import os
import re
import urllib
import math
import datetime

from django.conf import settings
from django.db.models import Q
from django.db.models.query import EmptyQuerySet
from django.forms import ValidationError
from django.utils.html import strip_tags, escape

from ietf.doc.models import Document, DocHistory, State
from ietf.doc.models import DocAlias, RelatedDocument, BallotType, DocReminder
from ietf.doc.models import DocEvent, BallotDocEvent, NewRevisionDocEvent, StateDocEvent
from ietf.doc.models import save_document_in_history, STATUSCHANGE_RELATIONS
from ietf.name.models import DocReminderTypeName, DocRelationshipName
from ietf.group.models import Role
from ietf.person.models import Email
from ietf.ietfauth.utils import has_role
from ietf.utils import draft, markup_txt
from ietf.utils.mail import send_mail

#FIXME - it would be better if this lived in ietf/doc/mails.py, but there's
#        an import order issue to work out.
def email_update_telechat(request, doc, text):
    to = set(['iesg@ietf.org','iesg-secretary@ietf.org'])
    to.update(set([x.strip() for x in doc.notify.replace(';', ',').split(',')]))

    if not to:
        return
    
    text = strip_tags(text)
    send_mail(request, list(to), None,
              "Telechat update notice: %s" % doc.file_tag(),
              "doc/mail/update_telechat.txt",
              dict(text=text,
                   url=settings.IDTRACKER_BASE_URL + doc.get_absolute_url()))

def get_state_types(doc):
    res = []

    if not doc:
        return res
    
    res.append(doc.type_id)

    if doc.type_id == "draft":
        if doc.stream_id and doc.stream_id != "legacy":
            res.append("draft-stream-%s" % doc.stream_id)

        res.append("draft-iesg")
        res.append("draft-iana-review")
        res.append("draft-iana-action")
        res.append("draft-rfceditor")
        
    return res

def get_tags_for_stream_id(stream_id):
    if stream_id == "ietf":
        return ["w-expert", "w-extern", "w-merge", "need-aut", "w-refdoc", "w-refing", "rev-wg", "rev-wglc", "rev-ad", "rev-iesg", "sheph-u", "no-adopt", "other"]
    elif stream_id == "iab":
        return ["need-ed", "w-part", "w-review", "need-rev", "sh-f-up"]
    elif stream_id == "irtf":
        return ["need-ed", "need-sh", "w-dep", "need-rev", "iesg-com"]
    elif stream_id == "ise":
        return ["w-dep", "w-review", "need-rev", "iesg-com"]
    else:
        return []

def can_adopt_draft(user, doc):
    if not user.is_authenticated():
        return False

    if has_role(user, "Secretariat"):
        return True

    #The IRTF chair can adopt a draft into any RG
    if has_role(user, "IRTF Chair"):
        return (doc.stream_id in (None, "irtf")
                and doc.group.type_id == "individ")

    return (doc.stream_id in (None, "ietf", "irtf")
            and doc.group.type_id == "individ"
            and Role.objects.filter(name__in=("chair", "delegate", "secr"),
                                    group__type__in=("wg", "rg"),
                                    group__state="active",
                                    person__user=user).exists())


def two_thirds_rule( recused=0 ):
    # For standards-track, need positions from 2/3 of the non-recused current IESG.
    active = Role.objects.filter(name="ad",group__type="area",group__state="active").count()
    return int(math.ceil((active - recused) * 2.0/3.0))

def needed_ballot_positions(doc, active_positions):
    '''Returns text answering the question "what does this document
    need to pass?".  The return value is only useful if the document
    is currently in IESG evaluation.'''
    yes = [p for p in active_positions if p and p.pos_id == "yes"]
    noobj = [p for p in active_positions if p and p.pos_id == "noobj"]
    blocking = [p for p in active_positions if p and p.pos.blocking]
    recuse = [p for p in active_positions if p and p.pos_id == "recuse"]

    answer = []
    if len(yes) < 1:
        answer.append("Needs a YES.")
    if blocking:
        if len(blocking) == 1:
            answer.append("Has a %s." % blocking[0].pos.name.upper())
        else:
            if blocking[0].pos.name.upper().endswith('S'):
                answer.append("Has %d %ses." % (len(blocking), blocking[0].pos.name.upper()))
            else:
                answer.append("Has %d %ss." % (len(blocking), blocking[0].pos.name.upper()))
    needed = 1
    if doc.type_id == "draft" and doc.intended_std_level_id in ("bcp", "ps", "ds", "std"):
        needed = two_thirds_rule(recused=len(recuse))
    elif doc.type_id == "statchg":
        if isinstance(doc,Document):
            related_set = doc.relateddocument_set
        elif isinstance(doc,DocHistory):
            related_set = doc.relateddochistory_set
        else:
            related_set = EmptyQuerySet()
        for rel in related_set.filter(relationship__slug__in=['tops', 'tois', 'tohist', 'toinf', 'tobcp', 'toexp']):
            if (rel.target.document.std_level.slug in ['bcp','ps','ds','std']) or (rel.relationship.slug in ['tops','tois','tobcp']):
                needed = two_thirds_rule(recused=len(recuse))
                break
    else:
        if len(yes) < 1:
            return " ".join(answer)

    have = len(yes) + len(noobj)
    if have < needed:
        more = needed - have
        if more == 1:
            answer.append("Needs one more YES or NO OBJECTION position to pass.")
        else:
            answer.append("Needs %d more YES or NO OBJECTION positions to pass." % more)
    else:
        if blocking:
            answer.append("Has enough positions to pass once %s positions are resolved." % blocking[0].pos.name.upper())
        else:
            answer.append("Has enough positions to pass.")

    return " ".join(answer)
    
def create_ballot_if_not_open(doc, by, ballot_slug, time=None):
    if not doc.ballot_open(ballot_slug):
        if time:
            e = BallotDocEvent(type="created_ballot", by=by, doc=doc, time=time)
        else:
            e = BallotDocEvent(type="created_ballot", by=by, doc=doc)
        e.ballot_type = BallotType.objects.get(doc_type=doc.type, slug=ballot_slug)
        e.desc = u'Created "%s" ballot' % e.ballot_type.name
        e.save()

def close_ballot(doc, by, ballot_slug):
    if doc.ballot_open(ballot_slug):
        e = BallotDocEvent(type="closed_ballot", doc=doc, by=by)
        e.ballot_type = BallotType.objects.get(doc_type=doc.type,slug=ballot_slug)
        e.desc = 'Closed "%s" ballot' % e.ballot_type.name
        e.save()

def close_open_ballots(doc, by):
    for t in BallotType.objects.filter(doc_type=doc.type_id):
        close_ballot(doc, by, t.slug )

def augment_with_start_time(docs):
    """Add a started_time attribute to each document with the time of
    the first revision."""
    docs = list(docs)

    docs_dict = {}
    for d in docs:
        docs_dict[d.pk] = d
        d.start_time = None

    seen = set()

    for e in DocEvent.objects.filter(type="new_revision", doc__in=docs).order_by('time'):
        if e.doc_id in seen:
            continue

        docs_dict[e.doc_id].start_time = e.time
        seen.add(e.doc_id)

    return docs

def get_chartering_type(doc):
    chartering = ""
    if doc.get_state_slug() not in ("notrev", "approved"):
        if doc.group.state_id in ("proposed", "bof"):
            chartering = "initial"
        elif doc.group.state_id == "active":
            chartering = "rechartering"

    return chartering

def augment_events_with_revision(doc, events):
    """Take a set of events for doc and add a .rev attribute with the
    revision they refer to by checking NewRevisionDocEvents."""

    event_revisions = list(NewRevisionDocEvent.objects.filter(doc=doc).order_by('time', 'id').values('id', 'rev', 'time'))

    if doc.type_id == "draft" and doc.get_state_slug() == "rfc":
        # add fake "RFC" revision
        e = doc.latest_event(type="published_rfc")
        if e:
            event_revisions.append(dict(id=e.id, time=e.time, rev="RFC"))
            event_revisions.sort(key=lambda x: (x["time"], x["id"]))

    for e in sorted(events, key=lambda e: (e.time, e.id), reverse=True):
        while event_revisions and (e.time, e.id) < (event_revisions[-1]["time"], event_revisions[-1]["id"]):
            event_revisions.pop()

        if event_revisions:
            cur_rev = event_revisions[-1]["rev"]
        else:
            cur_rev = "00"

        e.rev = cur_rev

def add_links_in_new_revision_events(doc, events, diff_revisions):
    """Add direct .txt links and diff links to new_revision events."""
    prev = None

    diff_urls = dict(((name, revision), url) for name, revision, time, url in diff_revisions)

    for e in sorted(events, key=lambda e: (e.time, e.id)):
        if not e.type == "new_revision":
            continue

        if not (e.doc.name, e.rev) in diff_urls:
            continue

        full_url = diff_url = diff_urls[(e.doc.name, e.rev)]

        if doc.type_id in "draft": # work around special diff url for drafts
            full_url = "https://tools.ietf.org/id/" + diff_url + ".txt"

        # build links
        links = r'<a href="%s">\1</a>' % full_url
        if prev:
            links += ""

        if prev != None:
            links += ' (<a href="%s?url1=%s&url2=%s">diff from previous</a>)' % (settings.RFCDIFF_BASE_URL, urllib.quote(prev, safe="~"), urllib.quote(diff_url, safe="~"))

        # replace the bold filename part
        e.desc = re.sub(r"<b>(.+-[0-9][0-9].txt)</b>", links, e.desc)

        prev = diff_url


def get_document_content(key, filename, split=True, markup=True):
    try:
        with open(filename, 'rb') as f:
            raw_content = f.read()
    except IOError:
        error = "Error; cannot read ("+key+")"
        return error

    if markup:
        return markup_txt.markup(raw_content, split)
    else:
        return raw_content

def add_state_change_event(doc, by, prev_state, new_state, prev_tags=[], new_tags=[], timestamp=None):
    """Add doc event to explain that state change just happened."""
    if prev_state and new_state:
        assert prev_state.type_id == new_state.type_id

    if prev_state == new_state and set(prev_tags) == set(new_tags):
        return None

    def tags_suffix(tags):
        return (u"::" + u"::".join(t.name for t in tags)) if tags else u""

    e = StateDocEvent(doc=doc, by=by)
    e.type = "changed_state"
    e.state_type = (prev_state or new_state).type
    e.state = new_state
    e.desc = "%s changed to <b>%s</b>" % (e.state_type.label, new_state.name + tags_suffix(new_tags))
    if prev_state:
        e.desc += " from %s" % (prev_state.name + tags_suffix(prev_tags))
    if timestamp:
        e.time = timestamp
    e.save()
    return e

def update_reminder(doc, reminder_type_slug, event, due_date):
    reminder_type = DocReminderTypeName.objects.get(slug=reminder_type_slug)

    try:
        reminder = DocReminder.objects.get(event__doc=doc, type=reminder_type, active=True)
    except DocReminder.DoesNotExist:
        reminder = None

    if due_date:
        # activate/update reminder
        if not reminder:
            reminder = DocReminder(type=reminder_type)

        reminder.event = event
        reminder.due = due_date
        reminder.active = True
        reminder.save()
    else:
        # deactivate reminder
        if reminder:
            reminder.active = False
            reminder.save()

def prettify_std_name(n, spacing=" "):
    if re.match(r"(rfc|bcp|fyi|std)[0-9]+", n):
        return n[:3].upper() + spacing + n[3:]
    else:
        return n

def nice_consensus(consensus):
    mapping = {
        None: "Unknown",
        True: "Yes",
        False: "No"
        }
    return mapping[consensus]

def has_same_ballot(doc, date1, date2=datetime.date.today()):
    """ Test if the most recent ballot created before the end of date1
        is the same as the most recent ballot created before the
        end of date 2. """
    ballot1 = doc.latest_event(BallotDocEvent,type='created_ballot',time__lt=date1+datetime.timedelta(days=1))
    ballot2 = doc.latest_event(BallotDocEvent,type='created_ballot',time__lt=date2+datetime.timedelta(days=1))
    return ballot1==ballot2

def make_notify_changed_event(request, doc, by, new_notify, time=None):

    # FOR REVIEW: This preserves the behavior from when
    # drafts and charters had separate edit_notify
    # functions. If it should be unified, there should
    # also be a migration function cause historic
    # events to match
    if doc.type.slug=='charter':
        event_type = 'changed_document'
        save_document_in_history(doc)
    else:
        event_type = 'added_comment'

    e = DocEvent(type=event_type, doc=doc, by=by)
    e.desc = "Notification list changed to %s" % (escape(new_notify) or "none")
    if doc.notify:
        e.desc += " from %s" % escape(doc.notify)
    if time:
        e.time = time
    e.save()

    return e

def update_telechat(request, doc, by, new_telechat_date, new_returning_item=None):
    from ietf.doc.models import TelechatDocEvent
    
    on_agenda = bool(new_telechat_date)

    prev = doc.latest_event(TelechatDocEvent, type="scheduled_for_telechat")
    prev_returning = bool(prev and prev.returning_item)
    prev_telechat = prev.telechat_date if prev else None
    prev_agenda = bool(prev_telechat)

    if new_returning_item == None:
        returning = prev_returning
    else:
        returning = new_returning_item

    if returning == prev_returning and new_telechat_date == prev_telechat:
        # fully updated, nothing to do
        return

    # auto-set returning item _ONLY_ if the caller did not provide a value
    if (     new_returning_item != None
         and on_agenda 
         and prev_agenda
         and new_telechat_date != prev_telechat
         and prev_telechat < datetime.date.today()
         and has_same_ballot(doc,prev.telechat_date)
       ):
        returning = True

    e = TelechatDocEvent()
    e.type = "scheduled_for_telechat"
    e.by = by
    e.doc = doc
    e.returning_item = returning
    e.telechat_date = new_telechat_date
    
    if on_agenda != prev_agenda:
        if on_agenda:
            e.desc = "Placed on agenda for telechat - %s" % (new_telechat_date)
        else:
            e.desc = "Removed from agenda for telechat"
    elif on_agenda and new_telechat_date != prev_telechat:
        e.desc = "Telechat date has been changed to <b>%s</b> from <b>%s</b>" % (
            new_telechat_date, prev_telechat)
    else:
        # we didn't reschedule but flipped returning item bit - let's
        # just explain that
        if returning:
            e.desc = "Set telechat returning item indication"
        else:
            e.desc = "Removed telechat returning item indication"

    e.save()
    email_update_telechat(request, doc, e.desc)

def rebuild_reference_relations(doc,filename=None):
    if doc.type.slug != 'draft':
        return None

    if not filename:
        if doc.get_state_slug() == 'rfc':
            filename=os.path.join(settings.RFC_PATH,doc.canonical_name()+".txt")
        else:
            filename=os.path.join(settings.INTERNET_DRAFT_PATH,doc.filename_with_rev())

    try:
       refs = draft.Draft(draft._gettext(filename), filename).get_refs()
    except IOError as e:
       return { 'errors': ["%s :%s" %  (e.strerror, filename)] }
    
    doc.relateddocument_set.filter(relationship__slug__in=['refnorm','refinfo','refold','refunk']).delete()

    warnings = []
    errors = []
    unfound = set()
    for ( ref, refType ) in refs.iteritems():
        refdoc = DocAlias.objects.filter( name=ref )
        count = refdoc.count()
        if count == 0:
            unfound.add( "%s" % ref )
            continue
        elif count > 1:
            errors.append("Too many DocAlias objects found for %s"%ref)
        else:
            # Don't add references to ourself
            if doc != refdoc[0].document:
                RelatedDocument.objects.get_or_create( source=doc, target=refdoc[ 0 ], relationship=DocRelationshipName.objects.get( slug='ref%s' % refType ) )
    if unfound:
        warnings.append('There were %d references with no matching DocAlias'%len(unfound))

    ret = {}
    if errors:
        ret['errors']=errors 
    if warnings:
        ret['warnings']=warnings 
    if unfound:
        ret['unfound']=list(unfound) 

    return ret

def collect_email_addresses(emails, doc):
    for author in doc.authors.all():
        if author.address not in emails:
            emails[author.address] = '"%s"' % (author.person.name)
    if doc.group and doc.group.acronym != 'none':
        for role in doc.group.role_set.filter(name='chair'):
            if role.email.address not in emails:
                emails[role.email.address] = '"%s"' % (role.person.name)
        if doc.group.type.slug == 'wg':
            address = '%s-ads@tools.ietf.org' % doc.group.acronym
            if address not in emails:
                emails[address] = '"%s-ads"' % (doc.group.acronym)
        elif doc.group.type.slug == 'rg':
            for role in doc.group.parent.role_set.filter(name='chair'):
                if role.email.address not in emails:
                    emails[role.email.address] = '"%s"' % (role.person.name)
    if doc.shepherd and doc.shepherd.address not in emails:
        emails[doc.shepherd.address] = u'"%s"' % (doc.shepherd.person.name or "")

def set_replaces_for_document(request, doc, new_replaces, by, email_subject, email_comment=""):
    emails = {}
    collect_email_addresses(emails, doc)

    relationship = DocRelationshipName.objects.get(slug='replaces')
    old_replaces = doc.related_that_doc("replaces")

    for d in old_replaces:
        if d not in new_replaces:
            collect_email_addresses(emails, d.document)
            RelatedDocument.objects.filter(source=doc, target=d, relationship=relationship).delete()
            if not RelatedDocument.objects.filter(target=d, relationship=relationship):
                s = 'active' if d.document.expires > datetime.datetime.now() else 'expired'
                d.document.set_state(State.objects.get(type='draft', slug=s))

    for d in new_replaces:
        if d not in old_replaces:
            collect_email_addresses(emails, d.document)
            RelatedDocument.objects.create(source=doc, target=d, relationship=relationship)
            d.document.set_state(State.objects.get(type='draft', slug='repl'))

    e = DocEvent(doc=doc, by=by, type='changed_document')
    new_replaces_names = u", ".join(d.name for d in new_replaces) or u"None"
    old_replaces_names = u", ".join(d.name for d in old_replaces) or u"None"
    e.desc = u"This document now replaces <b>%s</b> instead of %s" % (new_replaces_names, old_replaces_names)
    e.save()

    # make sure there are no lingering suggestions duplicating new replacements
    RelatedDocument.objects.filter(source=doc, target__in=new_replaces, relationship="possibly-replaces").delete()

    email_desc = e.desc.replace(", ", "\n    ")

    if email_comment:
        email_desc += "\n" + email_comment

    to = [
        u'%s <%s>' % (emails[email], email) if emails[email] else u'<%s>' % email
        for email in sorted(emails)
    ]

    from ietf.doc.mails import html_to_text

    send_mail(request, to,
              "DraftTracker Mail System <iesg-secretary@ietf.org>",
              email_subject,
              "doc/mail/change_notice.txt",
              dict(text=html_to_text(email_desc),
                   doc=doc,
                   url=settings.IDTRACKER_BASE_URL + doc.get_absolute_url()))

def check_common_doc_name_rules(name):
    """Check common rules for document names for use in forms, throws
    ValidationError in case there's a problem."""

    errors = []
    if re.search("[^a-z0-9-]", name):
        errors.append("The name may only contain digits, lowercase letters and dashes.")
    if re.search("--", name):
        errors.append("Please do not put more than one hyphen between any two words in the name.")
    if re.search("-[0-9]{2}$", name):
        errors.append("This name looks like ends in a version number. -00 will be added automatically. Please adjust the end of the name.")

    if errors:
        raise ValidationError(errors)

def get_initial_notify(doc,extra=None):
    # set change state notice to something sensible
    receivers = []

    if doc.type.slug=='draft':
        if doc.group.type_id in ("individ", "area"):
             for a in doc.authors.all():
                 receivers.append(a.address)
        else:
            receivers.append("%s-chairs@%s" % (doc.group.acronym, settings.DRAFT_ALIAS_DOMAIN))
            for editor in Email.objects.filter(role__name="editor", role__group=doc.group):
                receivers.append(editor.address)

        receivers.append("%s@%s" % (doc.name, settings.DRAFT_ALIAS_DOMAIN))
        receivers.append("%s.ad@%s" % (doc.name, settings.DRAFT_ALIAS_DOMAIN))
        receivers.append("%s.shepherd@%s" % (doc.name, settings.DRAFT_ALIAS_DOMAIN))

    elif doc.type.slug=='charter':
        receivers.extend([role.person.formatted_email() for role in doc.group.role_set.filter(name__slug__in=['ad','chair','secr','techadv'])])

    else:
        pass

    for relation in doc.relateddocument_set.filter(Q(relationship='conflrev')|Q(relationship__in=STATUSCHANGE_RELATIONS)):
        if relation.relationship.slug=='conflrev':
            doc_to_review = relation.target.document
            receivers.extend([x.person.formatted_email() for x in Role.objects.filter(group__acronym=doc_to_review.stream.slug,name='chair')])
            receivers.append("%s@%s" % (doc_to_review.name, settings.DRAFT_ALIAS_DOMAIN))
        elif relation.relationship.slug in STATUSCHANGE_RELATIONS:
            affected_doc = relation.target.document
            if affected_doc.notify:
                receivers.extend(affected_doc.notify.split(','))

    if doc.shepherd:
        receivers.append(doc.shepherd.email_address())

    if extra:
        if isinstance(extra,basestring):
            extra = extra.split(', ')
        receivers.extend(extra)

    return ", ".join(set([x.strip() for x in receivers]))

def uppercase_std_abbreviated_name(name):
    if re.match('(rfc|bcp|std|fyi) ?[0-9]+$', name):
        return name.upper()
    else:
        return name