using Data.SeaHavenIndustries;
using Data.SeaHavenIndustries.Enums;
using FluentValidation;
using FluentValidation.Results;
using SeaHaven.DataServices.Interfaces;
using SeaHaven.Services.DTOs;
using SeaHaven.Services.Helpers;
using SeaHaven.Services.Interfaces;
using SeaHaven.Services.Validation;

namespace SeaHaven.Services.Implementation
{
    public class VendorService : IVendorService
    {
        private static readonly string[] TerminalLegacyStatuses =
            { "completed", "cancelled", "canceled" };

        private readonly IVendorDataService _vendorDataService;
        private readonly ICreateVendorValidation _createValidator;
        private readonly IUpdateVendorValidation _updateValidator;
        private readonly IWorkOrderVendorUpdateValidation _workOrderUpdateValidator;

        public VendorService(
            IVendorDataService vendorDataService,
            ICreateVendorValidation createValidator,
            IUpdateVendorValidation updateValidator,
            IWorkOrderVendorUpdateValidation workOrderUpdateValidator)
        {
            _vendorDataService = vendorDataService;
            _createValidator = createValidator;
            _updateValidator = updateValidator;
            _workOrderUpdateValidator = workOrderUpdateValidator;
        }

        public async Task<VendorDTO?> GetVendorByIdAsync(int id)
        {
            var vendor = await _vendorDataService.GetByIdWithDetailsAsync(id);
            return vendor == null ? null : MapToDTO(vendor);
        }

        public async Task<VendorDTO?> GetVendorByIdWithDetailsAsync(int id)
        {
            var vendor = await _vendorDataService.GetByIdWithDetailsAsync(id);
            return vendor == null ? null : MapToDTO(vendor);
        }

        public async Task<IEnumerable<VendorDTO>> GetAllVendorsAsync()
        {
            var vendors = await _vendorDataService.GetAllAsync();
            return vendors.Select(MapToDTO);
        }

        public async Task<PagedResult<VendorDTO>> GetVendorsPagedAsync(
            int page,
            int pageSize,
            string? search = null,
            bool? isActive = true,
            IReadOnlyCollection<string>? companies = null,
            IReadOnlyCollection<string>? trades = null,
            IReadOnlyCollection<string>? locations = null,
            IReadOnlyCollection<string>? jobBuckets = null)
        {
            var (items, totalCount) = await _vendorDataService.GetPagedAsync(
                page,
                pageSize,
                search,
                isActive,
                companies,
                trades,
                locations,
                jobBuckets);
            return new PagedResult<VendorDTO>
            {
                Items = items.Select(MapToDTO).ToList(),
                TotalCount = totalCount,
                Page = page,
                PageSize = pageSize
            };
        }

        public async Task<VendorDTO> CreateVendorAsync(CreateVendorDTO dto, string userId)
        {
            NormalizePhoneFields(dto);
            var validationResult = await _createValidator.ValidateAsync(dto);
            if (!validationResult.IsValid)
            {
                throw new ValidationException(validationResult.Errors);
            }

            var company = await ResolveCompanyAsync(dto.CompanyId, dto.Name, dto, userId);

            var vendor = new Vendor
            {
                CompanyName = dto.Name,
                ContactName = dto.ContactName,
                Email = dto.Email,
                Phone = VendorPhoneNormalizer.NormalizeToCanonical(dto.Phone),
                CompanyPhone = VendorPhoneNormalizer.NormalizeToCanonical(dto.CompanyPhone),
                PreferredContact = dto.PreferredContact,
                Address = dto.Address,
                City = dto.City,
                State = dto.State,
                Zip = dto.Zipcode,
                TradeSpecialties = dto.TradeSpecialties,
                GoogleMapsUrl = dto.GoogleMapsUrl,
                Notes = dto.Notes,
                IsActive = dto.IsActive,
                CompanyId = company?.Id,
                CreatedDate = DateTime.UtcNow,
                createdby = userId
            };

            ApplyCompanyFields(vendor, company);

            var created = await _vendorDataService.AddAsync(vendor);
            return MapToDTO(created);
        }

        public async Task<VendorDTO> UpdateVendorAsync(int id, UpdateVendorDTO dto, string userId)
        {
            NormalizePhoneFields(dto);
            var validationResult = await _updateValidator.ValidateAsync(dto);
            if (!validationResult.IsValid)
            {
                throw new ValidationException(validationResult.Errors);
            }

            var vendor = await _vendorDataService.GetByIdAsync(id);
            if (vendor == null)
                throw new InvalidOperationException($"Vendor with ID {id} not found");

            if (dto.IsActive.HasValue && !dto.IsActive.Value)
                await AssertNoOpenLinkedWorkOrdersAsync(id);

            if (dto.Name != null) vendor.CompanyName = dto.Name;
            if (dto.ContactName != null) vendor.ContactName = dto.ContactName;
            if (dto.Email != null) vendor.Email = dto.Email;
            if (dto.Phone != null) vendor.Phone = VendorPhoneNormalizer.NormalizeToCanonical(dto.Phone);
            if (dto.PreferredContact != null) vendor.PreferredContact = dto.PreferredContact;
            if (dto.TradeSpecialties != null) vendor.TradeSpecialties = dto.TradeSpecialties;
            if (dto.Notes != null) vendor.Notes = dto.Notes;
            if (dto.IsActive.HasValue) vendor.IsActive = dto.IsActive.Value;

            if (dto.CompanyId.HasValue || dto.Name != null || HasCompanyFieldUpdate(dto))
            {
                var company = await ResolveCompanyAsync(
                    dto.CompanyId ?? vendor.CompanyId,
                    dto.Name ?? vendor.CompanyName,
                    dto,
                    userId);
                vendor.CompanyId = company?.Id;
                ApplyCompanyFields(vendor, company);
            }

            vendor.LastModificationTime = DateTime.UtcNow;
            if (int.TryParse(userId, out int userIdInt))
                vendor.LastModifierUserId = userIdInt;

            await _vendorDataService.UpdateAsync(vendor);
            return MapToDTO(vendor);
        }

        public async Task DeleteVendorAsync(int id, string userId)
        {
            var vendor = await _vendorDataService.GetByIdAsync(id);
            if (vendor == null)
                throw new InvalidOperationException($"Vendor with ID {id} not found");

            await AssertNoOpenLinkedWorkOrdersAsync(id);

            vendor.IsActive = false;
            vendor.LastModificationTime = DateTime.UtcNow;
            if (int.TryParse(userId, out int userIdInt))
                vendor.LastModifierUserId = userIdInt;

            await _vendorDataService.UpdateAsync(vendor);
        }

        public async Task<bool> VendorExistsAsync(int id)
        {
            return await _vendorDataService.ExistsAsync(id);
        }

        public async Task<int> GetTotalVendorCountAsync()
        {
            return await _vendorDataService.CountAsync();
        }

        public async Task<VendorDeactivationImpactDTO> GetDeactivationImpactAsync(int vendorId)
        {
            if (!await _vendorDataService.ExistsAsync(vendorId))
                throw new InvalidOperationException($"Vendor with ID {vendorId} not found");

            var linked = await _vendorDataService.GetLinkedWorkOrdersAsync(vendorId);
            var openWorkOrders = linked
                .Where(wo => !IsTerminalWorkOrderStatus(wo.LifecycleStatus, wo.Status))
                .Select(MapToLinkedWorkOrderDTO)
                .ToList();

            return new VendorDeactivationImpactDTO
            {
                VendorId = vendorId,
                CanDeactivate = openWorkOrders.Count == 0,
                OpenWorkOrders = openWorkOrders
            };
        }

        public async Task<VendorDTO> UpdateVendorFromWorkOrderAsync(
            int vendorId,
            WorkOrderVendorUpdateDTO dto,
            string userId)
        {
            dto.Phone = VendorPhoneNormalizer.NormalizeToCanonical(dto.Phone);
            var validationResult = await _workOrderUpdateValidator.ValidateAsync(dto);
            if (!validationResult.IsValid)
            {
                throw new ValidationException(validationResult.Errors);
            }

            var vendor = await _vendorDataService.GetByIdAsync(vendorId);
            if (vendor == null)
                throw new InvalidOperationException($"Vendor with ID {vendorId} not found");

            var isAssigned = await _vendorDataService.IsVendorAssignedToWorkOrderAsync(vendorId, dto.WorkOrderId);
            if (!isAssigned)
                throw new InvalidOperationException(
                    $"Vendor {vendorId} is not actively linked to work order {dto.WorkOrderId}.");

            var changes = new List<VendorAuditLog>();
            var now = DateTime.UtcNow;

            void RecordChange(string fieldName, string? oldValue, string? newValue)
            {
                if (!string.Equals(oldValue, newValue, StringComparison.Ordinal))
                {
                    changes.Add(new VendorAuditLog
                    {
                        VendorId = vendorId,
                        WorkOrderId = dto.WorkOrderId,
                        FieldName = fieldName,
                        OldValue = oldValue,
                        NewValue = newValue,
                        Actor = userId,
                        CreatedAt = now
                    });
                }
            }

            if (dto.ContactName != null)
            {
                RecordChange(nameof(Vendor.ContactName), vendor.ContactName, dto.ContactName);
                vendor.ContactName = dto.ContactName;
            }

            if (dto.PreferredContact != null)
            {
                RecordChange(nameof(Vendor.PreferredContact), vendor.PreferredContact, dto.PreferredContact);
                vendor.PreferredContact = dto.PreferredContact;
            }

            if (dto.Phone != null)
            {
                var normalized = VendorPhoneNormalizer.NormalizeToCanonical(dto.Phone);
                RecordChange(nameof(Vendor.Phone), vendor.Phone, normalized);
                vendor.Phone = normalized;
            }

            if (dto.Email != null)
            {
                RecordChange(nameof(Vendor.Email), vendor.Email, dto.Email);
                vendor.Email = dto.Email;
            }

            if (dto.Notes != null)
            {
                RecordChange(nameof(Vendor.Notes), vendor.Notes, dto.Notes);
                vendor.Notes = dto.Notes;
            }

            vendor.LastModificationTime = now;
            if (int.TryParse(userId, out int userIdInt))
                vendor.LastModifierUserId = userIdInt;

            await _vendorDataService.UpdateWithAuditLogsAsync(vendor, changes);

            return MapToDTO(vendor);
        }

        private async Task<VendorCompany?> ResolveCompanyAsync(
            int? requestedCompanyId,
            string? companyName,
            object dto,
            string userId)
        {
            if (requestedCompanyId.HasValue)
            {
                var byId = await _vendorDataService.GetCompanyByIdAsync(requestedCompanyId.Value);
                if (byId != null)
                {
                    ApplyCompanyUpdates(byId, companyName, dto, userId);
                    await _vendorDataService.UpdateCompanyAsync(byId);
                    return byId;
                }

                throw new ValidationException(new[]
                {
                    new ValidationFailure(
                        nameof(CreateVendorDTO.CompanyId),
                        $"No vendor company exists with ID {requestedCompanyId.Value}.")
                });
            }

            if (string.IsNullOrWhiteSpace(companyName))
                return null;

            var normalizedName = companyName.Trim().ToLowerInvariant();
            var existing = await _vendorDataService.GetCompanyByNormalizedNameAsync(normalizedName);
            if (existing != null)
            {
                ApplyCompanyUpdates(existing, companyName, dto, userId);
                await _vendorDataService.UpdateCompanyAsync(existing);
                return existing;
            }

            string? companyPhone = null;
            string? email = null;
            string? address = null;
            string? city = null;
            string? state = null;
            string? zip = null;
            string? mapsUrl = null;

            if (dto is CreateVendorDTO create)
            {
                companyPhone = VendorPhoneNormalizer.NormalizeToCanonical(create.CompanyPhone);
                email = create.Email;
                address = create.Address;
                city = create.City;
                state = create.State;
                zip = create.Zipcode;
                mapsUrl = create.GoogleMapsUrl;
            }
            else if (dto is UpdateVendorDTO update)
            {
                companyPhone = VendorPhoneNormalizer.NormalizeToCanonical(update.CompanyPhone);
                email = update.Email;
                address = update.Address;
                city = update.City;
                state = update.State;
                zip = update.Zipcode;
                mapsUrl = update.GoogleMapsUrl;
            }

            var company = new VendorCompany
            {
                Name = companyName.Trim(),
                NormalizedName = normalizedName,
                CompanyPhone = companyPhone,
                Email = email,
                Address = address,
                City = city,
                State = state,
                Zip = zip,
                GoogleMapsUrl = mapsUrl,
                CreatedDate = DateTime.UtcNow,
                createdby = userId
            };

            return await _vendorDataService.AddCompanyAsync(company);
        }

        private static void ApplyCompanyFields(Vendor vendor, VendorCompany? company)
        {
            if (company == null)
                return;

            if (company.CompanyPhone != null) vendor.CompanyPhone = company.CompanyPhone;
            if (company.Address != null) vendor.Address = company.Address;
            if (company.City != null) vendor.City = company.City;
            if (company.State != null) vendor.State = company.State;
            if (company.Zip != null) vendor.Zip = company.Zip;
            if (company.GoogleMapsUrl != null) vendor.GoogleMapsUrl = company.GoogleMapsUrl;
        }

        private static bool HasCompanyFieldUpdate(UpdateVendorDTO dto) =>
            dto.CompanyPhone != null ||
            dto.Address != null ||
            dto.City != null ||
            dto.State != null ||
            dto.Zipcode != null ||
            dto.GoogleMapsUrl != null;

        private static void ApplyCompanyUpdates(
            VendorCompany company,
            string? companyName,
            object dto,
            string userId)
        {
            if (!string.IsNullOrWhiteSpace(companyName))
            {
                company.Name = companyName.Trim();
                company.NormalizedName = company.Name.ToLowerInvariant();
            }

            if (dto is CreateVendorDTO create)
            {
                if (create.CompanyPhone != null) company.CompanyPhone = create.CompanyPhone;
                if (create.Address != null) company.Address = create.Address;
                if (create.City != null) company.City = create.City;
                if (create.State != null) company.State = create.State;
                if (create.Zipcode != null) company.Zip = create.Zipcode;
                if (create.GoogleMapsUrl != null) company.GoogleMapsUrl = create.GoogleMapsUrl;
            }
            else if (dto is UpdateVendorDTO update)
            {
                if (update.CompanyPhone != null) company.CompanyPhone = update.CompanyPhone;
                if (update.Address != null) company.Address = update.Address;
                if (update.City != null) company.City = update.City;
                if (update.State != null) company.State = update.State;
                if (update.Zipcode != null) company.Zip = update.Zipcode;
                if (update.GoogleMapsUrl != null) company.GoogleMapsUrl = update.GoogleMapsUrl;
            }

            company.LastModificationTime = DateTime.UtcNow;
            if (int.TryParse(userId, out int userIdInt))
                company.LastModifierUserId = userIdInt;
        }

        private static void NormalizePhoneFields(CreateVendorDTO dto)
        {
            dto.Phone = VendorPhoneNormalizer.NormalizeToCanonical(dto.Phone);
            dto.CompanyPhone = VendorPhoneNormalizer.NormalizeToCanonical(dto.CompanyPhone);
        }

        private static void NormalizePhoneFields(UpdateVendorDTO dto)
        {
            dto.Phone = VendorPhoneNormalizer.NormalizeToCanonical(dto.Phone);
            dto.CompanyPhone = VendorPhoneNormalizer.NormalizeToCanonical(dto.CompanyPhone);
        }

        private async Task AssertNoOpenLinkedWorkOrdersAsync(int vendorId)
        {
            var linked = await _vendorDataService.GetLinkedWorkOrdersAsync(vendorId);
            var openWorkOrders = linked
                .Where(wo => !IsTerminalWorkOrderStatus(wo.LifecycleStatus, wo.Status))
                .Select(MapToLinkedWorkOrderDTO)
                .ToList();

            if (openWorkOrders.Count > 0)
            {
                throw new VendorDeactivationBlockedException(
                    "Vendor cannot be deactivated while linked work orders are open or scheduled.",
                    openWorkOrders);
            }
        }

        private static bool IsTerminalWorkOrderStatus(LifecycleStatus? lifecycleStatus, string? legacyStatus)
        {
            if (lifecycleStatus == LifecycleStatus.Completed || lifecycleStatus == LifecycleStatus.Canceled)
                return true;

            if (!string.IsNullOrWhiteSpace(legacyStatus) &&
                TerminalLegacyStatuses.Contains(legacyStatus.Trim().ToLowerInvariant()))
                return true;

            return false;
        }

        private static LinkedWorkOrderDTO MapToLinkedWorkOrderDTO(LinkedWorkOrderInfo info) => new()
        {
            WorkOrderId = info.WorkOrderId,
            WorkOrderNumber = info.WorkOrderNumber,
            WorkOrderTitle = info.WorkOrderTitle,
            Status = info.Status,
            ScheduledDate = info.ScheduledDate,
            DispatchId = info.DispatchId
        };

        private VendorDTO MapToDTO(Vendor vendor)
        {
            return new VendorDTO
            {
                Id = vendor.Id,
                Name = vendor.CompanyName,
                CompanyId = vendor.CompanyId,
                ContactName = vendor.ContactName,
                Email = vendor.Email,
                Phone = vendor.Phone,
                CompanyPhone = vendor.CompanyPhone,
                PreferredContact = vendor.PreferredContact,
                Address = vendor.Address,
                City = vendor.City,
                State = vendor.State,
                Zipcode = vendor.Zip,
                TradeSpecialties = vendor.TradeSpecialties,
                GoogleMapsUrl = vendor.GoogleMapsUrl,
                Notes = vendor.Notes,
                IsActive = vendor.IsActive,
                TotalJobs = vendor.Dispatches == null
                    ? vendor.TotalJobs
                    : CountDistinctWorkOrders(vendor)
            };
        }

        private static int CountDistinctWorkOrders(Vendor vendor)
        {
            if (vendor.Dispatches == null)
                return 0;

            return vendor.Dispatches
                .SelectMany(dispatch =>
                {
                    var linked = dispatch.DispatchWorkOrders?.Select(item => item.WorkOrderId)
                        ?? Enumerable.Empty<int>();
                    return dispatch.WorkOrderId.HasValue
                        ? linked.Append(dispatch.WorkOrderId.Value)
                        : linked;
                })
                .Distinct()
                .Count();
        }
    }
}