import os
import re
from django.conf import settings
from django.http import StreamingHttpResponse, Http404, HttpResponseNotModified, FileResponse
from django.views.static import was_modified_since
from wsgiref.util import FileWrapper

def serve_video_with_range(request, path):
    """
    Serve a media file with HTTP Range support. Required for HTML5 video
    seeking in Chrome/Safari using the Django development server.
    """
    clean_path = path.lstrip('/')
    full_path = os.path.normpath(os.path.join(settings.MEDIA_ROOT, clean_path))
    
    # Security check to prevent directory traversal
    if not full_path.startswith(os.path.normpath(settings.MEDIA_ROOT)):
        raise Http404("Invalid path")
        
    if not os.path.exists(full_path):
        raise Http404(f"File {path} not found")
        
    statobj = os.stat(full_path)
    size = statobj.st_size
    
    # Very simple content type mapping for videos
    content_type = "video/mp4"
    if full_path.endswith('.webm'): content_type = "video/webm"
    elif full_path.endswith('.mkv'): content_type = "video/x-matroska"
    elif full_path.endswith('.svg'): content_type = "image/svg+xml"
    elif full_path.endswith('.png'): content_type = "image/png"
    elif full_path.endswith('.jpg') or full_path.endswith('.jpeg'): content_type = "image/jpeg"

    range_header = request.META.get('HTTP_RANGE', '').strip()
    if range_header.startswith('bytes='):
        range_match = re.match(r'bytes=(\d+)-(\d*)', range_header)
        if range_match:
            first_byte, last_byte = range_match.groups()
            first_byte = int(first_byte)
            last_byte = int(last_byte) if last_byte else size - 1
            if last_byte >= size:
                last_byte = size - 1
            length = last_byte - first_byte + 1

            def file_iterator(file_path, offset=0, bytes_to_read=None):
                with open(file_path, 'rb') as f:
                    f.seek(offset)
                    remaining = bytes_to_read
                    while remaining > 0:
                        chunk_size = min(8192, remaining)
                        data = f.read(chunk_size)
                        if not data:
                            break
                        yield data
                        remaining -= len(data)

            resp = StreamingHttpResponse(
                file_iterator(full_path, offset=first_byte, bytes_to_read=length),
                status=206,
                content_type=content_type
            )
            resp['Content-Range'] = f'bytes {first_byte}-{last_byte}/{size}'
            resp['Content-Length'] = str(length)
            resp['Accept-Ranges'] = 'bytes'
            return resp

    # Fallback to standard 200 FileResponse if no range
    resp = FileResponse(open(full_path, 'rb'), content_type=content_type)
    resp['Content-Length'] = str(size)
    resp['Accept-Ranges'] = 'bytes'
    return resp