package services

import (
	"errors"

	"gorm.io/gorm"

	"github.com/treytartt/casera-api/internal/apperrors"
	"github.com/treytartt/casera-api/internal/dto/requests"
	"github.com/treytartt/casera-api/internal/dto/responses"
	"github.com/treytartt/casera-api/internal/models"
	"github.com/treytartt/casera-api/internal/repositories"
)

// Document-related errors
// DEPRECATED: These constants are deprecated. Use apperrors package instead.
// var (
// 	ErrDocumentNotFound     = errors.New("document not found")
// 	ErrDocumentAccessDenied = errors.New("you do not have access to this document")
// )

// DocumentService handles document business logic
type DocumentService struct {
	documentRepo  *repositories.DocumentRepository
	residenceRepo *repositories.ResidenceRepository
}

// NewDocumentService creates a new document service
func NewDocumentService(documentRepo *repositories.DocumentRepository, residenceRepo *repositories.ResidenceRepository) *DocumentService {
	return &DocumentService{
		documentRepo:  documentRepo,
		residenceRepo: residenceRepo,
	}
}

// GetDocument gets a document by ID with access check
func (s *DocumentService) GetDocument(documentID, userID uint) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.FindByID(documentID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, apperrors.NotFound("error.document_not_found")
		}
		return nil, apperrors.Internal(err)
	}

	// Check access via residence
	hasAccess, err := s.residenceRepo.HasAccess(document.ResidenceID, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}
	if !hasAccess {
		return nil, apperrors.Forbidden("error.document_access_denied")
	}

	resp := responses.NewDocumentResponse(document)
	return &resp, nil
}

// ListDocuments lists all documents accessible to a user, with optional filters.
func (s *DocumentService) ListDocuments(userID uint, filter *repositories.DocumentFilter) ([]responses.DocumentResponse, error) {
	// Get residence IDs (lightweight - no preloads)
	residenceIDs, err := s.residenceRepo.FindResidenceIDsByUser(userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	if len(residenceIDs) == 0 {
		return []responses.DocumentResponse{}, nil
	}

	// If a specific residence filter is set, narrow to that single residence (if user has access)
	if filter != nil && filter.ResidenceID != nil {
		found := false
		for _, rid := range residenceIDs {
			if rid == *filter.ResidenceID {
				found = true
				break
			}
		}
		if !found {
			return nil, apperrors.Forbidden("error.residence_access_denied")
		}
		residenceIDs = []uint{*filter.ResidenceID}
	}

	documents, err := s.documentRepo.FindByUserFiltered(residenceIDs, filter)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	return responses.NewDocumentListResponse(documents), nil
}

// ListWarranties lists all warranty documents
func (s *DocumentService) ListWarranties(userID uint) ([]responses.DocumentResponse, error) {
	// Get residence IDs (lightweight - no preloads)
	residenceIDs, err := s.residenceRepo.FindResidenceIDsByUser(userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	if len(residenceIDs) == 0 {
		return []responses.DocumentResponse{}, nil
	}

	documents, err := s.documentRepo.FindWarranties(residenceIDs)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	return responses.NewDocumentListResponse(documents), nil
}

// CreateDocument creates a new document
func (s *DocumentService) CreateDocument(req *requests.CreateDocumentRequest, userID uint) (*responses.DocumentResponse, error) {
	// Check residence access
	hasAccess, err := s.residenceRepo.HasAccess(req.ResidenceID, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}
	if !hasAccess {
		return nil, apperrors.Forbidden("error.residence_access_denied")
	}

	documentType := req.DocumentType
	if documentType == "" {
		documentType = models.DocumentTypeGeneral
	}

	document := &models.Document{
		ResidenceID:   req.ResidenceID,
		CreatedByID:   userID,
		Title:         req.Title,
		Description:   req.Description,
		DocumentType:  documentType,
		FileURL:       req.FileURL,
		FileName:      req.FileName,
		FileSize:      req.FileSize,
		MimeType:      req.MimeType,
		PurchaseDate:  req.PurchaseDate,
		ExpiryDate:    req.ExpiryDate,
		PurchasePrice: req.PurchasePrice,
		Vendor:        req.Vendor,
		SerialNumber:  req.SerialNumber,
		ModelNumber:   req.ModelNumber,
		TaskID:        req.TaskID,
		IsActive:      true,
	}

	if err := s.documentRepo.Create(document); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Create images if provided
	for _, imageURL := range req.ImageURLs {
		if imageURL != "" {
			img := &models.DocumentImage{
				DocumentID: document.ID,
				ImageURL:   imageURL,
			}
			if err := s.documentRepo.CreateDocumentImage(img); err != nil {
				// Log but don't fail the whole operation
				continue
			}
		}
	}

	// Reload with relations
	document, err = s.documentRepo.FindByID(document.ID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	resp := responses.NewDocumentResponse(document)
	return &resp, nil
}

// UpdateDocument updates a document
func (s *DocumentService) UpdateDocument(documentID, userID uint, req *requests.UpdateDocumentRequest) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.FindByID(documentID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, apperrors.NotFound("error.document_not_found")
		}
		return nil, apperrors.Internal(err)
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(document.ResidenceID, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}
	if !hasAccess {
		return nil, apperrors.Forbidden("error.document_access_denied")
	}

	// Apply updates
	if req.Title != nil {
		document.Title = *req.Title
	}
	if req.Description != nil {
		document.Description = *req.Description
	}
	if req.DocumentType != nil {
		document.DocumentType = *req.DocumentType
	}
	if req.FileURL != nil {
		document.FileURL = *req.FileURL
	}
	if req.FileName != nil {
		document.FileName = *req.FileName
	}
	if req.FileSize != nil {
		document.FileSize = req.FileSize
	}
	if req.MimeType != nil {
		document.MimeType = *req.MimeType
	}
	if req.PurchaseDate != nil {
		document.PurchaseDate = req.PurchaseDate
	}
	if req.ExpiryDate != nil {
		document.ExpiryDate = req.ExpiryDate
	}
	if req.PurchasePrice != nil {
		document.PurchasePrice = req.PurchasePrice
	}
	if req.Vendor != nil {
		document.Vendor = *req.Vendor
	}
	if req.SerialNumber != nil {
		document.SerialNumber = *req.SerialNumber
	}
	if req.ModelNumber != nil {
		document.ModelNumber = *req.ModelNumber
	}
	if req.TaskID != nil {
		document.TaskID = req.TaskID
	}

	if err := s.documentRepo.Update(document); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Reload
	document, err = s.documentRepo.FindByID(documentID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	resp := responses.NewDocumentResponse(document)
	return &resp, nil
}

// DeleteDocument soft-deletes a document
func (s *DocumentService) DeleteDocument(documentID, userID uint) error {
	document, err := s.documentRepo.FindByID(documentID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return apperrors.NotFound("error.document_not_found")
		}
		return apperrors.Internal(err)
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(document.ResidenceID, userID)
	if err != nil {
		return apperrors.Internal(err)
	}
	if !hasAccess {
		return apperrors.Forbidden("error.document_access_denied")
	}

	if err := s.documentRepo.Delete(documentID); err != nil {
		return apperrors.Internal(err)
	}

	return nil
}

// ActivateDocument activates a document
func (s *DocumentService) ActivateDocument(documentID, userID uint) (*responses.DocumentResponse, error) {
	// First check if document exists (even if inactive)
	var document models.Document
	if err := s.documentRepo.FindByIDIncludingInactive(documentID, &document); err != nil {
		return nil, apperrors.NotFound("error.document_not_found")
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(document.ResidenceID, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}
	if !hasAccess {
		return nil, apperrors.Forbidden("error.document_access_denied")
	}

	if err := s.documentRepo.Activate(documentID); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Reload
	doc, err := s.documentRepo.FindByID(documentID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	resp := responses.NewDocumentResponse(doc)
	return &resp, nil
}

// DeactivateDocument deactivates a document
func (s *DocumentService) DeactivateDocument(documentID, userID uint) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.FindByID(documentID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, apperrors.NotFound("error.document_not_found")
		}
		return nil, apperrors.Internal(err)
	}

	// Check access
	hasAccess, err := s.residenceRepo.HasAccess(document.ResidenceID, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}
	if !hasAccess {
		return nil, apperrors.Forbidden("error.document_access_denied")
	}

	if err := s.documentRepo.Deactivate(documentID); err != nil {
		return nil, apperrors.Internal(err)
	}

	document.IsActive = false
	resp := responses.NewDocumentResponse(document)
	return &resp, nil
}

// UploadDocumentImage adds an image to an existing document
func (s *DocumentService) UploadDocumentImage(documentID, userID uint, imageURL, caption string) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.FindByID(documentID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, apperrors.NotFound("error.document_not_found")
		}
		return nil, apperrors.Internal(err)
	}

	// Check access via residence
	hasAccess, err := s.residenceRepo.HasAccess(document.ResidenceID, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}
	if !hasAccess {
		return nil, apperrors.Forbidden("error.document_access_denied")
	}

	img := &models.DocumentImage{
		DocumentID: documentID,
		ImageURL:   imageURL,
		Caption:    caption,
	}
	if err := s.documentRepo.CreateDocumentImage(img); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Reload with relations
	document, err = s.documentRepo.FindByID(documentID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	resp := responses.NewDocumentResponse(document)
	return &resp, nil
}

// DeleteDocumentImage removes an image from a document
func (s *DocumentService) DeleteDocumentImage(documentID, imageID, userID uint) (*responses.DocumentResponse, error) {
	// Find the image first
	image, err := s.documentRepo.FindImageByID(imageID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, apperrors.NotFound("error.document_image_not_found")
		}
		return nil, apperrors.Internal(err)
	}

	// Verify image belongs to the specified document
	if image.DocumentID != documentID {
		return nil, apperrors.NotFound("error.document_image_not_found")
	}

	// Find parent document to check access
	document, err := s.documentRepo.FindByID(documentID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, apperrors.NotFound("error.document_not_found")
		}
		return nil, apperrors.Internal(err)
	}

	// Check access via residence
	hasAccess, err := s.residenceRepo.HasAccess(document.ResidenceID, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}
	if !hasAccess {
		return nil, apperrors.Forbidden("error.document_access_denied")
	}

	if err := s.documentRepo.DeleteDocumentImage(imageID); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Reload with relations
	document, err = s.documentRepo.FindByID(documentID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

	resp := responses.NewDocumentResponse(document)
	return &resp, nil
}