#
# Copyright (c) 2014 ThoughtWorks, Inc.
#
# Pixelated is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Pixelated is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PCULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with Pixelated. If not, see <http://www.gnu.org/licenses/>.
import json
import os
import re
import logging
import dateutil.parser as dateparser
from uuid import uuid4
from email import message_from_file
from email.mime.text import MIMEText
from email.header import decode_header
from email.MIMEMultipart import MIMEMultipart
from pycryptopp.hash import sha256
from leap.mail.adaptors import soledad_indexes as fields
import leap.mail.walk as walk
from pixelated.adapter.model.status import Status
from pixelated.support import date
from pixelated.support.functional import compact


logger = logging.getLogger(__name__)

TYPE_KEY = 'type'
CONTENT_HASH_KEY = 'chash'
HEADERS_KEY = 'headers'
DATE_KEY = 'date'
SUBJECT_KEY = 'subject'
PARTS_MAP_KEY = 'part_map'
BODY_KEY = 'body'
MSGID_KEY = 'msgid'
MULTIPART_KEY = 'multi'
SIZE_KEY = 'size'


class Mail(object):
    @property
    def to(self):
        return self.headers['To']

    @property
    def cc(self):
        return self.headers['Cc']

    @property
    def bcc(self):
        return self.headers['Bcc']

    @property
    def date(self):
        return self.headers['Date']

    @property
    def status(self):
        return Status.from_flags(self.flags)

    @property
    def flags(self):
        return self.fdoc.content.get('flags')

    @property
    def mailbox_name(self):
        # FIXME mbox is no longer available, instead we now have mbox_uuid
        return self.fdoc.content.get('mbox_uuid')

    @property
    def _mime_multipart(self):
        if self._mime:
            return self._mime
        mime = MIMEMultipart()
        for key, value in self.headers.items():
            mime[str(key)] = str(value)

        try:
            body_to_use = self.body
        except AttributeError:
            body_to_use = self.text_plain_body

        mime.attach(MIMEText(body_to_use, 'plain', self._charset()))
        self._mime = mime
        return mime

    def _charset(self):
        if 'content_type' in self.headers and 'charset' in self.headers['content_type']:
            return self._parse_charset_header(self.headers['content_type'])
        else:
            return 'utf-8'

    def _parse_charset_header(self, charset_header, default_charset='utf-8'):
        try:
            return re.compile('.*charset=([a-zA-Z0-9-]+)', re.MULTILINE | re.DOTALL).match(charset_header).group(1)
        except:
            return default_charset

    @property
    def raw(self):
        return self._mime_multipart.as_string()

    def _get_chash(self):
        return sha256.SHA256(self.raw).hexdigest()


class InputMail(Mail):
    FROM_EMAIL_ADDRESS = None

    def __init__(self):
        self._raw_message = None
        self._fd = None
        self._hd = None
        self._bd = None
        self._chash = None
        self._mime = None
        self.headers = {}
        self.body = ''
        self._status = []

    @property
    def ident(self):
        return self._get_chash()

    def get_for_save(self, next_uid, mailbox):
        docs = [self._fdoc(next_uid, mailbox), self._hdoc()]
        docs.extend([m for m in self._cdocs()])
        return docs

    def _fdoc(self, next_uid, mailbox):
        if self._fd:
            return self._fd

        fd = {}
        fd[fields.MBOX] = mailbox
        fd[fields.MBOX_UUID] = next_uid
        fd[fields.CONTENT_HASH] = self._get_chash()
        fd[SIZE_KEY] = len(self.raw)
        fd[MULTIPART_KEY] = True
        fd[fields.RECENT] = True
        fd[fields.TYPE] = fields.FLAGS
        fd[fields.FLAGS] = Status.to_flags(self._status)
        self._fd = fd
        return fd

    def _get_body_phash(self):
        return walk.get_body_phash(self._mime_multipart)

    def _hdoc(self):
        if self._hd:
            return self._hd

        # InputMail does not have a from header but we need it when persisted into soledad.
        headers = self.headers.copy()
        headers['From'] = InputMail.FROM_EMAIL_ADDRESS

        hd = {}
        hd[HEADERS_KEY] = headers
        hd[DATE_KEY] = headers['Date']
        hd[CONTENT_HASH_KEY] = self._get_chash()
        hd[MSGID_KEY] = ''
        hd[MULTIPART_KEY] = True
        hd[SUBJECT_KEY] = headers.get('Subject')
        hd[TYPE_KEY] = fields.HEADERS
        hd[BODY_KEY] = self._get_body_phash()
        hd[PARTS_MAP_KEY] = \
            walk.walk_msg_tree(walk.get_parts(self._mime_multipart), body_phash=self._get_body_phash())['part_map']

        self._hd = hd
        return hd

    def _cdocs(self):
        return walk.get_raw_docs(self._mime_multipart, self._mime_multipart.walk())

    def to_mime_multipart(self):
        mime_multipart = MIMEMultipart()

        for header in ['To', 'Cc', 'Bcc']:
            if self.headers[header]:
                mime_multipart[header] = ", ".join(self.headers[header])

        if self.headers['Subject']:
            mime_multipart['Subject'] = self.headers['Subject']

        mime_multipart['Date'] = self.headers['Date']
        if type(self.body) is list:
            for part in self.body:
                mime_multipart.attach(MIMEText(part['raw'], part['content-type']))
        else:
            mime_multipart.attach(MIMEText(self.body, 'plain', 'utf-8'))
        return mime_multipart

    def to_smtp_format(self):
        mime_multipart = self.to_mime_multipart()
        mime_multipart['From'] = InputMail.FROM_EMAIL_ADDRESS
        return mime_multipart.as_string()

    @staticmethod
    def delivery_error_template(delivery_address):
        return InputMail.from_dict({
            'body': "Mail undelivered for %s" % delivery_address,
            'header': {
                'bcc': [],
                'cc': [],
                'subject': "Mail undelivered for %s" % delivery_address
            }
        })

    @staticmethod
    def from_dict(mail_dict):
        input_mail = InputMail()
        input_mail.headers = {key.capitalize(): value for key, value in mail_dict.get('header', {}).items()}

        # XXX this is overriding the property in PixelatedMail
        input_mail.headers['Date'] = date.iso_now()

        # XXX this is overriding the property in PixelatedMail
        input_mail.body = mail_dict.get('body', '')

        # XXX this is overriding the property in the PixelatedMail
        input_mail.tags = set(mail_dict.get('tags', []))

        input_mail._status = set(mail_dict.get('status', []))
        return input_mail

    @staticmethod
    def from_python_mail(mail):
        input_mail = InputMail()
        input_mail.headers = {key.capitalize(): value for key, value in mail.items()}
        input_mail.headers['Date'] = date.iso_now()
        input_mail.headers['Subject'] = mail['Subject']
        input_mail.headers['To'] = InputMail.FROM_EMAIL_ADDRESS
        input_mail._mime = MIMEMultipart()
        for payload in mail.get_payload():
            input_mail._mime.attach(payload)
            if payload.get_content_type() == 'text/plain':
                input_mail.body = payload.as_string()
        return input_mail


class PixelatedMail(Mail):

    @staticmethod
    def from_soledad(fdoc, hdoc, bdoc, parts=None, soledad_querier=None):
        mail = PixelatedMail()
        mail.parts = parts
        mail.boundary = str(uuid4()).replace('-', '')
        mail.bdoc = bdoc
        mail.fdoc = fdoc
        mail.hdoc = hdoc
        mail.querier = soledad_querier
        mail._mime = None
        return mail

    def _decode_part(self, part):
        encoding = part['headers'].get('Content-Transfer-Encoding', '')
        content_type = self._parse_charset_header(part['headers'].get('Content-Type'))

        try:
            decoding_func = self._decoding_function_for_encoding(encoding)
            return self._decode_content_with_fallback(part['content'], decoding_func, content_type)
        except Exception:
            logger.error('Failed to decode mail part with:')
            logger.error('Content-Transfer-Encoding: %s' % encoding)
            logger.error('Content-Type: %s' % part['headers'].get('Content-Type'))
            raise

    def _decoding_function_for_encoding(self, encoding):
        decoding_map = {
            'quoted-printable': lambda content, content_type: content.decode('quopri').decode(content_type),
            'base64': lambda content, content_type: content.decode('base64').decode('utf-8'),
            '7bit': lambda content, content_type: content.encode(content_type),
            '8bit': lambda content, content_type: content.encode(content_type)
        }
        if encoding in decoding_map:
            return decoding_map[encoding]
        else:
            return decoding_map['8bit']

    def _decode_content_with_fallback(self, content, decode_func, content_type):
        try:
            return decode_func(content, content_type)
            # return content.encode(content_type)
        except ValueError:
            return content.encode('ascii', 'ignore')

    @property
    def alternatives(self):
        return self.parts.get('alternatives')

    @property
    def text_plain_body(self):
        if self.parts and len(self.alternatives) >= 1:
            return self._decode_part(self.alternatives[0])
        else:
            return self.bdoc.content['raw']  # plain

    @property
    def html_body(self):
        if self.parts and len(self.alternatives) > 1:
            html_parts = [e for e in self.alternatives if re.match('text/html', e['headers'].get('Content-Type', ''))]
            if len(html_parts):
                return self._decode_part(html_parts[0])

    @property
    def headers(self):
        _headers = {
            'To': [],
            'Cc': [],
            'Bcc': []
        }
        hdoc_headers = self.hdoc.content['headers']

        for header in ['To', 'Cc', 'Bcc']:
            header_value = self._decode_header(hdoc_headers.get(header))
            if not header_value:
                continue
            _headers[header] = header_value if type(header_value) is list else header_value.split(',')
            _headers[header] = [head.strip() for head in compact(_headers[header])]

        for header in ['From', 'Subject']:
            _headers[header] = self._decode_header(hdoc_headers.get(header))

        try:
            _headers['Date'] = self._get_date()
        except Exception:
            _headers['Date'] = date.iso_now()

        if self.parts and len(self.parts['alternatives']) > 1:
            _headers['content_type'] = 'multipart/alternative; boundary="%s"' % self.boundary
        elif self.hdoc.content['headers'].get('Content-Type'):
            _headers['content_type'] = hdoc_headers.get('Content-Type')

        if hdoc_headers.get('Reply-To'):
            _headers['Reply-To'] = hdoc_headers.get('Reply-To')

        return _headers

    def _decode_header_with_fallback(self, entry):
        try:
            return decode_header(entry)[0][0]
        except Exception:
            return entry.encode('ascii', 'ignore')

    def _decode_header(self, header):
        if not header:
            return None
        if isinstance(header, list):
            return [self._decode_header_with_fallback(entry) for entry in header]
        else:
            return self._decode_header_with_fallback(header)

    def _get_date(self):
        date = self.hdoc.content.get('date', None)
        try:
            if not date:
                received = self.hdoc.content.get('received', None)
                if received:
                        date = received.split(";")[-1].strip()
                else:
                    # we can't get a date for this mail, so lets just use now
                    logger.warning('Encountered a mail with missing date and received header fields. ID %s' % self.fdoc.content.get('uid', None))
                    date = date.iso_now()
            return dateparser.parse(date).isoformat()
        except (ValueError, TypeError):
            date = date.iso_now()
            return dateparser.parse(date).isoformat()

    @property
    def security_casing(self):
        casing = {"imprints": [], "locks": []}
        casing["imprints"] = self.signature_information
        if self.encrypted == "true":
            casing["locks"] = [{"state": "valid"}]
        elif self.encrypted == "fail":
            casing["locks"] = [{"state": "failure"}]
        return casing

    @property
    def tags(self):
        _tags = self.fdoc.content.get('tags', '[]')
        return set(_tags) if type(_tags) is list or type(_tags) is set else set(json.loads(_tags))

    @property
    def ident(self):
        return self.fdoc.content.get('chash')

    @property
    def mailbox_name(self):
        # FIXME mbox is no longer available, instead we now have mbox_uuid
        return self.fdoc.content.get('mbox_uuid')

    @property
    def is_recent(self):
        return Status('recent') in self.status

    @property
    def uid(self):
        return self.fdoc.content['uid']

    @property
    def flags(self):
        return self.fdoc.content['flags']

    def save(self):
        return self.querier.save_mail(self)

    def set_mailbox(self, mailbox_name):
        self.fdoc.content['mbox'] = mailbox_name

    def remove_all_tags(self):
        self.update_tags(set([]))

    def update_tags(self, tags):
        self._persist_mail_tags(tags)
        return self.tags

    def mark_as_read(self):
        if Status.SEEN in self.flags:
            return self
        self.flags.append(Status.SEEN)
        self.save()
        return self

    def mark_as_unread(self):
        if Status.SEEN in self.flags:
            self.flags.remove(Status.SEEN)
            self.save()
        return self

    def mark_as_not_recent(self):
        if Status.RECENT in self.flags:
            self.flags.remove(Status.RECENT)
            self.save()
        return self

    def _persist_mail_tags(self, current_tags):
        self.fdoc.content['tags'] = json.dumps(list(current_tags))
        self.save()

    def has_tag(self, tag):
        return tag in self.tags

    @property
    def signature_information(self):
        signature = self.hdoc.content["headers"].get("X-Leap-Signature", None)
        if signature is None or signature.startswith("could not verify"):
            return [{"state": "no_signature_information"}]
        else:
            if signature.startswith("valid"):
                return [{"state": "valid", "seal": {"validity": "valid"}}]
            else:
                return []

    @property
    def encrypted(self):
        return self.hdoc.content["headers"].get("X-Pixelated-encryption-status", "false")

    @property
    def bounced(self):
        content_type = self.hdoc.content["headers"].get("Content-Type", '')
        if re.compile('delivery-status').search(content_type):
            bounce_recipient = self._extract_bounced_address(self.hdoc.content)
            bounce_daemon = self.headers["From"]
            return [bounce_recipient, bounce_daemon] if bounce_recipient else False

        return False

    def _extract_bounced_address(self, part):
        part_header = dict(part.get('headers', {}))
        if 'Final-Recipient' in part_header:
            if self._bounce_permanent(part_header):
                return part_header['Final-Recipient'].split(';')[1].strip()
            else:
                return False
        elif 'part_map' in part:
            for subpart in part['part_map'].values():
                result = self._extract_bounced_address(subpart)
                if result:
                    return result
                else:
                    continue
        return False

    def _bounce_permanent(self, part_headers):
        status = part_headers.get('Status', '')
        return status.startswith('5')

    def as_dict(self):
        dict_mail = {'header': {k.lower(): v for k, v in self.headers.items()},
                     'ident': self.ident,
                     'tags': list(self.tags),
                     'status': list(self.status),
                     'security_casing': self.security_casing,
                     'textPlainBody': self.text_plain_body,
                     'htmlBody': self.html_body,
                     'mailbox': self.mailbox_name.lower(),
                     'attachments': self.parts['attachments'] if self.parts else []}
        dict_mail['replying'] = {'single': None, 'all': {'to-field': [], 'cc-field': []}}

        sender_mail = self.headers.get('Reply-To', self.headers.get('From'))
        # Issue #215: Fix for existing mails without any from address.
        if sender_mail is None:
            sender_mail = InputMail.FROM_EMAIL_ADDRESS

        recipients = [recipient for recipient in self.headers['To'] if recipient != InputMail.FROM_EMAIL_ADDRESS]
        recipients.append(sender_mail)
        ccs = [cc for cc in self.headers['Cc'] if cc != InputMail.FROM_EMAIL_ADDRESS]

        dict_mail['replying']['single'] = sender_mail
        dict_mail['replying']['all']['to-field'] = recipients
        dict_mail['replying']['all']['cc-field'] = ccs
        return dict_mail


def welcome_mail():
    current_path = os.path.dirname(os.path.abspath(__file__))
    with open(os.path.join(current_path, '..', '..', 'assets', 'welcome.mail')) as mail_template_file:
        mail_template = message_from_file(mail_template_file)
    return InputMail.from_python_mail(mail_template)