using AutoMapper;
using Marco.Pms.DataAccess.Data;
using Marco.Pms.Model.Dtos.ServiceProject;
using Marco.Pms.Model.Employees;
using Marco.Pms.Model.ServiceProject;
using Marco.Pms.Model.Utilities;
using Marco.Pms.Model.ViewModels.Activities;
using Marco.Pms.Model.ViewModels.Master;
using Marco.Pms.Model.ViewModels.Organization;
using Marco.Pms.Model.ViewModels.ServiceProject;
using Marco.Pms.Services.Helpers;
using Marco.Pms.Services.Service.ServiceInterfaces;
using MarcoBMS.Services.Service;
using Microsoft.EntityFrameworkCore;

namespace Marco.Pms.Services.Service
{
    public class ServiceProjectService : IServiceProject
    {

        private readonly IDbContextFactory<ApplicationDbContext> _dbContextFactory;
        private readonly IServiceScopeFactory _serviceScopeFactory;
        private readonly ApplicationDbContext _context; // Keeping this for direct scoped context use where appropriate
        private readonly ILoggingService _logger;
        private readonly CacheUpdateHelper _cache;
        private readonly IMapper _mapper;

        private readonly Guid NewStatus = Guid.Parse("32d76a02-8f44-4aa0-9b66-c3716c45a918");
        private readonly Guid AssignedStatus = Guid.Parse("cfa1886d-055f-4ded-84c6-42a2a8a14a66");

        public ServiceProjectService(IDbContextFactory<ApplicationDbContext> dbContextFactory,
            IServiceScopeFactory serviceScopeFactory,
            ApplicationDbContext context,
            ILoggingService logger,
            CacheUpdateHelper cache,
            IMapper mapper)
        {
            _serviceScopeFactory = serviceScopeFactory;
            _context = context;
            _logger = logger;
            _cache = cache;
            _mapper = mapper;
            _dbContextFactory = dbContextFactory;
        }

        #region =================================================================== Service Project Functions ===================================================================
        public async Task<ApiResponse<object>> GetServiceProjectListAsync(int pageNumber, int pageSize, Employee loggedInEmployee, Guid tenantId)
        {
            try
            {

                var serviceProjectQuery = _context.ServiceProjects
                    .Include(sp => sp.Client)
                    .Include(sp => sp.Status)
                    .Include(sp => sp.CreatedBy).ThenInclude(e => e!.JobRole)
                    .Where(sp => sp.TenantId == tenantId && sp.IsActive);

                var totalEntites = await serviceProjectQuery.CountAsync();
                var totalPages = (int)Math.Ceiling((double)totalEntites / pageSize);

                var serviceProjects = await serviceProjectQuery
                    .OrderByDescending(e => e.CreatedAt)
                    .Skip((pageNumber - 1) * pageSize)
                    .Take(pageSize)
                    .ToListAsync();

                var serviceProjectIds = serviceProjects.Select(sp => sp.Id).ToList();
                var serviceProjectServiceMappings = await _context.ServiceProjectServiceMapping
                    .Include(sps => sps.Service)
                    .Where(sps => serviceProjectIds.Contains(sps.ProjectId) &&
                    sps.Service != null &&
                    sps.TenantId == tenantId)
                    .ToListAsync();

                var serviceProjectVMs = serviceProjects.Select(sp =>
                {
                    var services = serviceProjectServiceMappings.Where(sps => sps.ProjectId == sp.Id).Select(sps => sps.Service!).ToList();
                    var result = _mapper.Map<ServiceProjectVM>(sp);
                    result.Services = _mapper.Map<List<ServiceMasterVM>>(services);
                    return result;
                }).ToList();

                var response = new
                {
                    CurrentPage = pageNumber,
                    TotalPages = totalPages,
                    TotalEntites = totalEntites,
                    Data = serviceProjectVMs,
                };

                _logger.LogInfo("Successfully retrieved a total of {ProjectCount} projects.", serviceProjectVMs.Count);
                return ApiResponse<object>.SuccessResponse(response, "Projects retrieved successfully.", 200);

            }
            catch (Exception ex)
            {
                // --- Step 5: Graceful Error Handling ---
                _logger.LogError(ex, "An unexpected error occurred in GetAllProjects for tenant {TenantId}.", tenantId);
                return ApiResponse<object>.ErrorResponse("An internal server error occurred. Please try again later.", null, 500);
            }

        }
        public async Task<ApiResponse<object>> GetServiceProjectDetailsAsync(Guid id, Employee loggedInEmployee, Guid tenantId)
        {
            var serviceProject = await _context.ServiceProjects
                .Include(sp => sp.Client)
                .Include(sp => sp.Status)
                .Include(sp => sp.CreatedBy).ThenInclude(e => e!.JobRole)
                .Include(sp => sp.UpdatedBy).ThenInclude(e => e!.JobRole)
                .FirstOrDefaultAsync(sp => sp.Id == id && sp.TenantId == tenantId);
            if (serviceProject == null)
            {
                return ApiResponse<object>.ErrorResponse("Service Project not found", "Service Project not found", 404);
            }
            var services = await _context.ServiceProjectServiceMapping
                    .Include(sps => sps.Service)
                    .Where(sps => sps.ProjectId == serviceProject.Id &&
                        sps.Service != null &&
                        sps.TenantId == tenantId)
                    .Select(sps => sps.Service!)
                    .ToListAsync();
            //var numberOfJobs = await _context.JobTickets.Where(jt => jt.ProjectId == serviceProject.Id && jt.TenantId == tenantId).CountAsync();

            var response = _mapper.Map<ServiceProjectDetailsVM>(serviceProject);
            response.Services = _mapper.Map<List<ServiceMasterVM>>(services);
            //response.NumberOfJobs = numberOfJobs;
            response.NumberOfJobs = 0;
            return ApiResponse<object>.SuccessResponse(response, "Service Project Details fetched successfully", 200);
        }
        public async Task<ApiResponse<object>> CreateServiceProjectAsync(ServiceProjectDto model, Employee loggedInEmployee, Guid tenantId)
        {
            var serviceIds = model.Services.Where(s => s.IsActive).Select(s => s.ServiceId).ToList();
            var clientTask = Task.Run(async () =>
            {
                await using var context = await _dbContextFactory.CreateDbContextAsync();
                return await context.Organizations.FirstOrDefaultAsync(o => o.Id == model.ClientId && o.IsActive);
            });
            var serviceTask = Task.Run(async () =>
            {
                await using var context = await _dbContextFactory.CreateDbContextAsync();
                return await context.ServiceMasters.Where(s => serviceIds.Contains(s.Id) && s.TenantId == tenantId && s.IsActive).ToListAsync();
            });
            var statusTask = Task.Run(async () =>
            {
                await using var context = await _dbContextFactory.CreateDbContextAsync();
                return await context.StatusMasters.FirstOrDefaultAsync(s => s.Id == model.StatusId);
            });

            await Task.WhenAll(clientTask, serviceTask, statusTask);

            var client = clientTask.Result;
            var services = serviceTask.Result;
            var status = statusTask.Result;

            if (client == null)
            {
                return ApiResponse<object>.ErrorResponse("Client not found", "Client not found", 404);
            }
            if (status == null)
            {
                return ApiResponse<object>.ErrorResponse("Project Status not found", "Project Status not found", 404);
            }

            var serviceProject = _mapper.Map<ServiceProject>(model);
            serviceProject.Id = Guid.NewGuid();
            serviceProject.CreatedById = loggedInEmployee.Id;
            serviceProject.CreatedAt = DateTime.UtcNow;
            serviceProject.IsActive = true;
            serviceProject.TenantId = tenantId;

            var projectServiceMapping = model.Services.Where(sdto => services.Any(s => s.Id == sdto.ServiceId)).Select(sdto => new ServiceProjectServiceMapping
            {
                ServiceId = sdto.ServiceId,
                ProjectId = serviceProject.Id,
                TenantId = tenantId
            }).ToList();
            try
            {
                _context.ServiceProjects.Add(serviceProject);
                _context.ServiceProjectServiceMapping.AddRange(projectServiceMapping);

                await _context.SaveChangesAsync();

                _logger.LogInfo("Service Project {ProjectId} created successfully for TenantId={TenantId}, by Employee {EmployeeId}.",
                  serviceProject.Id, tenantId, loggedInEmployee);

                var serviceProjectVM = _mapper.Map<ServiceProjectVM>(serviceProject);

                serviceProjectVM.Client = _mapper.Map<BasicOrganizationVm>(client);
                serviceProjectVM.Status = status;

                serviceProjectVM.Services = services.Where(s => serviceIds.Contains(s.Id)).Select(s => _mapper.Map<ServiceMasterVM>(s)).ToList();

                serviceProjectVM.CreatedBy = _mapper.Map<BasicEmployeeVM>(loggedInEmployee);
                return ApiResponse<object>.SuccessResponse(serviceProjectVM, "An Successfullly occurred while saving the project.", 201);

            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "DB Failure: Service Project creation failed for TenantId={TenantId}. Rolling back.", tenantId);
                return ApiResponse<object>.ErrorResponse("An error occurred while saving the project.", ex.Message, 500);
            }


        }
        public async Task<ApiResponse<object>> UpdateServiceProjectAsync(Guid id, ServiceProjectDto model, Employee loggedInEmployee, Guid tenantId)
        {
            try
            {
                var serviceIds = model.Services.Select(s => s.ServiceId).ToList();
                var clientTask = Task.Run(async () =>
                {
                    await using var context = await _dbContextFactory.CreateDbContextAsync();
                    return await context.Organizations.FirstOrDefaultAsync(o => o.Id == model.ClientId && o.IsActive);
                });
                var serviceTask = Task.Run(async () =>
                {
                    await using var context = await _dbContextFactory.CreateDbContextAsync();
                    return await context.ServiceMasters.Where(s => serviceIds.Contains(s.Id) && s.TenantId == tenantId && s.IsActive).ToListAsync();
                });
                var statusTask = Task.Run(async () =>
                {
                    await using var context = await _dbContextFactory.CreateDbContextAsync();
                    return await context.StatusMasters.FirstOrDefaultAsync(s => s.Id == model.StatusId);
                });

                await Task.WhenAll(clientTask, serviceTask, statusTask);

                var client = clientTask.Result;
                var services = serviceTask.Result;
                var status = statusTask.Result;

                if (client == null)
                {
                    return ApiResponse<object>.ErrorResponse("Client not found", "Client not found", 404);
                }
                if (status == null)
                {
                    return ApiResponse<object>.ErrorResponse("Project Status not found", "Project Status not found", 404);
                }

                var serviceProject = await _context.ServiceProjects.Where(sp => sp.Id == id && sp.TenantId == tenantId && sp.IsActive).FirstOrDefaultAsync();

                if (serviceProject == null)
                {
                    _logger.LogWarning("Attempt to update non-existent Service project with ID {ProjectId} by user {UserId}.", id, loggedInEmployee.Id);
                    return ApiResponse<object>.ErrorResponse("Project not found.", $"No project found with ID {id}.", 404);
                }

                _mapper.Map(model, serviceProject);

                serviceProject.UpdatedAt = DateTime.UtcNow;
                serviceProject.UpdatedById = loggedInEmployee.Id;

                var serviceProjectServiceMappings = await _context.ServiceProjectServiceMapping
                    .AsNoTracking()
                    .Where(sps => sps.ProjectId == serviceProject.Id && sps.TenantId == tenantId)
                    .ToListAsync();

                var newMapping = new List<ServiceProjectServiceMapping>();
                var removedMapping = new List<ServiceProjectServiceMapping>();

                foreach (var dto in model.Services)
                {
                    var serviceProjectServiceMapping = serviceProjectServiceMappings
                        .FirstOrDefault(sps => sps.ServiceId == dto.ServiceId);

                    if (dto.IsActive && serviceProjectServiceMapping == null)
                    {
                        newMapping.Add(new ServiceProjectServiceMapping
                        {
                            Id = Guid.NewGuid(),
                            ServiceId = dto.ServiceId,
                            ProjectId = serviceProject.Id,
                            TenantId = tenantId,
                        });
                    }
                    else if (!dto.IsActive && serviceProjectServiceMapping != null)
                    {
                        removedMapping.Add(serviceProjectServiceMapping);
                    }
                }

                _context.ServiceProjectServiceMapping.AddRange(newMapping);
                _context.ServiceProjectServiceMapping.RemoveRange(removedMapping);

                await _context.SaveChangesAsync();

                var serviceProjectTask = Task.Run(async () =>
                {
                    await using var context = await _dbContextFactory.CreateDbContextAsync();
                    return await context.ServiceProjects
                        .Include(sp => sp.Client)
                        .Include(sp => sp.Status)
                        .Include(sp => sp.CreatedBy).ThenInclude(e => e!.JobRole)
                        .Where(sp => sp.TenantId == tenantId && sp.IsActive).FirstOrDefaultAsync();
                });

                var servicesTask = Task.Run(async () =>
                {
                    await using var context = await _dbContextFactory.CreateDbContextAsync();
                    return await context.ServiceProjectServiceMapping
                        .Include(sps => sps.Service)
                        .Where(sps => sps.ProjectId == serviceProject.Id && sps.Service != null && sps.TenantId == tenantId)
                        .Select(sps => sps.Service!)
                        .ToListAsync();
                });

                await Task.WhenAll(serviceProjectTask, servicesTask);


                serviceProject = serviceProjectTask.Result;
                services = servicesTask.Result;

                ServiceProjectVM serviceProjectVm = _mapper.Map<ServiceProjectVM>(serviceProject);
                serviceProjectVm.Services = _mapper.Map<List<ServiceMasterVM>>(services);

                return ApiResponse<object>.SuccessResponse(serviceProjectVm, "Service Project updated successfully.", 200);

            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "An unexpected error occurred in Updating Service Project for tenant {TenantId}.", tenantId);
                return ApiResponse<object>.ErrorResponse("An internal server error occurred. Please try again later.", null, 500);
            }

        }
        public async Task<ApiResponse<object>> DeActivateServiceProjectAsync(Guid id, bool isActive, Employee loggedInEmployee, Guid tenantId)
        {
            try
            {

                var serviceProject = await _context.ServiceProjects
                    .Where(sp => sp.Id == id && sp.TenantId == tenantId).FirstOrDefaultAsync();

                if (serviceProject == null)
                {
                    _logger.LogWarning("Attempt to de-activate non-existent Service project with ID {ProjectId} by user {UserId}.", id, loggedInEmployee.Id);
                    return ApiResponse<object>.ErrorResponse("Project not found.", $"No project found with ID {id}.", 404);
                }

                serviceProject.IsActive = isActive;

                await _context.SaveChangesAsync();

                _logger.LogInfo("Successfully de-activated service project {ProjectId}", id);
                return ApiResponse<object>.SuccessResponse(new { }, "Projects de-activated successfully.", 200);

            }
            catch (Exception ex)
            {
                // --- Step 5: Graceful Error Handling ---
                _logger.LogError(ex, "An unexpected error occurred in DeActivateServiceProject for tenant {TenantId}.", tenantId);
                return ApiResponse<object>.ErrorResponse("An internal server error occurred. Please try again later.", null, 500);
            }
        }

        #endregion

        #region =================================================================== Expense Functions ===================================================================
        #endregion

        #region =================================================================== Job Tickets Functions ===================================================================

        /// <summary>
        /// Creates a new job ticket with optional assignees and tags within a transactional scope.
        /// </summary>
        /// <param name="model">Data transfer object containing job ticket details.</param>
        /// <param name="loggedInEmployee">Employee initiating the creation.</param>
        /// <param name="tenantId">Tenant identifier for multi-tenant context.</param>
        /// <returns>ApiResponse containing the created job ticket view or error details.</returns>
        public async Task<ApiResponse<object>> CreateJobTicketAsync(CreateJobTicketDto model, Employee loggedInEmployee, Guid tenantId)
        {
            await using var transaction = await _context.Database.BeginTransactionAsync();
            try
            {
                _logger.LogInfo("Starting job ticket creation for project {ProjectId} by employee {EmployeeId} in tenant {TenantId}",
                    model.ProjectId, loggedInEmployee.Id, tenantId);

                // Load project and relevant statuses in parallel with separate DbContext instances for concurrency efficiency
                var serviceProjectTask = Task.Run(async () =>
                {
                    await using var context = await _dbContextFactory.CreateDbContextAsync();
                    return await context.ServiceProjects.FirstOrDefaultAsync(sp => sp.Id == model.ProjectId && sp.TenantId == tenantId && sp.IsActive);
                });

                var statusTask = Task.Run(async () =>
                {
                    await using var context = await _dbContextFactory.CreateDbContextAsync();
                    return await context.JobStatus.Where(js => js.Id == NewStatus || js.Id == AssignedStatus).ToListAsync();
                });

                await Task.WhenAll(serviceProjectTask, statusTask);

                var serviceProject = serviceProjectTask.Result;
                var statusList = statusTask.Result;

                if (serviceProject == null)
                {
                    _logger.LogWarning("Service project with ID {ProjectId} not found or inactive in tenant {TenantId}", model.ProjectId, tenantId);
                    return ApiResponse<object>.ErrorResponse("Service project not found", "Service project not found or inactive", 404);
                }

                var hasAssignees = model.Assignees?.Any(a => a.IsActive) ?? false;

                // Map DTO to entity
                var jobTicket = _mapper.Map<JobTicket>(model);
                jobTicket.Id = Guid.NewGuid();
                jobTicket.StatusId = hasAssignees ? AssignedStatus : NewStatus;
                jobTicket.CreatedAt = DateTime.UtcNow;
                jobTicket.CreatedById = loggedInEmployee.Id;
                jobTicket.TenantId = tenantId;

                _context.JobTickets.Add(jobTicket);
                await _context.SaveChangesAsync();

                // Handle assignees if any
                List<BasicEmployeeVM> assigneeVMs = new();
                if (hasAssignees)
                {
                    var activeAssigneeIds = model.Assignees!.Where(a => a.IsActive).Select(a => a.EmployeeId).ToList();

                    var assignees = await _context.Employees
                        .Include(e => e.JobRole)
                        .Where(e => activeAssigneeIds.Contains(e.Id) && e.IsActive)
                        .ToListAsync();

                    var jobEmployeeMappings = assignees.Select(e => new JobEmployeeMapping
                    {
                        AssigneeId = e.Id,
                        JobTicketId = jobTicket.Id,
                        TenantId = tenantId
                    }).ToList();

                    _context.JobEmployeeMappings.AddRange(jobEmployeeMappings);
                    assigneeVMs = _mapper.Map<List<BasicEmployeeVM>>(assignees);
                }

                // Handle tags if any
                var jobTags = new List<JobTag>();
                if (model.Tags?.Any(t => t.IsActive) ?? false)
                {
                    var activeTagNames = model.Tags.Where(t => t.IsActive).Select(t => t.Name).Distinct().ToList();

                    var existingTags = await _context.JobTags.Where(jt => activeTagNames.Contains(jt.Name) && jt.TenantId == tenantId).ToListAsync();

                    var newTags = new List<JobTag>();
                    var tagMappings = new List<JobTagMapping>();

                    foreach (var tagDto in model.Tags.Where(t => t.IsActive).DistinctBy(t => t.Name))
                    {
                        var tag = existingTags.FirstOrDefault(jt => jt.Name == tagDto.Name);
                        if (tag == null)
                        {
                            tag = new JobTag
                            {
                                Id = Guid.NewGuid(),
                                Name = tagDto.Name,
                                TenantId = tenantId
                            };
                            newTags.Add(tag);
                        }
                        tagMappings.Add(new JobTagMapping
                        {
                            Id = Guid.NewGuid(),
                            JobTagId = tag.Id,
                            JobTicketId = jobTicket.Id,
                            TenantId = tenantId
                        });
                    }

                    if (newTags.Any()) _context.JobTags.AddRange(newTags);
                    _context.JobTagMappings.AddRange(tagMappings);

                    jobTags.AddRange(existingTags);
                    jobTags.AddRange(newTags);
                }

                // Create job update logs for status change
                var updateLogs = new List<JobUpdateLog>();

                const string creationMessage = "A new job has been successfully created and added to the system. It is now ready for assignment and further processing.";
                updateLogs.Add(new JobUpdateLog
                {
                    JobTicketId = jobTicket.Id,
                    NextStatusId = NewStatus,
                    Description = creationMessage,
                    Comment = creationMessage,
                    UpdatedAt = DateTime.UtcNow,
                    UpdatedById = loggedInEmployee.Id,
                    TenantId = tenantId
                });

                if (hasAssignees)
                {
                    const string assignmentMessage = "The designated assignee(s) have been successfully assigned to the job and are now responsible for managing and completing the associated tasks.";
                    updateLogs.Add(new JobUpdateLog
                    {
                        JobTicketId = jobTicket.Id,
                        StatusId = NewStatus,
                        NextStatusId = AssignedStatus,
                        Description = assignmentMessage,
                        Comment = assignmentMessage,
                        UpdatedAt = DateTime.UtcNow.AddTicks(10), // Small offset to preserve time order
                        UpdatedById = loggedInEmployee.Id,
                        TenantId = tenantId
                    });
                }

                _context.JobUpdateLogs.AddRange(updateLogs);

                await _context.SaveChangesAsync();

                await transaction.CommitAsync();

                // Prepare response VM
                var currentStatus = statusList.FirstOrDefault(js => js.Id == jobTicket.StatusId);
                var vm = _mapper.Map<JobTicketVM>(jobTicket);
                vm.Status = currentStatus;
                vm.Project = _mapper.Map<BasicServiceProjectVM>(serviceProject);
                vm.Assignees = assigneeVMs;
                vm.CreatedBy = _mapper.Map<BasicEmployeeVM>(loggedInEmployee);
                vm.Tags = _mapper.Map<List<TagVM>>(jobTags.Distinct().ToList());

                _logger.LogInfo("Job ticket {JobTicketId} successfully created with status {StatusId} by employee {EmployeeId} in tenant {TenantId}",
                    jobTicket.Id, jobTicket.StatusId, loggedInEmployee.Id, tenantId);

                return ApiResponse<object>.SuccessResponse(vm, "Job created successfully", 201);
            }
            catch (DbUpdateException dbEx)
            {
                await transaction.RollbackAsync();
                _logger.LogError(dbEx, "Database error while creating job ticket for project {ProjectId} by employee {EmployeeId} in tenant {TenantId}",
                    model.ProjectId, loggedInEmployee.Id, tenantId);
                return ApiResponse<object>.ErrorResponse("Database Error", "An error occurred while saving data to the database.", 500);
            }
            catch (Exception ex)
            {
                await transaction.RollbackAsync();
                _logger.LogError(ex, "Unhandled exception while creating job ticket for project {ProjectId} by employee {EmployeeId} in tenant {TenantId}",
                    model.ProjectId, loggedInEmployee.Id, tenantId);
                return ApiResponse<object>.ErrorResponse("Internal Server Error", "An unexpected error occurred.", 500);
            }
        }

        #endregion
    }
}