[FIX] mail: send image with base64 src as attachment

Before this fix, the base64 image are remove and never send. The images
were in the body increasing the size of the database unnecessarily
(cfr some odoo users with the chatter)

NB: According to the prophecy Khoi will come and dominate the world,
ask him anything

addons/mail/models/mail_message.py

@@ -2,6 +2,7 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 import logging
+import re
 
 from email.utils import formataddr
 
@@ -11,6 +12,7 @@ from odoo.osv import expression
 
 
 _logger = logging.getLogger(__name__)
+_image_dataurl = re.compile(r'(data:image/[a-z]+?);base64,([a-z0-9+/]{3,}=*)([\'"])', re.I)
 
 
 class Message(models.Model):
@@ -721,6 +723,28 @@ class Message(models.Model):
         if 'record_name' not in values and 'default_record_name' not in self.env.context:
             values['record_name'] = self._get_record_name(values)
 
+        if 'attachment_ids' not in values:
+            values.setdefault('attachment_ids', [])
+
+        # extract base64 images
+        if 'body' in values:
+            Attachments = self.env['ir.attachment']
+            data_to_url = {}
+            def base64_to_boundary(match):
+                key = match.group(2)
+                if not data_to_url.get(key):
+                    name = 'image%s' % len(data_to_url)
+                    attachment = Attachments.create({
+                        'name': name,
+                        'datas': match.group(2),
+                        'datas_fname': name,
+                        'res_model': 'mail.message',
+                    })
+                    values['attachment_ids'].append((4, attachment.id))
+                    data_to_url[key] = '/web/image/%s' % attachment.id
+                return '%s%s alt="%s"' % (data_to_url[key], match.group(3), name)
+            values['body'] = _image_dataurl.sub(base64_to_boundary, values['body'])
+
         message = super(Message, self).create(values)
         message._invalidate_documents()