using AutoMapper;
using PowderCoating.Shared.Constants;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.EntityFrameworkCore;
using PowderCoating.Application.DTOs.Appointment;
using PowderCoating.Application.DTOs.Common;
using PowderCoating.Application.Services;
using PowderCoating.Core.Entities;
using PowderCoating.Core.Interfaces;

namespace PowderCoating.Web.Controllers;

[Authorize(Policy = AppConstants.Policies.CanManageCalendar)]
public class AppointmentsController : Controller
{
    private readonly IUnitOfWork _unitOfWork;
    private readonly IMapper _mapper;
    private readonly ILogger<AppointmentsController> _logger;
    private readonly ITenantContext _tenantContext;
    private readonly ILookupCacheService _lookupCache;
    private readonly UserManager<ApplicationUser> _userManager;

    public AppointmentsController(
        IUnitOfWork unitOfWork,
        IMapper mapper,
        ILogger<AppointmentsController> logger,
        ITenantContext tenantContext,
        ILookupCacheService lookupCache,
        UserManager<ApplicationUser> userManager)
    {
        _unitOfWork = unitOfWork;
        _mapper = mapper;
        _logger = logger;
        _tenantContext = tenantContext;
        _lookupCache = lookupCache;
        _userManager = userManager;
    }

    /// <summary>
    /// Renders the paginated, searchable appointment list. Filtering is built as a single
    /// SQL-translatable LINQ expression to avoid pulling all rows into memory before applying
    /// predicates. Sorting is driven by a column-name switch so the database handles ordering
    /// rather than doing it client-side. Type and status dropdowns are served from
    /// <see cref="ILookupCacheService"/> to avoid repeated round-trips on every page load.
    /// </summary>
    // GET: Appointments
    public async Task<IActionResult> Index(
        string? searchTerm,
        int? typeFilter,
        int? statusFilter,
        string? sortColumn,
        string sortDirection = "asc",
        int pageNumber = 1,
        int pageSize = 25)
    {
        try
        {
            // Create and validate grid request
            var gridRequest = new GridRequest
            {
                PageNumber = pageNumber,
                PageSize = pageSize,
                SortColumn = sortColumn ?? "ScheduledStartTime",
                SortDirection = sortColumn == null ? "asc" : sortDirection,
                SearchTerm = searchTerm
            };
            gridRequest.Validate();

            // Build filter expression — each predicate is a pure SQL-translatable expression.
            // Avoid chaining via .Compile() which forces in-memory evaluation.
            System.Linq.Expressions.Expression<Func<Appointment, bool>>? filter = null;
            if (!string.IsNullOrWhiteSpace(searchTerm) || typeFilter.HasValue || statusFilter.HasValue)
            {
                var hasSearch = !string.IsNullOrWhiteSpace(searchTerm);
                var search    = searchTerm?.ToLower() ?? string.Empty;
                var typeId    = typeFilter ?? 0;
                var statusId  = statusFilter ?? 0;

                filter = a =>
                    (!hasSearch || (
                        a.AppointmentNumber.ToLower().Contains(search)
                        || a.Title.ToLower().Contains(search)
                        || (a.Description != null && a.Description.ToLower().Contains(search))
                        || a.Customer.CompanyName.ToLower().Contains(search)
                        || (a.Location != null && a.Location.ToLower().Contains(search))))
                    && (!typeFilter.HasValue   || a.AppointmentTypeId   == typeId)
                    && (!statusFilter.HasValue || a.AppointmentStatusId == statusId);
            }

            // Build orderBy function
            Func<IQueryable<Appointment>, IOrderedQueryable<Appointment>> orderBy = gridRequest.SortColumn switch
            {
                "AppointmentNumber" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(a => a.AppointmentNumber) : q.OrderByDescending(a => a.AppointmentNumber),
                "Title" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(a => a.Title) : q.OrderByDescending(a => a.Title),
                "Customer" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(a => a.Customer.CompanyName) : q.OrderByDescending(a => a.Customer.CompanyName),
                "Type" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(a => a.AppointmentType.DisplayOrder) : q.OrderByDescending(a => a.AppointmentType.DisplayOrder),
                "Status" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(a => a.AppointmentStatus.DisplayOrder) : q.OrderByDescending(a => a.AppointmentStatus.DisplayOrder),
                "ScheduledStartTime" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(a => a.ScheduledStartTime) : q.OrderByDescending(a => a.ScheduledStartTime),
                "CreatedAt" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(a => a.CreatedAt) : q.OrderByDescending(a => a.CreatedAt),
                _ => q => q.OrderBy(a => a.ScheduledStartTime)
            };

            // Get paged data with eager loading
            var (items, totalCount) = await _unitOfWork.Appointments.GetPagedAsync(
                gridRequest.PageNumber,
                gridRequest.PageSize,
                filter,
                orderBy,
                a => a.Customer,
                a => a.AppointmentType,
                a => a.AppointmentStatus,
                a => a.AssignedUser);

            // Map to DTOs
            var appointmentDtos = _mapper.Map<List<AppointmentListDto>>(items);

            // Create paged result
            var pagedResult = new PagedResult<AppointmentListDto>
            {
                Items = appointmentDtos,
                PageNumber = gridRequest.PageNumber,
                PageSize = gridRequest.PageSize,
                TotalCount = totalCount
            };

            // Set ViewBag
            ViewBag.SearchTerm = searchTerm;
            ViewBag.TypeFilter = typeFilter;
            ViewBag.StatusFilter = statusFilter;
            ViewBag.SortColumn = gridRequest.SortColumn;
            ViewBag.SortDirection = gridRequest.SortDirection;

            // Populate filter dropdowns
            await PopulateFilterDropdowns();

            return View(pagedResult);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error retrieving appointments");
            TempData["Error"] = "An error occurred while loading appointments.";
            return View(new PagedResult<AppointmentListDto>());
        }
    }

    /// <summary>
    /// Shows the full detail view for a single appointment, eagerly loading the customer, linked
    /// job, appointment type, appointment status, and assigned user so the view renders in a
    /// single database round-trip.
    /// </summary>
    // GET: Appointments/Details/5
    public async Task<IActionResult> Details(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        try
        {
            var appointment = await _unitOfWork.Appointments.GetByIdAsync(id.Value, false,
                a => a.Customer,
                a => a.Job,
                a => a.AppointmentType,
                a => a.AppointmentStatus,
                a => a.AssignedUser);

            if (appointment == null)
            {
                return NotFound();
            }

            var dto = _mapper.Map<AppointmentDto>(appointment);
            return View(dto);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error retrieving appointment {Id}", id);
            TempData["Error"] = "An error occurred while loading the appointment.";
            return RedirectToAction(nameof(Index));
        }
    }

    /// <summary>
    /// Renders the appointment creation form with all dropdowns pre-populated via
    /// <see cref="PopulateCreateDropdowns"/>.
    /// </summary>
    // GET: Appointments/Create
    public async Task<IActionResult> Create()
    {
        try
        {
            await PopulateCreateDropdowns();
            return View();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error loading create form");
            TempData["Error"] = "An error occurred while loading the form.";
            return RedirectToAction(nameof(Index));
        }
    }

    /// <summary>
    /// Persists a new appointment after validating time ordering rules (all-day events require
    /// end date &gt;= start date; timed events require end &gt; start) and the business rule that
    /// appointment types marked <c>RequiresJobLink</c> must reference a specific job. The
    /// appointment number is generated in APT-YYMM-#### format (see
    /// <see cref="GenerateAppointmentNumberAsync"/>) and the initial status is always "SCHEDULED"
    /// looked up by its status code rather than a hard-coded ID.
    /// </summary>
    // POST: Appointments/Create
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Create(CreateAppointmentDto dto)
    {
        if (!ModelState.IsValid)
        {
            _logger.LogWarning("Model validation failed. Errors: {Errors}",
                string.Join(", ", ModelState.Values.SelectMany(v => v.Errors).Select(e => e.ErrorMessage)));
            await PopulateCreateDropdowns();
            return View(dto);
        }

        try
        {
            // Validate start time < end time (for all-day events, allow same date)
            if (dto.IsAllDay)
            {
                // For all-day events, end date must be >= start date
                if (dto.ScheduledEndTime.Date < dto.ScheduledStartTime.Date)
                {
                    ModelState.AddModelError("ScheduledEndTime", "End date must be on or after start date.");
                    await PopulateCreateDropdowns();
                    return View(dto);
                }
            }
            else
            {
                // For timed events, end time must be after start time
                if (dto.ScheduledStartTime >= dto.ScheduledEndTime)
                {
                    ModelState.AddModelError("ScheduledEndTime", "End time must be after start time.");
                    await PopulateCreateDropdowns();
                    return View(dto);
                }
            }

            // Validate JobId required for JOB_WORK type
            var appointmentType = await _unitOfWork.AppointmentTypeLookups.GetByIdAsync(dto.AppointmentTypeId);
            if (appointmentType?.RequiresJobLink == true && !dto.JobId.HasValue)
            {
                ModelState.AddModelError("JobId", "Job is required for this appointment type.");
                await PopulateCreateDropdowns();
                return View(dto);
            }

            // Map to entity
            var appointment = _mapper.Map<Appointment>(dto);

            // Generate appointment number
            appointment.AppointmentNumber = await GenerateAppointmentNumberAsync();

            // Set default status to SCHEDULED
            var scheduledStatus = (await _unitOfWork.AppointmentStatusLookups.FindAsync(s => s.StatusCode == "SCHEDULED")).FirstOrDefault();
            if (scheduledStatus != null)
            {
                appointment.AppointmentStatusId = scheduledStatus.Id;
            }

            // Save
            await _unitOfWork.Appointments.AddAsync(appointment);
            await _unitOfWork.CompleteAsync();

            TempData["Success"] = "Appointment created successfully.";
            return RedirectToAction(nameof(Details), new { id = appointment.Id });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error creating appointment");
            ModelState.AddModelError("", "An error occurred while creating the appointment.");
            await PopulateCreateDropdowns();
            return View(dto);
        }
    }

    /// <summary>
    /// Loads the edit form for an existing appointment, mapping the entity to
    /// <see cref="PowderCoating.Application.DTOs.Appointment.UpdateAppointmentDto"/> and
    /// populating all dropdowns including the status list (which is only available on edits,
    /// not creates — users cannot choose status during initial creation).
    /// </summary>
    // GET: Appointments/Edit/5
    public async Task<IActionResult> Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        try
        {
            var appointment = await _unitOfWork.Appointments.GetByIdAsync(id.Value, false,
                a => a.Customer,
                a => a.Job,
                a => a.AppointmentType,
                a => a.AppointmentStatus);

            if (appointment == null)
            {
                return NotFound();
            }

            var dto = _mapper.Map<UpdateAppointmentDto>(appointment);
            await PopulateEditDropdowns();
            return View(dto);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error loading edit form for appointment {Id}", id);
            TempData["Error"] = "An error occurred while loading the form.";
            return RedirectToAction(nameof(Index));
        }
    }

    /// <summary>
    /// Saves changes to an existing appointment. Applies the same time-ordering and
    /// job-link validation rules as <see cref="Create(CreateAppointmentDto)"/>. Uses
    /// AutoMapper to merge only the DTO fields onto the tracked entity so EF Core generates
    /// a minimal UPDATE statement.
    /// </summary>
    // POST: Appointments/Edit/5
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Edit(int id, UpdateAppointmentDto dto)
    {
        if (id != dto.Id)
        {
            return NotFound();
        }

        if (!ModelState.IsValid)
        {
            await PopulateEditDropdowns();
            return View(dto);
        }

        try
        {
            // Validate start time < end time (for all-day events, allow same date)
            if (dto.IsAllDay)
            {
                // For all-day events, end date must be >= start date
                if (dto.ScheduledEndTime.Date < dto.ScheduledStartTime.Date)
                {
                    ModelState.AddModelError("ScheduledEndTime", "End date must be on or after start date.");
                    await PopulateEditDropdowns();
                    return View(dto);
                }
            }
            else
            {
                // For timed events, end time must be after start time
                if (dto.ScheduledStartTime >= dto.ScheduledEndTime)
                {
                    ModelState.AddModelError("ScheduledEndTime", "End time must be after start time.");
                    await PopulateEditDropdowns();
                    return View(dto);
                }
            }

            // Get existing appointment
            var appointment = await _unitOfWork.Appointments.GetByIdAsync(id);
            if (appointment == null)
            {
                return NotFound();
            }

            // Validate JobId required for JOB_WORK type
            var appointmentType = await _unitOfWork.AppointmentTypeLookups.GetByIdAsync(dto.AppointmentTypeId);
            if (appointmentType?.RequiresJobLink == true && !dto.JobId.HasValue)
            {
                ModelState.AddModelError("JobId", "Job is required for this appointment type.");
                await PopulateEditDropdowns();
                return View(dto);
            }

            // Map changes
            _mapper.Map(dto, appointment);

            // Update
            await _unitOfWork.Appointments.UpdateAsync(appointment);
            await _unitOfWork.CompleteAsync();

            TempData["Success"] = "Appointment updated successfully.";
            return RedirectToAction(nameof(Details), new { id = appointment.Id });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error updating appointment {Id}", id);
            ModelState.AddModelError("", "An error occurred while updating the appointment.");
            await PopulateEditDropdowns();
            return View(dto);
        }
    }

    /// <summary>
    /// Soft-deletes an appointment (sets <c>IsDeleted = true</c>) and redirects to the
    /// calendar rather than the list so the user lands back in the context they most likely
    /// came from. The global query filter automatically hides soft-deleted records from
    /// all subsequent queries.
    /// </summary>
    // POST: Appointments/Delete/5
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Delete(int id)
    {
        try
        {
            var appointment = await _unitOfWork.Appointments.GetByIdAsync(id);
            if (appointment == null)
            {
                TempData["Error"] = "Appointment not found.";
                return RedirectToAction(nameof(Calendar));
            }

            await _unitOfWork.Appointments.SoftDeleteAsync(id);
            await _unitOfWork.CompleteAsync();

            TempData["Success"] = "Appointment deleted successfully.";
            return RedirectToAction(nameof(Calendar));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error deleting appointment {Id}", id);
            TempData["Error"] = "An error occurred while deleting the appointment.";
            return RedirectToAction(nameof(Calendar));
        }
    }

    /// <summary>
    /// Renders the full-calendar shell view (FullCalendar JS). The server only sets the
    /// initial view mode and date context in ViewBag; actual event data is fetched client-side
    /// by <see cref="GetCalendarEvents"/>. Appointment type legends and quick-create dropdowns
    /// are pre-loaded here so the page is self-contained for the first render.
    /// </summary>
    // GET: Appointments/Calendar
    public async Task<IActionResult> Calendar(string view = "month", DateTime? date = null)
    {
        try
        {
            var currentDate = date ?? DateTime.Today;
            ViewBag.CurrentView = view;
            ViewBag.CurrentDate = currentDate;

            // Populate dropdowns for quick create modal
            await PopulateCreateDropdowns();

            // Load appointment types for legend (cached)
            var companyId = _tenantContext.GetCurrentCompanyId() ?? 0;
            var appointmentTypes = await _lookupCache.GetAppointmentTypeLookupsAsync(companyId);
            ViewBag.AppointmentTypesForLegend = appointmentTypes
                .Where(t => t.IsActive)
                .OrderBy(t => t.DisplayOrder)
                .ToList();

            return View();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error loading calendar view");
            TempData["Error"] = "An error occurred while loading the calendar.";
            return RedirectToAction(nameof(Index));
        }
    }

    /// <summary>
    /// Returns a JSON array of calendar events covering appointments, maintenance records, and
    /// active jobs for the requested date window. Called by the FullCalendar JS library on
    /// every view change or navigation. Maintenance records that have no time component (midnight)
    /// are defaulted to 8:00 AM so they appear in the week-view time grid rather than collapsing
    /// to invisible. Jobs are rendered as all-day events using their scheduled date or falling
    /// back to the due date; fall-back events past today are coloured red to signal overdue
    /// scheduling. Terminal statuses (COMPLETED, DELIVERED, CANCELLED) are excluded from jobs.
    /// </summary>
    // GET: Appointments/GetCalendarEvents
    [HttpGet]
    public async Task<IActionResult> GetCalendarEvents(DateTime start, DateTime end)
    {
        try
        {
            var events = new List<CalendarEventDto>();

            // 1. Fetch appointments in date range
            var allAppointments = await _unitOfWork.Appointments.GetAllAsync(false,
                a => a.Customer,
                a => a.AppointmentType,
                a => a.AppointmentStatus);

            var appointments = allAppointments
                .Where(a => a.ScheduledStartTime >= start && a.ScheduledStartTime <= end)
                .ToList();

            var appointmentEvents = _mapper.Map<List<CalendarEventDto>>(appointments);
            events.AddRange(appointmentEvents);

            // 2. Fetch maintenance records in date range
            var allMaintenanceRecords = await _unitOfWork.MaintenanceRecords.GetAllAsync(false,
                m => m.Equipment);

            var maintenanceRecords = allMaintenanceRecords
                .Where(m => m.ScheduledDate.Date >= start.Date && m.ScheduledDate.Date <= end.Date &&
                           (m.Status == Core.Enums.MaintenanceStatus.Scheduled ||
                            m.Status == Core.Enums.MaintenanceStatus.InProgress))
                .ToList();

            // Convert maintenance records to calendar events
            foreach (var maintenance in maintenanceRecords)
            {
                // Default to 8:00 AM when ScheduledDate has no time component (midnight),
                // so events are visible in the week view time grid (which shows 6 AM – 8 PM).
                var scheduledStart = maintenance.ScheduledDate.TimeOfDay == TimeSpan.Zero
                    ? maintenance.ScheduledDate.AddHours(8)
                    : maintenance.ScheduledDate;

                var maintenanceEvent = new CalendarEventDto
                {
                    Id = maintenance.Id,
                    EventType = "Maintenance",
                    Title = $"{maintenance.Equipment?.EquipmentName ?? "Equipment"} - {maintenance.MaintenanceType}",
                    Start = scheduledStart.ToString("yyyy-MM-ddTHH:mm:ss"),
                    End = scheduledStart.AddHours(2).ToString("yyyy-MM-ddTHH:mm:ss"), // Default 2-hour duration
                    AllDay = false,
                    BackgroundColor = GetMaintenanceColor(maintenance.Priority),
                    BorderColor = GetMaintenanceColor(maintenance.Priority),
                    TextColor = "#ffffff",
                    CustomerName = maintenance.Equipment?.EquipmentName ?? "Equipment",
                    TypeDisplayName = maintenance.MaintenanceType,
                    StatusCode = maintenance.Status.ToString(),
                    Location = maintenance.Equipment?.Location
                };
                events.Add(maintenanceEvent);
            }

            // 3. Fetch jobs and add as all-day events
            var allJobs = await _unitOfWork.Jobs.GetAllAsync(false,
                j => j.Customer,
                j => j.JobStatus);

            var terminalCodes = new[] { "COMPLETED", "DELIVERED", "CANCELLED" };
            var jobsInRange = allJobs.Where(j =>
                !terminalCodes.Contains(j.JobStatus.StatusCode) &&
                ((j.ScheduledDate.HasValue && j.ScheduledDate.Value.Date >= start.Date && j.ScheduledDate.Value.Date <= end.Date) ||
                 (!j.ScheduledDate.HasValue && j.DueDate.HasValue && j.DueDate.Value.Date >= start.Date && j.DueDate.Value.Date <= end.Date))
            ).ToList();

            foreach (var job in jobsInRange)
            {
                var displayDate = job.ScheduledDate ?? job.DueDate!.Value;
                var isFallback = !job.ScheduledDate.HasValue;
                var color = GetJobStatusColor(job.JobStatus.StatusCode, isFallback, displayDate);
                var customerName = !string.IsNullOrWhiteSpace(job.Customer.CompanyName)
                    ? job.Customer.CompanyName
                    : $"{job.Customer.ContactFirstName} {job.Customer.ContactLastName}".Trim();

                events.Add(new CalendarEventDto
                {
                    Id = job.Id,
                    EventType = "Job",
                    Title = $"{job.JobNumber} — {customerName}",
                    Start = displayDate.Date.ToString("yyyy-MM-ddT00:00:00"),
                    End = displayDate.Date.ToString("yyyy-MM-ddT00:00:00"),
                    AllDay = true,
                    BackgroundColor = color,
                    BorderColor = color,
                    TextColor = "#ffffff",
                    CustomerName = customerName,
                    TypeDisplayName = job.JobStatus.DisplayName ?? job.JobStatus.StatusCode,
                    StatusCode = job.JobStatus.StatusCode,
                    JobNumber = job.JobNumber,
                    IsFallbackDate = isFallback
                });
            }

            return Json(events);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error retrieving calendar events");
            return Json(new List<CalendarEventDto>());
        }
    }

    /// <summary>
    /// Returns a Bootstrap-compatible hex colour for a maintenance event based on its priority.
    /// Critical is red, High is orange, Normal is yellow, and Low is muted grey — intentionally
    /// matching the severity-colour convention used throughout the rest of the application UI.
    /// </summary>
    private string GetMaintenanceColor(Core.Enums.MaintenancePriority priority)
    {
        return priority switch
        {
            Core.Enums.MaintenancePriority.Critical => "#dc3545", // Red
            Core.Enums.MaintenancePriority.High => "#fd7e14",     // Orange
            Core.Enums.MaintenancePriority.Normal => "#ffc107",   // Yellow
            Core.Enums.MaintenancePriority.Low => "#6c757d",      // Gray
            _ => "#ffc107" // Default yellow
        };
    }

    /// <summary>
    /// Returns a hex colour for a job calendar event given its status code. When the displayed
    /// date is a fallback (due date used because no scheduled date is set) and that date is in
    /// the past, the event is forced to red to draw immediate attention regardless of the job's
    /// current status. Otherwise colours follow the job lifecycle: grey for pre-approval, blue for
    /// active prep, orange for oven, green for completed, etc.
    /// </summary>
    private static string GetJobStatusColor(string statusCode, bool isFallback, DateTime displayDate)
    {
        if (isFallback && displayDate.Date < DateTime.Today)
            return "#dc3545"; // Red — overdue, no scheduled date

        return statusCode switch
        {
            "PENDING" or "QUOTED"                                    => "#6c757d", // Gray
            "APPROVED"                                               => "#0dcaf0", // Cyan
            "IN_PREPARATION" or "SANDBLASTING" or
            "MASKING_TAPING" or "CLEANING"                          => "#0d6efd", // Blue
            "IN_OVEN" or "CURING"                                    => "#fd7e14", // Orange
            "COATING"                                                => "#6610f2", // Indigo
            "QUALITY_CHECK"                                          => "#20c997", // Teal
            "COMPLETED" or "DELIVERED" or "READY_FOR_PICKUP"        => "#198754", // Green
            "ON_HOLD"                                                => "#ffc107", // Yellow
            "CANCELLED"                                              => "#adb5bd", // Light gray
            _ => "#0d6efd"
        };
    }

    /// <summary>
    /// AJAX endpoint called from the calendar's "quick create" modal. Applies the same
    /// time-ordering validation as the full <see cref="Create(CreateAppointmentDto)"/> action but
    /// returns JSON rather than redirecting, so the calendar view can add the new event without
    /// a full page reload.
    /// </summary>
    // POST: Appointments/QuickCreate
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> QuickCreate(QuickCreateAppointmentDto dto)
    {
        if (!ModelState.IsValid)
        {
            return Json(new { success = false, message = "Invalid data provided." });
        }

        try
        {
            // Validate start time < end time (for all-day events, allow same date)
            if (dto.IsAllDay)
            {
                // For all-day events, end date must be >= start date
                if (dto.ScheduledEndTime.Date < dto.ScheduledStartTime.Date)
                {
                    return Json(new { success = false, message = "End date must be on or after start date." });
                }
            }
            else
            {
                // For timed events, end time must be after start time
                if (dto.ScheduledStartTime >= dto.ScheduledEndTime)
                {
                    return Json(new { success = false, message = "End time must be after start time." });
                }
            }

            // Map to entity
            var appointment = _mapper.Map<Appointment>(dto);

            // Generate appointment number
            appointment.AppointmentNumber = await GenerateAppointmentNumberAsync();

            // Set default status to SCHEDULED
            var scheduledStatus = (await _unitOfWork.AppointmentStatusLookups.FindAsync(s => s.StatusCode == "SCHEDULED")).FirstOrDefault();
            if (scheduledStatus != null)
            {
                appointment.AppointmentStatusId = scheduledStatus.Id;
            }

            // Save
            await _unitOfWork.Appointments.AddAsync(appointment);
            await _unitOfWork.CompleteAsync();

            return Json(new { success = true, message = "Appointment created successfully.", appointmentId = appointment.Id });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error quick creating appointment");
            return Json(new { success = false, message = "An error occurred while creating the appointment." });
        }
    }

    /// <summary>
    /// AJAX endpoint that supports drag-and-drop event rescheduling on the FullCalendar view.
    /// Accepts the new <paramref name="start"/> and <paramref name="end"/> datetimes supplied
    /// by FullCalendar's <c>eventDrop</c> and <c>eventResize</c> callbacks and writes them
    /// directly to the appointment without re-running type/job-link validation (the existing
    /// appointment already passed those checks).
    /// </summary>
    // POST: Appointments/UpdateEventTime
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> UpdateEventTime(int id, DateTime start, DateTime end)
    {
        try
        {
            var appointment = await _unitOfWork.Appointments.GetByIdAsync(id);
            if (appointment == null)
            {
                return Json(new { success = false, message = "Appointment not found." });
            }

            // Calculate duration and update times
            var duration = appointment.ScheduledEndTime - appointment.ScheduledStartTime;
            appointment.ScheduledStartTime = start;
            appointment.ScheduledEndTime = end;

            await _unitOfWork.Appointments.UpdateAsync(appointment);
            await _unitOfWork.CompleteAsync();

            return Json(new { success = true, message = "Appointment time updated successfully." });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error updating appointment time for {Id}", id);
            return Json(new { success = false, message = "An error occurred while updating the appointment." });
        }
    }

    /// <summary>
    /// Returns a JSON list of active jobs that have no <c>ScheduledDate</c> set, ordered by
    /// due date. Used by the calendar's "Unscheduled Jobs" sidebar so dispatchers can drag a
    /// job onto a date to schedule it. Each job includes up to six items with colour names
    /// (resolved from associated coats) so the dispatcher can see at a glance what powder is
    /// needed. Coats are loaded in a separate filtered query to avoid a cross-join that would
    /// inflate the main job rows.
    /// </summary>
    // GET: Appointments/GetUnscheduledJobs
    [HttpGet]
    public async Task<IActionResult> GetUnscheduledJobs()
    {
        try
        {
            var terminalCodes = new[] { "COMPLETED", "DELIVERED", "CANCELLED" };
            var allJobs = await _unitOfWork.Jobs.GetAllAsync(false,
                j => j.Customer, j => j.JobStatus, j => j.JobItems);

            // Load coats separately — filter by JobItemId using already-loaded item IDs
            var jobItemIds = allJobs.SelectMany(j => j.JobItems.Select(i => i.Id)).ToList();
            var allCoats = await _unitOfWork.JobItemCoats.FindAsync(
                c => jobItemIds.Contains(c.JobItemId));

            var coatsByItemId = allCoats
                .Where(c => !c.IsDeleted)
                .GroupBy(c => c.JobItemId)
                .ToDictionary(g => g.Key, g => g.OrderBy(c => c.Sequence).ToList());

            var jobs = allJobs
                .Where(j => !j.ScheduledDate.HasValue && !terminalCodes.Contains(j.JobStatus.StatusCode))
                .OrderBy(j => j.DueDate)
                .Select(j => new
                {
                    id = j.Id,
                    jobNumber = j.JobNumber,
                    customerName = !string.IsNullOrWhiteSpace(j.Customer.CompanyName)
                        ? j.Customer.CompanyName
                        : $"{j.Customer.ContactFirstName} {j.Customer.ContactLastName}".Trim(),
                    statusCode = j.JobStatus.StatusCode,
                    statusName = j.JobStatus.DisplayName ?? j.JobStatus.StatusCode,
                    dueDate = j.DueDate.HasValue ? j.DueDate.Value.ToString("yyyy-MM-dd") : (string?)null,
                    isOverdue = j.DueDate.HasValue && j.DueDate.Value.Date < DateTime.Today,
                    color = GetJobStatusColor(j.JobStatus.StatusCode, false, j.DueDate ?? DateTime.Today),
                    specialInstructions = j.SpecialInstructions,
                    quotedPrice = j.QuotedPrice,
                    items = j.JobItems
                        .Where(i => !i.IsDeleted)
                        .OrderBy(i => i.Id)
                        .Take(6)
                        .Select(i => new
                        {
                            description = i.Description,
                            quantity = (int)i.Quantity,
                            colorName = coatsByItemId.TryGetValue(i.Id, out var coats)
                                ? string.Join(" / ", coats
                                    .Where(c => !string.IsNullOrWhiteSpace(c.ColorName))
                                    .Select(c => c.ColorName!)
                                    .Distinct())
                                : null
                        })
                        .ToList(),
                    itemCount = j.JobItems.Count(i => !i.IsDeleted)
                })
                .ToList();

            return Json(jobs);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error retrieving unscheduled jobs");
            return Json(new List<object>());
        }
    }

    /// <summary>
    /// Assigns or clears the <c>ScheduledDate</c> on a job, typically triggered by dragging an
    /// unscheduled job card onto a calendar date. When the date changes and the job was previously
    /// in an oven batch scheduled for the old date, the corresponding <c>OvenBatchItem</c> is
    /// soft-deleted so the batch capacity is freed; the caller receives the removed batch number
    /// so the UI can display a warning without needing a full page reload.
    /// </summary>
    // POST: Appointments/ScheduleJob
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> ScheduleJob(int id, DateTime? date)
    {
        try
        {
            var job = await _unitOfWork.Jobs.GetByIdAsync(id);
            if (job == null)
                return Json(new { success = false, message = "Job not found." });

            var oldDate = job.ScheduledDate;
            job.ScheduledDate = date?.Date;

            // If moved to a different day, remove from any oven batch on the old day
            string? removedFromBatch = null;
            if (oldDate.HasValue)
            {
                bool dateChanged = !date.HasValue || date.Value.Date != oldDate.Value.Date;
                if (dateChanged)
                {
                    var batchItems = await _unitOfWork.OvenBatchItems.FindAsync(
                        bi => bi.JobId == id,
                        false,
                        bi => bi.Batch);

                    foreach (var item in batchItems.Where(bi => bi.Batch.ScheduledDate.Date == oldDate.Value.Date))
                    {
                        removedFromBatch = item.Batch.BatchNumber;
                        await _unitOfWork.OvenBatchItems.SoftDeleteAsync(item.Id);
                    }
                }
            }

            await _unitOfWork.Jobs.UpdateAsync(job);
            await _unitOfWork.CompleteAsync();

            return Json(new { success = true, removedFromBatch });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error scheduling job {Id}", id);
            return Json(new { success = false, message = "An error occurred." });
        }
    }

    #region Helper Methods

    /// <summary>
    /// Generates a unique appointment number in the format APT-YYMM-####. Queries all
    /// appointments for the current month (including soft-deleted ones via
    /// <c>ignoreQueryFilters: true</c>) to determine the highest sequence already used, then
    /// increments by one. Checking soft-deleted records prevents number reuse if an appointment
    /// was created and then deleted within the same month.
    /// </summary>
    private async Task<string> GenerateAppointmentNumberAsync()
    {
        var now = DateTime.UtcNow;
        var prefix = $"APT-{now:yyMM}-";

        // Get all appointments for current month (including soft-deleted)
        var allAppointments = await _unitOfWork.Appointments.GetAllAsync(ignoreQueryFilters: true);

        var monthAppointments = allAppointments
            .Where(a => a.AppointmentNumber.StartsWith(prefix))
            .OrderByDescending(a => a.AppointmentNumber)
            .ToList();

        var lastNumber = 0;
        if (monthAppointments.Any())
        {
            var lastAppointmentNumber = monthAppointments.First().AppointmentNumber;
            var numberPart = lastAppointmentNumber.Split('-').Last();
            int.TryParse(numberPart, out lastNumber);
        }

        var newNumber = lastNumber + 1;
        return $"{prefix}{newNumber:D4}";
    }

    /// <summary>
    /// Populates the customer, appointment type, assigned user, and job dropdowns required by
    /// the Create form. Appointment types are served from <see cref="ILookupCacheService"/> to
    /// avoid a database hit on every form render. Commercial customers display their company name;
    /// individual (non-commercial) customers display "FirstName LastName".
    /// </summary>
    private async Task PopulateCreateDropdowns()
    {
        var customers = await _unitOfWork.Customers.GetAllAsync();
        var customerList = customers.Select(c => new
        {
            c.Id,
            DisplayName = !string.IsNullOrWhiteSpace(c.CompanyName)
                ? c.CompanyName  // Commercial customer
                : $"{c.ContactFirstName} {c.ContactLastName}".Trim()  // Individual customer
        })
        .OrderBy(c => c.DisplayName)
        .ToList();
        ViewBag.Customers = new SelectList(customerList, "Id", "DisplayName");

        // Use cached appointment types
        var companyId = _tenantContext.GetCurrentCompanyId() ?? 0;
        var types = await _lookupCache.GetAppointmentTypeLookupsAsync(companyId);
        ViewBag.AppointmentTypes = new SelectList(types.Where(t => t.IsActive).OrderBy(t => t.DisplayOrder), "Id", "DisplayName");

        var companyIdForWorkers = _tenantContext.GetCurrentCompanyId() ?? 0;
        var workers = await _userManager.Users
            .Where(u => u.CompanyId == companyIdForWorkers && u.IsActive && u.CompanyRole != null)
            .OrderBy(u => u.FirstName).ThenBy(u => u.LastName)
            .ToListAsync();
        ViewBag.Workers = new SelectList(workers.Select(u => new { u.Id, FullName = u.FullName }), "Id", "FullName");

        var jobs = await _unitOfWork.Jobs.GetAllAsync();
        ViewBag.Jobs = new SelectList(jobs.OrderBy(j => j.JobNumber), "Id", "JobNumber");
    }

    /// <summary>
    /// Extends <see cref="PopulateCreateDropdowns"/> by additionally loading the appointment
    /// status list (from cache) so editors can change an appointment's status — an option not
    /// available during initial creation where the status is always set to SCHEDULED.
    /// </summary>
    private async Task PopulateEditDropdowns()
    {
        await PopulateCreateDropdowns();

        // Use cached appointment statuses
        var companyId = _tenantContext.GetCurrentCompanyId() ?? 0;
        var statuses = await _lookupCache.GetAppointmentStatusLookupsAsync(companyId);
        ViewBag.AppointmentStatuses = new SelectList(statuses.Where(s => s.IsActive).OrderBy(s => s.DisplayOrder), "Id", "DisplayName");
    }

    /// <summary>
    /// Populates the type and status filter dropdowns shown at the top of the appointment list.
    /// Both are served from <see cref="ILookupCacheService"/> so this method adds no extra
    /// database round-trips beyond the main paged query.
    /// </summary>
    private async Task PopulateFilterDropdowns()
    {
        // Use cached lookups for filters
        var companyId = _tenantContext.GetCurrentCompanyId() ?? 0;
        var types = await _lookupCache.GetAppointmentTypeLookupsAsync(companyId);
        ViewBag.TypeFilterList = new SelectList(types.Where(t => t.IsActive).OrderBy(t => t.DisplayOrder), "Id", "DisplayName");

        var statuses = await _lookupCache.GetAppointmentStatusLookupsAsync(companyId);
        ViewBag.StatusFilterList = new SelectList(statuses.Where(s => s.IsActive).OrderBy(s => s.DisplayOrder), "Id", "DisplayName");
    }

    /// <summary>
    /// Calculates the calendar window's start and end datetimes for the given view mode and
    /// focal date. Dispatches to <see cref="GetWeekStartEnd"/> or <see cref="GetMonthStartEnd"/>;
    /// any unrecognised view name defaults to week. This helper exists so the view-range logic
    /// is shared between any server-side code that needs a date window without duplicating the
    /// Monday-anchor arithmetic.
    /// </summary>
    private (DateTime start, DateTime end) GetCalendarStartEnd(string view, DateTime date)
    {
        return view.ToLower() switch
        {
            "week" => GetWeekStartEnd(date),
            "month" => GetMonthStartEnd(date),
            _ => GetWeekStartEnd(date)
        };
    }

    /// <summary>
    /// Returns the Monday–Sunday window that contains <paramref name="date"/>. The week is
    /// anchored to Monday (ISO week convention) rather than Sunday so it aligns with the
    /// FullCalendar locale configured in the views.
    /// </summary>
    private (DateTime start, DateTime end) GetWeekStartEnd(DateTime date)
    {
        // Get start of week (Monday)
        int diff = (7 + (date.DayOfWeek - DayOfWeek.Monday)) % 7;
        var weekStart = date.AddDays(-diff).Date;
        var weekEnd = weekStart.AddDays(7).Date;
        return (weekStart, weekEnd);
    }

    /// <summary>
    /// Returns the first and last instant of the calendar month that contains
    /// <paramref name="date"/>. The end is the first day of the following month (exclusive)
    /// so range comparisons can use simple &lt; rather than &lt;=.
    /// </summary>
    private (DateTime start, DateTime end) GetMonthStartEnd(DateTime date)
    {
        var monthStart = new DateTime(date.Year, date.Month, 1);
        var monthEnd = monthStart.AddMonths(1);
        return (monthStart, monthEnd);
    }

    #endregion
}