"""
django-helpdesk - A Django powered ticket tracker for small enterprise.

(c) Copyright 2008 Jutda. All Rights Reserved. See LICENSE for details.

lib.py - Common functions (eg multipart e-mail)
"""

import logging

try:
    from base64 import urlsafe_b64encode as b64encode
except ImportError:
    from base64 import encodestring as b64encode
try:
    from base64 import urlsafe_b64decode as b64decode
except ImportError:
    from base64 import decodestring as b64decode

from django.utils.encoding import smart_str
from django.db.models import Q
from django.utils.safestring import mark_safe

logger = logging.getLogger('helpdesk')


def send_templated_mail(template_name,
                        email_context,
                        recipients,
                        sender=None,
                        bcc=None,
                        fail_silently=False,
                        files=None):
    """
    send_templated_mail() is a warpper around Django's e-mail routines that
    allows us to easily send multipart (text/plain & text/html) e-mails using
    templates that are stored in the database. This lets the admin provide
    both a text and a HTML template for each message.

    template_name is the slug of the template to use for this message (see
        models.EmailTemplate)

    email_context is a dictionary to be used when rendering the template

    recipients can be either a string, eg 'a@b.com', or a list of strings.

    sender should contain a string, eg 'My Site <me@z.com>'. If you leave it
        blank, it'll use settings.DEFAULT_FROM_EMAIL as a fallback.

    bcc is an optional list of addresses that will receive this message as a
        blind carbon copy.

    fail_silently is passed to Django's mail routine. Set to 'True' to ignore
        any errors at send time.

    files can be a list of tuple. Each tuple should be a filename to attach,
        along with the File objects to be read. files can be blank.

    """
    from django import VERSION
    from django.conf import settings
    from django.core.mail import EmailMultiAlternatives
    from django.template import loader, Context

    from helpdesk.models import EmailTemplate
    from helpdesk.settings import HELPDESK_EMAIL_SUBJECT_TEMPLATE, \
        HELPDESK_EMAIL_FALLBACK_LOCALE
    import os

    # RemovedInDjango110Warning: render() must be called with a dict, not a Context.
    if VERSION >= (1, 8):
        context = email_context
    else:
        context = Context(email_context)

    if hasattr(context['queue'], 'locale'):
        locale = getattr(context['queue'], 'locale', '')
    else:
        locale = context['queue'].get('locale', HELPDESK_EMAIL_FALLBACK_LOCALE)
    if not locale:
        locale = HELPDESK_EMAIL_FALLBACK_LOCALE

    t = None
    try:
        t = EmailTemplate.objects.get(template_name__iexact=template_name, locale=locale)
    except EmailTemplate.DoesNotExist:
        pass

    if not t:
        try:
            t = EmailTemplate.objects.get(template_name__iexact=template_name, locale__isnull=True)
        except EmailTemplate.DoesNotExist:
            logger.warning('template "%s" does not exist, no mail sent',
                           template_name)
            return  # just ignore if template doesn't exist

    if not sender:
        sender = settings.DEFAULT_FROM_EMAIL

    footer_file = os.path.join('helpdesk', locale, 'email_text_footer.txt')

    # get_template_from_string was removed in Django 1.8
    # http://django.readthedocs.org/en/1.8.x/ref/templates/upgrading.html
    try:
        from django.template import engines
        template_func = engines['django'].from_string
    except ImportError:  # occurs in django < 1.8
        template_func = loader.get_template_from_string

    text_part = template_func(
        "%s{%% include '%s' %%}" % (t.plain_text, footer_file)
    ).render(context)

    email_html_base_file = os.path.join('helpdesk', locale, 'email_html_base.html')

    # keep new lines in html emails
    if 'comment' in context:
        html_txt = context['comment']
        html_txt = html_txt.replace('\r\n', '<br>')
        context['comment'] = mark_safe(html_txt)

    # get_template_from_string was removed in Django 1.8
    # http://django.readthedocs.org/en/1.8.x/ref/templates/upgrading.html
    html_part = template_func(
        "{%% extends '%s' %%}{%% block title %%}"
        "%s"
        "{%% endblock %%}{%% block content %%}%s{%% endblock %%}" %
        (email_html_base_file, t.heading, t.html)).render(context)

    # get_template_from_string was removed in Django 1.8
    # http://django.readthedocs.org/en/1.8.x/ref/templates/upgrading.html
    subject_part = template_func(
        HELPDESK_EMAIL_SUBJECT_TEMPLATE % {
            "subject": t.subject,
        }).render(context)

    if isinstance(recipients, str):
        if recipients.find(','):
            recipients = recipients.split(',')
    elif type(recipients) != list:
        recipients = [recipients, ]

    msg = EmailMultiAlternatives(
        subject_part.replace('\n', '').replace('\r', ''),
        text_part, sender, recipients, bcc=bcc)
    msg.attach_alternative(html_part, "text/html")

    if files:
        for attachment in files:
            file_to_attach = attachment[1]
            file_to_attach.open()
            msg.attach(filename=attachment[0], content=file_to_attach.read())
            file_to_attach.close()

    return msg.send(fail_silently)


def query_to_dict(results, descriptions):
    """
    Replacement method for cursor.dictfetchall() as that method no longer
    exists in psycopg2, and I'm guessing in other backends too.

    Converts the results of a raw SQL query into a list of dictionaries, suitable
    for use in templates etc.
    """

    output = []
    for data in results:
        row = {}
        i = 0
        for column in descriptions:
            row[column[0]] = data[i]
            i += 1

        output.append(row)
    return output


def apply_query(queryset, params):
    """
    Apply a dict-based set of filters & parameters to a queryset.

    queryset is a Django queryset, eg MyModel.objects.all() or
             MyModel.objects.filter(user=request.user)

    params is a dictionary that contains the following:
        filtering: A dict of Django ORM filters, eg:
            {'user__id__in': [1, 3, 103], 'title__contains': 'foo'}

        search_string: A freetext search string

        sorting: The name of the column to sort by
    """
    for key in params['filtering'].keys():
        filter = {key: params['filtering'][key]}
        queryset = queryset.filter(**filter)

    search = params.get('search_string', None)
    if search:
        qset = (
            Q(title__icontains=search) |
            Q(description__icontains=search) |
            Q(resolution__icontains=search) |
            Q(submitter_email__icontains=search)
        )

        queryset = queryset.filter(qset)

    sorting = params.get('sorting', None)
    if sorting:
        sortreverse = params.get('sortreverse', None)
        if sortreverse:
            sorting = "-%s" % sorting
        queryset = queryset.order_by(sorting)

    return queryset


def safe_template_context(ticket):
    """
    Return a dictionary that can be used as a template context to render
    comments and other details with ticket or queue parameters. Note that
    we don't just provide the Ticket & Queue objects to the template as
    they could reveal confidential information. Just imagine these two options:
        * {{ ticket.queue.email_box_password }}
        * {{ ticket.assigned_to.password }}

    Ouch!

    The downside to this is that if we make changes to the model, we will also
    have to update this code. Perhaps we can find a better way in the future.
    """

    context = {
        'queue': {},
        'ticket': {}
    }
    queue = ticket.queue

    for field in ('title', 'slug', 'email_address', 'from_address', 'locale'):
        attr = getattr(queue, field, None)
        if callable(attr):
            context['queue'][field] = attr()
        else:
            context['queue'][field] = attr

    for field in ('title', 'created', 'modified', 'submitter_email',
                  'status', 'get_status_display', 'on_hold', 'description',
                  'resolution', 'priority', 'get_priority_display',
                  'last_escalation', 'ticket', 'ticket_for_url',
                  'get_status', 'ticket_url', 'staff_url', '_get_assigned_to'
                  ):
        attr = getattr(ticket, field, None)
        if callable(attr):
            context['ticket'][field] = '%s' % attr()
        else:
            context['ticket'][field] = attr

    context['ticket']['queue'] = context['queue']
    context['ticket']['assigned_to'] = context['ticket']['_get_assigned_to']

    return context


def text_is_spam(text, request):
    # Based on a blog post by 'sciyoshi':
    # http://sciyoshi.com/blog/2008/aug/27/using-akismet-djangos-new-comments-framework/
    # This will return 'True' is the given text is deemed to be spam, or
    # False if it is not spam. If it cannot be checked for some reason, we
    # assume it isn't spam.
    from django.contrib.sites.models import Site
    from django.conf import settings
    try:
        from helpdesk.akismet import Akismet
    except:
        return False
    try:
        site = Site.objects.get_current()
    except:
        site = Site(domain='configure-django-sites.com')

    ak = Akismet(
        blog_url='http://%s/' % site.domain,
        agent='django-helpdesk',
    )

    if hasattr(settings, 'TYPEPAD_ANTISPAM_API_KEY'):
        ak.setAPIKey(key=settings.TYPEPAD_ANTISPAM_API_KEY)
        ak.baseurl = 'api.antispam.typepad.com/1.1/'
    elif hasattr(settings, 'AKISMET_API_KEY'):
        ak.setAPIKey(key=settings.AKISMET_API_KEY)
    else:
        return False

    if ak.verify_key():
        ak_data = {
            'user_ip': request.META.get('REMOTE_ADDR', '127.0.0.1'),
            'user_agent': request.META.get('HTTP_USER_AGENT', ''),
            'referrer': request.META.get('HTTP_REFERER', ''),
            'comment_type': 'comment',
            'comment_author': '',
        }

        return ak.comment_check(smart_str(text), data=ak_data)

    return False