import mimetypes

import os

import random

import time

from email import Charset, Encoders

from email.MIMEText import MIMEText

from email.MIMEMultipart import MIMEMultipart

from email.MIMEBase import MIMEBase

from email.Header import Header

from email.Utils import formatdate, getaddresses, formataddr

from django.conf import settings

from django.core.mail.utils import DNS_NAME

from django.utils.encoding import smart_str, force_unicode

# Don't BASE64-encode UTF-8 messages so that we avoid unwanted attention from

# some spam filters.

Charset.add_charset('utf-8', Charset.SHORTEST, Charset.QP, 'utf-8')

# Default MIME type to use on attachments (if it is not explicitly given

# and cannot be guessed).

DEFAULT_ATTACHMENT_MIME_TYPE = 'application/octet-stream'

class BadHeaderError(ValueError):

    pass

# Copied from Python standard library, with the following modifications:

# * Used cached hostname for performance.

# * Added try/except to support lack of getpid() in Jython (#5496).

def make_msgid(idstring=None):

    """Returns a string suitable for RFC 2822 compliant Message-ID, e.g:

    <20020201195627.33539.96671@nightshade.la.mastaler.com>

    Optional idstring if given is a string used to strengthen the

    uniqueness of the message id.

    """

    timeval = time.time()

    utcdate = time.strftime('%Y%m%d%H%M%S', time.gmtime(timeval))

    try:

        pid = os.getpid()

    except AttributeError:

        # No getpid() in Jython, for example.

        pid = 1

    randint = random.randrange(100000)

    if idstring is None:

        idstring = ''

    else:

        idstring = '.' + idstring

    idhost = DNS_NAME

    msgid = '<%s.%s.%s%s@%s>' % (utcdate, pid, randint, idstring, idhost)

    return msgid

def forbid_multi_line_headers(name, val, encoding):

    """Forbids multi-line headers, to prevent header injection."""

    encoding = encoding or settings.DEFAULT_CHARSET

    val = force_unicode(val)

    if '\n' in val or '\r' in val:

        raise BadHeaderError("Header values can't contain newlines (got %r for header %r)" % (val, name))

    try:

        val = val.encode('ascii')

    except UnicodeEncodeError:

        if name.lower() in ('to', 'from', 'cc'):

            result = []

            for nm, addr in getaddresses((val,)):

                nm = str(Header(nm.encode(encoding), encoding))

                result.append(formataddr((nm, str(addr))))

            val = ', '.join(result)

        else:

            val = Header(val.encode(encoding), encoding)

    else:

        if name.lower() == 'subject':

            val = Header(val)

    return name, val

class SafeMIMEText(MIMEText):

    def __init__(self, text, subtype, charset):

        self.encoding = charset

        MIMEText.__init__(self, text, subtype, charset)

    def __setitem__(self, name, val):    

        name, val = forbid_multi_line_headers(name, val, self.encoding)

        MIMEText.__setitem__(self, name, val)

class SafeMIMEMultipart(MIMEMultipart):

    def __init__(self, _subtype='mixed', boundary=None, _subparts=None, encoding=None, **_params):

        self.encoding = encoding

        MIMEMultipart.__init__(self, _subtype, boundary, _subparts, **_params)

    def __setitem__(self, name, val):

        name, val = forbid_multi_line_headers(name, val, self.encoding)

        MIMEMultipart.__setitem__(self, name, val)

class EmailMessage(object):

    """

    A container for email information.

    """

    content_subtype = 'plain'

    mixed_subtype = 'mixed'

    encoding = None     # None => use settings default

    def __init__(self, subject='', body='', from_email=None, to=None, bcc=None,

                 connection=None, attachments=None, headers=None):

        """

        Initialize a single email message (which can be sent to multiple

        recipients).

        All strings used to create the message can be unicode strings

        (or UTF-8 bytestrings). The SafeMIMEText class will handle any

        necessary encoding conversions.

        """

        if to:

            assert not isinstance(to, basestring), '"to" argument must be a list or tuple'

            self.to = list(to)

        else:

            self.to = []

        if bcc:

            assert not isinstance(bcc, basestring), '"bcc" argument must be a list or tuple'

            self.bcc = list(bcc)

        else:

            self.bcc = []

        self.from_email = from_email or settings.DEFAULT_FROM_EMAIL

        self.subject = subject

        self.body = body

        self.attachments = attachments or []

        self.extra_headers = headers or {}

        self.connection = connection

    def get_connection(self, fail_silently=False):

        from django.core.mail import get_connection

        if not self.connection:

            self.connection = get_connection(fail_silently=fail_silently)

        return self.connection

    def message(self):

        encoding = self.encoding or settings.DEFAULT_CHARSET

        msg = SafeMIMEText(smart_str(self.body, encoding),

                           self.content_subtype, encoding)

        msg = self._create_message(msg)

        msg['Subject'] = self.subject

        msg['From'] = self.extra_headers.get('From', self.from_email)

        msg['To'] = ', '.join(self.to)

        # Email header names are case-insensitive (RFC 2045), so we have to

        # accommodate that when doing comparisons.

        header_names = [key.lower() for key in self.extra_headers]

        if 'date' not in header_names:

            msg['Date'] = formatdate()

        if 'message-id' not in header_names:

            msg['Message-ID'] = make_msgid()

        for name, value in self.extra_headers.items():

            if name.lower() == 'from':  # From is already handled

                continue

            msg[name] = value

        return msg

    def recipients(self):

        """

        Returns a list of all recipients of the email (includes direct

        addressees as well as Bcc entries).

        """

        return self.to + self.bcc

    def send(self, fail_silently=False):

        """Sends the email message."""

        if not self.recipients():

            # Don't bother creating the network connection if there's nobody to

            # send to.

            return 0

        return self.get_connection(fail_silently).send_messages([self])

    def attach(self, filename=None, content=None, mimetype=None):

        """

        Attaches a file with the given filename and content. The filename can

        be omitted and the mimetype is guessed, if not provided.

        If the first parameter is a MIMEBase subclass it is inserted directly

        into the resulting message attachments.

        """

        if isinstance(filename, MIMEBase):

            assert content == mimetype == None

            self.attachments.append(filename)

        else:

            assert content is not None

            self.attachments.append((filename, content, mimetype))

    def attach_file(self, path, mimetype=None):

        """Attaches a file from the filesystem."""

        filename = os.path.basename(path)

        content = open(path, 'rb').read()

        self.attach(filename, content, mimetype)

    def _create_message(self, msg):

        return self._create_attachments(msg)

    def _create_attachments(self, msg):

        if self.attachments:

            encoding = self.encoding or settings.DEFAULT_CHARSET

            body_msg = msg

            msg = SafeMIMEMultipart(_subtype=self.mixed_subtype, encoding=encoding)

            if self.body:

                msg.attach(body_msg)

            for attachment in self.attachments:

                if isinstance(attachment, MIMEBase):

                    msg.attach(attachment)

                else:

                    msg.attach(self._create_attachment(*attachment))

        return msg

    def _create_mime_attachment(self, content, mimetype):

        """

        Converts the content, mimetype pair into a MIME attachment object.

        """

        basetype, subtype = mimetype.split('/', 1)

        if basetype == 'text':

            encoding = self.encoding or settings.DEFAULT_CHARSET

            attachment = SafeMIMEText(smart_str(content, encoding), subtype, encoding)

        else:

            # Encode non-text attachments with base64.

            attachment = MIMEBase(basetype, subtype)

            attachment.set_payload(content)

            Encoders.encode_base64(attachment)

        return attachment

    def _create_attachment(self, filename, content, mimetype=None):

        """

        Converts the filename, content, mimetype triple into a MIME attachment

        object.

        """

        if mimetype is None:

            mimetype, _ = mimetypes.guess_type(filename)

            if mimetype is None:

                mimetype = DEFAULT_ATTACHMENT_MIME_TYPE

        attachment = self._create_mime_attachment(content, mimetype)

        if filename:

            attachment.add_header('Content-Disposition', 'attachment',

                                  filename=filename)

        return attachment

class EmailMultiAlternatives(EmailMessage):

    """

    A version of EmailMessage that makes it easy to send multipart/alternative

    messages. For example, including text and HTML versions of the text is

    made easier.

    """

    alternative_subtype = 'alternative'

    def __init__(self, subject='', body='', from_email=None, to=None, bcc=None,

            connection=None, attachments=None, headers=None, alternatives=None):

        """

        Initialize a single email message (which can be sent to multiple

        recipients).

        All strings used to create the message can be unicode strings (or UTF-8

        bytestrings). The SafeMIMEText class will handle any necessary encoding

        conversions.

        """

        super(EmailMultiAlternatives, self).__init__(subject, body, from_email, to, bcc, connection, attachments, headers)

        self.alternatives=alternatives or []

    def attach_alternative(self, content, mimetype):

        """Attach an alternative content representation."""

        assert content is not None

        assert mimetype is not None

        self.alternatives.append((content, mimetype))

    def _create_message(self, msg):

        return self._create_attachments(self._create_alternatives(msg))

    def _create_alternatives(self, msg):

        encoding = self.encoding or settings.DEFAULT_CHARSET

        if self.alternatives:

            body_msg = msg

            msg = SafeMIMEMultipart(_subtype=self.alternative_subtype, encoding=encoding)

            if self.body:

                msg.attach(body_msg)

            for alternative in self.alternatives:

                msg.attach(self._create_mime_attachment(*alternative))

        return msg