from django.db import models from django.contrib.auth import get_user_model from django.utils import timezone from decimal import Decimal from hr.models import Employee, Department import uuid User = get_user_model() class ExpenseCategory(models.Model): name = models.CharField(max_length=100, unique=True) description = models.TextField(blank=True) is_active = models.BooleanField(default=True) created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) def __str__(self): return self.name class Meta: ordering = ['name'] verbose_name_plural = "Expense Categories" class BudgetAllocation(models.Model): ALLOCATION_PERIOD_CHOICES = [ ('monthly', 'Monthly'), ('quarterly', 'Quarterly'), ('yearly', 'Yearly'), ] employee = models.ForeignKey(Employee, on_delete=models.CASCADE, related_name='budget_allocations') category = models.ForeignKey(ExpenseCategory, on_delete=models.CASCADE, related_name='allocations') allocated_amount = models.DecimalField(max_digits=12, decimal_places=2) spent_amount = models.DecimalField(max_digits=12, decimal_places=2, default=Decimal('0.00')) allocation_period = models.CharField(max_length=20, choices=ALLOCATION_PERIOD_CHOICES, default='monthly') start_date = models.DateField() end_date = models.DateField() notes = models.TextField(blank=True) is_active = models.BooleanField(default=True) created_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, related_name='created_allocations') created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) @property def remaining_amount(self): return self.allocated_amount - self.spent_amount @property def utilization_percentage(self): if self.allocated_amount > 0: return (self.spent_amount / self.allocated_amount) * 100 return 0 def __str__(self): return f"{self.employee.full_name} - {self.category.name}: KSh {self.allocated_amount}" class Meta: ordering = ['-created_at'] unique_together = ['employee', 'category', 'start_date', 'end_date'] class Expense(models.Model): STATUS_CHOICES = [ ('pending', 'Pending Approval'), ('approved', 'Approved'), ('rejected', 'Rejected'), ('paid', 'Paid'), ] expense_number = models.CharField(max_length=50, unique=True, editable=False) employee = models.ForeignKey(Employee, on_delete=models.CASCADE, related_name='expenses') category = models.ForeignKey(ExpenseCategory, on_delete=models.CASCADE, related_name='expenses') budget_allocation = models.ForeignKey(BudgetAllocation, on_delete=models.SET_NULL, null=True, blank=True) # Link to payslip for salary/bonus expenses related_payslip = models.ForeignKey('hr.Payslip', on_delete=models.SET_NULL, null=True, blank=True, related_name='expenses') # Expense Details title = models.CharField(max_length=200, help_text="Brief description of the expense") description = models.TextField(help_text="Detailed description of what this expense is for") amount = models.DecimalField(max_digits=12, decimal_places=2) expense_date = models.DateField(default=timezone.now) # Vendor/Supplier Information vendor_name = models.CharField(max_length=200, blank=True, help_text="Name of vendor/supplier") vendor_contact = models.CharField(max_length=100, blank=True, help_text="Vendor contact info") # Approval Workflow status = models.CharField(max_length=20, choices=STATUS_CHOICES, default='pending') submitted_at = models.DateTimeField(auto_now_add=True) approved_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, related_name='approved_expenses') approved_at = models.DateTimeField(null=True, blank=True) rejected_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, blank=True, related_name='rejected_expenses') rejected_at = models.DateTimeField(null=True, blank=True) rejection_reason = models.TextField(blank=True) # Payment Information paid_at = models.DateTimeField(null=True, blank=True) payment_method = models.CharField(max_length=50, blank=True) payment_reference = models.CharField(max_length=100, blank=True) # Additional Information notes = models.TextField(blank=True) is_reimbursable = models.BooleanField(default=True, help_text="Should this expense be reimbursed to the employee?") created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) def save(self, *args, **kwargs): if not self.expense_number: # Generate unique expense number year_month = timezone.now().strftime('%Y%m') last_expense = Expense.objects.filter( expense_number__startswith=f'EXP{year_month}' ).order_by('-expense_number').first() if last_expense: last_number = int(last_expense.expense_number[-4:]) new_number = last_number + 1 else: new_number = 1 self.expense_number = f"EXP{year_month}{new_number:04d}" super().save(*args, **kwargs) # Update budget allocation spent amount if self.budget_allocation and self.status in ['approved', 'paid']: total_spent = Expense.objects.filter( budget_allocation=self.budget_allocation, status__in=['approved', 'paid'] ).aggregate(total=models.Sum('amount'))['total'] or Decimal('0.00') self.budget_allocation.spent_amount = total_spent self.budget_allocation.save() def __str__(self): return f"{self.expense_number} - {self.title}" class Meta: ordering = ['-submitted_at'] class ExpenseAttachment(models.Model): ATTACHMENT_TYPE_CHOICES = [ ('receipt', 'Receipt'), ('invoice', 'Invoice'), ('photo', 'Photo'), ('document', 'Document'), ('other', 'Other'), ] expense = models.ForeignKey(Expense, on_delete=models.CASCADE, related_name='attachments') attachment_type = models.CharField(max_length=20, choices=ATTACHMENT_TYPE_CHOICES, default='receipt') title = models.CharField(max_length=200, help_text="Description of the attachment") file = models.FileField(upload_to='expenses/attachments/') uploaded_at = models.DateTimeField(auto_now_add=True) file_size = models.PositiveIntegerField(help_text="File size in bytes", editable=False) def save(self, *args, **kwargs): if self.file: self.file_size = self.file.size super().save(*args, **kwargs) @property def file_size_formatted(self): """Return file size in human readable format""" if self.file_size: size = self.file_size for unit in ['B', 'KB', 'MB', 'GB']: if size < 1024: return f"{size:.1f} {unit}" size /= 1024 return f"{size:.1f} TB" return "Unknown" def __str__(self): return f"{self.expense.expense_number} - {self.title}" class Meta: ordering = ['-uploaded_at'] class ExpenseApprovalLog(models.Model): ACTION_CHOICES = [ ('submitted', 'Submitted'), ('approved', 'Approved'), ('rejected', 'Rejected'), ('paid', 'Marked as Paid'), ('modified', 'Modified'), ] expense = models.ForeignKey(Expense, on_delete=models.CASCADE, related_name='approval_logs') action = models.CharField(max_length=20, choices=ACTION_CHOICES) performed_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True) comments = models.TextField(blank=True) timestamp = models.DateTimeField(auto_now_add=True) def __str__(self): return f"{self.expense.expense_number} - {self.get_action_display()}" class Meta: ordering = ['-timestamp']