__author__ = "Andreas Fritz - sources.e-blue.eu"
__copyright__ = "Copyright (c) " + "28.08.2010" + " Andreas Fritz"
__licence__ = """New BSD Licence"""
__doc__ = """Dynamic donload links with timeout and maximum rate of ckicks.
The content will served by a stream. Path of the file on the system is covered
through the dynamicly generated pathname in the url.py """

import os
import presettings
from django.http import HttpResponse, HttpResponseNotFound
from django.shortcuts import render_to_response
from django.template import RequestContext
import mimetypes
from django.views.decorators.cache import cache_control
from django.utils.translation import ugettext_lazy as _
from models import Download, IsExpiredError


def expired(key):
    expired_objects = Download.objects.filter(active=False)
    # check expired objects
    for obj in expired_objects:
        if key == obj.link_key:
            return obj

def active(key):
    active_objects = Download.objects.filter(active=True)
    # check active objects
    for obj in active_objects:
        if key == obj.link_key:
            return obj

def error(request, text=_(u'Sorry, your request is mot available')):
    """returns the error page"""
    extra_context = {'message': text}
    template = 'dynamicLink/not_avallible.html'
    return render_to_response(template, extra_context, context_instance=RequestContext(request))

def site(request, offset):
    """process site requests"""
    offset = offset.split('-') # turn offset to keylist
    obj = {'actives':[], 'expired':[], 'notexist':[]}
    # Test if keys are valid
    for key in offset:
        if active(key):
            obj['actives'].append(active(key))
        elif expired(key):
            obj['expired'].append(expired(key))
        else:
            obj['notexist'].append(key)
    template = 'dynamicLink/provide.html'
    extra_context = {'basepath': presettings.DYNAMIC_LINK_URL_BASE_COMPONENT, 'downloads':obj}
    return render_to_response(template, extra_context, context_instance=RequestContext(request))

def fetch(request, offset):
    """process link requests. make desissions for every single download link"""
    if active(offset):
        return provide(request, offset)
    elif expired(offset):
        return error(request, presettings.TEXT_REQUEST_IS_EXPIRED)
    else:
        return error(request, presettings.TEXT_REQUEST_DOES_NOT_EXIST)

@cache_control(private=True)
def provide(request, key):
    """
    Return a download without the rael path to the served file. The content will
    served by a stream.

    The file will read in byte code to a socket wich will be used in the response
    object. Headers in the response will set for the specific served content
    referable to its type.
    """
    # Read database
    # This code runs only with python >= 2.6
#    stored_file_obj = Download.objects.get(link_key=key)
#    try:
#        filepath = stored_file_obj.get_path() # model method to validate and deliver path
#    except IsExpiredError as e: # works only with python 2.6 or later (for a solution of older versions see below!)
#        return error(request, e.value)

    # alternate code that also run in older python before 2.6
    stored_file_obj = Download.objects.get(link_key=key)
    try:
        filepath = stored_file_obj.get_path() # model method to validate and deliver path
    except IsExpiredError: # works with pyhton before 2.6
        return error(request)
    
    # make file path suitable for different installations
    delimiter = presettings.DYNAMIC_LINK_MEDIA.strip('/').split('/')[-1]
    # now we use the objects get_paht() method to be sure the object instance keep up to date.
    file_path = os.path.normpath(presettings.DYNAMIC_LINK_MEDIA + '/' + filepath.split(delimiter)[-1])

    # read file as binary
    try:
        fsocket = open(file_path, 'rb') # garbage collector will deal with not closed fsocket
    except IOError:
        stored_file_obj.active = False
        stored_file_obj.save() # only raise the following once
        return HttpResponseNotFound(unicode(_(u'File not found!'))) # admin will get informed by mail

#    # read file as binary
#    try:
#        f = open(file_path, 'rb')
#    except IOError:
#        stored_file_obj.active = False
#        stored_file_obj.save() # only raise the following once
#        return HttpResponseNotFound(unicode(_(u'File not found!'))) # admin will get informed by mail
#    fsocket = f.read()
#    f.close()

    # get file parameters
    file_name = os.path.basename(file_path)
    file_size = os.path.getsize(file_path)

    # specify mimetype and encoding
    auto_mimetype, auto_encoding = mimetypes.guess_type(file_path)
    if not auto_mimetype: # for unknown types use stream
        auto_mimetype = 'application/octet-stream'

    # response object
    response = HttpResponse(fsocket, mimetype=auto_mimetype) # object instance with mimetype and file
    # set headers in the response object
    # a list of headers: http://en.wikipedia.org/wiki/List_of_HTTP_header_fields
    # encode('utf-8') assuming you're running on a server with UTF-8 as the filesystem encoding.
    response['Content-Disposition'] = 'attachment; filename=%s' % file_name.encode('utf-8') # add correct filename
    if auto_encoding and auto_encoding is not 'gzip':
        # set encoding but exclude gzip from encoding headers
        # GZip uses zlib, but on its own zlib produces content that's improperly
        # encoded for a browser seeing 'gzip' as the content encoding.
        response['Content-Encoding'] = auto_encoding
    response['Content-Length'] = file_size # set response file size for the browsers progress bar
    
    return response
