package customer

import (
	"context"
	"errors"
	"time"

	"tm/internal/company"
	"tm/pkg/logger"
	"tm/pkg/response"

	"tm/pkg/authorization"

	"go.mongodb.org/mongo-driver/bson/primitive"
	"golang.org/x/crypto/bcrypt"
)

// Service defines business logic for customer operations
type Service interface {
	// Core customer operations
	Register(ctx context.Context, form *CreateCustomerForm) (*CustomerResponse, error)
	GetByID(ctx context.Context, id string) (*CustomerResponse, error)
	Search(ctx context.Context, form *SearchCustomersForm, pagination *response.Pagination) (*CustomerListResponse, error)
	Update(ctx context.Context, id string, form *UpdateCustomerForm) (*CustomerResponse, error)
	Delete(ctx context.Context, id string) error
	UpdateStatus(ctx context.Context, id string, form *UpdateStatusForm) error

	// Authentication operations
	Login(ctx context.Context, form *LoginForm) (*AuthResponse, error)
	RefreshToken(ctx context.Context, refreshToken string) (*AuthResponse, error)
	GetProfileWithCompanies(ctx context.Context, id string) (*CustomerResponse, error)
	Logout(ctx context.Context, id string, accessToken string) error
}

// customerService implements the Service interface
type customerService struct {
	repository     Repository
	logger         logger.Logger
	authService    authorization.AuthorizationService
	companyService company.Service
}

// NewCustomerService creates a new customer service
func NewCustomerService(repository Repository, logger logger.Logger, authService authorization.AuthorizationService, companyService company.Service) Service {
	return &customerService{
		repository:     repository,
		logger:         logger,
		authService:    authService,
		companyService: companyService,
	}
}

// Register creates a new customer
func (s *customerService) Register(ctx context.Context, form *CreateCustomerForm) (*CustomerResponse, error) {
	// Check if email already exists
	existingCustomer, _ := s.repository.GetByEmail(ctx, form.Email)
	if existingCustomer != nil {
		return nil, errors.New("customer with this email already exists")
	}

	// Verify that all company IDs exist
	var companyIDs []string
	if len(form.CompanyIDs) > 0 {
		for _, companyID := range form.CompanyIDs {
			_, err := s.companyService.GetCompanyByID(ctx, companyID)
			if err != nil {
				s.logger.Error("Invalid company ID provided", map[string]interface{}{
					"error":      err.Error(),
					"company_id": companyID,
				})
				return nil, errors.New("invalid company ID: " + companyID)
			}
		}
		companyIDs = form.CompanyIDs
	}

	// Hash password
	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(form.Password), bcrypt.DefaultCost)
	if err != nil {
		s.logger.Error("Failed to hash password", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, errors.New("failed to process password")
	}

	// Create customer
	customer := &Customer{
		Type:       CustomerType(form.Type),
		Status:     CustomerStatusActive,
		CompanyIDs: companyIDs,
		FullName:   form.FullName,
		Username:   form.Username,
		Email:      form.Email,
		Password:   string(hashedPassword),
		Phone:      form.Phone,
	}

	// Save to database
	err = s.repository.Register(ctx, customer)
	if err != nil {
		s.logger.Error("Failed to create customer", map[string]interface{}{
			"error":    err.Error(),
			"email":    form.Email,
			"username": form.Username,
		})
		return nil, err
	}

	s.logger.Info("Customer created successfully", map[string]interface{}{
		"customer_id": customer.ID,
		"email":       customer.Email,
		"type":        customer.Type,
		"company_ids": companyIDs,
	})

	return customer.ToResponse(nil), nil
}

// GetByID retrieves a customer by ID
func (s *customerService) GetByID(ctx context.Context, id string) (*CustomerResponse, error) {
	customer, err := s.repository.GetByID(ctx, id)
	if err != nil {
		s.logger.Error("Failed to get customer by ID", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
		})
		return nil, err
	}

	var companies []*CompanySummary
	if len(customer.CompanyIDs) > 0 {
		companies, err = s.loadCompaniesForCustomer(ctx, customer)
		if err != nil {
			s.logger.Error("Failed to load companies for customer", map[string]interface{}{
				"error":       err.Error(),
				"customer_id": customer.ID,
			})
		}
	}

	s.logger.Info("Customer retrieved successfully", map[string]interface{}{
		"customer_id": customer.ID,
		"email":       customer.Email,
	})

	return customer.ToResponse(companies), nil
}

// Search searches for customers
func (s *customerService) Search(ctx context.Context, form *SearchCustomersForm, pagination *response.Pagination) (*CustomerListResponse, error) {
	customers, total, err := s.repository.Search(ctx, form, pagination)
	if err != nil {
		s.logger.Error("Failed to search customers", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, errors.New("failed to search customers")
	}

	var customerResponses []*CustomerResponse
	for _, customer := range customers {
		companies, err := s.loadCompaniesForCustomer(ctx, &customer)
		if err != nil {
			s.logger.Error("Failed to load companies for customer", map[string]interface{}{
				"error":       err.Error(),
				"customer_id": customer.ID,
			})
		}

		customerResponses = append(customerResponses, customer.ToResponse(companies))
	}

	return &CustomerListResponse{
		Customers: customerResponses,
		Meta:      pagination.Response(total),
	}, nil
}

// Update updates a customer
func (s *customerService) Update(ctx context.Context, id string, form *UpdateCustomerForm) (*CustomerResponse, error) {
	// Get existing customer
	customer, err := s.repository.GetByID(ctx, id)
	if err != nil {
		s.logger.Error("Failed to get customer for update", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
		})
		return nil, errors.New("customer not found")
	}

	// Check if email already exists (if changing email)
	if form.Email != "" && form.Email != customer.Email {
		existingCustomer, _ := s.repository.GetByEmail(ctx, form.Email)
		if existingCustomer != nil {
			return nil, errors.New("customer with this email already exists")
		}
		customer.Email = form.Email
	}

	// Check if username already exists (if changing username)
	if form.Username != "" && form.Username != customer.Username {
		existingCustomer, _ := s.repository.GetByUsername(ctx, form.Username)
		if existingCustomer != nil {
			return nil, errors.New("customer with this username already exists")
		}
		customer.Username = form.Username
	}

	// Handle company assignments
	if len(form.CompanyIDs) > 0 {
		// Verify that all company IDs exist
		var validCompanyIDs []string
		for _, companyID := range form.CompanyIDs {
			_, err := s.companyService.GetCompanyByID(ctx, companyID)
			if err != nil {
				s.logger.Error("Invalid company ID provided in update", map[string]interface{}{
					"error":      err.Error(),
					"company_id": companyID,
				})
				return nil, errors.New("invalid company ID: " + companyID)
			}
			validCompanyIDs = append(validCompanyIDs, companyID)
		}
		customer.CompanyIDs = validCompanyIDs
	}

	if form.FullName != nil {
		customer.FullName = form.FullName
	}

	if form.Phone != nil {
		customer.Phone = form.Phone
	}

	// Update in database
	err = s.repository.Update(ctx, customer)
	if err != nil {
		s.logger.Error("Failed to update customer", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
		})
		return nil, errors.New("failed to update customer")
	}

	s.logger.Info("Customer updated successfully", map[string]interface{}{
		"customer_id": customer.ID,
		"email":       customer.Email,
	})

	return customer.ToResponse(nil), nil
}

// Delete deletes a customer (soft delete)
func (s *customerService) Delete(ctx context.Context, id string) error {
	// Get customer to check if exists
	_, err := s.repository.GetByID(ctx, id)
	if err != nil {
		s.logger.Error("Failed to get customer for delete", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
		})
		return errors.New("customer not found")
	}

	// Delete customer (soft delete)
	err = s.repository.Delete(ctx, id)
	if err != nil {
		s.logger.Error("Failed to delete customer", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
		})
		return errors.New("failed to delete customer")
	}

	s.logger.Info("Customer deleted successfully", map[string]interface{}{
		"customer_id": id,
	})

	return nil
}

// UpdateStatus updates customer status
func (s *customerService) UpdateStatus(ctx context.Context, id string, form *UpdateStatusForm) error {
	// Get customer to check if exists
	_, err := s.repository.GetByID(ctx, id)
	if err != nil {
		return errors.New("customer not found")
	}

	// Update status
	status := CustomerStatus(form.Status)
	err = s.repository.UpdateStatus(ctx, id, status)
	if err != nil {
		s.logger.Error("Failed to update customer status", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
			"status":      form.Status,
		})
		return errors.New("failed to update customer status")
	}

	s.logger.Info("Customer status updated successfully", map[string]interface{}{
		"customer_id": id,
		"status":      form.Status,
	})

	return nil
}

// AssignCompanies assigns companies to a customer
func (s *customerService) AssignCompanies(ctx context.Context, customerID string, companyIDs []string) error {
	// Get customer to check if exists
	customer, err := s.repository.GetByID(ctx, customerID)
	if err != nil {
		return errors.New("customer not found")
	}

	// Verify companies exist and update customer's company IDs
	var validCompanyIDs []string
	for _, companyID := range companyIDs {
		_, err = s.companyService.GetCompanyByID(ctx, companyID)
		if err != nil {
			s.logger.Error("Company not found during assignment", map[string]interface{}{
				"error":       err.Error(),
				"customer_id": customerID,
				"company_id":  companyID,
			})
			continue // Skip invalid company IDs
		}
		validCompanyIDs = append(validCompanyIDs, companyID)
	}

	// Update customer's company IDs
	customer.CompanyIDs = append(customer.CompanyIDs, validCompanyIDs...)
	customer.UpdatedAt = time.Now().Unix()

	err = s.repository.Update(ctx, customer)
	if err != nil {
		s.logger.Error("Failed to update customer with company assignments", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customerID,
		})
		return errors.New("failed to assign companies to customer")
	}

	s.logger.Info("Companies assigned to customer successfully", map[string]interface{}{
		"customer_id": customerID,
		"company_ids": validCompanyIDs,
	})

	return nil
}

// RemoveCompaniesFromCustomer removes companies from a customer
func (s *customerService) RemoveCompanies(ctx context.Context, customerID string, companyIDs []string) error {
	// Get customer to check if exists
	customer, err := s.repository.GetByID(ctx, customerID)
	if err != nil {
		return errors.New("customer not found")
	}

	// Remove company IDs from customer's list
	var updatedCompanyIDs []string
	for _, existingID := range customer.CompanyIDs {
		shouldRemove := false
		for _, removeID := range companyIDs {
			if existingID == removeID {
				shouldRemove = true
				break
			}
		}
		if !shouldRemove {
			updatedCompanyIDs = append(updatedCompanyIDs, existingID)
		}
	}

	// Update customer's company IDs
	customer.CompanyIDs = updatedCompanyIDs
	customer.UpdatedAt = time.Now().Unix()

	err = s.repository.Update(ctx, customer)
	if err != nil {
		s.logger.Error("Failed to update customer after removing company assignments", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customerID,
		})
		return errors.New("failed to remove companies from customer")
	}

	s.logger.Info("Companies removed from customer successfully", map[string]interface{}{
		"customer_id": customerID,
		"company_ids": companyIDs,
	})

	return nil
}

// Suspend suspends a customer
func (s *customerService) Suspend(ctx context.Context, id string, reason string) error {
	// Get customer to check if exists
	_, err := s.repository.GetByID(ctx, id)
	if err != nil {
		return errors.New("customer not found")
	}

	// Update status to suspended
	err = s.repository.UpdateStatus(ctx, id, CustomerStatusSuspended)
	if err != nil {
		s.logger.Error("Failed to suspend customer", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
		})
		return errors.New("failed to suspend customer")
	}

	s.logger.Info("Customer suspended successfully", map[string]interface{}{
		"customer_id": id,
		"reason":      reason,
	})

	return nil
}

// Activate activates a customer
func (s *customerService) Activate(ctx context.Context, id string) error {
	// Get customer to check if exists
	_, err := s.repository.GetByID(ctx, id)
	if err != nil {
		return errors.New("customer not found")
	}

	// Update status to active
	err = s.repository.UpdateStatus(ctx, id, CustomerStatusActive)
	if err != nil {
		s.logger.Error("Failed to activate customer", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": id,
		})
		return errors.New("failed to activate customer")
	}

	s.logger.Info("Customer activated successfully", map[string]interface{}{
		"customer_id": id,
	})

	return nil
}

// Login handles customer authentication
func (s *customerService) Login(ctx context.Context, form *LoginForm) (*AuthResponse, error) {
	s.logger.Info("Customer login attempt", map[string]interface{}{
		"username": form.Username,
	})

	// Get customer by username
	customer, err := s.repository.GetByUsername(ctx, form.Username)
	if err != nil {
		s.logger.Warn("Customer login failed - username not found", map[string]interface{}{
			"username": form.Username,
		})
		return nil, errors.New("invalid credentials")
	}

	// Check if customer is active
	if customer.Status != CustomerStatusActive {
		s.logger.Warn("Customer login failed - account not active", map[string]interface{}{
			"username":    form.Username,
			"customer_id": customer.ID,
			"status":      string(customer.Status),
		})
		return nil, errors.New("account is not active")
	}

	// Verify password
	err = bcrypt.CompareHashAndPassword([]byte(customer.Password), []byte(form.Password))
	if err != nil {
		s.logger.Warn("Customer login failed - wrong password", map[string]interface{}{
			"customer_id": customer.ID,
			"email":       customer.Email,
		})
		return nil, errors.New("invalid credentials")
	}

	// Generate JWT tokens using authorization service
	companyID := ""
	if len(customer.CompanyIDs) > 0 {
		companyID = customer.CompanyIDs[0] // Use first company ID for JWT token
	}

	tokenPair, err := s.authService.GenerateTokenPair(
		customer.ID.Hex(),
		customer.Email,
		"customer", // Role for customers
		companyID,
	)
	if err != nil {
		s.logger.Error("Failed to generate JWT tokens", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customer.ID,
		})
		return nil, errors.New("failed to generate authentication tokens")
	}

	err = s.repository.Login(ctx, customer.ID.Hex())
	if err != nil {
		s.logger.Error("Failed to update customer last login", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customer.ID,
		})
	}

	companies, err := s.loadCompaniesForCustomer(ctx, customer)
	if err != nil {
		s.logger.Error("Failed to load companies for customer", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customer.ID,
		})
	}

	s.logger.Info("Customer login successful", map[string]interface{}{
		"username":      form.Username,
		"customer_id":   customer.ID,
		"customer_type": string(customer.Type),
	})

	return &AuthResponse{
		Customer:     customer.ToResponse(companies),
		AccessToken:  tokenPair.AccessToken,
		RefreshToken: tokenPair.RefreshToken,
		ExpiresAt:    time.Now().Add(15 * time.Minute).Unix(), // 15 minutes from now
	}, nil
}

// RefreshToken handles token refresh for customers
func (s *customerService) RefreshToken(ctx context.Context, refreshToken string) (*AuthResponse, error) {
	s.logger.Info("Customer token refresh attempt", map[string]interface{}{
		"refresh_token": refreshToken[:10] + "...", // Log only first 10 chars for security
	})

	// Validate refresh token and generate new access token
	newAccessToken, err := s.authService.RefreshAccessToken(refreshToken)
	if err != nil {
		s.logger.Warn("Failed to refresh access token", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, errors.New("invalid or expired refresh token")
	}

	// Parse the new access token to get customer information
	validationResult, err := s.authService.ValidateAccessToken(newAccessToken)
	if err != nil {
		s.logger.Error("Failed to validate new access token", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, errors.New("failed to generate valid access token")
	}

	if !validationResult.Valid {
		s.logger.Error("New access token validation failed", map[string]interface{}{
			"error": validationResult.Error,
		})
		return nil, errors.New("failed to generate valid access token")
	}

	// Get customer information
	customerID, err := primitive.ObjectIDFromHex(validationResult.Claims.UserID)
	if err != nil {
		s.logger.Error("Failed to parse customer ID from token", map[string]interface{}{
			"error": err.Error(),
		})
		return nil, errors.New("invalid token format")
	}

	customer, err := s.repository.GetByID(ctx, customerID.Hex())
	if err != nil {
		s.logger.Error("Failed to get customer for token refresh", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customerID.Hex(),
		})
		return nil, errors.New("customer not found")
	}

	// Check if customer is still active
	if customer.Status != CustomerStatusActive {
		return nil, errors.New("customer account is inactive")
	}

	companies, err := s.loadCompaniesForCustomer(ctx, customer)
	if err != nil {
		s.logger.Error("Failed to load companies for customer", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customer.ID,
		})
	}

	s.logger.Info("Access token refreshed successfully", map[string]interface{}{
		"customer_id":   customer.ID,
		"customer_type": string(customer.Type),
	})

	return &AuthResponse{
		Customer:     customer.ToResponse(companies),
		AccessToken:  newAccessToken,
		RefreshToken: refreshToken,                            // Return the same refresh token
		ExpiresAt:    time.Now().Add(15 * time.Minute).Unix(), // 15 minutes from now
	}, nil
}

// GetProfile retrieves customer profile information
func (s *customerService) GetProfile(ctx context.Context, customerID string) (*Customer, error) {
	s.logger.Info("Getting customer profile", map[string]interface{}{
		"customer_id": customerID,
	})

	customer, err := s.repository.GetByID(ctx, customerID)
	if err != nil {
		s.logger.Error("Failed to get customer profile", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customerID,
		})
		return nil, errors.New("customer not found")
	}

	s.logger.Info("Customer profile retrieved successfully", map[string]interface{}{
		"customer_id":   customerID,
		"customer_type": string(customer.Type),
	})

	return customer, nil
}

// GetProfileWithCompanies retrieves customer profile information including companies
func (s *customerService) GetProfileWithCompanies(ctx context.Context, customerID string) (*CustomerResponse, error) {
	s.logger.Info("Getting customer profile with companies", map[string]interface{}{
		"customer_id": customerID,
	})

	customer, err := s.repository.GetByID(ctx, customerID)
	if err != nil {
		s.logger.Error("Failed to get customer profile with companies", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customerID,
		})
		return nil, errors.New("customer not found")
	}

	// Load companies for the customer
	companies, err := s.loadCompaniesForCustomer(ctx, customer)
	if err != nil {
		s.logger.Error("Failed to load companies for customer profile", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customer.ID,
		})
		// Continue without companies if loading fails
		companies = []*CompanySummary{}
	}

	customerResponse := customer.ToResponse(companies)

	s.logger.Info("Customer profile retrieved with companies successfully", map[string]interface{}{
		"customer_id":   customerID,
		"customer_type": string(customer.Type),
	})

	return customerResponse, nil
}

// Logout handles customer logout
func (s *customerService) Logout(ctx context.Context, customerID string, accessToken string) error {
	s.logger.Info("Customer logout", map[string]interface{}{
		"customer_id":  customerID,
		"access_token": accessToken[:10] + "...", // Log only first 10 chars for security
	})

	// Invalidate the access token
	err := s.authService.InvalidateToken(accessToken)
	if err != nil {
		s.logger.Error("Failed to invalidate access token", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customerID,
		})
		// Don't return error here as the customer should still be logged out
	}

	s.logger.Info("Customer logout successful", map[string]interface{}{
		"customer_id": customerID,
	})

	return nil
}

// loadCompaniesForCustomer loads company summaries for a customer
func (s *customerService) loadCompaniesForCustomer(ctx context.Context, customer *Customer) ([]*CompanySummary, error) {
	if len(customer.CompanyIDs) == 0 {
		return []*CompanySummary{}, nil
	}

	// Load companies in batch using the new GetCompaniesByIDs method
	companies, err := s.companyService.GetCompaniesByIDs(ctx, customer.CompanyIDs)
	if err != nil {
		s.logger.Error("Failed to load companies for customer", map[string]interface{}{
			"error":       err.Error(),
			"customer_id": customer.ID,
			"company_ids": customer.CompanyIDs,
		})
		return []*CompanySummary{}, err
	}

	// Convert to CompanySummary format
	var companySummaries []*CompanySummary
	for _, company := range companies {
		companySummaries = append(companySummaries, &CompanySummary{
			ID:   company.ID.Hex(),
			Name: company.Name,
		})
	}

	s.logger.Info("Companies loaded for customer", map[string]interface{}{
		"customer_id":     customer.ID,
		"requested_count": len(customer.CompanyIDs),
		"loaded_count":    len(companySummaries),
	})

	return companySummaries, nil
}