# -*- coding: utf-8 -*-

"""Provide a convienience method to serve a static file from an
  asset specification::
  
      # E.g. in a view callable
      return request.serve_spec('mypkg:foo/bar.js')
      
"""

import logging
logger = logging.getLogger(__name__)

import mimetypes
import requests as requests_lib
from cStringIO import StringIO

from pyramid.httpexceptions import HTTPNotFound
from pyramid.response import FileIter
from pyramid.response import Response

def get_serve_spec(request, requests=None, buf_cls=None, iter_cls=None,
        response_cls=None, not_found=None):
    """Return a function that serves an asset specification as a static file."""
    
    # Compose.
    if requests is None:
        requests = requests_lib
    if buf_cls is None:
        buf_cls = StringIO
    if iter_cls is None:
        iter_cls = FileIter
    if response_cls is None:
        response_cls = Response
    if not_found is None:
        not_found = HTTPNotFound
    
    # Prepare.
    not_found_msg = u'The static file could not be found.'
    err_message = u'There was a problem downloading the file. Try again later.'
    
    # Return the serving function.
    def serve(spec):
        """Resolve the asset ``spec`` to a file path and return a static
          file response that serves it. If the file isn't found, return
          a 404.
        """
        
        # Resolve the spec to a url.
        url = request.static_url(spec)
        if url.startswith('//'):
            url = 'https:' + url
        
        # Download the url.
        r = requests.get(url)
        if r.status_code != requests.codes.ok:
            msg = not_found_msg if r.status_code == 404 else err_message
            return not_found(explanation=msg)
        
        # Return the file response.
        filename = spec.split('/')[-1]
        disposition = 'attachment; filename="{0}"'.format(filename)
        mime_type = mimetypes.guess_type(filename)[0] or 'application/octet-stream'
        response = Response(content_type=mime_type)
        response.headers['Content-Disposition'] = disposition
        response.body = r.content
        return response
    
    
    return serve

