from django.shortcuts import render, redirect
from django.contrib.auth.decorators import login_required, user_passes_test
from django.contrib import messages
from django.http import JsonResponse
from django.views.generic import TemplateView
from django.db import connection
from django.conf import settings
import sqlite3
import os
import shutil
from datetime import datetime, timedelta
from django.utils import timezone
from django.db.models import Sum, Count, Avg
from decimal import Decimal

from inventory.models import Product, StockMovement
from purchase.models import PurchaseOrder, PurchaseOrderItem
from manufacture.models import ManufacturingOrder
from sales.models import SaleOrder, SaleOrderItem

def is_admin(user):
    return user.is_superuser

class DashboardView(TemplateView):
    template_name = 'core/dashboard.html'
    
    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        
        # Get current date and calculate date ranges
        today = timezone.now().date()
        week_ago = today - timedelta(days=7)
        month_ago = today - timedelta(days=30)
        
        # Production data
        context['daily_production'] = ManufacturingOrder.objects.filter(
            date=today
        ).aggregate(
            total_quantity=Sum('quantity'),
            total_orders=Count('id')
        )
        
        context['weekly_production'] = ManufacturingOrder.objects.filter(
            date__gte=week_ago
        ).aggregate(
            total_quantity=Sum('quantity'),
            total_orders=Count('id')
        )
        
        context['monthly_production'] = ManufacturingOrder.objects.filter(
            date__gte=month_ago
        ).aggregate(
            total_quantity=Sum('quantity'),
            total_orders=Count('id')
        )
        
        # Sales data
        context['daily_sales'] = SaleOrder.objects.filter(
            date=today
        ).aggregate(
            total_amount=Sum('total_amount'),
            total_orders=Count('id')
        )
        
        context['weekly_sales'] = SaleOrder.objects.filter(
            date__gte=week_ago
        ).aggregate(
            total_amount=Sum('total_amount'),
            total_orders=Count('id')
        )
        
        context['monthly_sales'] = SaleOrder.objects.filter(
            date__gte=month_ago
        ).aggregate(
            total_amount=Sum('total_amount'),
            total_orders=Count('id')
        )
        
        # Purchase data
        context['daily_purchases'] = PurchaseOrder.objects.filter(
            date=today
        ).aggregate(
            total_amount=Sum('total_amount'),
            total_orders=Count('id')
        )
        
        context['weekly_purchases'] = PurchaseOrder.objects.filter(
            date__gte=week_ago
        ).aggregate(
            total_amount=Sum('total_amount'),
            total_orders=Count('id')
        )
        
        context['monthly_purchases'] = PurchaseOrder.objects.filter(
            date__gte=month_ago
        ).aggregate(
            total_amount=Sum('total_amount'),
            total_orders=Count('id')
        )
        
        # Inventory turnover (last 30 days)
        context['inventory_turnover'] = StockMovement.objects.filter(
            date__gte=month_ago
        ).aggregate(
            total_movements=Count('id'),
            total_quantity=Sum('quantity')
        )
        
        # Profit/Loss calculation (simplified)
        total_sales = context['monthly_sales']['total_amount'] or Decimal('0')
        total_purchases = context['monthly_purchases']['total_amount'] or Decimal('0')
        context['monthly_profit'] = total_sales - total_purchases
        
        # Recent activities
        context['recent_manufacturing'] = ManufacturingOrder.objects.order_by('-date')[:5]
        context['recent_sales'] = SaleOrder.objects.order_by('-date')[:5]
        context['recent_purchases'] = PurchaseOrder.objects.order_by('-date')[:5]
        
        # Low stock alerts
        context['low_stock_products'] = Product.objects.filter(
            current_stock__lte=10
        )[:5]
        
        return context

class DatabaseManagementView(TemplateView):
    template_name = 'core/database_management.html'
    
    def dispatch(self, request, *args, **kwargs):
        if not is_admin(request.user):
            messages.error(request, 'Access denied. Admin privileges required.')
            return redirect('core:dashboard')
        return super().dispatch(request, *args, **kwargs)

@login_required
@user_passes_test(is_admin)
def backup_database(request):
    if request.method == 'POST':
        try:
            # Create backup directory if it doesn't exist
            backup_dir = os.path.join(settings.BASE_DIR, 'backups')
            os.makedirs(backup_dir, exist_ok=True)
            
            # Generate backup filename with timestamp
            timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
            backup_filename = f'manufacture_app_backup_{timestamp}.sqlite3'
            backup_path = os.path.join(backup_dir, backup_filename)
            
            # Copy the database file
            db_path = os.path.join(settings.BASE_DIR, 'db.sqlite3')
            shutil.copy2(db_path, backup_path)
            
            messages.success(request, f'Database backed up successfully to {backup_filename}')
        except Exception as e:
            messages.error(request, f'Backup failed: {str(e)}')
    
    return redirect('core:database_management')

@login_required
@user_passes_test(is_admin)
def restore_database(request):
    if request.method == 'POST':
        try:
            backup_file = request.FILES.get('backup_file')
            if backup_file:
                # Create backup of current database first
                current_db = os.path.join(settings.BASE_DIR, 'db.sqlite3')
                timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
                safety_backup = os.path.join(settings.BASE_DIR, f'safety_backup_{timestamp}.sqlite3')
                shutil.copy2(current_db, safety_backup)
                
                # Restore from uploaded backup
                with open(current_db, 'wb') as f:
                    for chunk in backup_file.chunks():
                        f.write(chunk)
                
                messages.success(request, 'Database restored successfully. Previous database backed up as safety measure.')
            else:
                messages.error(request, 'No backup file provided.')
        except Exception as e:
            messages.error(request, f'Restore failed: {str(e)}')
    
    return redirect('core:database_management')

@login_required
@user_passes_test(is_admin)
def duplicate_database(request):
    if request.method == 'POST':
        try:
            # Create backup directory if it doesn't exist
            backup_dir = os.path.join(settings.BASE_DIR, 'backups')
            os.makedirs(backup_dir, exist_ok=True)
            
            # Generate duplicate filename with timestamp
            timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
            duplicate_filename = f'manufacture_app_duplicate_{timestamp}.sqlite3'
            duplicate_path = os.path.join(backup_dir, duplicate_filename)
            
            # Copy the database file
            db_path = os.path.join(settings.BASE_DIR, 'db.sqlite3')
            shutil.copy2(db_path, duplicate_path)
            
            messages.success(request, f'Database duplicated successfully to {duplicate_filename}')
        except Exception as e:
            messages.error(request, f'Duplication failed: {str(e)}')
    
    return redirect('core:database_management')