django-helpdesk/lib.py

"""
Jutda 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)
"""

chart_colours = ('80C65A', '990066', 'FF9900', '3399CC', 'BBCCED', '3399CC', 'FFCC33')

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

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 file paths to be attached, or it can be left blank.
        eg ('/tmp/file1.txt', '/tmp/image.png')

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

    from helpdesk.models import EmailTemplate
    import os

    context = Context(email_context)
    locale = getattr(context['queue'], 'locale', 'en')

    if locale:
        template_localized = template_name + ':' + locale
    else:
        template_localized = None

    t = None
    if template_localized:
        try:
            t = EmailTemplate.objects.get(template_name__iexact=template_localized)
        except EmailTemplate.DoesNotExist:
            pass
    
    if not t:
        t = EmailTemplate.objects.get(template_name__iexact=template_name)

    if not sender:
        sender = settings.DEFAULT_FROM_EMAIL

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

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

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

    html_part = loader.get_template_from_string(
        "{%% extends '%s' %%}{%% block title %%}%s{%% endblock %%}{%% block content %%}%s{%% endblock %%}" % (email_html_base_file, t.heading, t.html)
        ).render(context)

    subject_part = loader.get_template_from_string(
        "{{ ticket.ticket }} {{ ticket.title }} %s" % t.subject
        ).render(context)

    if type(recipients) != list:
        recipients = [recipients,]

    msg = EmailMultiAlternatives(   subject_part,
                                    text_part,
                                    sender,
                                    recipients,
                                    bcc=bcc)
    msg.attach_alternative(html_part, "text/html")

    if files:
        if type(files) != list:
            files = [files,]

        for file in files:
            msg.attach_file(file)

    return msg.send(fail_silently)


def send_multipart_mail(template_name, email_context, subject, recipients, sender=None, bcc=None, fail_silently=False, files=None):
    """
    This function will send a multi-part e-mail with both HTML and
    Text parts. Note we don't use this any more; wsee send_templated_mail
    instead.

    template_name must NOT contain an extension. Both HTML (.html) and TEXT
        (.txt) versions must exist, eg 'emails/public_submit' will use both
        public_submit.html and public_submit.txt.

    email_context should be a plain python dictionary. It is applied against
        both the email messages (templates) & the subject.

    subject can be plain text or a Django template string, eg:
        New Job: {{ job.id }} {{ job.title }}

    recipients can be either a string, eg 'a@b.com' or a list, eg:
        ['a@b.com', 'c@d.com']. Type conversion is done if needed.

    sender can be an e-mail, 'Name <email>' or None. If unspecified, the
        DEFAULT_FROM_EMAIL will be used.

    Originally posted on my blog at http://www.rossp.org/
    """
    from django.core.mail import EmailMultiAlternatives
    from django.template import loader, Context
    from django.conf import settings

    if not sender:
        sender = settings.DEFAULT_FROM_EMAIL

    context = Context(email_context)

    text_part = loader.get_template('%s.txt' % template_name).render(context)
    html_part = loader.get_template('%s.html' % template_name).render(context)
    subject_part = loader.get_template_from_string(subject).render(context)

    if type(recipients) != list:
        recipients = [recipients,]

    msg = EmailMultiAlternatives(subject_part, text_part, sender, recipients, bcc=bcc)
    msg.attach_alternative(html_part, "text/html")

    if files:
        if type(files) != list:
            files = [files,]

        for file in files:
            msg.attach_file(file)

    return msg.send(fail_silently)


def normalise_data(data, to=100):
    """
    Used for normalising data prior to graphing with Google charting API. EG:

        [1, 4, 10] becomes [10, 40, 100]
        [36, 54, 240] becomes [15, 23, 100]
    """
    max_value = max(data)
    if max_value > to:
        new_data = []
        for d in data:
            new_data.append(int(d/float(max_value)*to))
        data = new_data
    return data


def line_chart(data):
    """
    'data' is a list of lists making a table.
    Row 1, columns 2-n are data headings (the time periods)
    Rows 2-n are data, with column 1 being the line labels
    """

    column_headings = data[0][1:]
    max = 0
    for row in data[1:]:
        for field in row[1:]:
            if field > max:
                max = field


    # Set width to '65px * number of months + 100 for headings.'.
    chart_url = 'http://chart.apis.google.com/chart?cht=lc&chs=%sx150&chd=t:' % (len(column_headings)*65+100)
    first_row = True
    row_headings = []
    for row in data[1:]:
        # Add data to URL, normalised to the maximum for all lines on this chart
        norm = normalise_data(row[1:], max)
        if not first_row:
            chart_url += '|'
        chart_url += ','.join([str(num) for num in norm])
        row_headings.append(row[0])
        first_row = False

    chart_url += '&chds='
    rows = len(data)-1
    first = True
    for row in range(rows):
        # Set maximum data ranges to '0:x' where 'x' is the maximum number in use.
        if not first:
            chart_url += ','
        chart_url += '0,%s' % max
        first = False
    chart_url += '&chdl=%s' % '|'.join(row_headings) # Display legend/labels
    chart_url += '&chco=%s' % ','.join(chart_colours) # Default colour set
    chart_url += '&chxt=x,y' # Turn on axis labels
    chart_url += '&chxl=0:|%s|1:|0|%s' % ('|'.join(column_headings), max) # Axis Label Text

    return chart_url


def bar_chart(data):
    """
    'data' is a list of lists making a table.
    Row 1, columns 2-n are data headings
    Rows 2-n are data, with column 1 being the line labels
    """

    column_headings = data[0][1:]
    max = 0
    for row in data[1:]:
        for field in row[1:]:
            if field > max:
                max = field


    # Set width to '220px * number of months'.
    chart_url = 'http://chart.apis.google.com/chart?cht=bvg&chs=%sx150&chd=t:' % (len(column_headings) * 220)
    first_row = True
    row_headings = []
    for row in data[1:]:
        # Add data to URL, normalised to the maximum for all lines on this chart
        norm = normalise_data(row[1:], max)
        if not first_row:
            chart_url += '|'
        chart_url += ','.join([str(num) for num in norm])
        row_headings.append(row[0])
        first_row = False

    chart_url += '&chds=0,%s' % max
    chart_url += '&chdl=%s' % '|'.join(row_headings) # Display legend/labels
    chart_url += '&chco=%s' % ','.join(chart_colours) # Default colour set
    chart_url += '&chxt=x,y' # Turn on axis labels
    chart_url += '&chxl=0:|%s|1:|0|%s' % ('|'.join(column_headings), max) # Axis Label Text

    return chart_url


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 & paramaters 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'}
        other_filter: Another filter of some type, most likely a 
            set of Q() objects.
        sorting: The name of the column to sort by
    """
    for key in params['filtering'].keys():
        filter = {key: params['filtering'][key]}
        queryset = queryset.filter(**filter)

    if params.get('other_filter', None):
        # eg a Q() set
        queryset = queryset.filter(params['other_filter'])

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