emailreply

export/emailreply.py

@@ -0,0 +1,166 @@
+import re
+
+
+class EmailReplyParser(object):
+    """ Represents a email message that is parsed.
+    """
+
+    @staticmethod
+    def read(text):
+        """ Factory method that splits email into list of fragments
+
+            text - A string email body
+
+            Returns an EmailMessage instance
+        """
+        return EmailMessage(text).read()
+
+    @staticmethod
+    def parse_reply(text):
+        """ Provides the reply portion of email.
+
+            text - A string email body
+
+            Returns reply body message
+        """
+        return EmailReplyParser.read(text).reply
+
+
+class EmailMessage(object):
+    """ An email message represents a parsed email body.
+    """
+
+    SIG_REGEX = re.compile(r'(--|__|-\w)|(^Sent from my (\w+\s*){1,3})')
+    QUOTE_HDR_REGEX = re.compile('On.*wrote:$')
+    QUOTED_REGEX = re.compile(r'(>+)')
+    HEADER_REGEX = re.compile(r'^\*?(From|Sent|To|Subject):\*? .+')
+    _MULTI_QUOTE_HDR_REGEX = r'(?!On.*On\s.+?wrote:)(On\s(.+?)wrote:)'
+    MULTI_QUOTE_HDR_REGEX = re.compile(_MULTI_QUOTE_HDR_REGEX, re.DOTALL | re.MULTILINE)
+    MULTI_QUOTE_HDR_REGEX_MULTILINE = re.compile(_MULTI_QUOTE_HDR_REGEX, re.DOTALL)
+
+    def __init__(self, text):
+        self.fragments = []
+        self.fragment = None
+        self.text = text.replace('\r\n', '\n')
+        self.found_visible = False
+
+    def read(self):
+        """ Creates new fragment for each line
+            and labels as a signature, quote, or hidden.
+
+            Returns EmailMessage instance
+        """
+
+        self.found_visible = False
+
+        is_multi_quote_header = self.MULTI_QUOTE_HDR_REGEX_MULTILINE.search(self.text)
+        if is_multi_quote_header:
+            self.text = self.MULTI_QUOTE_HDR_REGEX.sub(is_multi_quote_header.groups()[0].replace('\n', ''), self.text)
+
+        # Fix any outlook style replies, with the reply immediately above the signature boundary line
+        #   See email_2_2.txt for an example
+        self.text = re.sub('([^\n])(?=\n ?[_-]{7,})', '\\1\n', self.text, re.MULTILINE)
+
+        self.lines = self.text.split('\n')
+        self.lines.reverse()
+
+        for line in self.lines:
+            self._scan_line(line)
+
+        self._finish_fragment()
+
+        self.fragments.reverse()
+
+        return self
+
+    @property
+    def reply(self):
+        """ Captures reply message within email
+        """
+        reply = []
+        for f in self.fragments:
+            if not (f.hidden or f.quoted):
+                reply.append(f.content)
+        return '\n'.join(reply)
+
+    def _scan_line(self, line):
+        """ Reviews each line in email message and determines fragment type
+
+            line - a row of text from an email message
+        """
+        is_quote_header = self.QUOTE_HDR_REGEX.match(line) is not None
+        is_quoted = self.QUOTED_REGEX.match(line) is not None
+        is_header = is_quote_header or self.HEADER_REGEX.match(line) is not None
+
+        if self.fragment and len(line.strip()) == 0:
+            if self.SIG_REGEX.match(self.fragment.lines[-1].strip()):
+                self.fragment.signature = True
+                self._finish_fragment()
+
+        if self.fragment \
+                and ((self.fragment.headers == is_header and self.fragment.quoted == is_quoted) or
+                         (self.fragment.quoted and (is_quote_header or len(line.strip()) == 0))):
+
+            self.fragment.lines.append(line)
+        else:
+            self._finish_fragment()
+            self.fragment = Fragment(is_quoted, line, headers=is_header)
+
+    def quote_header(self, line):
+        """ Determines whether line is part of a quoted area
+
+            line - a row of the email message
+
+            Returns True or False
+        """
+        return self.QUOTE_HDR_REGEX.match(line[::-1]) is not None
+
+    def _finish_fragment(self):
+        """ Creates fragment
+        """
+
+        if self.fragment:
+            self.fragment.finish()
+            if self.fragment.headers:
+                # Regardless of what's been seen to this point, if we encounter a headers fragment,
+                # all the previous fragments should be marked hidden and found_visible set to False.
+                self.found_visible = False
+                for f in self.fragments:
+                    f.hidden = True
+            if not self.found_visible:
+                if self.fragment.quoted \
+                        or self.fragment.headers \
+                        or self.fragment.signature \
+                        or (len(self.fragment.content.strip()) == 0):
+
+                    self.fragment.hidden = True
+                else:
+                    self.found_visible = True
+            self.fragments.append(self.fragment)
+        self.fragment = None
+
+
+class Fragment(object):
+    """ A Fragment is a part of
+        an Email Message, labeling each part.
+    """
+
+    def __init__(self, quoted, first_line, headers=False):
+        self.signature = False
+        self.headers = headers
+        self.hidden = False
+        self.quoted = quoted
+        self._content = None
+        self.lines = [first_line]
+
+    def finish(self):
+        """ Creates block of content with lines
+            belonging to fragment.
+        """
+        self.lines.reverse()
+        self._content = '\n'.join(self.lines)
+        self.lines = None
+
+    @property
+    def content(self):
+        return self._content.strip()