using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text;
using System.Threading;
using HikvisionAttendanceService.Data;
using MySql.Data.MySqlClient;

namespace HikvisionAttendanceService;

/// <summary>
/// Separate onboarding path: HRMS department employees + portal JPEG photos → new Hikvision device.
/// Does not read or write attendance_machine_face_templates (existing DB↔device flows stay unchanged).
/// </summary>
internal sealed partial class HikvisionAttendanceManager
{
    /// <summary>
    /// Provisions users/faces onto TargetMachineIps from InitialSyncDepartmentIds + employee-photo URL.
    /// Gated by EnableInitialDepartmentSync only.
    /// </summary>
    public void RunInitialDepartmentSyncCycle(CancellationToken ct)
    {
        if (!_config.EnableInitialDepartmentSync)
            return;

        ct.ThrowIfCancellationRequested();

        if (!_config.InitialSyncLocationSiteId.HasValue ||
            _config.InitialSyncLocationSiteId.Value <= 0)
        {
            const string reason =
                "InitialSyncLocationSiteId is not configured; Initial Department Sync requires an explicit location-site filter.";
            _logger.OpsWarn("INITIAL_SYNC", "skipped — " + reason);
            _logger.Biz(BizChannel.DepartmentalSync,
                "DEPARTMENTAL SYNC FAILED",
                "",
                "Reason : " + reason,
                "");
            _logger.BizSeparator(BizChannel.DepartmentalSync);
            return;
        }
        var locationSiteId = _config.InitialSyncLocationSiteId.Value;

        var deptIds = (_config.InitialSyncDepartmentIds ?? new List<string>())
            .Where(x => !string.IsNullOrWhiteSpace(x))
            .Select(x => x.Trim())
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .ToList();
        var allActiveDepartmentsMode = deptIds.Count == 0;

        var targets = ResolveInitialSyncTargets();
        if (targets.Count == 0)
        {
            _logger.OpsWarn("INITIAL_SYNC", "skipped — no valid TargetMachineIps");
            _logger.Biz(BizChannel.DepartmentalSync,
                "DEPARTMENTAL SYNC FAILED",
                "",
                "Reason : No valid target machines are configured.",
                "");
            _logger.BizSeparator(BizChannel.DepartmentalSync);
            return;
        }

        var employeeIdFilter = (_config.InitialSyncEmployeeIds ?? new List<string>())
            .Where(x => !string.IsNullOrWhiteSpace(x))
            .Select(x => x.Trim())
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .ToList();

        if (allActiveDepartmentsMode && employeeIdFilter.Count > 0)
        {
            _logger.OpsWarn("INITIAL_SYNC",
                "InitialSyncEmployeeIds ignored because InitialSyncDepartmentIds is empty; " +
                "mode=ALL_ACTIVE_DEPARTMENTS_AND_EMPLOYEES");
            employeeIdFilter.Clear();
        }

        var selection = LoadEmployeesForInitialDepartmentSync(
            deptIds,
            employeeIdFilter,
            locationSiteId,
            out var loadErr);
        if (!string.IsNullOrWhiteSpace(loadErr))
        {
            _logger.Warn("INITIAL_SYNC: employee lookup failed err=" + loadErr);
            _logger.Biz(BizChannel.DepartmentalSync,
                "DEPARTMENTAL SYNC FAILED",
                "",
                "Reason : " + loadErr,
                "");
            _logger.BizSeparator(BizChannel.DepartmentalSync);
            return;
        }

        LogInitialDepartmentSelection(deptIds, employeeIdFilter, selection);
        var employees = selection.Employees;

        var maxRetries = Math.Max(1, SyncPol.HttpMaxRetries);
        var photoBase = (_config.EmployeePhotoBaseUrl ?? "").Trim();
        if (!string.IsNullOrWhiteSpace(photoBase) && !photoBase.EndsWith("/", StringComparison.Ordinal))
            photoBase += "/";

        foreach (var target in targets)
        {
            ct.ThrowIfCancellationRequested();
            var hasSession = _sessions.Any(s =>
                string.Equals((s.Device.Ip ?? "").Trim(), (target.Ip ?? "").Trim(), StringComparison.OrdinalIgnoreCase) ||
                DeviceIdentity.CanonicalLookupKey(s.Device.DeviceId) == DeviceIdentity.CanonicalLookupKey(target.DeviceId));
            if (!hasSession)
            {
                _logger.OpsWarn("INITIAL_SYNC",
                    "target=" + (target.DeviceId ?? "") + " ip=" + (target.Ip ?? "") +
                    " SKIPPED reason=\"target offline\"");
                _logger.Biz(BizChannel.UserSync,
                    "MACHINE " + (target.DeviceId ?? ""),
                    "",
                    "Machine is not connected.",
                    "");
                _logger.BizSeparator(BizChannel.UserSync);
                WriteDepartmentalSyncSummary(
                    target,
                    selection,
                    employeeIdFilter,
                    false,
                    Array.Empty<InitialSyncEmployeeOutcome>());
                continue;
            }

            _logger.Biz(BizChannel.UserSync,
                "MACHINE " + (target.DeviceId ?? "") + " -> Total Users : " + employees.Count,
                "");

            if (employees.Count == 0)
            {
                WriteDepartmentalSyncSummary(
                    target,
                    selection,
                    employeeIdFilter,
                    true,
                    Array.Empty<InitialSyncEmployeeOutcome>());
                _logger.BizSeparator(BizChannel.UserSync);
                continue;
            }

            var existing = FetchAllUsersIsapiForSync(target, maxRetries, ct);
            var existingNos = new HashSet<string>(existing.Select(u => u.EmployeeNo), StringComparer.OrdinalIgnoreCase);
            var faceRejectedEmployees = new List<(string EmployeeNo, string Reason)>();
            var employeeOutcomes = new List<InitialSyncEmployeeOutcome>();

            foreach (var emp in employees)
            {
                ct.ThrowIfCancellationRequested();
                var employeeNo = emp.SerialNumber;
                var employeeId = emp.Id;
                var photoUrl = "";
                var photoDownloaded = false;
                var userCreated = false;
                var faceUploaded = false;
                var reason = "";

                try
                {
                    if (!existingNos.Contains(employeeNo))
                    {
                        var dto = new UserDto
                        {
                            EmployeeNo = employeeNo,
                            Name = emp.Name ?? "",
                            NumOfFace = 0,
                            NumOfFp = 0
                        };
                        if (!CreateUserOnTarget(target, dto, maxRetries, ct, out var createErr))
                        {
                            reason = string.IsNullOrWhiteSpace(createErr) ? "user_create_failed" : createErr;
                            continue;
                        }

                        userCreated = true;
                        existingNos.Add(employeeNo);
                        if (_config.EnableDbIntegration && _attendanceMachineUserRepository != null)
                        {
                            _attendanceMachineUserRepository.UpsertMachineUser(
                                target.DeviceId ?? "",
                                employeeNo,
                                emp.Name ?? "",
                                "hikvision-service-initial",
                                out _);
                        }
                    }

                    if (!_config.EnableEmployeePhotoSource || string.IsNullOrWhiteSpace(photoBase))
                    {
                        reason = "photo_source_disabled";
                        continue;
                    }

                    if (string.IsNullOrWhiteSpace(employeeId))
                    {
                        reason = "missing_employee_id";
                        continue;
                    }

                    photoUrl = photoBase + employeeId.Trim() + ".jpeg";
                    if (!TryDownloadEmployeePortalPhoto(photoUrl, out var jpegBytes, out var photoErr))
                    {
                        reason = string.IsNullOrWhiteSpace(photoErr) ? "photo_not_found" : photoErr;
                        continue;
                    }

                    photoDownloaded = true;
                    if (!IsJpegMagic(jpegBytes))
                    {
                        reason = "invalid_jpeg";
                        continue;
                    }

                    if (!TryPrepareInitialSyncFaceJpeg(employeeNo, jpegBytes, out var uploadBytes))
                    {
                        reason = "FACE_NOT_DETECTED";
                        faceRejectedEmployees.Add((employeeNo, reason));
                        continue;
                    }

                    if (!UploadFaceOnTarget(target, employeeNo, uploadBytes, maxRetries, ct, out var upErr))
                    {
                        reason = string.IsNullOrWhiteSpace(upErr) ? "face_upload_failed" : upErr;
                        faceRejectedEmployees.Add((employeeNo, reason));
                        continue;
                    }

                    faceUploaded = true;
                }
                finally
                {
                    employeeOutcomes.Add(new InitialSyncEmployeeOutcome
                    {
                        DepartmentId = emp.DepartmentId,
                        EmployeeNo = employeeNo,
                        Synced = faceUploaded,
                        Reason = faceUploaded
                            ? ""
                            : (string.IsNullOrWhiteSpace(reason) ? "face_upload_failed" : reason)
                    });
                    WriteInitialSyncEmployeeBizLog(target, employeeNo, userCreated, faceUploaded, reason);

                    if (photoDownloaded && faceUploaded)
                    {
                        _logger.Ops("INITIAL_SYNC",
                            "employeeNo=" + employeeNo +
                            " employeeId=" + employeeId +
                            " photoUrl=" + photoUrl +
                            " photoDownloaded=true" +
                            " userCreated=" + (userCreated ? "true" : "false") +
                            " faceUploaded=true");
                    }
                    else if (!photoDownloaded)
                    {
                        _logger.Ops("INITIAL_SYNC",
                            "employeeNo=" + employeeNo +
                            (string.IsNullOrWhiteSpace(employeeId) ? "" : (" employeeId=" + employeeId)) +
                            (string.IsNullOrWhiteSpace(photoUrl) ? "" : (" photoUrl=" + photoUrl)) +
                            " photoDownloaded=false" +
                            " reason=" + (string.IsNullOrWhiteSpace(reason) ? "photo_not_found" : reason));
                    }
                    else
                    {
                        _logger.Ops("INITIAL_SYNC",
                            "employeeNo=" + employeeNo +
                            " employeeId=" + employeeId +
                            " photoUrl=" + photoUrl +
                            " photoDownloaded=true" +
                            " userCreated=" + (userCreated ? "true" : "false") +
                            " faceUploaded=false" +
                            " reason=" + (string.IsNullOrWhiteSpace(reason) ? "face_upload_failed" : reason));
                    }
                }
            }

            WriteFaceRejectedEmployeeSummary("INITIAL_SYNC", target, faceRejectedEmployees);
            WriteDepartmentalSyncSummary(target, selection, employeeIdFilter, true, employeeOutcomes);
            _logger.BizSeparator(BizChannel.UserSync);
        }
    }

    /// <summary>
    /// Mirrors the DB→device sync wording in logs/user_sync_logs so provisioned users are visible
    /// alongside the "removed successfully" entries, not only in internal_logs.
    /// </summary>
    private void WriteInitialSyncEmployeeBizLog(
        HikvisionAttendanceWindowsService.DeviceConfig target,
        string employeeNo,
        bool userCreated,
        bool faceUploaded,
        string reason)
    {
        if (userCreated)
        {
            _logger.Totals.UsersAdded++;
            _logger.Biz(BizChannel.UserSync,
                "Machine ID : " + (target.DeviceId ?? ""),
                "Machine IP : " + (target.Ip ?? ""),
                "",
                employeeNo + " added successfully.",
                "");
        }

        if (faceUploaded)
        {
            _logger.Totals.TemplatesSaved++;
            _logger.Biz(BizChannel.UserSync, employeeNo + " face enrolled successfully.", "");
            return;
        }

        _logger.Totals.TemplatesFailed++;
        _logger.Biz(BizChannel.UserSync,
            employeeNo + " face enrollment failed.",
            "",
            "Reason :",
            "",
            DescribeInitialSyncFailure(reason),
            "");
    }

    private static string DescribeInitialSyncFailure(string reason)
    {
        if (string.IsNullOrWhiteSpace(reason))
            return "Unknown error.";

        switch (reason)
        {
            case "FACE_NOT_DETECTED":
                return "No face detected in the employee photo.";
            case "photo_not_found":
                return "Employee photo not found on the HRMS portal.";
            case "invalid_jpeg":
                return "Employee photo is not a valid JPEG.";
            case "photo_source_disabled":
                return "Employee photo source is disabled.";
            case "missing_employee_id":
                return "Employee has no HRMS id, photo URL cannot be built.";
            case "user_create_failed":
                return "User could not be created on the device.";
            default:
                return reason;
        }
    }

    /// <summary>
    /// Initial-sync only: crops/normalizes the HRMS photo around the detected face before FaceDataRecord.
    /// Returns false only when no face is found; decode/encode problems fall back to the raw portal JPEG.
    /// </summary>
    private bool TryPrepareInitialSyncFaceJpeg(string employeeNo, byte[] downloadedJpeg, out byte[] uploadBytes)
    {
        uploadBytes = downloadedJpeg;
        var processed = EmployeePhotoFaceProcessor.Process(downloadedJpeg);

        if (processed.Status == EmployeePhotoFaceProcessor.PhotoStatus.NoFace)
        {
            _logger.OpsWarn("INITIAL_SYNC",
                "FACE_NOT_DETECTED employeeNo=" + employeeNo +
                " original=" + processed.Original.Width + "x" + processed.Original.Height +
                " uploadSkipped=true");
            return false;
        }

        if (processed.Status != EmployeePhotoFaceProcessor.PhotoStatus.Ok)
        {
            _logger.OpsWarn("INITIAL_SYNC",
                "PHOTO_PROCESS_FAILED employeeNo=" + employeeNo +
                " err=" + processed.Error +
                " fallback=original-jpeg bytes=" + downloadedJpeg.Length);
            return true;
        }

        _logger.Ops("INITIAL_SYNC", "PHOTO_PROCESSED employeeNo=" + employeeNo + " " + processed.Describe());
        _logger.Diag("INITIAL_SYNC",
            "PHOTO_PROCESSED employeeNo=" + employeeNo + " " + processed.Describe() +
            " jpegQuality=" + processed.JpegQuality +
            " downloadedBytes=" + downloadedJpeg.Length +
            " enhance[" + processed.Enhancement + "]");

        uploadBytes = processed.JpegBytes;
        return true;
    }

    private List<HikvisionAttendanceWindowsService.DeviceConfig> ResolveInitialSyncTargets()
    {
        var targets = new List<HikvisionAttendanceWindowsService.DeviceConfig>();
        foreach (var targetIp in _config.TargetMachineIps ?? Enumerable.Empty<string>())
        {
            var t = ResolveDeviceConfigByIp(targetIp);
            if (t == null || string.IsNullOrWhiteSpace(t.Ip))
            {
                _logger.OpsWarn("INITIAL_SYNC", "target skipped — not found or IP empty. TargetMachineIp=\"" + targetIp + "\"");
                continue;
            }
            if (targets.Any(x => string.Equals(x.Ip, t.Ip, StringComparison.OrdinalIgnoreCase)))
                continue;
            targets.Add(t);
        }

        foreach (var tid in _config.TargetDeviceIds ?? Enumerable.Empty<string>())
        {
            var t = ResolveDeviceConfig(tid);
            if (t == null || string.IsNullOrWhiteSpace(t.Ip))
                continue;
            if (targets.Any(x => string.Equals(x.Ip, t.Ip, StringComparison.OrdinalIgnoreCase)))
                continue;
            targets.Add(t);
        }

        return targets;
    }

    private InitialSyncSelection LoadEmployeesForInitialDepartmentSync(
        IReadOnlyList<string> departmentIds,
        IReadOnlyList<string> employeeIdAllowList,
        int locationSiteId,
        out string error)
    {
        error = "";
        var result = new InitialSyncSelection { LocationSiteId = locationSiteId };
        if (!_config.EnableDbIntegration || _dbConnectionFactory == null)
        {
            error = "DB integration not available for initial department sync.";
            return result;
        }

        if (!_dbConnectionFactory.TryBuildConnectionString(out var cs, out error))
            return result;

        var hasDepartmentFilter = departmentIds != null && departmentIds.Count > 0;
        var hasAllowList = hasDepartmentFilter &&
            employeeIdAllowList != null &&
            employeeIdAllowList.Count > 0;

        try
        {
            using var conn = new MySqlConnection(cs);
            conn.Open();

            if (hasDepartmentFilter)
            {
                var departmentSql = new StringBuilder(
                    "SELECT id, is_active FROM department WHERE id IN (");
                AppendSqlParameters(departmentSql, "@d", departmentIds.Count);
                departmentSql.Append(')');

                using var departmentCmd = new MySqlCommand(departmentSql.ToString(), conn);
                AddSqlParameters(departmentCmd, "@d", departmentIds);
                var foundDepartmentIds = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
                using (var departmentReader = departmentCmd.ExecuteReader())
                {
                    while (departmentReader.Read())
                    {
                        var departmentId = departmentReader["id"]?.ToString()?.Trim() ?? "";
                        if (departmentId.Length == 0)
                            continue;

                        foundDepartmentIds.Add(departmentId);
                        if (IsDatabaseActive(departmentReader["is_active"]))
                            result.ActiveDepartmentIds.Add(departmentId);
                        else
                            result.InactiveDepartmentIds.Add(departmentId);
                    }
                }

                foreach (var requestedId in departmentIds)
                {
                    if (!foundDepartmentIds.Contains(requestedId))
                        result.MissingDepartmentIds.Add(requestedId);
                }
            }
            else
            {
                using var departmentCmd = new MySqlCommand(
                    "SELECT id FROM department WHERE is_active = 1", conn);
                using (var departmentReader = departmentCmd.ExecuteReader())
                {
                    while (departmentReader.Read())
                    {
                        var departmentId = departmentReader["id"]?.ToString()?.Trim() ?? "";
                        if (departmentId.Length > 0)
                            result.ActiveDepartmentIds.Add(departmentId);
                    }
                }

                using var inactiveDepartmentCmd = new MySqlCommand(
                    "SELECT COUNT(*) FROM department WHERE is_active IS NULL OR is_active <> 1", conn);
                result.InactiveDepartmentCount = Convert.ToInt32(inactiveDepartmentCmd.ExecuteScalar() ?? 0);
            }

            if (result.ActiveDepartmentIds.Count == 0)
                return result;

            var employeeSql = new StringBuilder(
                "SELECT e.id, e.serial_number, e.department_id " +
                "FROM employee e " +
                "INNER JOIN department d ON d.id = e.department_id " +
                "WHERE d.is_active = 1 AND e.is_active = 1 " +
                "AND e.location_site_id = @locationSiteId AND e.department_id IN (");
            AppendSqlParameters(employeeSql, "@activeDept", result.ActiveDepartmentIds.Count);
            employeeSql.Append(')');
            if (hasAllowList)
            {
                employeeSql.Append(" AND e.serial_number IN (");
                AppendSqlParameters(employeeSql, "@e", employeeIdAllowList.Count);
                employeeSql.Append(')');
            }

            using var cmd = new MySqlCommand(employeeSql.ToString(), conn);
            cmd.Parameters.AddWithValue("@locationSiteId", locationSiteId);
            AddSqlParameters(cmd, "@activeDept", result.ActiveDepartmentIds);
            if (hasAllowList)
                AddSqlParameters(cmd, "@e", employeeIdAllowList);

            var seenSerial = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            using (var rd = cmd.ExecuteReader())
            {
                while (rd.Read())
                {
                    var serial = rd["serial_number"]?.ToString()?.Trim() ?? "";
                    if (serial.Length == 0 || !seenSerial.Add(serial))
                        continue;
                    result.Employees.Add(new InitialSyncEmployee
                    {
                        Id = rd["id"]?.ToString()?.Trim() ?? "",
                        SerialNumber = serial,
                        DepartmentId = rd["department_id"]?.ToString()?.Trim() ?? "",
                        Name = ""
                    });
                }
            }

            var inactiveEmployeeSql = new StringBuilder(
                "SELECT COUNT(*) " +
                "FROM employee e " +
                "INNER JOIN department d ON d.id = e.department_id " +
                "WHERE d.is_active = 1 AND (e.is_active IS NULL OR e.is_active <> 1) " +
                "AND e.location_site_id = @inactiveLocationSiteId AND e.department_id IN (");
            AppendSqlParameters(inactiveEmployeeSql, "@inactiveDept", result.ActiveDepartmentIds.Count);
            inactiveEmployeeSql.Append(')');
            if (hasAllowList)
            {
                inactiveEmployeeSql.Append(" AND e.serial_number IN (");
                AppendSqlParameters(inactiveEmployeeSql, "@inactiveEmp", employeeIdAllowList.Count);
                inactiveEmployeeSql.Append(')');
            }

            using var inactiveEmployeeCmd = new MySqlCommand(inactiveEmployeeSql.ToString(), conn);
            inactiveEmployeeCmd.Parameters.AddWithValue("@inactiveLocationSiteId", locationSiteId);
            AddSqlParameters(inactiveEmployeeCmd, "@inactiveDept", result.ActiveDepartmentIds);
            if (hasAllowList)
                AddSqlParameters(inactiveEmployeeCmd, "@inactiveEmp", employeeIdAllowList);
            result.SkippedInactiveEmployeeCount =
                Convert.ToInt32(inactiveEmployeeCmd.ExecuteScalar() ?? 0);
        }
        catch (Exception ex)
        {
            error = ex.Message;
        }

        return result;
    }

    private void LogInitialDepartmentSelection(
        IReadOnlyList<string> requestedDepartmentIds,
        IReadOnlyList<string> employeeIdAllowList,
        InitialSyncSelection selection)
    {
        var allDepartments = requestedDepartmentIds == null || requestedDepartmentIds.Count == 0;
        var selectiveEmployees = !allDepartments &&
            employeeIdAllowList != null &&
            employeeIdAllowList.Count > 0;
        var inactiveCount = allDepartments
            ? selection.InactiveDepartmentCount
            : selection.InactiveDepartmentIds.Count;

        _logger.Ops("INITIAL_SYNC",
            "InitialSyncLocationSiteId=" + selection.LocationSiteId +
            " departmentMode=" + (allDepartments ? "ALL_ACTIVE" : "SELECTED") +
            " selectedDepartmentCount=" + (allDepartments
                ? selection.ActiveDepartmentIds.Count
                : requestedDepartmentIds.Count) +
            " activeDepartmentCount=" + selection.ActiveDepartmentIds.Count +
            " inactiveDepartmentCount=" + inactiveCount +
            " activeDepartments=" + FormatLogValues(selection.ActiveDepartmentIds) +
            " inactiveDepartments=" + (allDepartments
                ? "(all inactive departments excluded)"
                : FormatLogValues(selection.InactiveDepartmentIds)) +
            " missingDepartments=" + FormatLogValues(selection.MissingDepartmentIds));

        _logger.Ops("INITIAL_SYNC",
            "employeeFilterMode=" + (selectiveEmployees ? "SELECTIVE" : "ALL") +
            (selectiveEmployees
                ? " allowListCount=" + employeeIdAllowList.Count +
                  " allowList=" + FormatLogValues(employeeIdAllowList)
                : "") +
            " finalEmployeeCount=" + selection.Employees.Count +
            " skippedInactiveEmployees=" + selection.SkippedInactiveEmployeeCount);
    }

    private void WriteDepartmentalSyncSummary(
        HikvisionAttendanceWindowsService.DeviceConfig target,
        InitialSyncSelection selection,
        IReadOnlyList<string> employeeIdAllowList,
        bool targetOnline,
        IReadOnlyList<InitialSyncEmployeeOutcome> outcomes)
    {
        var lines = new List<string>
        {
            "DEPARTMENTAL SYNC SUMMARY",
            "",
            "Machine ID : " + (target.DeviceId ?? ""),
            "Machine IP : " + (target.Ip ?? ""),
            "InitialSyncLocationSiteId : " + selection.LocationSiteId,
            "Employee Filter : " + (employeeIdAllowList.Count > 0 ? "SELECTIVE" : "ALL"),
            "Active Departments : " + selection.ActiveDepartmentIds.Count,
            "Inactive Departments Skipped : " +
                (selection.InactiveDepartmentIds.Count + selection.InactiveDepartmentCount),
            "Eligible Active Employees : " + selection.Employees.Count,
            "Skipped Inactive Employees : " + selection.SkippedInactiveEmployeeCount,
            ""
        };

        foreach (var departmentId in selection.ActiveDepartmentIds
                     .OrderBy(x => x, StringComparer.OrdinalIgnoreCase))
        {
            var eligibleCount = selection.Employees.Count(x =>
                string.Equals(x.DepartmentId, departmentId, StringComparison.OrdinalIgnoreCase));
            var departmentOutcomes = outcomes.Where(x =>
                string.Equals(x.DepartmentId, departmentId, StringComparison.OrdinalIgnoreCase)).ToList();
            var syncedCount = departmentOutcomes.Count(x => x.Synced);
            var failedCount = Math.Max(0, eligibleCount - syncedCount);

            string status;
            string reason = "";
            if (!targetOnline)
            {
                status = "NOT SYNCED";
                reason = "Target machine is offline.";
            }
            else if (eligibleCount == 0)
            {
                status = "NOT SYNCED";
                reason = employeeIdAllowList.Count > 0
                    ? "No selected active employees belong to this active department."
                    : "Department has no active employees.";
            }
            else if (syncedCount == eligibleCount)
            {
                status = "SYNCED";
            }
            else if (syncedCount > 0)
            {
                status = "PARTIALLY SYNCED";
            }
            else
            {
                status = "NOT SYNCED";
            }

            lines.Add("Department " + departmentId + " : " + status);
            lines.Add("Eligible Users : " + eligibleCount);
            lines.Add("Synced Users : " + syncedCount);
            lines.Add("Failed Users : " + failedCount);
            if (failedCount > 0)
                lines.Add("Failed Employee Numbers : " +
                    string.Join(",", targetOnline
                        ? departmentOutcomes.Where(x => !x.Synced).Select(x => x.EmployeeNo)
                        : selection.Employees
                            .Where(x => string.Equals(
                                x.DepartmentId,
                                departmentId,
                                StringComparison.OrdinalIgnoreCase))
                            .Select(x => x.SerialNumber)));
            if (!string.IsNullOrWhiteSpace(reason))
                lines.Add("Reason : " + reason);

            foreach (var failureGroup in departmentOutcomes
                         .Where(x => !x.Synced)
                         .GroupBy(x => DescribeInitialSyncFailure(x.Reason))
                         .OrderBy(x => x.Key, StringComparer.OrdinalIgnoreCase))
            {
                lines.Add("Failure Reason : " + failureGroup.Key +
                    " (" + failureGroup.Count() + " user(s))");
            }

            lines.Add("");
        }

        foreach (var departmentId in selection.InactiveDepartmentIds
                     .OrderBy(x => x, StringComparer.OrdinalIgnoreCase))
        {
            lines.Add("Department " + departmentId + " : NOT SYNCED");
            lines.Add("Eligible Users : 0");
            lines.Add("Synced Users : 0");
            lines.Add("Failed Users : 0");
            lines.Add("Reason : Department is inactive.");
            lines.Add("");
        }

        foreach (var departmentId in selection.MissingDepartmentIds
                     .OrderBy(x => x, StringComparer.OrdinalIgnoreCase))
        {
            lines.Add("Department " + departmentId + " : NOT SYNCED");
            lines.Add("Eligible Users : 0");
            lines.Add("Synced Users : 0");
            lines.Add("Failed Users : 0");
            lines.Add("Reason : Department was not found.");
            lines.Add("");
        }

        if (selection.ActiveDepartmentIds.Count == 0 &&
            selection.InactiveDepartmentIds.Count == 0 &&
            selection.MissingDepartmentIds.Count == 0)
        {
            lines.Add("No active departments were available for synchronization.");
            lines.Add("");
        }

        var totalSynced = outcomes.Count(x => x.Synced);
        lines.Add("TOTAL SYNCED USERS : " + totalSynced);
        lines.Add("TOTAL FAILED USERS : " + Math.Max(0, selection.Employees.Count - totalSynced));
        lines.Add("");

        _logger.Biz(BizChannel.DepartmentalSync, lines.ToArray());
        _logger.BizSeparator(BizChannel.DepartmentalSync);
    }

    private static void AppendSqlParameters(StringBuilder sql, string prefix, int count)
    {
        for (int i = 0; i < count; i++)
        {
            if (i > 0)
                sql.Append(',');
            sql.Append(prefix).Append(i);
        }
    }

    private static void AddSqlParameters(
        MySqlCommand command,
        string prefix,
        IReadOnlyList<string> values)
    {
        for (int i = 0; i < values.Count; i++)
            command.Parameters.AddWithValue(prefix + i, values[i]);
    }

    private static bool IsDatabaseActive(object value)
    {
        if (value == null || value == DBNull.Value)
            return false;

        if (value is bool boolValue)
            return boolValue;

        return string.Equals(
            Convert.ToString(value, System.Globalization.CultureInfo.InvariantCulture)?.Trim(),
            "1",
            StringComparison.Ordinal);
    }

    private static string FormatLogValues(IEnumerable<string> values)
    {
        var items = (values ?? Enumerable.Empty<string>())
            .Where(x => !string.IsNullOrWhiteSpace(x))
            .ToList();
        return items.Count == 0 ? "(none)" : string.Join(",", items);
    }

    private static bool TryDownloadEmployeePortalPhoto(string photoUrl, out byte[] bytes, out string error)
    {
        bytes = Array.Empty<byte>();
        error = "";
        if (string.IsNullOrWhiteSpace(photoUrl))
        {
            error = "photo_not_found";
            return false;
        }

        try
        {
            using var handler = new HttpClientHandler
            {
                AllowAutoRedirect = true,
                AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
            };
            using var client = new HttpClient(handler) { Timeout = TimeSpan.FromSeconds(60) };
            using var response = client.GetAsync(photoUrl).GetAwaiter().GetResult();
            if (response.StatusCode == HttpStatusCode.NotFound)
            {
                error = "photo_not_found";
                return false;
            }

            if (!response.IsSuccessStatusCode)
            {
                error = "photo_http_" + (int)response.StatusCode;
                return false;
            }

            bytes = response.Content.ReadAsByteArrayAsync().GetAwaiter().GetResult() ?? Array.Empty<byte>();
            if (bytes.Length == 0)
            {
                error = "photo_not_found";
                return false;
            }

            return true;
        }
        catch (Exception ex)
        {
            error = "photo_download_failed:" + ex.Message;
            return false;
        }
    }

    private static bool IsJpegMagic(byte[] bytes) =>
        bytes != null &&
        bytes.Length >= 3 &&
        bytes[0] == 0xFF &&
        bytes[1] == 0xD8 &&
        bytes[2] == 0xFF;

    private sealed class InitialSyncEmployee
    {
        public string Id { get; set; } = "";
        public string SerialNumber { get; set; } = "";
        public string DepartmentId { get; set; } = "";
        public string Name { get; set; } = "";
    }

    private sealed class InitialSyncEmployeeOutcome
    {
        public string DepartmentId { get; set; } = "";
        public string EmployeeNo { get; set; } = "";
        public bool Synced { get; set; }
        public string Reason { get; set; } = "";
    }

    private sealed class InitialSyncSelection
    {
        public int LocationSiteId { get; set; }
        public List<InitialSyncEmployee> Employees { get; } = new List<InitialSyncEmployee>();
        public List<string> ActiveDepartmentIds { get; } = new List<string>();
        public List<string> InactiveDepartmentIds { get; } = new List<string>();
        public List<string> MissingDepartmentIds { get; } = new List<string>();
        public int InactiveDepartmentCount { get; set; }
        public int SkippedInactiveEmployeeCount { get; set; }
    }
}