using ClosedXML.Excel;
using Microsoft.EntityFrameworkCore;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using TaskTrackingSystem.Database.AppDbContextModels;
using TaskTrackingSystem.Shared;
using TaskTrackingSystem.Shared.Models.Report;
using TaskTrackingSystem.Shared.Models.Issue;
using TaskTrackingSystem.Shared.Enums;
using TaskTrackingSystem.WebApi.Infrastructure;

namespace TaskTrackingSystem.WebApi.Features.Report
{
    public class ReportService
    {
        private readonly AppDbContext _db;
        private static readonly Dictionary<AppTaskStatus, string> StatusMap = new() { { AppTaskStatus.Todo, "To Do" }, { AppTaskStatus.InProgress, "In Progress" }, { AppTaskStatus.Done, "Done" } };
        private static readonly Dictionary<TaskPriority, string> PriorityMap = new() { { TaskPriority.Low, "Low" }, { TaskPriority.Medium, "Medium" }, { TaskPriority.High, "High" } };

        public ReportService(AppDbContext db)
        {
            _db = db;
        }

        public async Task<Result<List<IssueDto>>> GetIssuesReportAsync(long roleId, long currentUserId)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var list = await BuildAccessibleIssueQuery(isAdmin, isManager, currentUserId)
                .Include(i => i.Task)
                .ThenInclude(t => t.Project)
                .Include(i => i.AssignedToNavigation)
                .OrderBy(i => i.DueDate)
                .ThenBy(i => i.Title)
                .Select(i => new IssueDto
                {
                    Id = i.Id,
                    TaskId = i.TaskId,
                    TaskTitle = i.Task.Title,
                    ProjectId = i.Task.ProjectId,
                    ProjectName = i.Task.Project.Name,
                    Title = i.Title,
                    Description = i.Description,
                    AssignedTo = i.AssignedTo,
                    AssignedToName = i.AssignedToNavigation != null
                        ? i.AssignedToNavigation.FirstName + " " + i.AssignedToNavigation.LastName
                        : null,
                    EstimatedHours = i.EstimatedHours,
                    ActualHours = i.ActualHours,
                    DelayReason = i.DelayReason,
                    IsBlocked = i.IsBlocked,
                    BlockedBy = i.BlockedBy,
                    EscalationLevel = i.EscalationLevel,
                    StartDate = i.StartDate,
                    DueDate = i.DueDate,
                    StatusId = i.StatusId,
                    PriorityId = i.PriorityId,
                    CreatedAt = i.CreatedAt ?? DateTime.UtcNow,
                    UpdatedAt = i.UpdatedAt
                })
                .ToListAsync();

            return Result<List<IssueDto>>.Success(list);
        }

        private IQueryable<TaskTrackingSystem.Database.AppDbContextModels.Task> BuildAccessibleTaskQuery(bool isAdmin, bool isManager, long currentUserId)
        {
            return _db.Tasks.Where(t => t.IsDeleted != true && !t.IsArchived);
        }

        private IQueryable<TaskTrackingSystem.Database.AppDbContextModels.Project> BuildAccessibleProjectQuery(bool isAdmin, long currentUserId)
        {
            return _db.Projects.Where(p => p.IsDeleted != true);
        }

        private IQueryable<TaskTrackingSystem.Database.AppDbContextModels.User> BuildAccessibleUserQuery(bool isAdmin, long currentUserId)
        {
            return _db.Users.Where(u => !u.IsDeleted);
        }

        private IQueryable<TaskTrackingSystem.Database.AppDbContextModels.Issue> BuildAccessibleIssueQuery(bool isAdmin, bool isManager, long currentUserId)
        {
            var query = _db.Issues
                .Where(i => i.IsDeleted != true && i.Task.IsDeleted != true && i.Task.Project.IsDeleted != true);

            if (isAdmin)
            {
                return query;
            }

            if (isManager)
            {
                return query.Where(i =>
                    i.AssignedTo == currentUserId ||
                    i.CreatedBy == currentUserId ||
                    i.Task.Project.ProjectMembers.Any(pm => pm.UserId == currentUserId));
            }

            return query.Where(i =>
                i.AssignedTo == currentUserId ||
                i.CreatedBy == currentUserId);
        }

        private static PagedResult<TDestination> MapPagedResult<TSource, TDestination>(
            PagedResult<TSource> source,
            Func<TSource, TDestination> map)
        {
            return new PagedResult<TDestination>
            {
                Items = source.Items.Select(map).ToList(),
                TotalCount = source.TotalCount,
                Page = source.Page,
                PageSize = source.PageSize,
                TotalPages = source.TotalPages
            };
        }

        private async Task<List<long>> GetTeamUserIdsAsync(long currentUserId)
        {
            var myProjectIds = await _db.ProjectMembers
                .Where(pm => pm.UserId == currentUserId)
                .Select(pm => pm.ProjectId)
                .Distinct()
                .ToListAsync();

            return await _db.ProjectMembers
                .Where(pm => myProjectIds.Contains(pm.ProjectId) && pm.UserId != currentUserId)
                .Select(pm => pm.UserId)
                .Distinct()
                .ToListAsync();
        }

        private async Task<IQueryable<TaskTrackingSystem.Database.AppDbContextModels.Task>> BuildTaskReportQueryAsync(
            bool isAdmin,
            bool isManager,
            long currentUserId,
            DateTime? startDate,
            DateTime? endDate,
            string? status,
            int? projectId,
            bool? assignedToMe,
            bool? assignedToMyTeam)
        {
            var query = BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId)
                .Include(t => t.Project)
                .Include(t => t.AssignedToNavigation)
                .Include(t => t.AssignedByNavigation)
                .Where(t => t.IsDeleted != true);

            if (startDate.HasValue)
                query = query.Where(t => t.CreatedAt >= startDate.Value.Date);

            if (endDate.HasValue)
                query = query.Where(t => t.CreatedAt < endDate.Value.Date.AddDays(1));

            if (projectId.HasValue)
                query = query.Where(t => t.ProjectId == projectId.Value);

            if (!string.IsNullOrWhiteSpace(status))
            {
                var sl = status.Trim().ToLower();
                if (sl == "uncompleted")
                {
                    query = query.Where(t => t.StatusId != AppTaskStatus.Done);
                }
                else if (sl == "overdue")
                {
                    query = query.Where(t => t.DueDate < DateTime.Today && t.StatusId != AppTaskStatus.Done);
                }
                else
                {
                    AppTaskStatus? sid = sl switch
                    {
                        "to do" => AppTaskStatus.Todo,
                        "in progress" => AppTaskStatus.InProgress,
                        "done" => AppTaskStatus.Done,
                        _ => null
                    };

                    if (sid.HasValue)
                        query = query.Where(t => t.StatusId == sid.Value);
                    else if (Enum.TryParse<AppTaskStatus>(status, true, out var parsedStatus))
                        query = query.Where(t => t.StatusId == parsedStatus);
                }
            }

            if (assignedToMe == true || assignedToMyTeam == true)
            {
                var teamIds = assignedToMyTeam == true ? await GetTeamUserIdsAsync(currentUserId) : new List<long>();
                query = query.Where(t =>
                    (assignedToMe == true && t.AssignedTo == currentUserId) ||
                    (assignedToMyTeam == true && t.AssignedTo.HasValue && teamIds.Contains(t.AssignedTo.Value))
                );
            }

            return query;
        }

        private static TaskReportDto MapTaskReport(TaskTrackingSystem.Database.AppDbContextModels.Task t)
        {
            return new TaskReportDto
            {
                TaskId = t.Id,
                Title = t.Title,
                Description = t.Description,
                ProjectId = t.ProjectId,
                ProjectName = t.Project?.Name ?? string.Empty,
                StatusId = t.StatusId,
                StatusName = StatusMap.TryGetValue(t.StatusId, out var s) ? s : $"Status {t.StatusId}",
                PriorityId = t.PriorityId,
                PriorityName = PriorityMap.TryGetValue(t.PriorityId, out var p) ? p : $"Priority {t.PriorityId}",
                AssignedToUserId = t.AssignedTo,
                AssignedToUser = t.AssignedToNavigation != null ? $"{t.AssignedToNavigation.FirstName} {t.AssignedToNavigation.LastName}" : null,
                AssignedByUser = t.AssignedByNavigation != null ? $"{t.AssignedByNavigation.FirstName} {t.AssignedByNavigation.LastName}" : null,
                DueDate = t.DueDate,
                CreatedAt = t.CreatedAt ?? DateTime.UtcNow,
                LastActivity = t.UpdatedAt ?? t.CreatedAt ?? DateTime.UtcNow
            };
        }

        private async System.Threading.Tasks.Task EnrichTaskReportsAsync(List<TaskReportDto> reports)
        {
            if (reports.Count == 0)
            {
                return;
            }

            var today = DateTime.Today;
            var taskIds = reports.Select(r => r.TaskId).ToList();
            var issues = await _db.Issues
                .Where(i => i.IsDeleted != true && taskIds.Contains(i.TaskId))
                .Select(i => new
                {
                    i.TaskId,
                    i.Title,
                    i.StatusId,
                    i.PriorityId,
                    i.DueDate,
                    i.UpdatedAt,
                    i.CreatedAt,
                    i.IsBlocked
                })
                .ToListAsync();

            foreach (var report in reports)
            {
                var taskIssues = issues.Where(i => i.TaskId == report.TaskId).ToList();
                report.OpenIssues = taskIssues.Count(i => i.StatusId != AppTaskStatus.Done);
                report.OverdueIssues = taskIssues.Count(i => i.StatusId != AppTaskStatus.Done && i.DueDate.Date < today);
                report.IssueSummary = taskIssues.Count == 0
                    ? "No issues"
                    : $"{report.OpenIssues} open, {report.OverdueIssues} overdue, {taskIssues.Count(i => i.IsBlocked)} blocked";
                report.LastActivity = taskIssues
                    .Select(i => i.UpdatedAt ?? i.CreatedAt ?? report.LastActivity)
                    .DefaultIfEmpty(report.LastActivity)
                    .Max();

                report.TaskHealth = report.StatusId == AppTaskStatus.Done
                    ? "Healthy"
                    : report.OverdueIssues > 0 || report.DueDate.Date < today || taskIssues.Any(i => i.IsBlocked)
                        ? "Critical"
                        : report.PriorityId == TaskPriority.High || report.DueDate.Date <= today.AddDays(3)
                            ? "At Risk"
                            : "Healthy";
            }
        }

        private async System.Threading.Tasks.Task EnrichOverdueTaskReportsAsync(List<OverdueCriticalTaskDto> reports)
        {
            if (reports.Count == 0)
            {
                return;
            }

            var today = DateTime.Today;
            var taskIds = reports.Select(r => r.TaskId).ToList();
            var issues = await _db.Issues
                .Where(i => i.IsDeleted != true && taskIds.Contains(i.TaskId))
                .Select(i => new
                {
                    i.TaskId,
                    i.StatusId,
                    i.DueDate,
                    i.DelayReason,
                    i.IsBlocked,
                    i.BlockedBy,
                    i.EscalationLevel
                })
                .ToListAsync();

            foreach (var report in reports)
            {
                var taskIssues = issues.Where(i => i.TaskId == report.TaskId).ToList();
                report.OverdueIssues = taskIssues.Count(i => i.StatusId != AppTaskStatus.Done && i.DueDate.Date < today);
                var riskIssue = taskIssues
                    .OrderByDescending(i => i.IsBlocked)
                    .ThenByDescending(i => i.EscalationLevel)
                    .ThenBy(i => i.DueDate)
                    .FirstOrDefault();
                report.DelayReason = riskIssue?.DelayReason ?? (report.DaysOverdue > 0 ? "Past due date" : "High priority due soon");
                report.BlockedBy = riskIssue?.BlockedBy ?? string.Empty;
                report.EscalationLevel = riskIssue?.EscalationLevel ?? 0;
            }
        }

        // ——— Legacy endpoints (kept for backward compatibility) ———

        public async Task<Result<IEnumerable<TaskReportDto>>> GetTasksReportAsync(
            DateTime? startDate, DateTime? endDate, string? status, int? projectId, long roleId, long currentUserId,
            bool? assignedToMe = null, bool? assignedToMyTeam = null)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var query = await BuildTaskReportQueryAsync(isAdmin, isManager, currentUserId, startDate, endDate, status, projectId, assignedToMe, assignedToMyTeam);
            var tasks = await query
                .OrderBy(t => t.DueDate)
                .ThenByDescending(t => t.CreatedAt ?? DateTime.UtcNow)
                .ToListAsync();
            var list = tasks.Select(MapTaskReport).ToList();
            await EnrichTaskReportsAsync(list);
            return Result<IEnumerable<TaskReportDto>>.Success(list);
        }

        public async Task<PagedResult<TaskReportDto>> GetPagedTasksReportAsync(
            DateTime? startDate,
            DateTime? endDate,
            string? status,
            int? projectId,
            long roleId,
            long currentUserId,
            int page,
            int pageSize,
            bool? assignedToMe = null,
            bool? assignedToMyTeam = null)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var query = await BuildTaskReportQueryAsync(isAdmin, isManager, currentUserId, startDate, endDate, status, projectId, assignedToMe, assignedToMyTeam);
            var paged = await query
                .OrderBy(t => t.DueDate)
                .ThenByDescending(t => t.CreatedAt ?? DateTime.UtcNow)
                .ToPagedResultAsync(page, pageSize);

            var mapped = MapPagedResult(paged, MapTaskReport);
            await EnrichTaskReportsAsync(mapped.Items);
            return mapped;
        }

        public async Task<Result<IEnumerable<UserProductivityDto>>> GetUserProductivityReportAsync(long roleId, long currentUserId)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var users = await BuildAccessibleUserQuery(isAdmin, currentUserId).ToListAsync();
            var tasks = await BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId).ToListAsync();
            var list = new List<UserProductivityDto>();
            foreach (var user in users)
            {
                var userTasks = tasks.Where(t => t.AssignedTo == user.Id).ToList();
                int total = userTasks.Count;
                var completedTasks = userTasks.Where(t => t.StatusId == AppTaskStatus.Done).ToList();
                int done = completedTasks.Count;

                int onTimeCount = completedTasks.Count(t => (t.UpdatedAt ?? t.CreatedAt) <= t.DueDate);
                double onTimeDeliveryRate = done > 0 ? Math.Round(((double)onTimeCount / done) * 100, 2) : 0;

                list.Add(new UserProductivityDto
                {
                    UserId = user.Id,
                    Username = user.Username,
                    FullName = $"{user.FirstName} {user.LastName}".Trim(),
                    TotalAssignedTasks = total,
                    CompletedTasksCount = done,
                    EfficiencyRatio = total > 0 ? Math.Round(((double)done / total) * 100, 2) : 0,
                    OnTimeDeliveryRate = onTimeDeliveryRate
                });
            }
            return Result<IEnumerable<UserProductivityDto>>.Success(list);
        }

        public async Task<Result<IEnumerable<TaskStatusSummaryDto>>> GetTaskStatusSummaryAsync(
            string? search, AppTaskStatus? statusId, long? projectId, long roleId, long currentUserId)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var query = BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId)
                .Include(t => t.Project)
                .Include(t => t.AssignedToNavigation)
                .Where(t => t.IsDeleted != true);

            if (statusId.HasValue && Convert.ToInt64(statusId.Value) > 0)
                query = query.Where(t => t.StatusId == statusId.Value);
            if (projectId.HasValue && projectId > 0)
                query = query.Where(t => t.ProjectId == projectId.Value);

            var tasks = await query.OrderBy(t => t.DueDate).ThenByDescending(t => t.CreatedAt ?? DateTime.UtcNow).ToListAsync();

            if (!string.IsNullOrWhiteSpace(search))
            {
                var s = search.Trim().ToLower();
                tasks = tasks.Where(t =>
                    t.Title.ToLower().Contains(s) ||
                    (t.Project?.Name.ToLower().Contains(s) == true) ||
                    (t.AssignedToNavigation != null &&
                     ($"{t.AssignedToNavigation.FirstName} {t.AssignedToNavigation.LastName}").ToLower().Contains(s))
                ).ToList();
            }

            var list = tasks.Select(t => new TaskStatusSummaryDto
            {
                TaskId = t.Id,
                Title = t.Title,
                ProjectName = t.Project?.Name ?? "-",
                StatusName = StatusMap.TryGetValue(t.StatusId, out var s) ? s : $"Status {t.StatusId}",
                PriorityName = PriorityMap.TryGetValue(t.PriorityId, out var p) ? p : $"Priority {t.PriorityId}",
                AssignedTo = t.AssignedToNavigation != null ? $"{t.AssignedToNavigation.FirstName} {t.AssignedToNavigation.LastName}" : null,
                DueDate = t.DueDate,
                CreatedAt = t.CreatedAt ?? DateTime.UtcNow
            }).ToList();

            return Result<IEnumerable<TaskStatusSummaryDto>>.Success(list);
        }

        public byte[] ExportTaskStatusSummaryToExcel(IEnumerable<TaskStatusSummaryDto> data)
        {
            using var wb = new XLWorkbook();
            var ws = wb.Worksheets.Add("Task Status Summary");
            var headers = new[] { "Task ID", "Title", "Project", "Status", "Priority", "Assigned To", "Due Date", "Created At", "Overdue" };
            for (int i = 0; i < headers.Length; i++)
            {
                ws.Cell(1, i + 1).Value = headers[i];
                ws.Cell(1, i + 1).Style.Font.Bold = true;
                ws.Cell(1, i + 1).Style.Fill.BackgroundColor = XLColor.FromHtml("#6D28D9");
                ws.Cell(1, i + 1).Style.Font.FontColor = XLColor.White;
            }
            int row = 2;
            foreach (var item in data)
            {
                ws.Cell(row, 1).Value = item.TaskId;
                ws.Cell(row, 2).Value = item.Title;
                ws.Cell(row, 3).Value = item.ProjectName;
                ws.Cell(row, 4).Value = item.StatusName;
                ws.Cell(row, 5).Value = item.PriorityName;
                ws.Cell(row, 6).Value = item.AssignedTo ?? "Unassigned";
                ws.Cell(row, 7).Value = DisplayFormats.Date(item.DueDate);
                ws.Cell(row, 8).Value = DisplayFormats.Date(item.CreatedAt);
                ws.Cell(row, 9).Value = item.IsOverdue ? "Yes" : "No";
                if (item.IsOverdue) ws.Row(row).Style.Fill.BackgroundColor = XLColor.FromHtml("#FEE2E2");
                row++;
            }
            ws.Columns().AdjustToContents();
            using var ms = new MemoryStream();
            wb.SaveAs(ms);
            return ms.ToArray();
        }

        public async Task<PagedResult<TeamProductivityReportDto>> GetPagedTeamProductivityAsync(
            string? search,
            long roleId,
            long currentUserId,
            int page,
            int pageSize)
        {
            var full = await GetTeamProductivityAsync(search, roleId, currentUserId);
            if (!full.IsSuccess || full.Value == null)
            {
                return new PagedResult<TeamProductivityReportDto>();
            }

            var ordered = full.Value.OrderByDescending(u => u.CompletionRate).ToList();
            var normalizedPageSize = PaginationExtensions.NormalizePageSize(pageSize);
            var totalCount = ordered.Count;
            var totalPages = totalCount == 0 ? 0 : (int)Math.Ceiling(totalCount / (double)normalizedPageSize);
            var normalizedPage = Math.Max(page, 1);
            if (totalPages > 0 && normalizedPage > totalPages)
                normalizedPage = totalPages;

            var items = ordered
                .Skip((normalizedPage - 1) * normalizedPageSize)
                .Take(normalizedPageSize)
                .ToList();

            return new PagedResult<TeamProductivityReportDto>
            {
                Items = items,
                TotalCount = totalCount,
                Page = normalizedPage,
                PageSize = normalizedPageSize,
                TotalPages = totalPages
            };
        }

        // ——— Report 2: Team Productivity ———

        public async Task<Result<IEnumerable<TeamProductivityReportDto>>> GetTeamProductivityAsync(string? search, long roleId, long currentUserId)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var users = await BuildAccessibleUserQuery(isAdmin, currentUserId).ToListAsync();
            var allTasks = await BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId)
                .Where(t => t.AssignedTo != null)
                .ToListAsync();
            var now = DateTime.UtcNow;

            var list = users.Select(u =>
            {
                var uTasks = allTasks.Where(t => t.AssignedTo == u.Id).ToList();
                return new TeamProductivityReportDto
                {
                    UserId = u.Id,
                    FullName = $"{u.FirstName} {u.LastName}".Trim(),
                    Username = u.Username,
                    TotalAssigned = uTasks.Count,
                    Completed = uTasks.Count(t => t.StatusId == AppTaskStatus.Done),
                    InProgress = uTasks.Count(t => t.StatusId == AppTaskStatus.InProgress),
                    ToDo = uTasks.Count(t => t.StatusId == AppTaskStatus.Todo),
                    Overdue = uTasks.Count(t => t.DueDate < now && t.StatusId != AppTaskStatus.Done),
                    CompletionRate = uTasks.Count > 0 ? Math.Round((double)uTasks.Count(t => t.StatusId == AppTaskStatus.Done) / uTasks.Count * 100, 1) : 0
                };
            }).ToList();

            if (!string.IsNullOrWhiteSpace(search))
            {
                var s = search.Trim().ToLower();
                list = list.Where(u => u.FullName.ToLower().Contains(s) || u.Username.ToLower().Contains(s)).ToList();
            }

            return Result<IEnumerable<TeamProductivityReportDto>>.Success(list.OrderByDescending(u => u.CompletionRate));
        }

        public byte[] ExportTeamProductivityToExcel(IEnumerable<TeamProductivityReportDto> data)
        {
            using var wb = new XLWorkbook();
            var ws = wb.Worksheets.Add("Team Productivity");
            var headers = new[] { "User ID", "Full Name", "Username", "Total Assigned", "Completed", "In Progress", "To Do", "Overdue", "Completion Rate (%)" };
            for (int i = 0; i < headers.Length; i++)
            {
                ws.Cell(1, i + 1).Value = headers[i];
                ws.Cell(1, i + 1).Style.Font.Bold = true;
                ws.Cell(1, i + 1).Style.Fill.BackgroundColor = XLColor.FromHtml("#059669");
                ws.Cell(1, i + 1).Style.Font.FontColor = XLColor.White;
            }
            int row = 2;
            foreach (var item in data)
            {
                ws.Cell(row, 1).Value = item.UserId;
                ws.Cell(row, 2).Value = item.FullName;
                ws.Cell(row, 3).Value = item.Username;
                ws.Cell(row, 4).Value = item.TotalAssigned;
                ws.Cell(row, 5).Value = item.Completed;
                ws.Cell(row, 6).Value = item.InProgress;
                ws.Cell(row, 7).Value = item.ToDo;
                ws.Cell(row, 8).Value = item.Overdue;
                ws.Cell(row, 9).Value = item.CompletionRate;
                if (item.Overdue > 0) ws.Row(row).Style.Fill.BackgroundColor = XLColor.FromHtml("#FEF3C7");
                row++;
            }
            ws.Columns().AdjustToContents();
            using var ms = new MemoryStream();
            wb.SaveAs(ms);
            return ms.ToArray();
        }

        // ─── Report 3: Overdue & Critical Tasks ───────────────────────────────────

        public async Task<Result<IEnumerable<OverdueCriticalTaskDto>>> GetOverdueCriticalTasksAsync(
            string? search,
            long? projectId,
            long roleId,
            long currentUserId,
            int? priorityId = null,
            string? delayType = null,
            bool? assignedToMe = null,
            bool? assignedToMyTeam = null)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var now = DateTime.UtcNow;
            var today = DateTime.Today;
            var query = BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId)
                .Include(t => t.Project)
                .Include(t => t.AssignedToNavigation)
                .Where(t => t.IsDeleted != true && t.StatusId != AppTaskStatus.Done &&
                            (t.DueDate < now || t.PriorityId == TaskPriority.High)); // overdue OR high priority

            if (projectId.HasValue && projectId > 0)
                query = query.Where(t => t.ProjectId == projectId.Value);

            if (priorityId.HasValue && priorityId > 0)
                query = query.Where(t => (int)t.PriorityId == priorityId.Value);

            switch (delayType?.Trim().ToLower())
            {
                case "overdue":
                    query = query.Where(t => t.DueDate.Date < today);
                    break;
                case "soon":
                    query = query.Where(t => t.DueDate.Date >= today && t.DueDate.Date <= today.AddDays(3));
                    break;
            }

            if (assignedToMe == true || assignedToMyTeam == true)
            {
                var teamIds = assignedToMyTeam == true ? await GetTeamUserIdsAsync(currentUserId) : new List<long>();
                query = query.Where(t =>
                    (assignedToMe == true && t.AssignedTo == currentUserId) ||
                    (assignedToMyTeam == true && t.AssignedTo.HasValue && teamIds.Contains(t.AssignedTo.Value))
                );
            }

            var tasks = await query.OrderBy(t => t.DueDate).ToListAsync();

            if (!string.IsNullOrWhiteSpace(search))
            {
                var s = search.Trim().ToLower();
                tasks = tasks.Where(t =>
                    t.Title.ToLower().Contains(s) ||
                    (t.Project?.Name.ToLower().Contains(s) == true)
                ).ToList();
            }

            var list = tasks.Select(t => new OverdueCriticalTaskDto
            {
                TaskId = t.Id,
                Title = t.Title,
                Description = t.Description,
                ProjectName = t.Project?.Name ?? "-",
                StatusName = StatusMap.TryGetValue(t.StatusId, out var s) ? s : $"Status {t.StatusId}",
                PriorityName = PriorityMap.TryGetValue(t.PriorityId, out var p) ? p : $"Priority {t.PriorityId}",
                AssignedTo = t.AssignedToNavigation != null ? $"{t.AssignedToNavigation.FirstName} {t.AssignedToNavigation.LastName}" : null,
                AssignedToUserId = t.AssignedTo,
                DueDate = t.DueDate,
                DaysOverdue = t.DueDate < now ? (int)(now - t.DueDate).TotalDays : 0,
                CreatedAt = t.CreatedAt ?? DateTime.UtcNow
            }).ToList();
            await EnrichOverdueTaskReportsAsync(list);

            return Result<IEnumerable<OverdueCriticalTaskDto>>.Success(list);
        }

        public async Task<PagedResult<OverdueCriticalTaskDto>> GetPagedOverdueCriticalTasksAsync(
            string? search,
            long? projectId,
            long roleId,
            long currentUserId,
            int page,
            int pageSize,
            int? priorityId = null,
            string? delayType = null,
            bool? assignedToMe = null,
            bool? assignedToMyTeam = null)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var now = DateTime.UtcNow;
            var today = DateTime.Today;
            var query = BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId)
                .Include(t => t.Project)
                .Include(t => t.AssignedToNavigation)
                .Where(t => t.IsDeleted != true && t.StatusId != AppTaskStatus.Done &&
                            (t.DueDate < now || t.PriorityId == TaskPriority.High));

            if (projectId.HasValue && projectId > 0)
                query = query.Where(t => t.ProjectId == projectId.Value);

            if (priorityId.HasValue && priorityId > 0)
                query = query.Where(t => (int)t.PriorityId == priorityId.Value);

            switch (delayType?.Trim().ToLower())
            {
                case "overdue":
                    query = query.Where(t => t.DueDate.Date < today);
                    break;
                case "soon":
                    query = query.Where(t => t.DueDate.Date >= today && t.DueDate.Date <= today.AddDays(3));
                    break;
                default:
                    query = query.Where(t => t.DueDate.Date <= today.AddDays(3));
                    break;
            }

            if (assignedToMe == true || assignedToMyTeam == true)
            {
                var teamIds = assignedToMyTeam == true ? await GetTeamUserIdsAsync(currentUserId) : new List<long>();
                query = query.Where(t =>
                    (assignedToMe == true && t.AssignedTo == currentUserId) ||
                    (assignedToMyTeam == true && t.AssignedTo.HasValue && teamIds.Contains(t.AssignedTo.Value))
                );
            }

            if (!string.IsNullOrWhiteSpace(search))
            {
                var s = search.Trim().ToLower();
                query = query.Where(t =>
                    t.Title.ToLower().Contains(s) ||
                    (t.Project != null && t.Project.Name.ToLower().Contains(s)));
            }

            var paged = await query
                .OrderBy(t => t.DueDate)
                .ThenBy(t => t.Title)
                .ToPagedResultAsync(page, pageSize);

            var mapped = MapPagedResult(paged, t => new OverdueCriticalTaskDto
            {
                TaskId = t.Id,
                Title = t.Title,
                Description = t.Description,
                ProjectName = t.Project?.Name ?? "-",
                StatusName = StatusMap.TryGetValue(t.StatusId, out var s) ? s : $"Status {t.StatusId}",
                PriorityName = PriorityMap.TryGetValue(t.PriorityId, out var p) ? p : $"Priority {t.PriorityId}",
                AssignedTo = t.AssignedToNavigation != null ? $"{t.AssignedToNavigation.FirstName} {t.AssignedToNavigation.LastName}" : null,
                AssignedToUserId = t.AssignedTo,
                DueDate = t.DueDate,
                DaysOverdue = t.DueDate < now ? (int)(now - t.DueDate).TotalDays : 0,
                CreatedAt = t.CreatedAt ?? DateTime.UtcNow
            });
            await EnrichOverdueTaskReportsAsync(mapped.Items);

            return mapped;
        }

        public byte[] ExportOverdueCriticalToExcel(IEnumerable<OverdueCriticalTaskDto> data)
        {
            using var wb = new XLWorkbook();
            var ws = wb.Worksheets.Add("Overdue & Critical Tasks");
            var headers = new[] { "Task ID", "Title", "Project", "Status", "Priority", "Assigned To", "Due Date", "Days Overdue", "Created At" };
            for (int i = 0; i < headers.Length; i++)
            {
                ws.Cell(1, i + 1).Value = headers[i];
                ws.Cell(1, i + 1).Style.Font.Bold = true;
                ws.Cell(1, i + 1).Style.Fill.BackgroundColor = XLColor.FromHtml("#DC2626");
                ws.Cell(1, i + 1).Style.Font.FontColor = XLColor.White;
            }
            int row = 2;
            foreach (var item in data)
            {
                ws.Cell(row, 1).Value = item.TaskId;
                ws.Cell(row, 2).Value = item.Title;
                ws.Cell(row, 3).Value = item.ProjectName;
                ws.Cell(row, 4).Value = item.StatusName;
                ws.Cell(row, 5).Value = item.PriorityName;
                ws.Cell(row, 6).Value = item.AssignedTo ?? "Unassigned";
                ws.Cell(row, 7).Value = DisplayFormats.Date(item.DueDate);
                ws.Cell(row, 8).Value = item.DaysOverdue;
                ws.Cell(row, 9).Value = DisplayFormats.Date(item.CreatedAt);
                if (item.DaysOverdue > 0) ws.Row(row).Style.Fill.BackgroundColor = XLColor.FromHtml("#FEE2E2");
                row++;
            }
            ws.Columns().AdjustToContents();
            using var ms = new MemoryStream();
            wb.SaveAs(ms);
            return ms.ToArray();
        }

        public async Task<Result<IEnumerable<EmployeeProductivityReportDto>>> GetEmployeeProductivityReportAsync(
            string? search,
            DateTime? startDate,
            DateTime? endDate,
            string? status,
            long roleId,
            long currentUserId,
            bool? assignedToMe = null,
            bool? assignedToMyTeam = null)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var users = await BuildAccessibleUserQuery(isAdmin, currentUserId).ToListAsync();
            
            if (assignedToMe == true || assignedToMyTeam == true)
            {
                var teamIds = assignedToMyTeam == true ? await GetTeamUserIdsAsync(currentUserId) : new List<long>();
                users = users.Where(u =>
                    (assignedToMe == true && u.Id == currentUserId) ||
                    (assignedToMyTeam == true && teamIds.Contains(u.Id))
                ).ToList();
            }

            var tasks = await BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId).ToListAsync();
            var issues = await BuildAccessibleIssueQuery(isAdmin, isManager, currentUserId)
                .Include(i => i.Task)
                .ToListAsync();

            if (startDate.HasValue)
            {
                tasks = tasks.Where(t => t.CreatedAt >= startDate.Value.Date).ToList();
                issues = issues.Where(i => (i.CreatedAt ?? DateTime.UtcNow) >= startDate.Value.Date).ToList();
            }

            if (endDate.HasValue)
            {
                tasks = tasks.Where(t => t.CreatedAt < endDate.Value.Date.AddDays(1)).ToList();
                issues = issues.Where(i => (i.CreatedAt ?? DateTime.UtcNow) < endDate.Value.Date.AddDays(1)).ToList();
            }

            if (!string.IsNullOrWhiteSpace(status))
            {
                var sl = status.Trim().ToLower();
                if (sl == "overdue")
                {
                    tasks = tasks.Where(t => t.StatusId != AppTaskStatus.Done && t.DueDate < DateTime.Today).ToList();
                    issues = issues.Where(i => i.StatusId != AppTaskStatus.Done && i.DueDate.Date < DateTime.Today).ToList();
                }
                else if (sl != "0")
                {
                    if (Enum.TryParse<AppTaskStatus>(status, true, out var parsedStatus))
                    {
                        tasks = tasks.Where(t => t.StatusId == parsedStatus).ToList();
                        issues = issues.Where(i => i.StatusId == parsedStatus).ToList();
                    }
                }
            }

            var list = new List<EmployeeProductivityReportDto>();
            foreach (var user in users)
            {
                var userTasks = tasks.Where(t => t.AssignedTo == user.Id).ToList();
                var userIssues = issues.Where(i => i.AssignedTo == user.Id).ToList();
                int total = userTasks.Count;
                var completedTasks = userTasks.Where(t => t.StatusId == AppTaskStatus.Done).ToList();
                int done = completedTasks.Count;
                var completedIssues = userIssues.Where(i => i.StatusId == AppTaskStatus.Done).ToList();

                int onTimeCount = completedTasks.Count(t =>
                    (t.UpdatedAt ?? t.CreatedAt) <= t.DueDate);

                var onTimeIssueCount = completedIssues.Count(i => (i.UpdatedAt ?? i.CreatedAt ?? DateTime.UtcNow) <= i.DueDate);
                double onTimeDeliveryRate = completedIssues.Count > 0
                    ? Math.Round(((double)onTimeIssueCount / completedIssues.Count) * 100, 2)
                    : done > 0 ? Math.Round(((double)onTimeCount / done) * 100, 2) : 0;
                var openIssues = userIssues.Count(i => i.StatusId != AppTaskStatus.Done);
                var overdueIssues = userIssues.Count(i => i.StatusId != AppTaskStatus.Done && i.DueDate.Date < DateTime.Today);
                var completionRate = userIssues.Count > 0 ? Math.Round(((double)completedIssues.Count / userIssues.Count) * 100, 2) : 0;
                var avgCompletionDays = completedIssues.Count > 0
                    ? Math.Round(completedIssues.Average(i => Math.Max(0, ((i.UpdatedAt ?? i.CreatedAt ?? DateTime.UtcNow).Date - i.StartDate.Date).TotalDays)), 1)
                    : 0;

                list.Add(new EmployeeProductivityReportDto
                {
                    UserId = user.Id,
                    Username = user.Username,
                    FullName = $"{user.FirstName} {user.LastName}".Trim(),
                    AssignedCount = total,
                    CompletedCount = done,
                    AssignedIssues = userIssues.Count,
                    OpenIssues = openIssues,
                    OverdueIssues = overdueIssues,
                    ActualHours = userIssues.Sum(i => i.ActualHours ?? 0),
                    WorkloadLevel = openIssues >= 10 || overdueIssues >= 3 ? "High" : openIssues <= 2 ? "Light" : "Balanced",
                    AverageCompletionTimeDays = avgCompletionDays,
                    Trend = overdueIssues > 0 ? "Declining" : completionRate >= 80 ? "Improving" : "Stable",
                    CompletionRate = completionRate,
                    Efficiency = completionRate,
                    OnTimeDeliveryRate = onTimeDeliveryRate
                });
            }

            if (!string.IsNullOrWhiteSpace(search))
            {
                var s = search.Trim().ToLower();
                list = list.Where(u => u.FullName.ToLower().Contains(s) || u.Username.ToLower().Contains(s)).ToList();
            }

            return Result<IEnumerable<EmployeeProductivityReportDto>>.Success(list.OrderByDescending(u => u.OpenIssues).ThenByDescending(u => u.ActualHours));
        }

        public async Task<PagedResult<EmployeeProductivityReportDto>> GetPagedEmployeeProductivityReportAsync(
            string? search,
            DateTime? startDate,
            DateTime? endDate,
            string? status,
            long roleId,
            long currentUserId,
            int page,
            int pageSize,
            bool? assignedToMe = null,
            bool? assignedToMyTeam = null)
        {
            var full = await GetEmployeeProductivityReportAsync(search, startDate, endDate, status, roleId, currentUserId, assignedToMe, assignedToMyTeam);
            if (!full.IsSuccess || full.Value == null)
            {
                return new PagedResult<EmployeeProductivityReportDto>();
            }

            var ordered = full.Value.OrderByDescending(u => u.OpenIssues).ThenByDescending(u => u.ActualHours).ToList();
            var normalizedPageSize = PaginationExtensions.NormalizePageSize(pageSize);
            var totalCount = ordered.Count;
            var totalPages = totalCount == 0 ? 0 : (int)Math.Ceiling(totalCount / (double)normalizedPageSize);
            var normalizedPage = Math.Max(page, 1);
            if (totalPages > 0 && normalizedPage > totalPages)
                normalizedPage = totalPages;

            var items = ordered
                .Skip((normalizedPage - 1) * normalizedPageSize)
                .Take(normalizedPageSize)
                .ToList();

            return new PagedResult<EmployeeProductivityReportDto>
            {
                Items = items,
                TotalCount = totalCount,
                Page = normalizedPage,
                PageSize = normalizedPageSize,
                TotalPages = totalPages
            };
        }

        public async Task<Result<IEnumerable<ProjectProgressReportDto>>> GetProjectProgressReportAsync(
            string? search,
            DateTime? startDate,
            DateTime? endDate,
            string? status,
            long roleId,
            long currentUserId,
            bool? assignedToMe = null,
            bool? assignedToMyTeam = null)
        {
            var isAdmin = await DataScopeAuthorization.IsAdminScopeAsync(_db, roleId);
            var isManager = await DataScopeAuthorization.IsManagerScopeAsync(_db, roleId);
            var projects = await BuildAccessibleProjectQuery(isAdmin, currentUserId).ToListAsync();

            if (assignedToMe == true || assignedToMyTeam == true)
            {
                var myProjectIds = await _db.ProjectMembers
                    .Where(pm => pm.UserId == currentUserId)
                    .Select(pm => pm.ProjectId)
                    .Distinct()
                    .ToListAsync();

                projects = projects.Where(p => myProjectIds.Contains(p.Id) || p.CreatedById == currentUserId).ToList();
            }

            var tasks = await BuildAccessibleTaskQuery(isAdmin, isManager, currentUserId).ToListAsync();
            var issues = await BuildAccessibleIssueQuery(isAdmin, isManager, currentUserId)
                .Include(i => i.Task)
                .ToListAsync();
            var today = DateTime.Today;

            if (startDate.HasValue)
                projects = projects.Where(p => p.StartDate >= startDate.Value.Date).ToList();

            if (endDate.HasValue)
                projects = projects.Where(p => p.StartDate < endDate.Value.Date.AddDays(1)).ToList();

            var list = new List<ProjectProgressReportDto>();
            foreach (var project in projects)
            {
                var projectTasks = tasks.Where(t => t.ProjectId == project.Id).ToList();
                var projectIssues = issues.Where(i => i.Task.ProjectId == project.Id).ToList();

                if (!string.IsNullOrWhiteSpace(status))
                {
                    if (status.Equals("overdue", StringComparison.OrdinalIgnoreCase))
                    {
                        projectTasks = projectTasks.Where(t => t.DueDate.Date < today && t.StatusId != AppTaskStatus.Done).ToList();
                        projectIssues = projectIssues.Where(i => i.DueDate.Date < today && i.StatusId != AppTaskStatus.Done).ToList();
                    }
                    else if (status != "0" && Enum.TryParse<AppTaskStatus>(status, true, out var parsedStatus))
                    {
                        projectTasks = projectTasks.Where(t => t.StatusId == parsedStatus).ToList();
                        projectIssues = projectIssues.Where(i => i.StatusId == parsedStatus).ToList();
                    }
                }

                int totalTasks = projectTasks.Count;
                int completedTasks = projectTasks.Count(t => t.StatusId == AppTaskStatus.Done);
                double progress = totalTasks > 0 ? ((double)completedTasks / totalTasks) * 100 : 0;

                double elapsedPct;
                if (today < project.StartDate) elapsedPct = 0;
                else if (today > project.EndDate) elapsedPct = 100;
                else
                {
                    var totalDays = (project.EndDate - project.StartDate).TotalDays;
                    var elapsedDays = (today - project.StartDate).TotalDays;
                    elapsedPct = totalDays > 0 ? (elapsedDays / totalDays) * 100 : 100;
                }

                bool isAhead = progress > elapsedPct && progress > 0 && progress < 100;
                var openIssues = projectIssues.Count(i => i.StatusId != AppTaskStatus.Done);
                var overdueIssues = projectIssues.Count(i => i.StatusId != AppTaskStatus.Done && i.DueDate.Date < today);
                var blockedIssues = projectIssues.Count(i => i.IsBlocked);
                bool isAtRisk = (projectTasks.Any(t => t.StatusId != AppTaskStatus.Done && t.DueDate.Date < today)) ||
                                overdueIssues > 0 ||
                                blockedIssues > 0 ||
                                (project.EndDate.Date < today && progress < 100);
                var health = isAtRisk && (overdueIssues > 0 || blockedIssues > 0) ? "Critical" : isAtRisk ? "At Risk" : "Healthy";
                var lastActivity = projectIssues
                    .Select(i => i.UpdatedAt ?? i.CreatedAt ?? project.CreatedAt ?? DateTime.UtcNow)
                    .Concat(projectTasks.Select(t => t.UpdatedAt ?? t.CreatedAt ?? DateTime.UtcNow))
                    .DefaultIfEmpty(project.CreatedAt ?? DateTime.UtcNow)
                    .Max();

                list.Add(new ProjectProgressReportDto
                {
                    ProjectId = project.Id,
                    ProjectName = project.Name,
                    StartDate = project.StartDate,
                    EndDate = project.EndDate,
                    TotalTasks = totalTasks,
                    CompletedTasks = completedTasks,
                    OpenIssues = openIssues,
                    OverdueIssues = overdueIssues,
                    BlockedIssues = blockedIssues,
                    Progress = progress,
                    IsAhead = isAhead,
                    IsAtRisk = isAtRisk,
                    ProjectHealth = health,
                    LastActivity = lastActivity,
                    NextMilestone = project.EndDate.Date >= today ? project.EndDate : null,
                    ActualHours = projectIssues.Sum(i => i.ActualHours ?? 0)
                });
            }

            if (!string.IsNullOrWhiteSpace(search))
            {
                var s = search.Trim().ToLower();
                list = list.Where(p => p.ProjectName.ToLower().Contains(s)).ToList();
            }

            return Result<IEnumerable<ProjectProgressReportDto>>.Success(list.OrderBy(p => p.ProjectName));
        }

        public async Task<PagedResult<ProjectProgressReportDto>> GetPagedProjectProgressReportAsync(
            string? search,
            DateTime? startDate,
            DateTime? endDate,
            string? status,
            long roleId,
            long currentUserId,
            int page,
            int pageSize,
            bool? assignedToMe = null,
            bool? assignedToMyTeam = null)
        {
            var full = await GetProjectProgressReportAsync(search, startDate, endDate, status, roleId, currentUserId, assignedToMe, assignedToMyTeam);
            if (!full.IsSuccess || full.Value == null)
            {
                return new PagedResult<ProjectProgressReportDto>();
            }

            var ordered = full.Value.OrderBy(p => p.ProjectName).ToList();
            var normalizedPageSize = PaginationExtensions.NormalizePageSize(pageSize);
            var totalCount = ordered.Count;
            var totalPages = totalCount == 0 ? 0 : (int)Math.Ceiling(totalCount / (double)normalizedPageSize);
            var normalizedPage = Math.Max(page, 1);
            if (totalPages > 0 && normalizedPage > totalPages)
                normalizedPage = totalPages;

            var items = ordered
                .Skip((normalizedPage - 1) * normalizedPageSize)
                .Take(normalizedPageSize)
                .ToList();

            return new PagedResult<ProjectProgressReportDto>
            {
                Items = items,
                TotalCount = totalCount,
                Page = normalizedPage,
                PageSize = normalizedPageSize,
                TotalPages = totalPages
            };
        }
    }
}