"""RFC 2822 message manipulation.

Note: This is only a very rough sketch of a full RFC-822 parser; in particular

the tokenizing of addresses does not adhere to all the quoting rules.

Note: RFC 2822 is a long awaited update to RFC 822.  This module should

conform to RFC 2822, and is thus mis-named (it's not worth renaming it).  Some

effort at RFC 2822 updates have been made, but a thorough audit has not been

performed.  Consider any RFC 2822 non-conformance to be a bug.

    RFC 2822: http://www.faqs.org/rfcs/rfc2822.html

    RFC 822 : http://www.faqs.org/rfcs/rfc822.html (obsolete)

Directions for use:

To create a Message object: first open a file, e.g.:

  fp = open(file, 'r')

You can use any other legal way of getting an open file object, e.g. use

sys.stdin or call os.popen().  Then pass the open file object to the Message()

constructor:

  m = Message(fp)

This class can work with any input object that supports a readline method.  If

the input object has seek and tell capability, the rewindbody method will

work; also illegal lines will be pushed back onto the input stream.  If the

input object lacks seek but has an `unread' method that can push back a line

of input, Message will use that to push back illegal lines.  Thus this class

can be used to parse messages coming from a buffered stream.

The optional `seekable' argument is provided as a workaround for certain stdio

libraries in which tell() discards buffered data before discovering that the

lseek() system call doesn't work.  For maximum portability, you should set the

seekable argument to zero to prevent that initial \code{tell} when passing in

an unseekable object such as a a file object created from a socket object.  If

it is 1 on entry -- which it is by default -- the tell() method of the open

file object is called once; if this raises an exception, seekable is reset to

0.  For other nonzero values of seekable, this test is not made.

To get the text of a particular header there are several methods:

  str = m.getheader(name)

  str = m.getrawheader(name)

where name is the name of the header, e.g. 'Subject'.  The difference is that

getheader() strips the leading and trailing whitespace, while getrawheader()

doesn't.  Both functions retain embedded whitespace (including newlines)

exactly as they are specified in the header, and leave the case of the text

unchanged.

For addresses and address lists there are functions

  realname, mailaddress = m.getaddr(name)

  list = m.getaddrlist(name)

where the latter returns a list of (realname, mailaddr) tuples.

There is also a method

  time = m.getdate(name)

which parses a Date-like field and returns a time-compatible tuple,

i.e. a tuple such as returned by time.localtime() or accepted by

time.mktime().

See the class definition for lower level access methods.

There are also some utility functions here.

"""

# Cleanup and extensions by Eric S. Raymond <esr@thyrsus.com>

import time

__all__ = ["Message","AddressList","parsedate","parsedate_tz","mktime_tz"]

_blanklines = ('\r\n', '\n')            # Optimization for islast()

class Message:

    """Represents a single RFC 2822-compliant message."""

    def __init__(self, fp, seekable = 1):

        """Initialize the class instance and read the headers."""

        if seekable == 1:

            # Exercise tell() to make sure it works

            # (and then assume seek() works, too)

            try:

                fp.tell()

            except (AttributeError, IOError):

                seekable = 0

        self.fp = fp

        self.seekable = seekable

        self.startofheaders = None

        self.startofbody = None

        #

        if self.seekable:

            try:

                self.startofheaders = self.fp.tell()

            except IOError:

                self.seekable = 0

        #

        self.readheaders()

        #

        if self.seekable:

            try:

                self.startofbody = self.fp.tell()

            except IOError:

                self.seekable = 0

    def rewindbody(self):

        """Rewind the file to the start of the body (if seekable)."""

        if not self.seekable:

            raise IOError, "unseekable file"

        self.fp.seek(self.startofbody)

    def readheaders(self):

        """Read header lines.

        Read header lines up to the entirely blank line that terminates them.

        The (normally blank) line that ends the headers is skipped, but not

        included in the returned list.  If a non-header line ends the headers,

        (which is an error), an attempt is made to backspace over it; it is

        never included in the returned list.

        The variable self.status is set to the empty string if all went well,

        otherwise it is an error message.  The variable self.headers is a

        completely uninterpreted list of lines contained in the header (so

        printing them will reproduce the header exactly as it appears in the

        file).

        """

        self.dict = {}

        self.unixfrom = ''

        self.headers = lst = []

        self.status = ''

        headerseen = ""

        firstline = 1

        startofline = unread = tell = None

        if hasattr(self.fp, 'unread'):

            unread = self.fp.unread

        elif self.seekable:

            tell = self.fp.tell

        while 1:

            if tell:

                try:

                    startofline = tell()

                except IOError:

                    startofline = tell = None

                    self.seekable = 0

            line = self.fp.readline()

            if not line:

                self.status = 'EOF in headers'

                break

            # Skip unix From name time lines

            if firstline and line.startswith('From '):

                self.unixfrom = self.unixfrom + line

                continue

            firstline = 0

            if headerseen and line[0] in ' \t':

                # It's a continuation line.

                lst.append(line)

                x = (self.dict[headerseen] + "\n " + line.strip())

                self.dict[headerseen] = x.strip()

                continue

            elif self.iscomment(line):

                # It's a comment.  Ignore it.

                continue

            elif self.islast(line):

                # Note! No pushback here!  The delimiter line gets eaten.

                break

            headerseen = self.isheader(line)

            if headerseen:

                # It's a legal header line, save it.

                lst.append(line)

                self.dict[headerseen] = line[len(headerseen)+1:].strip()

                continue

            else:

                # It's not a header line; throw it back and stop here.

                if not self.dict:

                    self.status = 'No headers'

                else:

                    self.status = 'Non-header line where header expected'

                # Try to undo the read.

                if unread:

                    unread(line)

                elif tell:

                    self.fp.seek(startofline)

                else:

                    self.status = self.status + '; bad seek'

                break

    def isheader(self, line):

        """Determine whether a given line is a legal header.

        This method should return the header name, suitably canonicalized.

        You may override this method in order to use Message parsing on tagged

        data in RFC 2822-like formats with special header formats.

        """

        i = line.find(':')

        if i > 0:

            return line[:i].lower()

        return None

    def islast(self, line):

        """Determine whether a line is a legal end of RFC 2822 headers.

        You may override this method if your application wants to bend the

        rules, e.g. to strip trailing whitespace, or to recognize MH template

        separators ('--------').  For convenience (e.g. for code reading from

        sockets) a line consisting of \r\n also matches.

        """

        return line in _blanklines

    def iscomment(self, line):

        """Determine whether a line should be skipped entirely.

        You may override this method in order to use Message parsing on tagged

        data in RFC 2822-like formats that support embedded comments or

        free-text data.

        """

        return False

    def getallmatchingheaders(self, name):

        """Find all header lines matching a given header name.

        Look through the list of headers and find all lines matching a given

        header name (and their continuation lines).  A list of the lines is

        returned, without interpretation.  If the header does not occur, an

        empty list is returned.  If the header occurs multiple times, all

        occurrences are returned.  Case is not important in the header name.

        """

        name = name.lower() + ':'

        n = len(name)

        lst = []

        hit = 0

        for line in self.headers:

            if line[:n].lower() == name:

                hit = 1

            elif not line[:1].isspace():

                hit = 0

            if hit:

                lst.append(line)

        return lst

    def getfirstmatchingheader(self, name):

        """Get the first header line matching name.

        This is similar to getallmatchingheaders, but it returns only the

        first matching header (and its continuation lines).

        """

        name = name.lower() + ':'

        n = len(name)

        lst = []

        hit = 0

        for line in self.headers:

            if hit:

                if not line[:1].isspace():

                    break

            elif line[:n].lower() == name:

                hit = 1

            if hit:

                lst.append(line)

        return lst

    def getrawheader(self, name):

        """A higher-level interface to getfirstmatchingheader().

        Return a string containing the literal text of the header but with the

        keyword stripped.  All leading, trailing and embedded whitespace is

        kept in the string, however.  Return None if the header does not

        occur.

        """

        lst = self.getfirstmatchingheader(name)

        if not lst:

            return None

        lst[0] = lst[0][len(name) + 1:]

        return ''.join(lst)

    def getheader(self, name, default=None):

        """Get the header value for a name.

        This is the normal interface: it returns a stripped version of the

        header value for a given header name, or None if it doesn't exist.

        This uses the dictionary version which finds the *last* such header.

        """

        return self.dict.get(name.lower(), default)

    get = getheader

    def getheaders(self, name):

        """Get all values for a header.

        This returns a list of values for headers given more than once; each

        value in the result list is stripped in the same way as the result of

        getheader().  If the header is not given, return an empty list.

        """

        result = []

        current = ''

        have_header = 0

        for s in self.getallmatchingheaders(name):

            if s[0].isspace():

                if current:

                    current = "%s\n %s" % (current, s.strip())

                else:

                    current = s.strip()

            else:

                if have_header:

                    result.append(current)

                current = s[s.find(":") + 1:].strip()

                have_header = 1

        if have_header:

            result.append(current)

        return result

    def getaddr(self, name):

        """Get a single address from a header, as a tuple.

        An example return value:

        ('Guido van Rossum', 'guido@cwi.nl')

        """

        # New, by Ben Escoto

        alist = self.getaddrlist(name)

        if alist:

            return alist[0]

        else:

            return (None, None)

    def getaddrlist(self, name):

        """Get a list of addresses from a header.

        Retrieves a list of addresses from a header, where each address is a

        tuple as returned by getaddr().  Scans all named headers, so it works

        properly with multiple To: or Cc: headers for example.

        """

        raw = []

        for h in self.getallmatchingheaders(name):

            if h[0] in ' \t':

                raw.append(h)

            else:

                if raw:

                    raw.append(', ')

                i = h.find(':')

                if i > 0:

                    addr = h[i+1:]

                raw.append(addr)

        alladdrs = ''.join(raw)

        a = AddressList(alladdrs)

        return a.addresslist

    def getdate(self, name):

        """Retrieve a date field from a header.

        Retrieves a date field from the named header, returning a tuple

        compatible with time.mktime().

        """

        try:

            data = self[name]

        except KeyError:

            return None

        return parsedate(data)

    def getdate_tz(self, name):

        """Retrieve a date field from a header as a 10-tuple.

        The first 9 elements make up a tuple compatible with time.mktime(),

        and the 10th is the offset of the poster's time zone from GMT/UTC.

        """

        try:

            data = self[name]

        except KeyError:

            return None

        return parsedate_tz(data)

    # Access as a dictionary (only finds *last* header of each type):

    def __len__(self):

        """Get the number of headers in a message."""

        return len(self.dict)

    def __getitem__(self, name):

        """Get a specific header, as from a dictionary."""

        return self.dict[name.lower()]

    def __setitem__(self, name, value):

        """Set the value of a header.

        Note: This is not a perfect inversion of __getitem__, because any

        changed headers get stuck at the end of the raw-headers list rather

        than where the altered header was.

        """

        del self[name] # Won't fail if it doesn't exist

        self.dict[name.lower()] = value

        text = name + ": " + value

        for line in text.split("\n"):

            self.headers.append(line + "\n")

    def __delitem__(self, name):

        """Delete all occurrences of a specific header, if it is present."""

        name = name.lower()

        if not name in self.dict:

            return

        del self.dict[name]

        name = name + ':'

        n = len(name)

        lst = []

        hit = 0

        for i in range(len(self.headers)):

            line = self.headers[i]

            if line[:n].lower() == name:

                hit = 1

            elif not line[:1].isspace():

                hit = 0

            if hit:

                lst.append(i)

        for i in reversed(lst):

            del self.headers[i]

    def setdefault(self, name, default=""):

        lowername = name.lower()

        if lowername in self.dict:

            return self.dict[lowername]

        else:

            text = name + ": " + default

            for line in text.split("\n"):

                self.headers.append(line + "\n")

            self.dict[lowername] = default

            return default

    def has_key(self, name):

        """Determine whether a message contains the named header."""

        return name.lower() in self.dict

    def __contains__(self, name):

        """Determine whether a message contains the named header."""

        return name.lower() in self.dict

    def __iter__(self):

        return iter(self.dict)

    def keys(self):

        """Get all of a message's header field names."""

        return self.dict.keys()

    def values(self):

        """Get all of a message's header field values."""

        return self.dict.values()

    def items(self):

        """Get all of a message's headers.

        Returns a list of name, value tuples.

        """

        return self.dict.items()

    def __str__(self):

        return ''.join(self.headers)

# Utility functions

# -----------------

# XXX Should fix unquote() and quote() to be really conformant.

# XXX The inverses of the parse functions may also be useful.

def unquote(s):

    """Remove quotes from a string."""

    if len(s) > 1:

        if s.startswith('"') and s.endswith('"'):

            return s[1:-1].replace('\\\\', '\\').replace('\\"', '"')

        if s.startswith('<') and s.endswith('>'):

            return s[1:-1]

    return s

def quote(s):

    """Add quotes around a string."""

    return s.replace('\\', '\\\\').replace('"', '\\"')

def parseaddr(address):

    """Parse an address into a (realname, mailaddr) tuple."""

    a = AddressList(address)

    lst = a.addresslist

    if not lst:

        return (None, None)

    return lst[0]

class AddrlistClass:

    """Address parser class by Ben Escoto.

    To understand what this class does, it helps to have a copy of

    RFC 2822 in front of you.

    http://www.faqs.org/rfcs/rfc2822.html

    Note: this class interface is deprecated and may be removed in the future.

    Use rfc822.AddressList instead.

    """

    def __init__(self, field):

        """Initialize a new instance.

        `field' is an unparsed address header field, containing one or more

        addresses.

        """

        self.specials = '()<>@,:;.\"[]'

        self.pos = 0

        self.LWS = ' \t'

        self.CR = '\r\n'

        self.atomends = self.specials + self.LWS + self.CR

        # Note that RFC 2822 now specifies `.' as obs-phrase, meaning that it

        # is obsolete syntax.  RFC 2822 requires that we recognize obsolete

        # syntax, so allow dots in phrases.

        self.phraseends = self.atomends.replace('.', '')

        self.field = field

        self.commentlist = []

    def gotonext(self):

        """Parse up to the start of the next address."""

        while self.pos < len(self.field):

            if self.field[self.pos] in self.LWS + '\n\r':

                self.pos = self.pos + 1

            elif self.field[self.pos] == '(':

                self.commentlist.append(self.getcomment())

            else: break