adding trx operations and more complex features

delivery/controller/backbone_controller.go

@@ -1,6 +1,7 @@
 package controller
 
 import (
+	"log"
 	"net/http"
 	"users_management/m/middleware"
 	"users_management/m/model/dto/req"
@@ -54,6 +55,7 @@ func (bc *BackboneController) CreateBackbone() gin.HandlerFunc {
 		err := c.ShouldBindJSON(&backboneDTO)
 
 		if err != nil {
+			log.Println("Error binding JSON:", err)
 			common.ErrorResponses(c, http.StatusBadRequest, err.Error())
 			return
 		}
@@ -61,6 +63,7 @@ func (bc *BackboneController) CreateBackbone() gin.HandlerFunc {
 		err = bc.bu.CreateBackbone(backboneDTO)
 
 		if err != nil {
+			log.Println("Error creating backbone:", err)
 			common.ErrorResponses(c, http.StatusBadRequest, err.Error())
 			return
 		}

delivery/controller/device_details.go

@@ -6,7 +6,6 @@ import (
     "users_management/m/model/dto/req"
     "users_management/m/usecase"
     "users_management/m/utils/common"
-
     "github.com/gin-gonic/gin"
     "github.com/google/uuid"
 )

delivery/controller/tower_controller.go

@@ -63,19 +63,23 @@ func (tc *TowerController) CreateTower() gin.HandlerFunc {
         towerCode := c.PostForm("tower_code")
         longitudeStr := c.PostForm("longitude")
         latitudeStr := c.PostForm("latitude")
+        externalTowerStr := c.PostForm("external_tower")
 
         // Validate required fields
-        if deviceIDStr == "" || towerCode == "" || longitudeStr == "" || latitudeStr == "" {
+        if towerCode == "" || longitudeStr == "" || latitudeStr == "" {
             common.ErrorResponses(c, http.StatusBadRequest, "Missing required fields")
             return
         }
 
-        // Parse UUID
+        var deviceID *uuid.UUID
-        deviceID, err := uuid.Parse(deviceIDStr)
+        if deviceIDStr != "" {
+            parsedDeviceID, err := uuid.Parse(deviceIDStr)
             if err != nil {
                 common.ErrorResponses(c, http.StatusBadRequest, "Invalid device ID")
                 return
             }
+            deviceID = &parsedDeviceID
+        }
 
         // Parse coordinates
         longitude, err := strconv.ParseFloat(longitudeStr, 64)
@@ -90,12 +94,23 @@ func (tc *TowerController) CreateTower() gin.HandlerFunc {
             return
         }
 
+        var externalTower *bool
+        if externalTowerStr != "" {
+            parsedExternalTower, err := strconv.ParseBool(externalTowerStr)
+            if err != nil {
+                common.ErrorResponses(c, http.StatusBadRequest, "Invalid external_tower value")
+                return
+            }
+            externalTower = &parsedExternalTower
+        }
+
         // Create DTO
         towerDTO := req.TowerDTO{
             DeviceID:      deviceID,
             TowerCode:     towerCode,
             Longitude:     longitude,
             Latitude:      latitude,
+            ExternalTower: externalTower,
         }
 
         // Get image file (optional)

model/dto/req/tower_dto.go

@@ -3,18 +3,20 @@ package req
 import "github.com/google/uuid"
 
 type TowerDTO struct {
-	DeviceID uuid.UUID `json:"dev_id"`
+    DeviceID      *uuid.UUID `json:"dev_id,omitempty"`
-	DeviceName string `json:"device_name"`
+    DeviceName    *string    `json:"device_name,omitempty"`
-	TowerCode string `json:"tower_code"`
+    TowerCode     string     `json:"tower_code" validate:"required"`
-	Longitude float64 `json:"longitude"`
+    Longitude     float64    `json:"longitude" validate:"required"`
-	Latitude float64 `json:"latitude"`
+    Latitude      float64    `json:"latitude" validate:"required"`
+    ExternalTower *bool      `json:"external_tower,omitempty"` // Make nullable
 }
 
 type UpdateTowerDTO struct {
-    DeviceID  *uuid.UUID  `json:"device_id,omitempty" validate:"omitempty,min=3"` 
+    DeviceID      *uuid.UUID `json:"device_id,omitempty"`
-	DeviceName *string   `json:"device_name,omitempty" validate:"omitempty,min=3"`
+    DeviceName    *string    `json:"device_name,omitempty"`
-    TowerCode *string  `json:"tower_code,omitempty" validate:"omitempty"` 
+    TowerCode     *string    `json:"tower_code,omitempty"`
     Longitude     *float64   `json:"longitude,omitempty" validate:"omitempty,longitude"`
     Latitude      *float64   `json:"latitude,omitempty" validate:"omitempty,latitude"`
-	ImageURL  *string  `json:"image_url,omitempty" validate:"omitempty,url"`
+    ExternalTower *bool      `json:"external_tower,omitempty"` // Make nullable
+    ImageURL      *string    `json:"image_url,omitempty"`
 }

model/dto/res/device_details.go

@@ -35,5 +35,6 @@ type TowerConnectionDetail struct {
     ID        uuid.UUID `json:"id"`
     TowerCode string    `json:"tower_code"`
     Distance  float64   `json:"distance_km"` // Distance from tower to device
+    ExternalTower *bool    `json:"external_tower"` // Indicates if this is an external tower
     ImageURL  *string   `json:"image_url,omitempty"`
 }

model/dto/res/tower_res.go

@@ -2,17 +2,18 @@ package res
 
 import (
     "time"
-
     "github.com/google/uuid"
 )
 
 type TowerResponse struct {
     ID           uuid.UUID  `json:"id"`
-	DeviceCode string `json:"device_code"`
+    DeviceCode   *string    `json:"device_code,omitempty"` // Make nullable
     TowerCode    *string    `json:"tower_code"`
     Longitude    float64    `json:"longitude"`
     Latitude     float64    `json:"latitude"`
     Address      string     `json:"address"`
     ImageURL     string     `json:"image_url"`
+    ExternalTower *bool     `json:"external_tower,omitempty"` // Make nullable
     CreatedAt    time.Time  `json:"created_at"`
+    UpdatedAt    time.Time  `json:"updated_at"`
 }

model/entity/device_port.go

@@ -7,9 +7,11 @@ import (
 
 type DevicePort struct {
     ID            uuid.UUID `json:"id" gorm:"type:uuid;primaryKey"`
-    DeviceID      uuid.UUID `json:"device_id" gorm:"type:uuid;column:device_id;unique"`
+    DeviceID      uuid.UUID `json:"device_id" gorm:"type:uuid;not null"`
-    PortUsed      int       `json:"port_used" gorm:"default:0"`       // Auto-calculated
+    PortUsed      int       `json:"port_used"`
-    PortAvailable int       `json:"port_available" gorm:"default:0"`  // Auto-calculated
+    PortAvailable int       `json:"port_available"`
+    CustomerCount int       `json:"customer_count"` // Add this field
+    CustomerNames []string  `json:"customer_names" gorm:"type:json"` // Store customer names as JSON array
     CreatedAt     time.Time `json:"created_at"`
     UpdatedAt     time.Time `json:"updated_at"`
     

model/entity/devices.go

@@ -12,6 +12,8 @@ const (
     ODP DeviceType = "ODP"
     OTB DeviceType = "OTB"
 
+    Closure DeviceType = "closure"
+    
     ActiveDev      DeviceStatus = "active"
     InactiveDev    DeviceStatus = "inactive"
     MaintenanceDev DeviceStatus = "maintenance"

model/entity/tower.go

@@ -7,15 +7,16 @@ import (
 
 type Tower struct {
     ID           uuid.UUID  `json:"id" gorm:"type:uuid;primaryKey"`
-    DeviceID  uuid.UUID `json:"dev_id" gorm:"type:uuid;column:dev_id"`
+    DeviceID     *uuid.UUID `json:"dev_id,omitempty" gorm:"type:uuid;column:dev_id;null"` // Make nullable
     TowerCode    string     `json:"tower_code" gorm:"unique"`
     Longitude    float64    `json:"longitude"`
     Latitude     float64    `json:"latitude"`
     ImageURL     string     `json:"image_url" gorm:"column:image_url"`
+    ExternalTower *bool     `json:"external_tower,omitempty" gorm:"column:external_tower;null"` // Make nullable and fix typo
     CreatedAt    time.Time  `json:"created_at"`
     UpdatedAt    time.Time  `json:"updated_at"`
 
-    Device    Device    `gorm:"foreignKey:DeviceID"`
+    Device       *Device    `json:"device,omitempty" gorm:"foreignKey:DeviceID"` // Make nullable
 }
 
 func (Tower) TableName() string {

repository/backbone_repo.go

@@ -12,6 +12,7 @@ type BackboneRepo interface {
 	GetAll() ([]entity.Backbone, error)
 	Update(id uuid.UUID, updates map[string]interface{}) error
 	GetByID(id uuid.UUID) (entity.Backbone, error)
+	WithTransaction(fn func(*gorm.DB) error) error
 }
 
 type backboneRepo struct {
@@ -58,3 +59,7 @@ func (r *backboneRepo) GetByID(id uuid.UUID) (entity.Backbone, error) {
 	}
 	return backbone, nil
 }
+
+func (r *backboneRepo) WithTransaction(fn func(*gorm.DB) error) error {
+    return r.db.Transaction(fn)
+}

repository/device_details.go

@@ -2,7 +2,10 @@ package repository
 
 import (
 	"errors"
+	"fmt"
+	"time"
 	"users_management/m/model/entity"
+
 	"github.com/google/uuid"
 	"gorm.io/gorm"
 )
@@ -16,7 +19,7 @@ type DeviceDetailsRepo interface {
     
     // Port management
     UpdateDevicePortUsage(deviceID uuid.UUID) error
-    ValidatePortAvailability(deviceID uuid.UUID, requiredPorts int) error
+    // ValidatePortAvailability(deviceID uuid.UUID, requiredPorts int) error
     
     // Connection management
     GetBackbonesByDeviceID(deviceID uuid.UUID) ([]entity.Backbone, error)
@@ -24,8 +27,9 @@ type DeviceDetailsRepo interface {
     GetTowersByDeviceID(deviceID uuid.UUID) ([]entity.Tower, error)
     
     // Validation helpers
-    CheckDeviceExists(deviceID uuid.UUID) (bool, error)
     GetPortUsageByDevice(deviceID uuid.UUID) (portUsed, portAvailable int, err error)
+    AssignCustomerToPort(deviceID uuid.UUID, customerName string) error
+    RemoveCustomerFromPort(deviceID uuid.UUID, customerName string) error
 }
 
 type deviceDetailsRepo struct {
@@ -80,6 +84,7 @@ func (r *deviceDetailsRepo) GetAll() ([]entity.DeviceDetails, error) {
         Preload("FishbonesEnd.DeviceEnd").
         Preload("FishbonesEnd.Backbone").
         Preload("Towers").
+        Preload("Towers.Device").
         Find(&devices).Error
     return devices, err
 }
@@ -103,6 +108,7 @@ func (r *deviceDetailsRepo) GetByID(id uuid.UUID) (entity.DeviceDetails, error)
         Preload("FishbonesEnd.DeviceEnd").
         Preload("FishbonesEnd.Backbone").
         Preload("Towers").
+        Preload("Towers.Device").
         Where("id = ?", id).
         First(&device).Error
     return device, err
@@ -150,15 +156,19 @@ func (r *deviceDetailsRepo) updatePortAmountCascade(tx *gorm.DB, deviceID uuid.U
 
 func (r *deviceDetailsRepo) UpdateDevicePortUsage(deviceID uuid.UUID) error {
     return r.db.Transaction(func(tx *gorm.DB) error {
-        // Get device info
+        // Lock the device record to prevent race conditions
         var device entity.Device
-        if err := tx.Where("id = ?", deviceID).First(&device).Error; err != nil {
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("id = ?", deviceID).First(&device).Error; err != nil {
             return err
         }
         
         var portUsed int
+        var customerCount int
+        var customerNames []string
         
-        if device.DeviceType == "OTB" {
+        switch device.DeviceType {
+        case "OTB":
             // For OTB: count backbones (each backbone uses 1 port)
             var backboneCount int64
             if err := tx.Model(&entity.Backbone{}).
@@ -167,43 +177,104 @@ func (r *deviceDetailsRepo) UpdateDevicePortUsage(deviceID uuid.UUID) error {
                 return err
             }
             portUsed = int(backboneCount)
-        } else if device.DeviceType == "ODP" {
+            customerCount = 0 // OTB doesn't serve customers directly
-            // For ODP: sum fishbone core amounts (each core uses 1 port)
+            
+        case "closure":
+            // For closure: count fishbones where this device is the start device
+            var fishboneCount int64
+            if err := tx.Model(&entity.Fishbone{}).
+                Where("dev_start_id = ?", deviceID).
+                Count(&fishboneCount).Error; err != nil {
+                return err
+            }
+            portUsed = int(fishboneCount)
+            customerCount = 0 // Closure doesn't serve customers directly
+            
+        case "ODP":
+            // For ODP: sum fishbone core amounts where this device is the end device
             var totalCores int64
             if err := tx.Model(&entity.Fishbone{}).
-                Where("dev_start_id = ? OR dev_end_id = ?", deviceID, deviceID).
+                Where("dev_end_id = ?", deviceID).
                 Select("COALESCE(SUM(core_amount), 0)").
                 Scan(&totalCores).Error; err != nil {
                 return err
             }
             portUsed = int(totalCores)
+            
+            // For ODP: customer count should equal port_used
+            // Get existing customer assignments
+            var existingDevicePort entity.DevicePort
+            if err := tx.Where("device_id = ?", deviceID).First(&existingDevicePort).Error; err == nil {
+                customerNames = existingDevicePort.CustomerNames
             }
             
-        portAvailable := device.PortAmount - portUsed
+            // Ensure customer count matches port_used for ODP
+            customerCount = portUsed
             
-        return tx.Model(&entity.DevicePort{}).
+            // If we have more customers than ports used, trim the list
+            if len(customerNames) > portUsed {
+                customerNames = customerNames[:portUsed]
+            }
+            
+        default:
+            portUsed = 0
+            customerCount = 0
+        }
+        
+        // Calculate port available
+        portAvailable := device.PortAmount - portUsed
+        if portAvailable < 0 {
+            portAvailable = 0
+        }
+
+        // Update or create DevicePort record with locking
+        result := tx.Set("gorm:query_option", "FOR UPDATE").
+            Model(&entity.DevicePort{}).
             Where("device_id = ?", deviceID).
             Updates(map[string]interface{}{
                 "port_used":      portUsed,
                 "port_available": portAvailable,
+                "customer_count": customerCount,
+                "customer_names": customerNames,
                 "updated_at":     gorm.Expr("NOW()"),
-            }).Error
             })
+
+        if result.Error != nil {
+            return result.Error
         }
 
-func (r *deviceDetailsRepo) ValidatePortAvailability(deviceID uuid.UUID, requiredPorts int) error {
+        // If no record was updated, create a new one
-    var devicePort entity.DevicePort
+        if result.RowsAffected == 0 {
-    if err := r.db.Where("device_id = ?", deviceID).First(&devicePort).Error; err != nil {
+            devicePort := entity.DevicePort{
-        return err
+                ID:            uuid.New(),
+                DeviceID:      deviceID,
+                PortUsed:      portUsed,
+                PortAvailable: portAvailable,
+                CustomerCount: customerCount,
+                CustomerNames: customerNames,
+                CreatedAt:     time.Now(),
+                UpdatedAt:     time.Now(),
             }
-    
+            return tx.Create(&devicePort).Error
-    if devicePort.PortAvailable < requiredPorts {
-        return errors.New("insufficient available ports")
         }
 
         return nil
+    })
 }
 
+// func (r *deviceDetailsRepo) ValidatePortAvailability(deviceID uuid.UUID, requiredPorts int) error {
+//     var devicePort entity.DevicePort
+//     if err := r.db.Where("device_id = ?", deviceID).First(&devicePort).Error; err != nil {
+//         return err
+//     }
+    
+//     if devicePort.Portvailable < requiredPorts {
+//         return errors.New("insufficient available ports")
+//     }
+    
+//     return nil
+// }
+
 func (r *deviceDetailsRepo) GetBackbonesByDeviceID(deviceID uuid.UUID) ([]entity.Backbone, error) {
     var backbones []entity.Backbone
     err := r.db.Preload("DeviceStart").Preload("DeviceEnd").
@@ -226,11 +297,7 @@ func (r *deviceDetailsRepo) GetTowersByDeviceID(deviceID uuid.UUID) ([]entity.To
     return towers, err
 }
 
-func (r *deviceDetailsRepo) CheckDeviceExists(deviceID uuid.UUID) (bool, error) {
+
-    var count int64
-    err := r.db.Model(&entity.Device{}).Where("id = ?", deviceID).Count(&count).Error
-    return count > 0, err
-}
 
 func (r *deviceDetailsRepo) GetPortUsageByDevice(deviceID uuid.UUID) (portUsed, portAvailable int, err error) {
     var devicePort entity.DevicePort
@@ -252,3 +319,77 @@ func (r *deviceDetailsRepo) Delete(id uuid.UUID) error {
         return tx.Delete(&entity.Device{}, id).Error
     })
 }
+
+func (r *deviceDetailsRepo) AssignCustomerToPort(deviceID uuid.UUID, customerName string) error {
+    return r.db.Transaction(func(tx *gorm.DB) error {
+        // Lock both device and device_port records
+        var device entity.Device
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("id = ?", deviceID).First(&device).Error; err != nil {
+            return err
+        }
+
+        // Only ODP devices can have customers assigned
+        if device.DeviceType != "ODP" {
+            return fmt.Errorf("customers can only be assigned to ODP devices")
+        }
+
+        var devicePort entity.DevicePort
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("device_id = ?", deviceID).First(&devicePort).Error; err != nil {
+            return fmt.Errorf("device port record not found: %w", err)
+        }
+
+        // Check if there are available ports
+        if devicePort.PortAvailable <= 0 {
+            return fmt.Errorf("no available ports for customer assignment")
+        }
+
+        // Check if customer is already assigned
+        for _, existing := range devicePort.CustomerNames {
+            if existing == customerName {
+                return fmt.Errorf("customer %s is already assigned to this device", customerName)
+            }
+        }
+
+        // Add customer to the list
+        devicePort.CustomerNames = append(devicePort.CustomerNames, customerName)
+        devicePort.CustomerCount = len(devicePort.CustomerNames)
+        devicePort.PortAvailable = devicePort.PortAvailable - 1
+        devicePort.UpdatedAt = time.Now()
+
+        return tx.Save(&devicePort).Error
+    })
+}
+
+func (r *deviceDetailsRepo) RemoveCustomerFromPort(deviceID uuid.UUID, customerName string) error {
+    return r.db.Transaction(func(tx *gorm.DB) error {
+        var devicePort entity.DevicePort
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("device_id = ?", deviceID).First(&devicePort).Error; err != nil {
+            return fmt.Errorf("device port record not found: %w", err)
+        }
+
+        // Find and remove customer
+        newCustomerNames := make([]string, 0)
+        found := false
+        for _, existing := range devicePort.CustomerNames {
+            if existing != customerName {
+                newCustomerNames = append(newCustomerNames, existing)
+            } else {
+                found = true
+            }
+        }
+
+        if !found {
+            return fmt.Errorf("customer %s is not assigned to this device", customerName)
+        }
+
+        devicePort.CustomerNames = newCustomerNames
+        devicePort.CustomerCount = len(devicePort.CustomerNames)
+        devicePort.PortAvailable = devicePort.PortAvailable + 1
+        devicePort.UpdatedAt = time.Now()
+
+        return tx.Save(&devicePort).Error
+    })
+}

repository/devices_repo.go

@@ -1,6 +1,7 @@
 package repository
 
 import (
+	"time"
 	"users_management/m/model/entity"
 
 	"github.com/google/uuid"
@@ -27,13 +28,40 @@ func NewDevicesRepo(db *gorm.DB) DevicesRepo {
 }
 
 func (r *devicesRepo) Post(device entity.Device) error {
-	err := r.db.Create(&device).Error
+    return r.db.Transaction(func(tx *gorm.DB) error {
-	if err != nil {
+        // Create the device first
+        if err := tx.Create(&device).Error; err != nil {
             return err
         }
-	return nil
+
+        // Create the corresponding DevicePort record
+        customerCount := 0
+        customerNames := make([]string, 0)
+        
+        // For ODP devices, initialize customer tracking
+        if device.DeviceType == "ODP" {
+            // Customer count starts at 0, will be updated when fishbones are connected
+            customerCount = 0
         }
 
+        devicePort := entity.DevicePort{
+            ID:            uuid.New(),
+            DeviceID:      device.ID,
+            PortUsed:      0,
+            PortAvailable: device.PortAmount,
+            CustomerCount: customerCount,
+            CustomerNames: customerNames,
+            CreatedAt:     time.Now(),
+            UpdatedAt:     time.Now(),
+        }
+
+        if err := tx.Create(&devicePort).Error; err != nil {
+            return err
+        }
+
+        return nil
+    })
+}
 func (r *devicesRepo) GetAll() ([]entity.Device, error) {
 	var devices []entity.Device
 	err := r.db.Find(&devices).Error

repository/fishbone_repo.go

@@ -23,6 +23,7 @@ type FishboneRepo interface {
     CheckBackboneExists(id uuid.UUID) (bool, error)
     CheckDeviceExists(id uuid.UUID) (bool, error)
     Delete(id uuid.UUID) error
+    WithTransaction(fn func(*gorm.DB) error) error 
 }
 
 type fishboneRepo struct {
@@ -55,6 +56,10 @@ func (r *fishboneRepo) GetAll() ([]entity.Fishbone, error) {
     return fishbones, nil
 }
 
+func (r *fishboneRepo) WithTransaction(fn func(*gorm.DB) error) error {
+    return r.db.Transaction(fn)
+}
+
 func (r *fishboneRepo) Update(id uuid.UUID,updates map[string]interface{}) error {
     err := r.db.Model(&entity.Fishbone{}).Where("id = ?", id).Updates(updates).Error
     if err != nil {

repository/tower_repo.go

@@ -12,6 +12,7 @@ type TowerRepo interface {
 	GetAll() ([]entity.Tower, error)
 	Update(id uuid.UUID,updates map[string]interface{}) error
 	GetByID(id uuid.UUID) (entity.Tower, error)
+    CheckDeviceExists(deviceID uuid.UUID) (bool, error)
 }
 
 type towerRepo struct {
@@ -42,6 +43,11 @@ func (r *towerRepo) GetAll() ([]entity.Tower, error) {
 	return towers, nil
 }
 
+func (r *towerRepo) CheckDeviceExists(deviceID uuid.UUID) (bool, error) {
+    var count int64
+    err := r.db.Model(&entity.Device{}).Where("id = ?", deviceID).Count(&count).Error
+    return count > 0, err
+}
 func (r *towerRepo) Update(id uuid.UUID,updates map[string]interface{}) error {
 	err := r.db.Model(&entity.Tower{}).Where("id = ?", id).Updates(updates).Error
 	if err != nil {

usecase/backbone_usecase.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/go-playground/validator/v10"
 	"github.com/google/uuid"
+	"gorm.io/gorm"
 )
 
 type BackboneUseCase interface {
@@ -44,29 +45,51 @@ func (u *backboneUseCase) CreateBackbone(backbone req.BackboneDTO) error {
         return fmt.Errorf("validation error: %w", err)
     }
 
-    // Validate that both devices exist and are OTB type
+    return u.backboneRepo.WithTransaction(func(tx *gorm.DB) error {
-    startExists, err := u.deviceDetailsRepo.CheckDeviceExists(backbone.DeviceStartID)
+        // Lock device records to prevent race conditions
-    if err != nil {
+        var startDevice entity.Device
-        return fmt.Errorf("error checking start device: %w", err)
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
-    }
+            Where("id = ?", backbone.DeviceStartID).First(&startDevice).Error; err != nil {
-    if !startExists {
+            return fmt.Errorf("start device not found: %w", err)
-        return fmt.Errorf("start device does not exist")
         }
         
-    endExists, err := u.deviceDetailsRepo.CheckDeviceExists(backbone.DeviceEndID)
+        var endDevice entity.Device
-    if err != nil {
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
-        return fmt.Errorf("error checking end device: %w", err)
+            Where("id = ?", backbone.DeviceEndID).First(&endDevice).Error; err != nil {
-    }
+            return fmt.Errorf("end device not found: %w", err)
-    if !endExists {
-        return fmt.Errorf("end device does not exist")
         }
 
-    // Validate port availability (each backbone connection uses 1 port)
+        // Validate device types - both devices must be OTB for backbones
-    if err := u.deviceDetailsRepo.ValidatePortAvailability(backbone.DeviceStartID, 1); err != nil {
+        if startDevice.DeviceType != "OTB" {
-        return fmt.Errorf("start device: %w", err)
+            return fmt.Errorf("start device must be of type OTB, got %s", startDevice.DeviceType)
         }
-    if err := u.deviceDetailsRepo.ValidatePortAvailability(backbone.DeviceEndID, 1); err != nil {
+        
-        return fmt.Errorf("end device: %w", err)
+        if endDevice.DeviceType != "OTB" {
+            return fmt.Errorf("end device must be of type OTB, got %s", endDevice.DeviceType)
+        }
+
+        // Check port availability with locking
+        var startDevicePort entity.DevicePort
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("device_id = ?", backbone.DeviceStartID).First(&startDevicePort).Error; err != nil {
+            return fmt.Errorf("start device port record not found: %w", err)
+        }
+
+        var endDevicePort entity.DevicePort
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("device_id = ?", backbone.DeviceEndID).First(&endDevicePort).Error; err != nil {
+            return fmt.Errorf("end device port record not found: %w", err)
+        }
+
+        // Validate port availability - each backbone uses 1 port regardless of core amount
+        if startDevicePort.PortAvailable < 1 {
+            return fmt.Errorf("start device has no available ports (available: %d, required: 1)", 
+                startDevicePort.PortAvailable)
+        }
+
+        if endDevicePort.PortAvailable < 1 {
+            return fmt.Errorf("end device has no available ports (available: %d, required: 1)", 
+                endDevicePort.PortAvailable)
         }
 
         newBackbone := entity.Backbone{
@@ -80,16 +103,21 @@ func (u *backboneUseCase) CreateBackbone(backbone req.BackboneDTO) error {
         }
 
         // Create backbone
-    err = u.backboneRepo.Post(newBackbone)
+        if err := tx.Create(&newBackbone).Error; err != nil {
-    if err != nil {
             return err
         }
 
         // Update port usage for both devices
-    u.deviceDetailsRepo.UpdateDevicePortUsage(backbone.DeviceStartID)
+        if err := u.updateDevicePortUsageInTx(tx, backbone.DeviceStartID); err != nil {
-    u.deviceDetailsRepo.UpdateDevicePortUsage(backbone.DeviceEndID)
+            return fmt.Errorf("failed to update start device port usage: %w", err)
+        }
+
+        if err := u.updateDevicePortUsageInTx(tx, backbone.DeviceEndID); err != nil {
+            return fmt.Errorf("failed to update end device port usage: %w", err)
+        }
 
         return nil
+    })
 }
 
 
@@ -138,56 +166,51 @@ func (u *backboneUseCase) UpdateBackbone(id uuid.UUID, backbone req.UpdateBackbo
         return fmt.Errorf("validation error: %w", err)
     }
 
-    // Get original backbone to track changes
+    return u.backboneRepo.WithTransaction(func(tx *gorm.DB) error {
-    originalBackbone, err := u.backboneRepo.GetByID(id)
+        // Get original backbone for comparison with lock
-    if err != nil {
+        var originalBackbone entity.Backbone
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("id = ?", id).First(&originalBackbone).Error; err != nil {
+            if err == gorm.ErrRecordNotFound {
+                return fmt.Errorf("backbone not found")
+            }
             return err
         }
 
         updates := make(map[string]interface{})
-
-    // Track devices that need port recalculation
         devicesToUpdate := make(map[uuid.UUID]bool)
         devicesToUpdate[originalBackbone.DeviceStartID] = true
         devicesToUpdate[originalBackbone.DeviceEndID] = true
 
-    if backbone.DeviceStartID != nil {
+        // Validate device type changes if devices are being changed
-        // Validate new start device exists and has available ports
+        if backbone.DeviceStartID != nil && *backbone.DeviceStartID != originalBackbone.DeviceStartID {
-        exists, err := u.deviceDetailsRepo.CheckDeviceExists(*backbone.DeviceStartID)
+            var newStartDevice entity.Device
-        if err != nil {
+            if err := tx.Set("gorm:query_option", "FOR UPDATE").
-            return fmt.Errorf("error checking new start device: %w", err)
+                Where("id = ?", *backbone.DeviceStartID).First(&newStartDevice).Error; err != nil {
+                return fmt.Errorf("new start device not found: %w", err)
             }
-        if !exists {
+            if newStartDevice.DeviceType != "OTB" {
-            return fmt.Errorf("new start device does not exist")
+                return fmt.Errorf("new start device must be of type OTB, got %s", newStartDevice.DeviceType)
             }
-
-        if err := u.deviceDetailsRepo.ValidatePortAvailability(*backbone.DeviceStartID, 1); err != nil {
-            return fmt.Errorf("new start device: %w", err)
-        }
-
             updates["dev_start_id"] = *backbone.DeviceStartID
             devicesToUpdate[*backbone.DeviceStartID] = true
         }
 
-    if backbone.DeviceEndID != nil {
+        if backbone.DeviceEndID != nil && *backbone.DeviceEndID != originalBackbone.DeviceEndID {
-        // Validate new end device exists and has available ports
+            var newEndDevice entity.Device
-        exists, err := u.deviceDetailsRepo.CheckDeviceExists(*backbone.DeviceEndID)
+            if err := tx.Set("gorm:query_option", "FOR UPDATE").
-        if err != nil {
+                Where("id = ?", *backbone.DeviceEndID).First(&newEndDevice).Error; err != nil {
-            return fmt.Errorf("error checking new end device: %w", err)
+                return fmt.Errorf("new end device not found: %w", err)
             }
-        if !exists {
+            if newEndDevice.DeviceType != "OTB" {
-            return fmt.Errorf("new end device does not exist")
+                return fmt.Errorf("new end device must be of type OTB, got %s", newEndDevice.DeviceType)
             }
-
-        if err := u.deviceDetailsRepo.ValidatePortAvailability(*backbone.DeviceEndID, 1); err != nil {
-            return fmt.Errorf("new end device: %w", err)
-        }
-
             updates["dev_end_id"] = *backbone.DeviceEndID
             devicesToUpdate[*backbone.DeviceEndID] = true
         }
 
-    if backbone.CoreAmount != nil {
+        // Handle core amount changes
+        if backbone.CoreAmount != nil && *backbone.CoreAmount != originalBackbone.CoreAmount {
             updates["core_amount"] = *backbone.CoreAmount
         }
 
@@ -198,15 +221,79 @@ func (u *backboneUseCase) UpdateBackbone(id uuid.UUID, backbone req.UpdateBackbo
         updates["updated_at"] = time.Now()
 
         // Update backbone
-    err = u.backboneRepo.Update(id, updates)
+        if err := tx.Model(&entity.Backbone{}).Where("id = ?", id).Updates(updates).Error; err != nil {
-    if err != nil {
             return err
         }
 
-    // Recalculate port usage for all affected devices
+        // Update port usage for all affected devices
         for deviceID := range devicesToUpdate {
-        u.deviceDetailsRepo.UpdateDevicePortUsage(deviceID)
+            if err := u.updateDevicePortUsageInTx(tx, deviceID); err != nil {
+                return fmt.Errorf("failed to update device port usage for device %s: %w", deviceID, err)
+            }
         }
 
         return nil
+    })
+}
+
+func (u *backboneUseCase) updateDevicePortUsageInTx(tx *gorm.DB, deviceID uuid.UUID) error {
+    // Get device with lock
+    var device entity.Device
+    if err := tx.Set("gorm:query_option", "FOR UPDATE").
+        Where("id = ?", deviceID).First(&device).Error; err != nil {
+        return err
+    }
+    
+    var portUsed int
+    var customerCount int
+    
+    switch device.DeviceType {
+    case "OTB":
+        // For OTB: count backbones (each backbone uses 1 port regardless of core amount)
+        var backboneCount int64
+        if err := tx.Model(&entity.Backbone{}).
+            Where("dev_start_id = ? OR dev_end_id = ?", deviceID, deviceID).
+            Count(&backboneCount).Error; err != nil {
+            return err
+        }
+        portUsed = int(backboneCount)
+        customerCount = 0 // OTB doesn't serve customers directly
+        
+    case "closure":
+        // For closure: count fishbones where this device is the start device
+        var fishboneCount int64
+        if err := tx.Model(&entity.Fishbone{}).
+            Where("dev_start_id = ?", deviceID).
+            Count(&fishboneCount).Error; err != nil {
+            return err
+        }
+        portUsed = int(fishboneCount)
+        customerCount = 0 // Closure doesn't serve customers directly
+        
+    case "ODP":
+        // For ODP: sum fishbone core amounts where this device is the end device
+        var totalCores int64
+        if err := tx.Model(&entity.Fishbone{}).
+            Where("dev_end_id = ?", deviceID).
+            Select("COALESCE(SUM(core_amount), 0)").
+            Scan(&totalCores).Error; err != nil {
+            return err
+        }
+        portUsed = int(totalCores)
+        customerCount = portUsed // For ODP, customer count equals port_used
+    }
+    
+    portAvailable := device.PortAmount - portUsed
+    if portAvailable < 0 {
+        portAvailable = 0
+    }
+
+    return tx.Model(&entity.DevicePort{}).
+        Where("device_id = ?", deviceID).
+        Updates(map[string]interface{}{
+            "port_used":      portUsed,
+            "port_available": portAvailable,
+            "customer_count": customerCount,
+            "updated_at":     gorm.Expr("NOW()"),
+        }).Error
 }

usecase/device_details.go

@@ -23,7 +23,7 @@ type DeviceDetailsUseCase interface {
     DeleteDeviceDetails(id uuid.UUID) error
     
     // Port management
-    ValidatePortUsage(deviceID uuid.UUID, requiredPorts int) error
+    // ValidatePortUsage(deviceID uuid.UUID, requiredPorts int) error
     RecalculatePortUsage(deviceID uuid.UUID) error
 }
 
@@ -90,13 +90,6 @@ func (u *deviceDetailsUseCase) UpdateDeviceDetails(id uuid.UUID, deviceDTO req.U
     }
     
     // Check if device exists
-    exists, err := u.deviceDetailsRepo.CheckDeviceExists(id)
-    if err != nil {
-        return err
-    }
-    if !exists {
-        return errors.New("device not found")
-    }
     
     updates := map[string]interface{}{}
     
@@ -177,9 +170,6 @@ func (u *deviceDetailsUseCase) DeleteDeviceDetails(id uuid.UUID) error {
     return u.deviceDetailsRepo.Delete(id)
 }
 
-func (u *deviceDetailsUseCase) ValidatePortUsage(deviceID uuid.UUID, requiredPorts int) error {
-    return u.deviceDetailsRepo.ValidatePortAvailability(deviceID, requiredPorts)
-}
 
 func (u *deviceDetailsUseCase) RecalculatePortUsage(deviceID uuid.UUID) error {
     return u.deviceDetailsRepo.UpdateDevicePortUsage(deviceID)

usecase/device_usecase.go

@@ -58,6 +58,7 @@ func (u *deviceUseCase) CreateDevice(device req.DeviceDTO) error {
         UpdatedAt:  time.Now(),
     }
 	
+
 	return u.deviceRepo.Post(newDevice)
 }
 

usecase/fishbone_usecase.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/go-playground/validator/v10"
 	"github.com/google/uuid"
+	"gorm.io/gorm"
 )
 
 type FishboneUseCase interface {
@@ -47,29 +48,51 @@ func (u *fishboneUseCase) CreateFishbone(fishbone req.FishboneDTO) error {
         return fmt.Errorf("validation error: %w", err)
     }
 
-    // Validate that both devices exist and are ODP type
+    return u.fishboneRepo.WithTransaction(func(tx *gorm.DB) error {
-    startExists, err := u.deviceDetailsRepo.CheckDeviceExists(fishbone.DeviceStartID)
+        // Lock device records to prevent race conditions
-    if err != nil {
+        var startDevice entity.Device
-        return fmt.Errorf("error checking start device: %w", err)
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
-    }
+            Where("id = ?", fishbone.DeviceStartID).First(&startDevice).Error; err != nil {
-    if !startExists {
+            return fmt.Errorf("start device not found: %w", err)
-        return fmt.Errorf("start device does not exist")
         }
         
-    endExists, err := u.deviceDetailsRepo.CheckDeviceExists(fishbone.DeviceEndID)
+        var endDevice entity.Device
-    if err != nil {
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
-        return fmt.Errorf("error checking end device: %w", err)
+            Where("id = ?", fishbone.DeviceEndID).First(&endDevice).Error; err != nil {
-    }
+            return fmt.Errorf("end device not found: %w", err)
-    if !endExists {
-        return fmt.Errorf("end device does not exist")
         }
 
-    // Validate port availability for ODP devices (each core needs 1 port)
+        // Validate device types
-    if err := u.deviceDetailsRepo.ValidatePortAvailability(fishbone.DeviceStartID, fishbone.CoreAmount); err != nil {
+        if startDevice.DeviceType != "closure" {
-        return fmt.Errorf("start device: %w", err)
+            return fmt.Errorf("start device must be of type closure, got %s", startDevice.DeviceType)
         }
-    if err := u.deviceDetailsRepo.ValidatePortAvailability(fishbone.DeviceEndID, fishbone.CoreAmount); err != nil {
+        
-        return fmt.Errorf("end device: %w", err)
+        if endDevice.DeviceType != "ODP" {
+            return fmt.Errorf("end device must be of type ODP, got %s", endDevice.DeviceType)
+        }
+
+        // Check port availability with locking
+        var startDevicePort entity.DevicePort
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("device_id = ?", fishbone.DeviceStartID).First(&startDevicePort).Error; err != nil {
+            return fmt.Errorf("start device port record not found: %w", err)
+        }
+
+        var endDevicePort entity.DevicePort
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("device_id = ?", fishbone.DeviceEndID).First(&endDevicePort).Error; err != nil {
+            return fmt.Errorf("end device port record not found: %w", err)
+        }
+
+        // Validate port availability
+        if startDevicePort.PortAvailable < 1 {
+            return fmt.Errorf("start device has no available ports (available: %d, required: 1)", 
+                startDevicePort.PortAvailable)
+        }
+
+        if endDevicePort.PortAvailable < fishbone.CoreAmount {
+            return fmt.Errorf("end device has insufficient available ports (available: %d, required: %d)", 
+                endDevicePort.PortAvailable, fishbone.CoreAmount)
         }
 
         newFishbone := entity.Fishbone{
@@ -84,16 +107,70 @@ func (u *fishboneUseCase) CreateFishbone(fishbone req.FishboneDTO) error {
         }
 
         // Create fishbone
-    err = u.fishboneRepo.Post(newFishbone)
+        if err := tx.Create(&newFishbone).Error; err != nil {
-    if err != nil {
             return err
         }
 
         // Update port usage for both devices
-    u.deviceDetailsRepo.UpdateDevicePortUsage(fishbone.DeviceStartID)
+        if err := u.updateDevicePortUsageInTx(tx, fishbone.DeviceStartID); err != nil {
-    u.deviceDetailsRepo.UpdateDevicePortUsage(fishbone.DeviceEndID)
+            return fmt.Errorf("failed to update start device port usage: %w", err)
+        }
+
+        if err := u.updateDevicePortUsageInTx(tx, fishbone.DeviceEndID); err != nil {
+            return fmt.Errorf("failed to update end device port usage: %w", err)
+        }
 
         return nil
+    })
+}
+
+func (u *fishboneUseCase) updateDevicePortUsageInTx(tx *gorm.DB, deviceID uuid.UUID) error {
+    // Get device with lock
+    var device entity.Device
+    if err := tx.Set("gorm:query_option", "FOR UPDATE").
+        Where("id = ?", deviceID).First(&device).Error; err != nil {
+        return err
+    }
+    
+    var portUsed int
+    var customerCount int
+    
+    switch device.DeviceType {
+    case "closure":
+        var fishboneCount int64
+        if err := tx.Model(&entity.Fishbone{}).
+            Where("dev_start_id = ?", deviceID).
+            Count(&fishboneCount).Error; err != nil {
+            return err
+        }
+        portUsed = int(fishboneCount)
+        customerCount = 0
+        
+    case "ODP":
+        var totalCores int64
+        if err := tx.Model(&entity.Fishbone{}).
+            Where("dev_end_id = ?", deviceID).
+            Select("COALESCE(SUM(core_amount), 0)").
+            Scan(&totalCores).Error; err != nil {
+            return err
+        }
+        portUsed = int(totalCores)
+        customerCount = portUsed // For ODP, customer count equals port_used
+    }
+    
+    portAvailable := device.PortAmount - portUsed
+    if portAvailable < 0 {
+        portAvailable = 0
+    }
+
+    return tx.Model(&entity.DevicePort{}).
+        Where("device_id = ?", deviceID).
+        Updates(map[string]interface{}{
+            "port_used":      portUsed,
+            "port_available": portAvailable,
+            "customer_count": customerCount,
+            "updated_at":     gorm.Expr("NOW()"),
+        }).Error
 }
 
 func (u *fishboneUseCase) GetAllFishbone() ([]res.FishboneResponse, error) {
@@ -121,80 +198,61 @@ func (u *fishboneUseCase) UpdateFishbone(id uuid.UUID, fishbone req.UpdateFishbo
         return fmt.Errorf("validation error: %w", err)
     }
 
-    // Get original fishbone for comparison
+    return u.fishboneRepo.WithTransaction(func(tx *gorm.DB) error {
-    originalFishbone, err := u.fishboneRepo.GetByID(id)
+        // Get original fishbone for comparison with lock
-    if err != nil {
+        var originalFishbone entity.Fishbone
+        if err := tx.Set("gorm:query_option", "FOR UPDATE").
+            Where("id = ?", id).First(&originalFishbone).Error; err != nil {
+            if err == gorm.ErrRecordNotFound {
+                return fmt.Errorf("fishbone not found")
+            }
             return err
         }
 
         updates := make(map[string]interface{})
-
-    // Track devices that need port recalculation
         devicesToUpdate := make(map[uuid.UUID]bool)
         devicesToUpdate[originalFishbone.DeviceStartID] = true
         devicesToUpdate[originalFishbone.DeviceEndID] = true
 
-    // If core amount is changed, validate port availability
+        // Validate device type changes if devices are being changed
-    if fishbone.CoreAmount != nil && *fishbone.CoreAmount != originalFishbone.CoreAmount {
+        if fishbone.DeviceStartID != nil && *fishbone.DeviceStartID != originalFishbone.DeviceStartID {
-        coreDiff := *fishbone.CoreAmount - originalFishbone.CoreAmount
+            var newStartDevice entity.Device
-        if coreDiff > 0 {
+            if err := tx.Set("gorm:query_option", "FOR UPDATE").
-            // Increasing cores - check port availability
+                Where("id = ?", *fishbone.DeviceStartID).First(&newStartDevice).Error; err != nil {
-            if err := u.deviceDetailsRepo.ValidatePortAvailability(originalFishbone.DeviceStartID, coreDiff); err != nil {
+                return fmt.Errorf("new start device not found: %w", err)
-                return fmt.Errorf("start device: %w", err)
             }
-            if err := u.deviceDetailsRepo.ValidatePortAvailability(originalFishbone.DeviceEndID, coreDiff); err != nil {
+            if newStartDevice.DeviceType != "closure" {
-                return fmt.Errorf("end device: %w", err)
+                return fmt.Errorf("new start device must be of type closure, got %s", newStartDevice.DeviceType)
             }
-        }
-        updates["core_amount"] = *fishbone.CoreAmount
-    }
-
-    if fishbone.DeviceStartID != nil {
-        exists, err := u.deviceDetailsRepo.CheckDeviceExists(*fishbone.DeviceStartID)
-        if err != nil {
-            return fmt.Errorf("error checking new start device: %w", err)
-        }
-        if !exists {
-            return fmt.Errorf("new start device does not exist")
-        }
-
-        coreAmount := originalFishbone.CoreAmount
-        if fishbone.CoreAmount != nil {
-            coreAmount = *fishbone.CoreAmount
-        }
-
-        if err := u.deviceDetailsRepo.ValidatePortAvailability(*fishbone.DeviceStartID, coreAmount); err != nil {
-            return fmt.Errorf("new start device: %w", err)
-        }
-
             updates["dev_start_id"] = *fishbone.DeviceStartID
             devicesToUpdate[*fishbone.DeviceStartID] = true
         }
 
-    if fishbone.DeviceEndID != nil {
+        if fishbone.DeviceEndID != nil && *fishbone.DeviceEndID != originalFishbone.DeviceEndID {
-        exists, err := u.deviceDetailsRepo.CheckDeviceExists(*fishbone.DeviceEndID)
+            var newEndDevice entity.Device
-        if err != nil {
+            if err := tx.Set("gorm:query_option", "FOR UPDATE").
-            return fmt.Errorf("error checking new end device: %w", err)
+                Where("id = ?", *fishbone.DeviceEndID).First(&newEndDevice).Error; err != nil {
+                return fmt.Errorf("new end device not found: %w", err)
             }
-        if !exists {
+            if newEndDevice.DeviceType != "ODP" {
-            return fmt.Errorf("new end device does not exist")
+                return fmt.Errorf("new end device must be of type ODP, got %s", newEndDevice.DeviceType)
             }
-
-        coreAmount := originalFishbone.CoreAmount
-        if fishbone.CoreAmount != nil {
-            coreAmount = *fishbone.CoreAmount
-        }
-
-        if err := u.deviceDetailsRepo.ValidatePortAvailability(*fishbone.DeviceEndID, coreAmount); err != nil {
-            return fmt.Errorf("new end device: %w", err)
-        }
-
             updates["dev_end_id"] = *fishbone.DeviceEndID
             devicesToUpdate[*fishbone.DeviceEndID] = true
         }
 
+        // Handle core amount changes
+        if fishbone.CoreAmount != nil && *fishbone.CoreAmount != originalFishbone.CoreAmount {
+            updates["core_amount"] = *fishbone.CoreAmount
+        }
+
         if fishbone.BackboneID != nil {
-        updates["backbone_id"] = *fishbone.BackboneID
+            // Validate backbone exists
+            var backbone entity.Backbone
+            if err := tx.Where("id = ?", *fishbone.BackboneID).First(&backbone).Error; err != nil {
+                return fmt.Errorf("backbone not found: %w", err)
+            }
+            updates["bb_id"] = *fishbone.BackboneID
         }
 
         if fishbone.FishboneCode != nil {
@@ -208,19 +266,20 @@ func (u *fishboneUseCase) UpdateFishbone(id uuid.UUID, fishbone req.UpdateFishbo
         updates["updated_at"] = time.Now()
 
         // Update fishbone
-    err = u.fishboneRepo.Update(id, updates)
+        if err := tx.Model(&entity.Fishbone{}).Where("id = ?", id).Updates(updates).Error; err != nil {
-    if err != nil {
             return err
         }
 
-    // Recalculate port usage for all affected devices
+        // Update port usage for all affected devices
         for deviceID := range devicesToUpdate {
-        u.deviceDetailsRepo.UpdateDevicePortUsage(deviceID)
+            if err := u.updateDevicePortUsageInTx(tx, deviceID); err != nil {
+                return fmt.Errorf("failed to update device port usage for device %s: %w", deviceID, err)
+            }
         }
 
         return nil
+    })
 }
-
 func (u *fishboneUseCase) DeleteFishbone(id uuid.UUID) error {
     // Check if fishbone exists
     exists, err := u.fishboneRepo.CheckFishboneExists(id)

usecase/tower_usecase.go

@@ -2,6 +2,7 @@ package usecase
 
 import (
 	"errors"
+	"fmt"
 	"mime/multipart"
 	"time"
 	"users_management/m/model/dto/req"
@@ -42,6 +43,22 @@ func (u *towerUsecase) Post(tower req.TowerDTO, imageFile *multipart.FileHeader)
         return err
     }
 
+    // Validate that if it's not an external tower, DeviceID must be provided
+    if tower.ExternalTower != nil && !*tower.ExternalTower && tower.DeviceID == nil {
+        return fmt.Errorf("device_id is required for internal towers")
+    }
+
+    // Validate that if DeviceID is provided, the device exists
+    if tower.DeviceID != nil {
+        deviceExists, err := u.towerRepo.CheckDeviceExists(*tower.DeviceID)
+        if err != nil {
+            return err
+        }
+        if !deviceExists {
+            return fmt.Errorf("device not found")
+        }
+    }
+
     var imageURL string
     if imageFile != nil {
         imageURL, err = helper.SaveTowerImage(imageFile)
@@ -52,11 +69,12 @@ func (u *towerUsecase) Post(tower req.TowerDTO, imageFile *multipart.FileHeader)
 
     newTower := entity.Tower{
         ID:           uuid.New(),
-		DeviceID: tower.DeviceID,
+        DeviceID:     tower.DeviceID,      // Now nullable
         TowerCode:    tower.TowerCode,
         Longitude:    tower.Longitude,
         Latitude:     tower.Latitude,
         ImageURL:     imageURL,
+        ExternalTower: tower.ExternalTower, // Now nullable
         CreatedAt:    time.Now(),
         UpdatedAt:    time.Now(),
     }

utils/helper/device_details.go

@@ -82,16 +82,29 @@ func ConvertToDeviceDetailsResponse(device entity.DeviceDetails, geocoder servic
         fishboneInfos = append(fishboneInfos, info)
     }
     
-    // Convert tower connections
+    // Convert tower connections - safely handle nullable ExternalTower
     towerInfos := make([]res.TowerConnectionDetail, 0)
     for _, tower := range device.Towers {
         distance := calculateDistance(device.Latitude, device.Longitude, tower.Latitude, tower.Longitude)
         
+        // Safely handle nullable ExternalTower field
+        var externalTower *bool
+        if tower.ExternalTower != nil {
+            externalTower = tower.ExternalTower
+        } // If tower.ExternalTower is nil, externalTower remains nil
+        
+        // Safely handle nullable ImageURL
+        var imageURL *string
+        if tower.ImageURL != "" {
+            imageURL = &tower.ImageURL
+        }
+        
         info := res.TowerConnectionDetail{
             ID:           tower.ID,
             TowerCode:    tower.TowerCode,
             Distance:     distance,
-            ImageURL:  &tower.ImageURL,
+            ExternalTower: externalTower, // This will be null if tower.ExternalTower is nil
+            ImageURL:     imageURL,
         }
         towerInfos = append(towerInfos, info)
     }
@@ -122,4 +135,6 @@ func ConvertToDeviceDetailsResponse(device entity.DeviceDetails, geocoder servic
     return response, nil
 }
 
+
+
 // ... rest of helper functions remain the same

utils/helper/towerHelperRes.go

@@ -10,31 +10,34 @@ import (
 func ConvertToTowerResponses(towers []entity.Tower, geocoder service.GeocodingService) ([]res.TowerResponse, error) {
     var responses []res.TowerResponse
     
-	
     for _, tower := range towers {
         var address string
 
         if geocoder != nil {
             generatedAddress, err := geocoder.GetAddressFromCoordinates(tower.Latitude, tower.Longitude)
             if err != nil {
-				// Log specific geocoding error
                 log.Printf("Geocoding error for tower %s: %v", tower.TowerCode, err)
             } else {
                 address = generatedAddress
             }
-		} else {
+        }
-			log.Println("WARNING: Geocoder is nil")
+
+        var deviceCode *string
+        if tower.Device != nil {
+            deviceCode = &tower.Device.DeviceCode
         }
 
         towerResp := res.TowerResponse{
             ID:           tower.ID,
-			DeviceCode: tower.Device.DeviceCode,
+            DeviceCode:   deviceCode,         // Now nullable
             TowerCode:    &tower.TowerCode,
             Longitude:    tower.Longitude,
             Latitude:     tower.Latitude,
             Address:      address,
             ImageURL:     tower.ImageURL,
+            ExternalTower: tower.ExternalTower, // Now nullable
             CreatedAt:    tower.CreatedAt,
+            UpdatedAt:    tower.UpdatedAt,
         }
         responses = append(responses, towerResp)
     }
@@ -47,24 +50,28 @@ func ConvertToTowerIDResponses(tower entity.Tower, geocoder service.GeocodingSer
     if geocoder != nil {
         generatedAddress, err := geocoder.GetAddressFromCoordinates(tower.Latitude, tower.Longitude)
         if err != nil {
-			// Log specific geocoding error
             log.Printf("Geocoding error for tower %s: %v", tower.TowerCode, err)
         } else {
             address = generatedAddress
         }
-	} else {
+    }
-		log.Println("WARNING: Geocoder is nil")
+
+    var deviceCode *string
+    if tower.Device != nil {
+        deviceCode = &tower.Device.DeviceCode
     }
 
     towerResp := res.TowerResponse{
         ID:           tower.ID,
-		DeviceCode: tower.Device.DeviceCode,
+        DeviceCode:   deviceCode,         // Now nullable
         TowerCode:    &tower.TowerCode,
         Longitude:    tower.Longitude,
         Latitude:     tower.Latitude,
         Address:      address,
         ImageURL:     tower.ImageURL,
+        ExternalTower: tower.ExternalTower, // Now nullable
         CreatedAt:    tower.CreatedAt,
+        UpdatedAt:    tower.UpdatedAt,
     }
     return towerResp, nil
 }