from django.views.generic import TemplateView, View
from django.http import HttpResponse, JsonResponse
from django.shortcuts import get_object_or_404
from django.template.loader import render_to_string
from django.contrib.auth.mixins import LoginRequiredMixin
from django.core.exceptions import ValidationError
from django.db import transaction

from .models import VersionBranch, VersionTag, ChangeSet
from .managers import BranchManager, ChangeTracker, MergeStrategy

class VersionControlPanel(LoginRequiredMixin, TemplateView):
    """Main version control interface"""
    template_name = 'history_tracking/version_control_panel.html'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        branch_manager = BranchManager()
        
        context.update({
            'branches': branch_manager.list_branches(),
            'current_branch': self.request.GET.get('branch'),
        })
        return context

class BranchListView(LoginRequiredMixin, View):
    """HTMX view for branch list"""
    
    def get(self, request):
        branch_manager = BranchManager()
        branches = branch_manager.list_branches()
        
        content = render_to_string(
            'history_tracking/components/branch_list.html',
            {'branches': branches},
            request=request
        )
        return HttpResponse(content)

class HistoryView(LoginRequiredMixin, View):
    """HTMX view for change history"""
    
    def get(self, request):
        branch_name = request.GET.get('branch')
        if not branch_name:
            return HttpResponse("No branch selected")
            
        branch = get_object_or_404(VersionBranch, name=branch_name)
        tracker = ChangeTracker()
        changes = tracker.get_changes(branch)
        
        content = render_to_string(
            'history_tracking/components/history_view.html',
            {'changes': changes},
            request=request
        )
        return HttpResponse(content)

class MergeView(LoginRequiredMixin, View):
    """HTMX view for merge operations"""
    
    def get(self, request):
        source = request.GET.get('source')
        target = request.GET.get('target')
        
        if not (source and target):
            return HttpResponse("Source and target branches required")
            
        content = render_to_string(
            'history_tracking/components/merge_panel.html',
            {
                'source': source,
                'target': target
            },
            request=request
        )
        return HttpResponse(content)
    
    @transaction.atomic
    def post(self, request):
        source_name = request.POST.get('source')
        target_name = request.POST.get('target')
        
        if not (source_name and target_name):
            return JsonResponse({
                'error': 'Source and target branches required'
            }, status=400)
            
        try:
            source = get_object_or_404(VersionBranch, name=source_name)
            target = get_object_or_404(VersionBranch, name=target_name)
            
            branch_manager = BranchManager()
            success, conflicts = branch_manager.merge_branches(
                source=source,
                target=target,
                user=request.user
            )
            
            if success:
                content = render_to_string(
                    'history_tracking/components/merge_success.html',
                    {'source': source, 'target': target},
                    request=request
                )
                return HttpResponse(content)
            else:
                content = render_to_string(
                    'history_tracking/components/merge_conflicts.html',
                    {
                        'source': source,
                        'target': target,
                        'conflicts': conflicts
                    },
                    request=request
                )
                return HttpResponse(content)
                
        except ValidationError as e:
            return JsonResponse({'error': str(e)}, status=400)
        except Exception as e:
            return JsonResponse(
                {'error': 'Merge failed. Please try again.'},
                status=500
            )

class BranchCreateView(LoginRequiredMixin, View):
    """HTMX view for branch creation"""
    
    def get(self, request):
        content = render_to_string(
            'history_tracking/components/branch_create.html',
            request=request
        )
        return HttpResponse(content)
    
    @transaction.atomic
    def post(self, request):
        name = request.POST.get('name')
        parent_name = request.POST.get('parent')
        
        if not name:
            return JsonResponse({'error': 'Branch name required'}, status=400)
            
        try:
            branch_manager = BranchManager()
            parent = None
            if parent_name:
                parent = get_object_or_404(VersionBranch, name=parent_name)
                
            branch = branch_manager.create_branch(
                name=name,
                parent=parent,
                user=request.user
            )
            
            content = render_to_string(
                'history_tracking/components/branch_item.html',
                {'branch': branch},
                request=request
            )
            return HttpResponse(content)
            
        except ValidationError as e:
            return JsonResponse({'error': str(e)}, status=400)
        except Exception as e:
            return JsonResponse(
                {'error': 'Branch creation failed. Please try again.'},
                status=500
            )

class TagCreateView(LoginRequiredMixin, View):
    """HTMX view for version tagging"""
    
    def get(self, request):
        branch_name = request.GET.get('branch')
        if not branch_name:
            return HttpResponse("Branch required")
            
        content = render_to_string(
            'history_tracking/components/tag_create.html',
            {'branch_name': branch_name},
            request=request
        )
        return HttpResponse(content)
    
    @transaction.atomic
    def post(self, request):
        name = request.POST.get('name')
        branch_name = request.POST.get('branch')
        
        if not (name and branch_name):
            return JsonResponse(
                {'error': 'Tag name and branch required'},
                status=400
            )
            
        try:
            branch = get_object_or_404(VersionBranch, name=branch_name)
            
            # Get latest historical record for the branch
            latest_change = ChangeSet.objects.filter(
                branch=branch,
                status='applied'
            ).latest('created_at')
            
            if not latest_change:
                return JsonResponse(
                    {'error': 'No changes to tag'},
                    status=400
                )
                
            tag = VersionTag.objects.create(
                name=name,
                branch=branch,
                historical_record=latest_change.historical_records.latest('history_date'),
                created_by=request.user,
                metadata={
                    'tagged_at': timezone.now().isoformat(),
                    'changeset': latest_change.pk
                }
            )
            
            content = render_to_string(
                'history_tracking/components/tag_item.html',
                {'tag': tag},
                request=request
            )
            return HttpResponse(content)
            
        except ValidationError as e:
            return JsonResponse({'error': str(e)}, status=400)
        except Exception as e:
            return JsonResponse(
                {'error': 'Tag creation failed. Please try again.'},
                status=500
            )