from django.shortcuts import render, get_object_or_404, redirect
from django.contrib.auth.decorators import login_required, user_passes_test
from django.contrib import messages
from django.contrib.auth import get_user_model
from django.views.generic import ListView, DetailView, UpdateView
from django.utils.decorators import method_decorator
from django.urls import reverse_lazy
from .forms import ProfileEditForm, CustomUserCreationForm, CustomUserForm, UserGroupForm
from .models import UserGroup

User = get_user_model()

def is_admin_or_user_manager(user):
    """Check if user is admin or has user management permission"""
    return user.is_superuser or user.has_user_management_permission


def is_administrator(user):
    """Check if user is superuser or has administrator group"""
    if user.is_superuser:
        return True
    if user.group and user.group.name == 'Administrators':
        return True
    return False


@login_required
def profile(request):
    """User profile view"""
    return render(request, 'users/profile.html')

@login_required
def profile_edit(request):
    """Edit user profile"""
    if request.method == 'POST':
        form = ProfileEditForm(request.POST, request.FILES, instance=request.user)
        if form.is_valid():
            form.save()
            messages.success(request, 'Profile updated successfully!')
            return redirect('users:profile')
    else:
        form = ProfileEditForm(instance=request.user)
    
    return render(request, 'users/profile_edit.html', {'form': form})

@method_decorator(login_required, name='dispatch')
@method_decorator(user_passes_test(is_admin_or_user_manager), name='dispatch')
class UserListView(ListView):
    """List all users (admin and user managers only)"""
    model = User
    template_name = 'users/user_list.html'
    context_object_name = 'users'
    paginate_by = 20
    
    def get_queryset(self):
        return User.objects.all().order_by('username')

@method_decorator(login_required, name='dispatch')
@method_decorator(user_passes_test(is_admin_or_user_manager), name='dispatch')
class UserDetailView(DetailView):
    """User detail view (admin and user managers only)"""
    model = User
    template_name = 'users/user_detail.html'
    context_object_name = 'user_obj'

@login_required
@user_passes_test(is_admin_or_user_manager)
def user_create(request):
    """Create a new user"""
    if request.method == 'POST':
        form = CustomUserCreationForm(request.POST)
        if form.is_valid():
            user = form.save()
            messages.success(request, f'User "{user.username}" created successfully!')
            return redirect('users:user_list')
    else:
        form = CustomUserCreationForm()
    
    return render(request, 'users/user_form.html', {'form': form, 'title': 'Create User'})

@login_required
@user_passes_test(is_admin_or_user_manager)
def group_list(request):
    """List all user groups"""
    groups = UserGroup.objects.all().order_by('name')
    return render(request, 'users/group_list.html', {'groups': groups})

@login_required
@user_passes_test(is_admin_or_user_manager)
def group_create(request):
    """Create a new user group"""
    if request.method == 'POST':
        form = UserGroupForm(request.POST)
        if form.is_valid():
            group = form.save()
            messages.success(request, f'Group "{group.name}" created successfully!')
            return redirect('users:group_list')
    else:
        form = UserGroupForm()
    
    return render(request, 'users/group_form.html', {'form': form, 'title': 'Create Group'})

@login_required
@user_passes_test(is_admin_or_user_manager)
def user_edit(request, pk):
    """Edit an existing user"""
    user_obj = get_object_or_404(User, pk=pk)
    if request.method == 'POST':
        form = CustomUserForm(request.POST, instance=user_obj)
        if form.is_valid():
            user = form.save()
            messages.success(request, f'User "{user_obj.username}" updated successfully!')
            return redirect('users:user_list')
    else:
        form = CustomUserForm(instance=user_obj)
    
    return render(request, 'users/user_edit_form.html', {'form': form, 'title': f'Edit User: {user_obj.username}'})


@login_required
@user_passes_test(is_administrator)
def user_delete(request, pk):
    """Delete a user"""
    user_obj = get_object_or_404(User, pk=pk)
    
    # Prevent deletion of superuser by non-superusers
    if user_obj.is_superuser and not request.user.is_superuser:
        messages.error(request, 'Only superusers can delete other superusers.')
        return redirect('users:user_list')
    
    # Prevent self-deletion
    if user_obj.pk == request.user.pk:
        messages.error(request, 'You cannot delete your own account.')
        return redirect('users:user_list')
    
    if request.method == 'POST':
        username = user_obj.username
        user_obj.delete()
        messages.success(request, f'User "{username}" deleted successfully!')
        return redirect('users:user_list')
    
    return render(request, 'users/user_confirm_delete.html', {'user_obj': user_obj})

@login_required
@user_passes_test(is_admin_or_user_manager)
def group_edit(request, pk):
    """Edit an existing user group"""
    group = get_object_or_404(UserGroup, pk=pk)
    if request.method == 'POST':
        form = UserGroupForm(request.POST, instance=group)
        if form.is_valid():
            form.save()
            messages.success(request, f'Group "{group.name}" updated successfully!')
            return redirect('users:group_list')
    else:
        form = UserGroupForm(instance=group)
    
    return render(request, 'users/group_form.html', {'form': form, 'title': f'Edit Group: {group.name}', 'group': group})


@login_required
@user_passes_test(is_admin_or_user_manager)
def group_delete(request, pk):
    """Delete a user group"""
    group = get_object_or_404(UserGroup, pk=pk)
    
    # Check if group has users assigned to it
    if group.users.exists():
        messages.error(request, f'Cannot delete group "{group.name}" because it still has users assigned to it.')
        return redirect('users:group_list')
    
    if request.method == 'POST':
        group_name = group.name
        group.delete()
        messages.success(request, f'Group "{group_name}" deleted successfully!')
        return redirect('users:group_list')
    
    return render(request, 'users/group_confirm_delete.html', {'group': group})


def has_manufacturing_access(user):
    """Check if user has manufacturing access (either admin or manufacturing permission)"""
    if user.is_superuser:
        return True
    if user.group and user.group.name == 'Administrators':
        return True
    if hasattr(user, 'has_manufacturing_permission') and user.has_manufacturing_permission():
        return True
    return False