import os, urllib

from django.core.servers.basehttp import FileWrapper
from django.http import HttpResponse

class HttpResponseSendfile(HttpResponse):
    """
    HttpResponse for using X-Sendfile.
  
    Uses FileWrapper as a fallback if the front-end server doesn't intercept
    X-Sendfile headers.
    """
    def __init__(self, path, mimetype=None, content_type=None, fallback=True):
        exists = os.path.exists(path)
        status = 200 if exists else 404
    
        # Fallback for lack of X-Sendfile support
        content = ''
        if exists and fallback:
            content = FileWrapper(open(path, 'rb'))
    
        # Common elements
        super(HttpResponseSendfile, self).__init__(content, mimetype, status, content_type)
        self['Content-Length'] = os.path.getsize(path) if exists else 0
        filename = urllib.quote(os.path.basename(path).encode('utf8'))
        self['Content-Disposition'] = 'attachment; filename="%s"' % filename
    
        # X-Sendfile
        self['X-Sendfile'] = path