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 django.http import JsonResponse
from .models import ManufacturingOrder, BillOfMaterials
from inventory.models import Product
from .forms import ManufacturingOrderForm, BillOfMaterialsForm, MultipleBillOfMaterialsForm, BOMComponentFormSet
from users.views import has_manufacturing_access

@method_decorator(login_required, name='dispatch')
class ManufactureListView(ListView):
    model = ManufacturingOrder
    template_name = 'manufacture/manufacture_list.html'
    context_object_name = 'manufacturing_orders'
    paginate_by = 20


@method_decorator(login_required, name='dispatch')
class BillOfMaterialsListView(ListView):
    model = BillOfMaterials
    template_name = 'manufacture/bom_list.html'
    context_object_name = 'boms'
    paginate_by = 20
    
    def get_queryset(self):
        queryset = super().get_queryset()
        # Optionally filter by manufactured product
        product_id = self.request.GET.get('product_id')
        if product_id:
            queryset = queryset.filter(manufactured_product_id=product_id)
        return queryset


@login_required
def manufacture_create(request):
    """Create a new manufacturing order with simple input"""
    if request.method == 'POST':
        form = ManufacturingOrderForm(request.POST)
        if form.is_valid():
            manufacturing_order = form.save(commit=False)
            manufacturing_order.created_by = request.user
            # Generate order number if not provided
            if not manufacturing_order.order_number:
                # Get the next order number
                last_order = ManufacturingOrder.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
                manufacturing_order.order_number = f"MO-{new_number:06d}"
            
            # Set status to completed by default for simplicity
            manufacturing_order.status = 'completed'
            manufacturing_order.save()
            
            messages.success(request, f'Manufacturing order "{manufacturing_order.order_number}" created successfully!')
            return redirect('manufacture:manufacture_detail', pk=manufacturing_order.pk)
    else:
        form = ManufacturingOrderForm()
    
    return render(request, 'manufacture/manufacture_form.html', {'form': form, 'title': 'Create Manufacturing Order'})


@login_required
def manufacture_edit(request, pk):
    """Edit an existing manufacturing order"""
    if not has_manufacturing_access(request.user):
        messages.error(request, 'You do not have permission to edit manufacturing orders.')
        return redirect('manufacture:manufacture_detail', pk=pk)
    
    manufacturing_order = get_object_or_404(ManufacturingOrder, pk=pk)
    
    if request.method == 'POST':
        form = ManufacturingOrderForm(request.POST, instance=manufacturing_order)
        if form.is_valid():
            form.save()
            messages.success(request, f'Manufacturing order "{manufacturing_order.order_number}" updated successfully!')
            return redirect('manufacture:manufacture_detail', pk=manufacturing_order.pk)
    else:
        form = ManufacturingOrderForm(instance=manufacturing_order)
    
    return render(request, 'manufacture/manufacture_form.html', {
        'form': form,
        'title': 'Edit Manufacturing Order',
        'manufacturing_order': manufacturing_order
    })


@login_required
def manufacture_delete(request, pk):
    """Delete a manufacturing order"""
    if not has_manufacturing_access(request.user):
        messages.error(request, 'You do not have permission to delete manufacturing orders.')
        return redirect('manufacture:manufacture_list')
    
    manufacturing_order = get_object_or_404(ManufacturingOrder, pk=pk)
    
    if request.method == 'POST':
        order_number = manufacturing_order.order_number
        manufacturing_order.delete()
        messages.success(request, f'Manufacturing order "{order_number}" deleted successfully!')
        return redirect('manufacture:manufacture_list')
    
    return render(request, 'manufacture/manufacture_confirm_delete.html', {'manufacturing_order': manufacturing_order})


@login_required
def bom_create(request):
    """Create a new bill of materials entry"""
    if not has_manufacturing_access(request.user):
        messages.error(request, 'You do not have permission to create bill of materials entries.')
        return redirect('manufacture:bom_list')
        
    if request.method == 'POST':
        main_form = MultipleBillOfMaterialsForm(request.POST)
        component_formset = BOMComponentFormSet(request.POST)
        
        if main_form.is_valid() and component_formset.is_valid():
            manufactured_product = main_form.cleaned_data['manufactured_product']
            
            # Save all component entries
            saved_components = []
            for component_form in component_formset:
                # Skip empty forms
                if not component_form.cleaned_data:
                    continue
                    
                component = component_form.cleaned_data['component']
                quantity = component_form.cleaned_data['quantity']
                unit = component_form.cleaned_data['unit']
                
                # Create BOM entry
                bom = BillOfMaterials(
                    manufactured_product=manufactured_product,
                    component=component,
                    quantity=quantity,
                    unit=unit
                )
                bom.save()
                saved_components.append(bom)
            
            messages.success(request, f'Bill of Materials for "{manufactured_product.name}" with {len(saved_components)} components created successfully!')
            return redirect('manufacture:bom_list')
    else:
        main_form = MultipleBillOfMaterialsForm()
        component_formset = BOMComponentFormSet()
    
    return render(request, 'manufacture/bom_form.html', {
        'main_form': main_form,
        'component_formset': component_formset,
        'title': 'Create Bill of Materials'
    })


@login_required
def bom_edit(request, pk):
    """Edit an existing bill of materials entry"""
    if not has_manufacturing_access(request.user):
        messages.error(request, 'You do not have permission to edit bill of materials.')
        return redirect('manufacture:bom_list')
    
    # Get the BOM entry to edit
    bom = get_object_or_404(BillOfMaterials, pk=pk)
    
    if request.method == 'POST':
        main_form = MultipleBillOfMaterialsForm(request.POST)
        component_formset = BOMComponentFormSet(request.POST)
        
        if main_form.is_valid() and component_formset.is_valid():
            manufactured_product = main_form.cleaned_data['manufactured_product']
            
            # Delete existing BOM entries for this manufactured product
            BillOfMaterials.objects.filter(manufactured_product=manufactured_product).delete()
            
            # Save all component entries
            saved_components = []
            for component_form in component_formset:
                # Skip empty forms
                if not component_form.cleaned_data:
                    continue
                    
                component = component_form.cleaned_data['component']
                quantity = component_form.cleaned_data['quantity']
                unit = component_form.cleaned_data['unit']
                
                # Create BOM entry
                bom_entry = BillOfMaterials(
                    manufactured_product=manufactured_product,
                    component=component,
                    quantity=quantity,
                    unit=unit
                )
                bom_entry.save()
                saved_components.append(bom_entry)
            
            messages.success(request, f'Bill of Materials for "{manufactured_product.name}" with {len(saved_components)} components updated successfully!')
            return redirect('manufacture:bom_list')
    else:
        # Pre-populate the form with existing components
        main_form = MultipleBillOfMaterialsForm(initial={'manufactured_product': bom.manufactured_product})
        
        # Get all existing components for this manufactured product
        existing_components = BillOfMaterials.objects.filter(manufactured_product=bom.manufactured_product)
        
        # Create initial data for the formset
        initial_data = []
        for existing_bom in existing_components:
            initial_data.append({
                'component': existing_bom.component,
                'quantity': existing_bom.quantity,
                'unit': existing_bom.unit
            })
        
        # Add extra empty forms if needed
        while len(initial_data) < 1:
            initial_data.append({})
        
        component_formset = BOMComponentFormSet(initial=initial_data)
    
    return render(request, 'manufacture/bom_form.html', {
        'main_form': main_form,
        'component_formset': component_formset,
        'title': 'Edit Bill of Materials',
        'bom': bom
    })


@login_required
def bom_delete(request, pk):
    """Delete a bill of materials entry"""
    if not has_manufacturing_access(request.user):
        messages.error(request, 'You do not have permission to delete bill of materials entries.')
        return redirect('manufacture:bom_list')
    
    bom = get_object_or_404(BillOfMaterials, pk=pk)
    
    if request.method == 'POST':
        manufactured_product_name = bom.manufactured_product.name
        bom.delete()
        messages.success(request, f'Bill of Materials entry for "{manufactured_product_name}" deleted successfully!')
        return redirect('manufacture:bom_list')
    
    return render(request, 'manufacture/bom_confirm_delete.html', {'bom': bom})


@method_decorator(login_required, name='dispatch')
class ManufactureDetailView(DetailView):
    model = ManufacturingOrder
    template_name = 'manufacture/manufacture_detail.html'
    context_object_name = 'manufacturing_order'


@method_decorator(login_required, name='dispatch')
class BillOfMaterialsDetailView(DetailView):
    model = BillOfMaterials
    template_name = 'manufacture/bom_detail.html'
    context_object_name = 'bom'

@login_required
def get_product_info(request, product_id):
    """Return product information including unit as JSON"""
    if not has_manufacturing_access(request.user):
        return JsonResponse({'error': 'Permission denied'}, status=403)
    
    try:
        product = Product.objects.get(id=product_id)
        return JsonResponse({
            'id': product.id,
            'name': product.name,
            'unit': product.unit,
            'unit_display': product.get_unit_display()
        })
    except Product.DoesNotExist:
        return JsonResponse({'error': 'Product not found'}, status=404)