from django.shortcuts import render, redirect, get_object_or_404
from django.views.generic import ListView, DetailView
from django.contrib.auth.decorators import login_required
from django.utils.decorators import method_decorator
from django.contrib import messages
from .models import PurchaseOrder, PurchaseOrderItem
from .forms import PurchaseOrderForm

@method_decorator(login_required, name='dispatch')
class PurchaseListView(ListView):
    model = PurchaseOrder
    template_name = 'purchase/purchase_list.html'
    context_object_name = 'purchase_orders'
    paginate_by = 20

@login_required
def purchase_create(request):
    """Create a new purchase order"""
    if request.method == 'POST':
        form = PurchaseOrderForm(request.POST)
        if form.is_valid():
            purchase_order = form.save(commit=False)
            purchase_order.created_by = request.user
            # Generate order number if not provided
            if not purchase_order.order_number:
                # Get the next order number
                last_order = PurchaseOrder.objects.order_by('-id').first()
                if last_order:
                    try:
                        last_number = int(last_order.order_number.split('-')[-1])
                        new_number = last_number + 1
                    except:
                        new_number = 1
                else:
                    new_number = 1
                purchase_order.order_number = f"PO-{new_number:06d}"
            purchase_order.save()
            messages.success(request, f'Purchase order "{purchase_order.order_number}" created successfully!')
            return redirect('purchase:purchase_detail', pk=purchase_order.pk)
    else:
        form = PurchaseOrderForm()
    
    return render(request, 'purchase/purchase_form.html', {'form': form, 'title': 'Create Purchase Order'})

@login_required
def purchase_delete(request, pk):
    """Delete a purchase order"""
    from users.views import is_administrator
    if not is_administrator(request.user):
        messages.error(request, 'You do not have permission to delete purchase orders.')
        return redirect('purchase:purchase_list')
    
    purchase_order = get_object_or_404(PurchaseOrder, pk=pk)
    
    if request.method == 'POST':
        order_number = purchase_order.order_number
        purchase_order.delete()
        messages.success(request, f'Purchase order "{order_number}" deleted successfully!')
        return redirect('purchase:purchase_list')
    
    return render(request, 'purchase/purchase_confirm_delete.html', {'purchase_order': purchase_order})


@method_decorator(login_required, name='dispatch')
class PurchaseDetailView(DetailView):
    model = PurchaseOrder
    template_name = 'purchase/purchase_detail.html'
    context_object_name = 'purchase_order'