using AutoMapper;
using PowderCoating.Shared.Constants;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using PowderCoating.Application.DTOs.Common;
using PowderCoating.Application.DTOs.Equipment;
using PowderCoating.Application.DTOs.Maintenance;
using PowderCoating.Application.Interfaces;
using PowderCoating.Core.Entities;
using PowderCoating.Core.Enums;
using PowderCoating.Core.Interfaces;
using PowderCoating.Infrastructure.Data;
using PowderCoating.Shared.Constants;

namespace PowderCoating.Web.Controllers;

[Authorize(Policy = AppConstants.Policies.CanManageEquipment)]
public class EquipmentController : Controller
{
    private readonly IUnitOfWork _unitOfWork;
    private readonly IMapper _mapper;
    private readonly IFileService _fileService;  // Legacy - kept for backward compatibility
    private readonly IEquipmentManualService _manualService;
    private readonly ITenantContext _tenantContext;
    private readonly ILogger<EquipmentController> _logger;

    public EquipmentController(
        IUnitOfWork unitOfWork,
        IMapper mapper,
        IFileService fileService,
        IEquipmentManualService manualService,
        ITenantContext tenantContext,
        ILogger<EquipmentController> logger)
    {
        _unitOfWork = unitOfWork;
        _mapper = mapper;
        _fileService = fileService;
        _manualService = manualService;
        _tenantContext = tenantContext;
        _logger = logger;
    }

    /// <summary>
    /// Displays the paginated equipment list with optional keyword search and status filter.
    /// Search covers name, equipment number, serial number, manufacturer, and model so
    /// shop staff can find a piece of equipment using any identifier they have on hand.
    /// Sorting is resolved server-side via a switch expression so column names never reach
    /// raw SQL.
    /// </summary>
    public async Task<IActionResult> Index(
        string? searchTerm,
        EquipmentStatus? 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 ?? "Name",
                SortDirection = sortDirection,
                SearchTerm = searchTerm
            };
            gridRequest.Validate();

            // Build search and status filter
            System.Linq.Expressions.Expression<Func<Equipment, bool>>? filter = null;

            if (!string.IsNullOrWhiteSpace(searchTerm) && statusFilter.HasValue)
            {
                // Both search and status filter
                var search = searchTerm.ToLower();
                var status = statusFilter.Value;
                filter = e => (e.EquipmentName.ToLower().Contains(search)
                    || (e.EquipmentNumber != null && e.EquipmentNumber.ToLower().Contains(search))
                    || (e.SerialNumber != null && e.SerialNumber.ToLower().Contains(search))
                    || (e.Manufacturer != null && e.Manufacturer.ToLower().Contains(search))
                    || (e.Model != null && e.Model.ToLower().Contains(search)))
                    && e.Status == status;
            }
            else if (!string.IsNullOrWhiteSpace(searchTerm))
            {
                // Search only
                var search = searchTerm.ToLower();
                filter = e => e.EquipmentName.ToLower().Contains(search)
                    || (e.EquipmentNumber != null && e.EquipmentNumber.ToLower().Contains(search))
                    || (e.SerialNumber != null && e.SerialNumber.ToLower().Contains(search))
                    || (e.Manufacturer != null && e.Manufacturer.ToLower().Contains(search))
                    || (e.Model != null && e.Model.ToLower().Contains(search));
            }
            else if (statusFilter.HasValue)
            {
                // Status filter only
                var status = statusFilter.Value;
                filter = e => e.Status == status;
            }

            // Build orderBy function
            Func<IQueryable<Equipment>, IOrderedQueryable<Equipment>> orderBy = gridRequest.SortColumn switch
            {
                "Name" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(e => e.EquipmentName) : q.OrderByDescending(e => e.EquipmentName),
                "EquipmentCode" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(e => e.EquipmentNumber) : q.OrderByDescending(e => e.EquipmentNumber),
                "Status" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(e => e.Status) : q.OrderByDescending(e => e.Status),
                "PurchaseDate" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(e => e.PurchaseDate) : q.OrderByDescending(e => e.PurchaseDate),
                "NextMaintenanceDate" => q => gridRequest.SortDirection == "asc" ? q.OrderBy(e => e.NextScheduledMaintenance) : q.OrderByDescending(e => e.NextScheduledMaintenance),
                _ => q => q.OrderBy(e => e.EquipmentName)
            };

            // Get paged data
            var (items, totalCount) = await _unitOfWork.Equipment.GetPagedAsync(
                gridRequest.PageNumber,
                gridRequest.PageSize,
                filter,
                orderBy);

            // Map to DTOs
            var equipmentDtos = _mapper.Map<List<EquipmentListDto>>(items);

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

            // Set ViewBag for sorting and filters
            ViewBag.SearchTerm = searchTerm;
            ViewBag.StatusFilter = statusFilter;
            ViewBag.SortColumn = gridRequest.SortColumn;
            ViewBag.SortDirection = gridRequest.SortDirection;

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

    /// <summary>
    /// Renders the equipment detail page. Maintenance history is loaded via a separate
    /// FindAsync call (not eager loading on the Equipment entity) and sorted descending
    /// by ScheduledDate so the most recent maintenance tasks appear first. This gives
    /// technicians an at-a-glance view of the equipment's service history.
    /// </summary>
    public async Task<IActionResult> Details(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        try
        {
            var equipment = await _unitOfWork.Equipment.GetByIdAsync(id.Value);
            if (equipment == null)
            {
                return NotFound();
            }

            var equipmentDto = _mapper.Map<EquipmentDto>(equipment);

            // Load maintenance history
            var maintenanceRecords = await _unitOfWork.MaintenanceRecords
                .FindAsync(m => m.EquipmentId == id.Value);
            var maintenanceList = _mapper.Map<List<MaintenanceListDto>>(maintenanceRecords.OrderByDescending(m => m.ScheduledDate));

            ViewBag.MaintenanceHistory = maintenanceList;

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

    /// <summary>
    /// Renders the equipment creation form, defaulting status to Operational because new
    /// equipment entering the shop is presumed ready to use until a maintenance issue
    /// is logged. The full EquipmentStatus enum is passed to the view for the status
    /// dropdown so adding new statuses to the enum automatically appears in the form.
    /// </summary>
    public IActionResult Create()
    {
        var dto = new CreateEquipmentDto
        {
            Status = EquipmentStatus.Operational.ToString()
        };
        ViewBag.StatusList = Enum.GetValues<EquipmentStatus>();
        return View(dto);
    }

    /// <summary>
    /// Persists a new equipment record and sets IsActive to true. The equipment starts
    /// with no manual file; manuals are uploaded separately via <see cref="UploadManual"/>
    /// to avoid coupling file I/O to the core create transaction.
    /// </summary>
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Create(CreateEquipmentDto dto)
    {
        if (!ModelState.IsValid)
        {
            ViewBag.StatusList = Enum.GetValues<EquipmentStatus>();
            return View(dto);
        }

        try
        {
            var equipment = _mapper.Map<Equipment>(dto);
            equipment.CreatedAt = DateTime.UtcNow;
            equipment.IsActive = true;

            await _unitOfWork.Equipment.AddAsync(equipment);
            await _unitOfWork.SaveChangesAsync();

            TempData["Success"] = "Equipment created successfully.";
            return RedirectToAction(nameof(Index));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error creating equipment");
            TempData["Error"] = "An error occurred while creating the equipment.";
            ViewBag.StatusList = Enum.GetValues<EquipmentStatus>();
            return View(dto);
        }
    }

    /// <summary>
    /// Renders the equipment edit form, pre-populated via AutoMapper. The status dropdown
    /// is reloaded from the enum so it always reflects any additions to <see cref="EquipmentStatus"/>.
    /// </summary>
    public async Task<IActionResult> Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        try
        {
            var equipment = await _unitOfWork.Equipment.GetByIdAsync(id.Value);
            if (equipment == null)
            {
                return NotFound();
            }

            var dto = _mapper.Map<UpdateEquipmentDto>(equipment);
            ViewBag.StatusList = Enum.GetValues<EquipmentStatus>();
            return View(dto);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error retrieving equipment {EquipmentId} for edit", id);
            TempData["Error"] = "An error occurred while loading the equipment.";
            return RedirectToAction(nameof(Index));
        }
    }

    /// <summary>
    /// Persists edits to an existing equipment record. The Notes field is captured before
    /// AutoMapper runs and restored if the submitted dto.Notes is blank, because the Notes
    /// field doubles as legacy file metadata storage (the original upload path was stored
    /// there). This prevents an Edit save from silently erasing a manual reference that
    /// was uploaded before the dedicated ManualFilePath column existed.
    /// </summary>
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Edit(int id, UpdateEquipmentDto dto)
    {
        if (id != dto.Id)
        {
            return NotFound();
        }

        if (!ModelState.IsValid)
        {
            ViewBag.StatusList = Enum.GetValues<EquipmentStatus>();
            return View(dto);
        }

        try
        {
            var equipment = await _unitOfWork.Equipment.GetByIdAsync(id);
            if (equipment == null)
            {
                return NotFound();
            }

            // Preserve Notes field (contains file metadata)
            var preservedNotes = equipment.Notes;
            _mapper.Map(dto, equipment);

            // If dto.Notes is empty, restore the preserved notes (file metadata)
            if (string.IsNullOrWhiteSpace(dto.Notes))
            {
                equipment.Notes = preservedNotes;
            }

            equipment.UpdatedAt = DateTime.UtcNow;

            await _unitOfWork.Equipment.UpdateAsync(equipment);
            await _unitOfWork.SaveChangesAsync();

            TempData["Success"] = "Equipment updated successfully.";
            return RedirectToAction(nameof(Details), new { id });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error updating equipment {EquipmentId}", id);
            TempData["Error"] = "An error occurred while updating the equipment.";
            ViewBag.StatusList = Enum.GetValues<EquipmentStatus>();
            return View(dto);
        }
    }

    /// <summary>
    /// Renders the equipment delete confirmation page, showing a full summary so the user
    /// can verify they are removing the correct piece of equipment before confirming.
    /// </summary>
    public async Task<IActionResult> Delete(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        try
        {
            var equipment = await _unitOfWork.Equipment.GetByIdAsync(id.Value);
            if (equipment == null)
            {
                return NotFound();
            }

            var equipmentDto = _mapper.Map<EquipmentDto>(equipment);
            return View(equipmentDto);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error retrieving equipment {EquipmentId} for delete", id);
            TempData["Error"] = "An error occurred while loading the equipment.";
            return RedirectToAction(nameof(Index));
        }
    }

    /// <summary>
    /// Soft-deletes the equipment record and cleans up any associated manual file from
    /// both the new filesystem storage (ManualFilePath via <see cref="IEquipmentManualService"/>)
    /// and the legacy uploads folder (Notes field starting with "uploads/"). File cleanup
    /// runs before the soft delete so that orphaned files on disk are not left behind if
    /// the delete succeeds.
    /// </summary>
    [HttpPost, ActionName("Delete")]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> DeleteConfirmed(int id)
    {
        try
        {
            var equipment = await _unitOfWork.Equipment.GetByIdAsync(id);
            if (equipment == null)
            {
                return NotFound();
            }

            // Delete associated manual file if exists (new filesystem storage)
            if (!string.IsNullOrEmpty(equipment.ManualFilePath))
            {
                await _manualService.DeleteEquipmentManualAsync(equipment.ManualFilePath);
            }
            // Delete associated manual file if exists (legacy uploads folder)
            else if (!string.IsNullOrWhiteSpace(equipment.Notes) && equipment.Notes.StartsWith("uploads/"))
            {
                await _fileService.DeleteFileAsync(equipment.Notes);
            }

            await _unitOfWork.Equipment.SoftDeleteAsync(equipment);
            await _unitOfWork.SaveChangesAsync();

            TempData["Success"] = "Equipment deleted successfully.";
            return RedirectToAction(nameof(Index));
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error deleting equipment {EquipmentId}", id);
            TempData["Error"] = "An error occurred while deleting the equipment.";
            return RedirectToAction(nameof(Index));
        }
    }

    /// <summary>
    /// Accepts an equipment manual file upload and saves it to the filesystem via
    /// <see cref="IEquipmentManualService"/>. If a manual already exists (either in the
    /// new ManualFilePath column or in the legacy Notes/uploads path), it is deleted first
    /// to prevent orphaned files accumulating on disk. Returns JSON { success, message,
    /// fileName } so the Details page can update the manual section without a full reload.
    /// </summary>
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> UploadManual(int equipmentId, IFormFile manualFile)
    {
        try
        {
            if (manualFile == null || manualFile.Length == 0)
            {
                return Json(new { success = false, message = "No file was uploaded." });
            }

            var companyId = _tenantContext.GetCurrentCompanyId();
            if (companyId == null)
            {
                return Json(new { success = false, message = "User does not have a company ID." });
            }

            var equipment = await _unitOfWork.Equipment.GetByIdAsync(equipmentId);
            if (equipment == null)
            {
                return Json(new { success = false, message = "Equipment not found." });
            }

            // Delete old manual if exists (new filesystem storage)
            if (!string.IsNullOrEmpty(equipment.ManualFilePath))
            {
                await _manualService.DeleteEquipmentManualAsync(equipment.ManualFilePath);
            }
            // Delete old manual if exists (legacy uploads folder)
            else if (!string.IsNullOrWhiteSpace(equipment.Notes) && equipment.Notes.StartsWith("uploads/"))
            {
                await _fileService.DeleteFileAsync(equipment.Notes);
                equipment.Notes = null;  // Clear legacy field
            }

            // Save new file to filesystem
            var (success, filePath, errorMessage) = await _manualService.SaveEquipmentManualAsync(
                manualFile,
                companyId.Value,
                equipmentId);

            if (!success)
            {
                return Json(new { success = false, message = errorMessage });
            }

            // Update equipment record
            equipment.ManualFilePath = filePath;
            equipment.ManualFileName = manualFile.FileName;
            equipment.ManualFileSize = manualFile.Length;
            equipment.ManualContentType = manualFile.ContentType;
            equipment.ManualUploadedDate = DateTime.UtcNow;
            equipment.UpdatedAt = DateTime.UtcNow;

            await _unitOfWork.Equipment.UpdateAsync(equipment);
            await _unitOfWork.SaveChangesAsync();

            _logger.LogInformation("Equipment {EquipmentId} manual uploaded to filesystem", equipmentId);

            return Json(new
            {
                success = true,
                message = "Manual uploaded successfully.",
                fileName = manualFile.FileName
            });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error uploading manual for equipment {EquipmentId}", equipmentId);
            return Json(new { success = false, message = "An error occurred while uploading the file." });
        }
    }

    /// <summary>
    /// Streams the equipment manual file back to the browser as a file download. Checks
    /// the new ManualFilePath column first, then falls back to the legacy Notes/uploads
    /// path for equipment whose manuals were uploaded before the ManualFilePath column
    /// was added. For legacy files, the GUID prefix (added by the old upload service) is
    /// stripped from the download filename so the user sees the original filename.
    /// </summary>
    public async Task<IActionResult> DownloadManual(int id)
    {
        try
        {
            var equipment = await _unitOfWork.Equipment.GetByIdAsync(id);
            if (equipment == null)
            {
                return NotFound();
            }

            // Try new filesystem storage first
            if (!string.IsNullOrEmpty(equipment.ManualFilePath))
            {
                var (success, fileContent, contentType, errorMessage) = await _manualService.GetEquipmentManualAsync(equipment.ManualFilePath);
                if (success)
                {
                    var fileName = equipment.ManualFileName ?? Path.GetFileName(equipment.ManualFilePath);
                    return File(fileContent, contentType, fileName);
                }

                TempData["Error"] = errorMessage;
                return RedirectToAction(nameof(Details), new { id });
            }

            // Fallback to legacy storage (uploads folder)
            if (!string.IsNullOrWhiteSpace(equipment.Notes) && equipment.Notes.StartsWith("uploads/"))
            {
                var result = await _fileService.GetFileAsync(equipment.Notes);
                if (!result.Success)
                {
                    TempData["Error"] = result.ErrorMessage;
                    return RedirectToAction(nameof(Details), new { id });
                }

                var fileName = Path.GetFileName(equipment.Notes);
                // Remove GUID prefix from filename for download
                if (fileName.Length > 37 && fileName[36] == '-')
                {
                    fileName = fileName.Substring(37);
                }

                return File(result.FileContent, result.ContentType, fileName);
            }

            return NotFound();
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error downloading manual for equipment {EquipmentId}", id);
            TempData["Error"] = "An error occurred while downloading the file.";
            return RedirectToAction(nameof(Details), new { id });
        }
    }

    /// <summary>
    /// Deletes the equipment manual from disk and clears the manual metadata fields on the
    /// equipment entity. Handles both the current filesystem storage path (ManualFilePath)
    /// and the legacy Notes/uploads path so that manuals uploaded under either storage
    /// scheme can be removed without leaving orphaned files. Returns JSON so the Details
    /// page can remove the download link without a full reload.
    /// </summary>
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> DeleteManual(int equipmentId)
    {
        try
        {
            var equipment = await _unitOfWork.Equipment.GetByIdAsync(equipmentId);
            if (equipment == null)
            {
                return Json(new { success = false, message = "Equipment not found." });
            }

            // Check if manual exists
            if (string.IsNullOrEmpty(equipment.ManualFilePath) && string.IsNullOrWhiteSpace(equipment.Notes))
            {
                return Json(new { success = false, message = "No manual found." });
            }

            // Delete from new filesystem storage if exists
            if (!string.IsNullOrEmpty(equipment.ManualFilePath))
            {
                var (success, errorMessage) = await _manualService.DeleteEquipmentManualAsync(equipment.ManualFilePath);
                if (!success)
                {
                    return Json(new { success = false, message = errorMessage });
                }

                equipment.ManualFilePath = null;
                equipment.ManualFileName = null;
                equipment.ManualFileSize = null;
                equipment.ManualContentType = null;
                equipment.ManualUploadedDate = null;
            }
            // Delete from legacy storage if exists
            else if (!string.IsNullOrWhiteSpace(equipment.Notes) && equipment.Notes.StartsWith("uploads/"))
            {
                var result = await _fileService.DeleteFileAsync(equipment.Notes);
                if (!result.Success)
                {
                    return Json(new { success = false, message = result.ErrorMessage });
                }

                equipment.Notes = null;
            }

            equipment.UpdatedAt = DateTime.UtcNow;

            await _unitOfWork.Equipment.UpdateAsync(equipment);
            await _unitOfWork.SaveChangesAsync();

            _logger.LogInformation("Equipment {EquipmentId} manual deleted", equipmentId);

            return Json(new { success = true, message = "Manual deleted successfully." });
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Error deleting manual for equipment {EquipmentId}", equipmentId);
            return Json(new { success = false, message = "An error occurred while deleting the file." });
        }
    }
}