import difflib
from rest_framework.decorators import permission_classes
from adrf.views import APIView
from rest_framework.response import Response
from rest_framework import status
from rest_framework.permissions import AllowAny


@permission_classes([AllowAny])
class TextDiffView(APIView):
    def post(self, request):
        text_a = request.data.get('text_a')
        text_b = request.data.get('text_b')

        if text_a is None or text_b is None:
            return Response(
                {'error': 'text_a and text_b are required'},
                status=status.HTTP_400_BAD_REQUEST,
            )

        lines_a = text_a.splitlines()
        lines_b = text_b.splitlines()

        diff_result = list(difflib.ndiff(lines_a, lines_b))

        diff_lines = []
        line_a = 0
        line_b = 0
        added_count = 0
        removed_count = 0
        unchanged_count = 0

        for line in diff_result:
            if line.startswith('? '):
                continue
            elif line.startswith('+ '):
                line_b += 1
                added_count += 1
                diff_lines.append({
                    'line_number_a': None,
                    'line_number_b': line_b,
                    'type': 'added',
                    'content': line[2:],
                })
            elif line.startswith('- '):
                line_a += 1
                removed_count += 1
                diff_lines.append({
                    'line_number_a': line_a,
                    'line_number_b': None,
                    'type': 'removed',
                    'content': line[2:],
                })
            elif line.startswith('  '):
                line_a += 1
                line_b += 1
                unchanged_count += 1
                diff_lines.append({
                    'line_number_a': line_a,
                    'line_number_b': line_b,
                    'type': 'unchanged',
                    'content': line[2:],
                })

        stats = {
            'added_count': added_count,
            'removed_count': removed_count,
            'unchanged_count': unchanged_count,
            'total_lines': len(diff_lines),
        }

        return Response(
            {
                'diff_lines': diff_lines,
                'stats': stats,
                'text_a_lines': len(lines_a),
                'text_b_lines': len(lines_b),
            },
            status=status.HTTP_200_OK,
        )