# Copyright The IETF Trust 2010-2019, All Rights Reserved

import datetime
import email.utils
import email.header
import six
import uuid

from hashids import Hashids
from urllib.parse import urljoin

from django.conf import settings

from django.core.validators import validate_email
from django.core.exceptions import ObjectDoesNotExist
from django.db import models
from django.contrib.auth.models import User
from django.template.loader import render_to_string
from django.utils.encoding import smart_bytes
from django.utils.text import slugify
from simple_history.models import HistoricalRecords

import debug                            # pyflakes:ignore

from ietf.person.name import name_parts, initials, plain_name
from ietf.utils.mail import send_mail_preformatted
from ietf.utils.storage import NoLocationMigrationFileSystemStorage
from ietf.utils.mail import formataddr
from ietf.person.name import unidecode_name
from ietf.utils import log
from ietf.utils.models import ForeignKey, OneToOneField


class Person(models.Model):
    history = HistoricalRecords()
    user = OneToOneField(User, blank=True, null=True, on_delete=models.SET_NULL)
    time = models.DateTimeField(default=datetime.datetime.now)      # When this Person record entered the system
    # The normal unicode form of the name.  This must be
    # set to the same value as the ascii-form if equal.
    name = models.CharField("Full Name (Unicode)", max_length=255, db_index=True, help_text="Preferred form of name.")
    # The normal ascii-form of the name.
    ascii = models.CharField("Full Name (ASCII)", max_length=255, help_text="Name as rendered in ASCII (Latin, unaccented) characters.")
    # The short ascii-form of the name.  Also in alias table if non-null
    ascii_short = models.CharField("Abbreviated Name (ASCII)", max_length=32, null=True, blank=True, help_text="Example: A. Nonymous.  Fill in this with initials and surname only if taking the initials and surname of the ASCII name above produces an incorrect initials-only form. (Blank is OK).")
    biography = models.TextField(blank=True, help_text="Short biography for use on leadership pages. Use plain text or reStructuredText markup.")
    photo = models.ImageField(storage=NoLocationMigrationFileSystemStorage(), upload_to=settings.PHOTOS_DIRNAME, blank=True, default=None)
    photo_thumb = models.ImageField(storage=NoLocationMigrationFileSystemStorage(), upload_to=settings.PHOTOS_DIRNAME, blank=True, default=None)
    name_from_draft = models.CharField("Full Name (from submission)", null=True, max_length=255, editable=False, help_text="Name as found in a draft submission.")
    consent = models.NullBooleanField("I hereby give my consent to the use of the personal details I have provided (photo, bio, name, email) within the IETF Datatracker", null=True, default=None)

    def __str__(self):
        return self.plain_name()
    def name_parts(self):
        return name_parts(self.name)
    def ascii_parts(self):
        return name_parts(self.ascii)
    def short(self):
        if self.ascii_short:
            return self.ascii_short
        else:
            prefix, first, middle, last, suffix = self.ascii_parts()
            return (first and first[0]+"." or "")+(middle or "")+" "+last+(suffix and " "+suffix or "")
    def plain_name(self):
        if not hasattr(self, '_cached_plain_name'):
            self._cached_plain_name = plain_name(self.name)
        return self._cached_plain_name
    def ascii_name(self):
        if not hasattr(self, '_cached_ascii_name'):
            if self.ascii:
                # It's possibly overkill with unidecode() here, but needed until
                # we're validating the content of the ascii field, and have
                # verified that the field is ascii clean in the database:
                if not all(ord(c) < 128 for c in self.ascii):
                    self._cached_ascii_name = unidecode_name(self.ascii)
                else:
                    self._cached_ascii_name = self.ascii
            else:
                self._cached_ascii_name = unidecode_name(self.plain_name())
        return self._cached_ascii_name
    def plain_ascii(self):
        if not hasattr(self, '_cached_plain_ascii'):
            if self.ascii:
                ascii = unidecode_name(self.ascii)
            else:
                ascii = unidecode_name(self.name)
            prefix, first, middle, last, suffix = name_parts(ascii)
            self._cached_plain_ascii = " ".join([first, last])
        return self._cached_plain_ascii
    def initials(self):
        return initials(self.ascii or self.name)
    def last_name(self):
        return name_parts(self.name)[3]
    def first_name(self):
        return name_parts(self.name)[1]
    def role_email(self, role_name, group=None):
        """Lookup email for role for person, optionally on group which
        may be an object or the group acronym."""
        if group:
            from ietf.group.models import Group
            if isinstance(group, str) or isinstance(group, str):
                group = Group.objects.get(acronym=group)
            e = Email.objects.filter(person=self, role__group=group, role__name=role_name)
        else:
            e = Email.objects.filter(person=self, role__group__state="active", role__name=role_name)
        if e:
            return e[0]
        # no cigar, try the complete set before giving up
        e = self.email_set.order_by("-active", "-time")
        if e:
            return e[0]
        return None
    def email(self):
        if not hasattr(self, '_cached_email'):
            e = self.email_set.filter(primary=True).first()
            if not e:
                e = self.email_set.filter(active=True).order_by("-time").first()
            self._cached_email = e
        return self._cached_email
    def email_address(self):
        e = self.email()
        if e:
            return e.address
        else:
            return ""
    def formatted_ascii_email(self):
        e = self.email_set.filter(primary=True).first()
        if not e or not e.active:
            e = self.email_set.order_by("-active", "-time").first()
        if e:
            return e.formatted_ascii_email()
        else:
            return ""
    def formatted_email(self):
        e = self.email_set.filter(primary=True).first()
        if not e or not e.active:
            e = self.email_set.order_by("-active", "-time").first()
        if e:
            return e.formatted_email()
        else:
            return ""
    def full_name_as_key(self):
        # this is mostly a remnant from the old views, needed in the menu
        return self.plain_name().lower().replace(" ", ".")

    def photo_name(self,thumb=False):
        hasher = Hashids(salt='Person photo name salt',min_length=5)
        _, first, _, last, _ = name_parts(self.ascii)
        return '%s-%s%s' % ( slugify("%s %s" % (first, last)), hasher.encode(self.id), '-th' if thumb else '' )

    def has_drafts(self):
        from ietf.doc.models import Document
        return Document.objects.filter(documentauthor__person=self, type='draft').exists()

    def rfcs(self):
        from ietf.doc.models import Document
        rfcs = list(Document.objects.filter(documentauthor__person=self, type='draft', states__slug='rfc'))
        rfcs.sort(key=lambda d: d.canonical_name() )
        return rfcs

    def active_drafts(self):
        from ietf.doc.models import Document
        return Document.objects.filter(documentauthor__person=self, type='draft', states__slug='active').order_by('-time')

    def expired_drafts(self):
        from ietf.doc.models import Document
        return Document.objects.filter(documentauthor__person=self, type='draft', states__slug__in=['repl', 'expired', 'auth-rm', 'ietf-rm']).order_by('-time')

    def needs_consent(self):
        """
        Returns an empty list or a list of fields which holds information that
        requires consent to be given.
        """
        needs_consent = []
        if self.name != self.name_from_draft:
            needs_consent.append("full name")
        if self.ascii != self.name_from_draft:
            needs_consent.append("ascii name")
        if self.biography and not (self.role_set.exists() or self.rolehistory_set.exists()):
            needs_consent.append("biography")
        if self.user_id:
            needs_consent.append("login")
            try:
                if self.user.communitylist_set.exists():
                    needs_consent.append("draft notification subscription(s)")
            except ObjectDoesNotExist:
                pass
        for email in self.email_set.all():
            if not email.origin.split(':')[0] in ['author', 'role', 'reviewer', 'liaison', 'shepherd', ]:
                needs_consent.append("email address(es)")
                break
        return needs_consent

    def save(self, *args, **kwargs):
        created = not self.pk
        super(Person, self).save(*args, **kwargs)
        if created:
            if Person.objects.filter(name=self.name).count() > 1 :
                msg = render_to_string('person/mail/possible_duplicates.txt',
                                       dict(name=self.name,
                                            persons=Person.objects.filter(name=self.name),
                                            settings=settings
                                            ))
                send_mail_preformatted(None, msg)
        if not self.name in [ a.name for a in self.alias_set.filter(name=self.name) ]:
            self.alias_set.create(name=self.name)
        if self.ascii and self.name != self.ascii:
            if not self.ascii in [ a.name for a in self.alias_set.filter(name=self.ascii) ]:
                self.alias_set.create(name=self.ascii)

    #this variable, if not None, may be used by url() to keep the sitefqdn.
    default_hostscheme = None

    @property
    def defurl(self):
        return urljoin(self.default_hostscheme,self.json_url())

    def json_url(self):
        return "/person/%s.json" % (self.id, )

    # return info about the person
    def json_dict(self, hostscheme):
        ct1 = dict()
        ct1['person_id'] = self.id
        ct1['href']      = urljoin(hostscheme, self.json_url())
        ct1['name']      = self.name
        ct1['ascii']     = self.ascii
        return ct1

class Alias(models.Model):
    """This is used for alternative forms of a name.  This is the
    primary lookup point for names, and should always contain the
    unicode form (and ascii form, if different) of a name which is
    recorded in the Person record.
    """
    person = ForeignKey(Person)
    name = models.CharField(max_length=255, db_index=True)

    def save(self, *args, **kwargs):
        created = not self.pk
        super(Alias, self).save(*args, **kwargs)
        if created:
            if Alias.objects.filter(name=self.name).exclude(person=self.person).count() > 0 :
                msg = render_to_string('person/mail/possible_duplicates.txt',
                                       dict(name=self.name,
                                            persons=Person.objects.filter(alias__name=self.name).distinct(),
                                            settings=settings
                                            ))
                send_mail_preformatted(None, msg)


    def __str__(self):
        return self.name
    class Meta:
        verbose_name_plural = "Aliases"

class Email(models.Model):
    history = HistoricalRecords()
    address = models.CharField(max_length=64, primary_key=True, validators=[validate_email])
    person = ForeignKey(Person, null=True)
    time = models.DateTimeField(auto_now_add=True)
    primary = models.BooleanField(default=False)
    origin = models.CharField(max_length=150, blank=False, help_text="The origin of the address: the user's email address, or 'author: DRAFTNAME' if a draft, or 'role: GROUP/ROLE' if a role.")       # User.username or Document.name
    active = models.BooleanField(default=True)      # Old email addresses are *not* purged, as history
                                                    # information points to persons through these

    def __str__(self):
        return self.address or "Email object with id: %s"%self.pk

    def get_name(self):
        return self.person.plain_name() if self.person else self.address

    def formatted_ascii_email(self):
        if self.person:
                return email.utils.formataddr((self.person.plain_ascii(), self.address))
        else:
            return self.address

    def name_and_email(self):
        """
        Returns name and email, e.g.: u'Ano Nymous <ano@nymous.org>'
        Is intended for display use, not in email context.
        Use self.formatted_email() for that.
        """
        if self.person:
            return "%s <%s>" % (self.person.plain_name(), self.address)
        else:
            return "<%s>" % self.address

    def formatted_email(self):
        """
        Similar to name_and_email(), but with email header-field
        encoded words (RFC 2047) and quotes as needed.
        """
        if self.person:
            return formataddr((self.person.plain_name(), self.address))
        else:
            return self.address

    def email_address(self):
        """Get valid, current email address; in practise, for active,
        non-invalid addresses it is just the address field. In other
        cases, we default to person's email address."""
        if not self.active:
            if self.person:
                return self.person.email_address()
            return
        return self.address

    def save(self, *args, **kwargs):
        if not self.origin:
            log.assertion('self.origin')
        super(Email, self).save(*args, **kwargs)

# "{key.id}{salt}{hash}
KEY_STRUCT = "i12s32s"

def salt():
    return uuid.uuid4().bytes[:12]

# Manual maintenance: List all endpoints that use @require_api_key here
PERSON_API_KEY_ENDPOINTS = [
    ("/api/iesg/position", "/api/iesg/position"),
    ("/api/v2/person/person", "/api/v2/person/person"),
    ("/api/meeting/session/video/url", "/api/meeting/session/video/url"),
]

class PersonalApiKey(models.Model):
    person   = ForeignKey(Person, related_name='apikeys')
    endpoint = models.CharField(max_length=128, null=False, blank=False, choices=PERSON_API_KEY_ENDPOINTS)
    created  = models.DateTimeField(default=datetime.datetime.now, null=False)
    valid    = models.BooleanField(default=True)
    salt     = models.BinaryField(default=salt, max_length=12, null=False, blank=False)
    count    = models.IntegerField(default=0, null=False, blank=False)
    latest   = models.DateTimeField(blank=True, null=True)

    @classmethod
    def validate_key(cls, s):
        import struct, hashlib, base64
        try:
            key = base64.urlsafe_b64decode(s)
        except TypeError as e:
            return None

        id, salt, hash = struct.unpack(KEY_STRUCT, key)
        k = cls.objects.filter(id=id)
        if not k.exists():
            return None
        k = k.first()
        check = hashlib.sha256()
        for v in (str(id), str(k.person.id), k.created.isoformat(), k.endpoint, str(k.valid), salt, settings.SECRET_KEY):
            v = smart_bytes(v)
            check.update(v)
        return k if check.digest() == hash else None

    def hash(self):
        import struct, hashlib, base64
        if not hasattr(self, '_cached_hash'):
            hash = hashlib.sha256()
            # Hash over: ( id, person, created, endpoint, valid, salt, secret )
            for v in (str(self.id), str(self.person.id), self.created.isoformat(), self.endpoint, str(self.valid), self.salt, settings.SECRET_KEY):
                v = smart_bytes(v)
                hash.update(v)
            key = struct.pack(KEY_STRUCT, self.id, six.binary_type(self.salt), hash.digest())
            self._cached_hash =  base64.urlsafe_b64encode(key).decode('ascii')
        return self._cached_hash

    def __str__(self):
        return "%s (%s): %s ..." % (self.endpoint, self.created.strftime("%Y-%m-%d %H:%M"), self.hash()[:16])

PERSON_EVENT_CHOICES = [
    ("apikey_login", "API key login"),
    ("gdpr_notice_email", "GDPR consent request email sent"),
    ("email_address_deactivated", "Email address deactivated"),
    ]

class PersonEvent(models.Model):
    person = ForeignKey(Person)
    time = models.DateTimeField(default=datetime.datetime.now, help_text="When the event happened")
    type = models.CharField(max_length=50, choices=PERSON_EVENT_CHOICES)
    desc = models.TextField()

    def __str__(self):
        return "%s %s at %s" % (self.person.plain_name(), self.get_type_display().lower(), self.time)

    class Meta:
        ordering = ['-time', '-id']

class PersonApiKeyEvent(PersonEvent):
    key = ForeignKey(PersonalApiKey)