import binascii
import email.charset
import email.message
import email.errors
from email import quoprimime

class ContentManager:

 def __init__(self):
 self.get_handlers = {}
 self.set_handlers = {}

 def add_get_handler(self, key, handler):
 self.get_handlers[key] = handler

 def get_content(self, msg, *args, **kw):
 content_type = msg.get_content_type()
 if content_type in self.get_handlers:
 return self.get_handlers[content_type](msg, *args, **kw)
 maintype = msg.get_content_maintype()
 if maintype in self.get_handlers:
 return self.get_handlers[maintype](msg, *args, **kw)
 if '' in self.get_handlers:
 return self.get_handlers[''](msg, *args, **kw)
 raise KeyError(content_type)

 def add_set_handler(self, typekey, handler):
 self.set_handlers[typekey] = handler

 def set_content(self, msg, obj, *args, **kw):
 if msg.get_content_maintype() == 'multipart':
 # XXX: is this error a good idea or not? We can remove it later,
 # but we can't add it later, so do it for now.
 raise TypeError("set_content not valid on multipart")
 handler = self._find_set_handler(msg, obj)
 msg.clear_content()
 handler(msg, obj, *args, **kw)

 def _find_set_handler(self, msg, obj):
 full_path_for_error = None
 for typ in type(obj).__mro__:
 if typ in self.set_handlers:
 return self.set_handlers[typ]
 qname = typ.__qualname__
 modname = getattr(typ, '__module__', '')
 full_path = '.'.join((modname, qname)) if modname else qname
 if full_path_for_error is None:
 full_path_for_error = full_path
 if full_path in self.set_handlers:
 return self.set_handlers[full_path]
 if qname in self.set_handlers:
 return self.set_handlers[qname]
 name = typ.__name__
 if name in self.set_handlers:
 return self.set_handlers[name]
 if None in self.set_handlers:
 return self.set_handlers[None]
 raise KeyError(full_path_for_error)


raw_data_manager = ContentManager()


def get_text_content(msg, errors='replace'):
 content = msg.get_payload(decode=True)
 charset = msg.get_param('charset', 'ASCII')
 return content.decode(charset, errors=errors)
raw_data_manager.add_get_handler('text', get_text_content)


def get_non_text_content(msg):
 return msg.get_payload(decode=True)
for maintype in 'audio image video application'.split():
 raw_data_manager.add_get_handler(maintype, get_non_text_content)


def get_message_content(msg):
 return msg.get_payload(0)
for subtype in 'rfc822 external-body'.split():
 raw_data_manager.add_get_handler('message/'+subtype, get_message_content)


def get_and_fixup_unknown_message_content(msg):
 # If we don't understand a message subtype, we are supposed to treat it as
 # if it were application/octet-stream, per
 # tools.ietf.org/html/rfc2046#section-5.2.4. Feedparser doesn't do that,
 # so do our best to fix things up. Note that it is *not* appropriate to
 # model message/partial content as Message objects, so they are handled
 # here as well. (How to reassemble them is out of scope for this comment :)
 return bytes(msg.get_payload(0))
raw_data_manager.add_get_handler('message',
 get_and_fixup_unknown_message_content)


def _prepare_set(msg, maintype, subtype, headers):
 msg['Content-Type'] = '/'.join((maintype, subtype))
 if headers:
 if not hasattr(headers[0], 'name'):
 mp = msg.policy
 headers = [mp.header_factory(*mp.header_source_parse([header]))
 for header in headers]
 try:
 for header in headers:
 if header.defects:
 raise header.defects[0]
 msg[header.name] = header
 except email.errors.HeaderDefect as exc:
 raise ValueError("Invalid header: {}".format(
 header.fold(policy=msg.policy))) from exc


def _finalize_set(msg, disposition, filename, cid, params):
 if disposition is None and filename is not None:
 disposition = 'attachment'
 if disposition is not None:
 msg['Content-Disposition'] = disposition
 if filename is not None:
 msg.set_param('filename',
 filename,
 header='Content-Disposition',
 replace=True)
 if cid is not None:
 msg['Content-ID'] = cid
 if params is not None:
 for key, value in params.items():
 msg.set_param(key, value)


# XXX: This is a cleaned-up version of base64mime.body_encode (including a bug
# fix in the calculation of unencoded_bytes_per_line). It would be nice to
# drop both this and quoprimime.body_encode in favor of enhanced binascii
# routines that accepted a max_line_length parameter.
def _encode_base64(data, max_line_length):
 encoded_lines = []
 unencoded_bytes_per_line = max_line_length // 4 * 3
 for i in range(0, len(data), unencoded_bytes_per_line):
 thisline = data[i:i+unencoded_bytes_per_line]
 encoded_lines.append(binascii.b2a_base64(thisline).decode('ascii'))
 return ''.join(encoded_lines)


def _encode_text(string, charset, cte, policy):
 lines = string.encode(charset).splitlines()
 linesep = policy.linesep.encode('ascii')
 def embedded_body(lines): return linesep.join(lines) + linesep
 def normal_body(lines): return b'\n'.join(lines) + b'\n'
 if cte==None:
 # Use heuristics to decide on the "best" encoding.
 try:
 return '7bit', normal_body(lines).decode('ascii')
 except UnicodeDecodeError:
 pass
 if (policy.cte_type == '8bit' and
 max(len(x) for x in lines) <= policy.max_line_length):
 return '8bit', normal_body(lines).decode('ascii', 'surrogateescape')
 sniff = embedded_body(lines[:10])
 sniff_qp = quoprimime.body_encode(sniff.decode('latin-1'),
 policy.max_line_length)
 sniff_base64 = binascii.b2a_base64(sniff)
 # This is a little unfair to qp; it includes lineseps, base64 doesn't.
 if len(sniff_qp) > len(sniff_base64):
 cte = 'base64'
 else:
 cte = 'quoted-printable'
 if len(lines) <= 10:
 return cte, sniff_qp
 if cte == '7bit':
 data = normal_body(lines).decode('ascii')
 elif cte == '8bit':
 data = normal_body(lines).decode('ascii', 'surrogateescape')
 elif cte == 'quoted-printable':
 data = quoprimime.body_encode(normal_body(lines).decode('latin-1'),
 policy.max_line_length)
 elif cte == 'base64':
 data = _encode_base64(embedded_body(lines), policy.max_line_length)
 else:
 raise ValueError("Unknown content transfer encoding {}".format(cte))
 return cte, data


def set_text_content(msg, string, subtype="plain", charset='utf-8', cte=None,
 disposition=None, filename=None, cid=None,
 params=None, headers=None):
 _prepare_set(msg, 'text', subtype, headers)
 cte, payload = _encode_text(string, charset, cte, msg.policy)
 msg.set_payload(payload)
 msg.set_param('charset',
 email.charset.ALIASES.get(charset, charset),
 replace=True)
 msg['Content-Transfer-Encoding'] = cte
 _finalize_set(msg, disposition, filename, cid, params)
raw_data_manager.add_set_handler(str, set_text_content)


def set_message_content(msg, message, subtype="rfc822", cte=None,
 disposition=None, filename=None, cid=None,
 params=None, headers=None):
 if subtype == 'partial':
 raise ValueError("message/partial is not supported for Message objects")
 if subtype == 'rfc822':
 if cte not in (None, '7bit', '8bit', 'binary'):
 # http://tools.ietf.org/html/rfc2046#section-5.2.1 mandate.
 raise ValueError(
 "message/rfc822 parts do not support cte={}".format(cte))
 # 8bit will get coerced on serialization if policy.cte_type='7bit'. We
 # may end up claiming 8bit when it isn't needed, but the only negative
 # result of that should be a gateway that needs to coerce to 7bit
 # having to look through the whole embedded message to discover whether
 # or not it actually has to do anything.
 cte = '8bit' if cte is None else cte
 elif subtype == 'external-body':
 if cte not in (None, '7bit'):
 # http://tools.ietf.org/html/rfc2046#section-5.2.3 mandate.
 raise ValueError(
 "message/external-body parts do not support cte={}".format(cte))
 cte = '7bit'
 elif cte is None:
 # http://tools.ietf.org/html/rfc2046#section-5.2.4 says all future
 # subtypes should be restricted to 7bit, so assume that.
 cte = '7bit'
 _prepare_set(msg, 'message', subtype, headers)
 msg.set_payload([message])
 msg['Content-Transfer-Encoding'] = cte
 _finalize_set(msg, disposition, filename, cid, params)
raw_data_manager.add_set_handler(email.message.Message, set_message_content)


def set_bytes_content(msg, data, maintype, subtype, cte='base64',
 disposition=None, filename=None, cid=None,
 params=None, headers=None):
 _prepare_set(msg, maintype, subtype, headers)
 if cte == 'base64':
 data = _encode_base64(data, max_line_length=msg.policy.max_line_length)
 elif cte == 'quoted-printable':
 # XXX: quoprimime.body_encode won't encode newline characters in data,
 # so we can't use it. This means max_line_length is ignored. Another
 # bug to fix later. (Note: encoders.quopri is broken on line ends.)
 data = binascii.b2a_qp(data, istext=False, header=False, quotetabs=True)
 data = data.decode('ascii')
 elif cte == '7bit':
 # Make sure it really is only ASCII. The early warning here seems
 # worth the overhead...if you care write your own content manager :).
 data.encode('ascii')
 elif cte in ('8bit', 'binary'):
 data = data.decode('ascii', 'surrogateescape')
 msg.set_payload(data)
 msg['Content-Transfer-Encoding'] = cte
 _finalize_set(msg, disposition, filename, cid, params)
for typ in (bytes, bytearray, memoryview):
 raw_data_manager.add_set_handler(typ, set_bytes_content)