            {
                var sb = new StringBuilder();
                var stamp = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff");
                sb.Append(stamp).Append(" [INFO] ============================================================").Append(Environment.NewLine);
                foreach (var line in lines)
                    sb.Append(stamp).Append(" [INFO] ").Append(line ?? "").Append(Environment.NewLine);
                sb.Append(stamp).Append(" [INFO] ============================================================").Append(Environment.NewLine);
                File.AppendAllText(InternalLogPath(), sb.ToString());
            }
        }

        // ---- Business / operations logs (human-readable, no SDK) ----

        public void Biz(BizChannel channel, params string[] lines)
        {
            if (lines == null || lines.Length == 0)
                return;
            var sb = new StringBuilder();
            foreach (var line in lines)
                sb.AppendLine(line ?? "");
            AppendBiz(channel, sb.ToString());
        }

        public void BizBlank(BizChannel channel) => AppendBiz(channel, Environment.NewLine);

        public void BizSeparator(BizChannel channel) =>
            AppendBiz(channel, "------------------------------------------------------------" + Environment.NewLine + Environment.NewLine);

        public void WriteBizServiceStarted()
        {
            Totals.StartedAt = DateTime.Now;
            var block =
                "------------------------------------------------------------" + Environment.NewLine +
                "Service started at " + BizFriendlyReasons.FormatTime(Totals.StartedAt) + Environment.NewLine +
                "------------------------------------------------------------" + Environment.NewLine +
                Environment.NewLine;
            AppendBiz(BizChannel.Attendance, block);
            AppendBiz(BizChannel.UserSync, block);
            AppendBiz(BizChannel.Template, block);
            AppendBiz(BizChannel.Unreachable, block);
        }

        public void WriteBizServiceStopped()
        {
            var stopped =
                Environment.NewLine +
                "------------------------------------------------------------" + Environment.NewLine +
                "Service stopped at " + BizFriendlyReasons.FormatTime(DateTime.Now) + Environment.NewLine +
                Environment.NewLine +
                Totals.FormatSummaryBlock() +
                Environment.NewLine;
            AppendBiz(BizChannel.Attendance, stopped);
            AppendBiz(BizChannel.UserSync, stopped);
            AppendBiz(BizChannel.Template, stopped);
            AppendBiz(BizChannel.Unreachable, stopped);
        }

        public void WriteBizDatabaseFailed(string mysqlErrorCode, string friendlyReason)
        {
            Biz(BizChannel.Attendance,
                "Database connection failed.",
                "",
                "Reason :",
                "",
                string.IsNullOrWhiteSpace(mysqlErrorCode) ? "[MySQL Error]" : "[MySQL Error " + mysqlErrorCode + "]",
                "",
                string.IsNullOrWhiteSpace(friendlyReason) ? "Unable to connect to MySQL server." : friendlyReason,
                "",
                "Attendance synchronization cannot continue.",
                "");
        }

        private void AppendBiz(BizChannel channel, string text)
        {
            string path;
            switch (channel)
            {
                case BizChannel.Attendance:
                    path = Path.Combine(_attendanceBizDirectory, "attendance_logs_" + DateStamp() + ".txt");
                    break;
                case BizChannel.UserSync:
                    path = Path.Combine(_userSyncBizDirectory, "user_sync_logs_" + DateStamp() + ".txt");
                    break;
                case BizChannel.Template:
                    path = Path.Combine(_templateBizDirectory, "template_fetching_logs_" + DateStamp() + ".txt");
                    break;
                case BizChannel.Unreachable:
                    path = Path.Combine(_unreachableBizDirectory, "unreachable_devices_" + DateStamp() + ".txt");
                    break;
                default:
                    path = InternalLogPath();
                    break;
            }

            lock (_sync)
            {
                File.AppendAllText(path, text, Encoding.UTF8);
            }
        }

        private static string DateStamp() => DateTime.Now.ToString("yyyy-MM-dd");

        private string InternalLogPath() =>
            Path.Combine(_internalLogsDirectory, "internal_logs_" + DateStamp() + ".txt");

        private void WriteInternal(string level, string message)
        {
            var line = $"{DateTime.Now:yyyy-MM-dd HH:mm:ss.fff} [{level}] {message}{Environment.NewLine}";
            lock (_sync)
            {
                File.AppendAllText(InternalLogPath(), line);
            }
        }

        private void WriteInternalDiag(string jobName, string level, string message)
        {
            var tag = (jobName ?? "diag").Trim().ToUpperInvariant();
            if (tag.Length == 0) tag = "DIAG";
            WriteInternal(level, "[DIAG][" + tag + "] " + message);
        }

        public void Dispose() { }
    }

    // Manager implementation is in a separate file below for readability.
}