package services

import (
	"context"
	"errors"

	"gorm.io/gorm"

	"github.com/treytartt/honeydue-api/internal/apperrors"
	"github.com/treytartt/honeydue-api/internal/dto/requests"
	"github.com/treytartt/honeydue-api/internal/dto/responses"
	"github.com/treytartt/honeydue-api/internal/models"
	"github.com/treytartt/honeydue-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
	storageService *StorageService
	uploadService  *UploadService
	cache          *CacheService
}

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

// SetCacheService wires Redis caching for residence-ID lookups.
func (s *DocumentService) SetCacheService(cache *CacheService) {
	s.cache = cache
}

// SetStorageService wires the storage service so URLs for presigned uploads
// can be generated using the same BaseURL the legacy uploader uses.
func (s *DocumentService) SetStorageService(ss *StorageService) {
	s.storageService = ss
}

// SetUploadService wires the presigned-URL upload service so CreateDocument
// can claim pending_uploads rows by id and convert them into document_image
// rows (or, for category=document_file, set the document's main file fields).
func (s *DocumentService) SetUploadService(us *UploadService) {
	s.uploadService = us
}

// GetDocument gets a document by ID with access check
func (s *DocumentService) GetDocument(ctx context.Context, documentID, userID uint) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.WithContext(ctx).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.WithContext(ctx).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(ctx context.Context, userID uint, filter *repositories.DocumentFilter) ([]responses.DocumentResponse, error) {
	// Get residence IDs (lightweight - no preloads)
	residenceIDs, err := cachedResidenceIDsForUser(ctx, s.cache, s.residenceRepo, 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.WithContext(ctx).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(ctx context.Context, userID uint) ([]responses.DocumentResponse, error) {
	// Get residence IDs (lightweight - no preloads)
	residenceIDs, err := cachedResidenceIDsForUser(ctx, s.cache, s.residenceRepo, userID)
	if err != nil {
		return nil, apperrors.Internal(err)
	}

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

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

	return responses.NewDocumentListResponse(documents), nil
}

// CreateDocument creates a new document
func (s *DocumentService) CreateDocument(ctx context.Context, req *requests.CreateDocumentRequest, userID uint) (*responses.DocumentResponse, error) {
	// Check residence access
	hasAccess, err := s.residenceRepo.WithContext(ctx).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,
	}

	// Claim presigned uploads BEFORE the document insert. If the client
	// passed a category=document_file row, lift it onto the document's
	// FileURL/FileName/FileSize/MimeType fields rather than creating an
	// image row for it. Image categories produce DocumentImage rows below.
	var claimedUploads []models.PendingUpload
	if len(req.UploadIDs) > 0 && s.uploadService != nil {
		var claimErr error
		claimedUploads, claimErr = s.uploadService.VerifyAndClaim(ctx, userID, req.UploadIDs)
		if claimErr != nil {
			return nil, claimErr
		}
		// Lift the (single) document_file upload, if present, onto the
		// document fields. Multiple document_file claims aren't meaningful;
		// take the first and ignore extras to keep the surface narrow.
		for _, pu := range claimedUploads {
			if pu.Category == models.UploadCategoryDocumentFile {
				if document.FileURL == "" {
					document.FileURL = urlForUploadKey(s.storageService, pu.B2Key)
				}
				if document.MimeType == "" {
					document.MimeType = pu.ContentType
				}
				if document.FileSize == nil && pu.ActualBytes != nil {
					b := *pu.ActualBytes
					document.FileSize = &b
				}
				break
			}
		}
	}

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

	// Presigned-URL path — claimed image uploads become DocumentImage rows.
	// The document_file row (if any) was already lifted onto the document above.
	for i := range claimedUploads {
		pu := claimedUploads[i]
		if pu.Category == models.UploadCategoryDocumentFile {
			continue
		}
		img := &models.DocumentImage{
			DocumentID:      document.ID,
			ImageURL:        urlForUploadKey(s.storageService, pu.B2Key),
			PendingUploadID: &pu.ID,
		}
		if err := s.documentRepo.WithContext(ctx).CreateDocumentImage(img); err != nil {
			// Don't fail the whole document for an image insert failure;
			// matches the legacy ImageURLs behavior. The orphaned upload
			// row is benign (still claimed, just unreferenced).
			continue
		}
	}

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

	invalidateSubStatusForResidence(ctx, s.cache, s.residenceRepo, req.ResidenceID)

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

// UpdateDocument updates a document
func (s *DocumentService) UpdateDocument(ctx context.Context, documentID, userID uint, req *requests.UpdateDocumentRequest) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.WithContext(ctx).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.WithContext(ctx).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.WithContext(ctx).Update(document); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Reload
	document, err = s.documentRepo.WithContext(ctx).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(ctx context.Context, documentID, userID uint) error {
	document, err := s.documentRepo.WithContext(ctx).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.WithContext(ctx).HasAccess(document.ResidenceID, userID)
	if err != nil {
		return apperrors.Internal(err)
	}
	if !hasAccess {
		return apperrors.Forbidden("error.document_access_denied")
	}

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

	invalidateSubStatusForResidence(ctx, s.cache, s.residenceRepo, document.ResidenceID)

	return nil
}

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

	// Check access
	hasAccess, err := s.residenceRepo.WithContext(ctx).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.WithContext(ctx).Activate(documentID); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Reload
	doc, err := s.documentRepo.WithContext(ctx).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(ctx context.Context, documentID, userID uint) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.WithContext(ctx).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.WithContext(ctx).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.WithContext(ctx).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(ctx context.Context, documentID, userID uint, imageURL, caption string) (*responses.DocumentResponse, error) {
	document, err := s.documentRepo.WithContext(ctx).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.WithContext(ctx).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.WithContext(ctx).CreateDocumentImage(img); err != nil {
		return nil, apperrors.Internal(err)
	}

	// Reload with relations
	document, err = s.documentRepo.WithContext(ctx).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(ctx context.Context, documentID, imageID, userID uint) (*responses.DocumentResponse, error) {
	// Find the image first
	image, err := s.documentRepo.WithContext(ctx).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.WithContext(ctx).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.WithContext(ctx).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.WithContext(ctx).DeleteDocumentImage(imageID); err != nil {
		return nil, apperrors.Internal(err)
	}

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

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