"""This will be the home for the policy that hooks in the new
code that adds all the email6 features.
"""

import re
import sys
from email._policybase import Policy, Compat32, compat32, _extend_docstrings
from email.utils import _has_surrogates
from email.headerregistry import HeaderRegistry as HeaderRegistry
from email.contentmanager import raw_data_manager
from email.message import EmailMessage

__all__ = [
 'Compat32',
 'compat32',
 'Policy',
 'EmailPolicy',
 'default',
 'strict',
 'SMTP',
 'HTTP',
 ]

linesep_splitter = re.compile(r'\n|\r')

@_extend_docstrings
class EmailPolicy(Policy):

 """+
 PROVISIONAL

 The API extensions enabled by this policy are currently provisional.
 Refer to the documentation for details.

 This policy adds new header parsing and folding algorithms. Instead of
 simple strings, headers are custom objects with custom attributes
 depending on the type of the field. The folding algorithm fully
 implements RFCs 2047 and 5322.

 In addition to the settable attributes listed above that apply to
 all Policies, this policy adds the following additional attributes:

 utf8 -- if False (the default) message headers will be
 serialized as ASCII, using encoded words to encode
 any non-ASCII characters in the source strings. If
 True, the message headers will be serialized using
 utf8 and will not contain encoded words (see RFC
 6532 for more on this serialization format).

 refold_source -- if the value for a header in the Message object
 came from the parsing of some source, this attribute
 indicates whether or not a generator should refold
 that value when transforming the message back into
 stream form. The possible values are:

 none -- all source values use original folding
 long -- source values that have any line that is
 longer than max_line_length will be
 refolded
 all -- all values are refolded.

 The default is 'long'.

 header_factory -- a callable that takes two arguments, 'name' and
 'value', where 'name' is a header field name and
 'value' is an unfolded header field value, and
 returns a string-like object that represents that
 header. A default header_factory is provided that
 understands some of the RFC5322 header field types.
 (Currently address fields and date fields have
 special treatment, while all other fields are
 treated as unstructured. This list will be
 completed before the extension is marked stable.)

 content_manager -- an object with at least two methods: get_content
 and set_content. When the get_content or
 set_content method of a Message object is called,
 it calls the corresponding method of this object,
 passing it the message object as its first argument,
 and any arguments or keywords that were passed to
 it as additional arguments. The default
 content_manager is
 :data:`~email.contentmanager.raw_data_manager`.

 """

 message_factory = EmailMessage
 utf8 = False
 refold_source = 'long'
 header_factory = HeaderRegistry()
 content_manager = raw_data_manager

 def __init__(self, **kw):
 # Ensure that each new instance gets a unique header factory
 # (as opposed to clones, which share the factory).
 if 'header_factory' not in kw:
 object.__setattr__(self, 'header_factory', HeaderRegistry())
 super().__init__(**kw)

 def header_max_count(self, name):
 """+
 The implementation for this class returns the max_count attribute from
 the specialized header class that would be used to construct a header
 of type 'name'.
 """
 return self.header_factory[name].max_count

 # The logic of the next three methods is chosen such that it is possible to
 # switch a Message object between a Compat32 policy and a policy derived
 # from this class and have the results stay consistent. This allows a
 # Message object constructed with this policy to be passed to a library
 # that only handles Compat32 objects, or to receive such an object and
 # convert it to use the newer style by just changing its policy. It is
 # also chosen because it postpones the relatively expensive full rfc5322
 # parse until as late as possible when parsing from source, since in many
 # applications only a few headers will actually be inspected.

 def header_source_parse(self, sourcelines):
 """+
 The name is parsed as everything up to the ':' and returned unmodified.
 The value is determined by stripping leading whitespace off the
 remainder of the first line, joining all subsequent lines together, and
 stripping any trailing carriage return or linefeed characters. (This
 is the same as Compat32).

 """
 name, value = sourcelines[0].split(':', 1)
 value = value.lstrip(' \t') + ''.join(sourcelines[1:])
 return (name, value.rstrip('\r\n'))

 def header_store_parse(self, name, value):
 """+
 The name is returned unchanged. If the input value has a 'name'
 attribute and it matches the name ignoring case, the value is returned
 unchanged. Otherwise the name and value are passed to header_factory
 method, and the resulting custom header object is returned as the
 value. In this case a ValueError is raised if the input value contains
 CR or LF characters.

 """
 if hasattr(value, 'name') and value.name.lower() == name.lower():
 return (name, value)
 if isinstance(value, str) and len(value.splitlines())>1:
 # XXX this error message isn't quite right when we use splitlines
 # (see issue 22233), but I'm not sure what should happen here.
 raise ValueError("Header values may not contain linefeed "
 "or carriage return characters")
 return (name, self.header_factory(name, value))

 def header_fetch_parse(self, name, value):
 """+
 If the value has a 'name' attribute, it is returned to unmodified.
 Otherwise the name and the value with any linesep characters removed
 are passed to the header_factory method, and the resulting custom
 header object is returned. Any surrogateescaped bytes get turned
 into the unicode unknown-character glyph.

 """
 if hasattr(value, 'name'):
 return value
 # We can't use splitlines here because it splits on more than \r and \n.
 value = ''.join(linesep_splitter.split(value))
 return self.header_factory(name, value)

 def fold(self, name, value):
 """+
 Header folding is controlled by the refold_source policy setting. A
 value is considered to be a 'source value' if and only if it does not
 have a 'name' attribute (having a 'name' attribute means it is a header
 object of some sort). If a source value needs to be refolded according
 to the policy, it is converted into a custom header object by passing
 the name and the value with any linesep characters removed to the
 header_factory method. Folding of a custom header object is done by
 calling its fold method with the current policy.

 Source values are split into lines using splitlines. If the value is
 not to be refolded, the lines are rejoined using the linesep from the
 policy and returned. The exception is lines containing non-ascii
 binary data. In that case the value is refolded regardless of the
 refold_source setting, which causes the binary data to be CTE encoded
 using the unknown-8bit charset.

 """
 return self._fold(name, value, refold_binary=True)

 def fold_binary(self, name, value):
 """+
 The same as fold if cte_type is 7bit, except that the returned value is
 bytes.

 If cte_type is 8bit, non-ASCII binary data is converted back into
 bytes. Headers with binary data are not refolded, regardless of the
 refold_header setting, since there is no way to know whether the binary
 data consists of single byte characters or multibyte characters.

 If utf8 is true, headers are encoded to utf8, otherwise to ascii with
 non-ASCII unicode rendered as encoded words.

 """
 folded = self._fold(name, value, refold_binary=self.cte_type=='7bit')
 charset = 'utf8' if self.utf8 else 'ascii'
 return folded.encode(charset, 'surrogateescape')

 def _fold(self, name, value, refold_binary=False):
 if hasattr(value, 'name'):
 return value.fold(policy=self)
 maxlen = self.max_line_length if self.max_line_length else sys.maxsize
 lines = value.splitlines()
 refold = (self.refold_source == 'all' or
 self.refold_source == 'long' and
 (lines and len(lines[0])+len(name)+2 > maxlen or
 any(len(x) > maxlen for x in lines[1:])))
 if refold or refold_binary and _has_surrogates(value):
 return self.header_factory(name, ''.join(lines)).fold(policy=self)
 return name + ': ' + self.linesep.join(lines) + self.linesep


default = EmailPolicy()
# Make the default policy use the class default header_factory
del default.header_factory
strict = default.clone(raise_on_defect=True)
SMTP = default.clone(linesep='\r\n')
HTTP = default.clone(linesep='\r\n', max_line_length=None)
SMTPUTF8 = SMTP.clone(utf8=True)