datatracker/ietf/doc/utils.py

import os
import re
import urllib
import math
import datetime
import hashlib
import json
from collections import defaultdict

from django.conf import settings
from django.forms import ValidationError
from django.utils.html import escape
from django.core.urlresolvers import reverse as urlreverse

import debug                            # pyflakes:ignore

from ietf.doc.models import Document, DocHistory, State, DocumentAuthor, DocHistoryAuthor
from ietf.doc.models import DocAlias, RelatedDocument, RelatedDocHistory, BallotType, DocReminder
from ietf.doc.models import DocEvent, ConsensusDocEvent, BallotDocEvent, NewRevisionDocEvent, StateDocEvent
from ietf.doc.models import TelechatDocEvent
from ietf.name.models import DocReminderTypeName, DocRelationshipName
from ietf.group.models import Role
from ietf.ietfauth.utils import has_role
from ietf.utils import draft, markup_txt
from ietf.utils.mail import send_mail
from ietf.mailtrigger.utils import gather_address_lists

def save_document_in_history(doc):
    """Save a snapshot of document and related objects in the database."""
    def get_model_fields_as_dict(obj):
        return dict((field.name, getattr(obj, field.name))
                    for field in obj._meta.fields
                    if field is not obj._meta.pk)

    # copy fields
    fields = get_model_fields_as_dict(doc)
    fields["doc"] = doc
    fields["name"] = doc.canonical_name()

    dochist = DocHistory(**fields)
    dochist.save()

    # copy many to many
    for field in doc._meta.many_to_many:
        if field.rel.through and field.rel.through._meta.auto_created:
            setattr(dochist, field.name, getattr(doc, field.name).all())

    # copy remaining tricky many to many
    def transfer_fields(obj, HistModel):
        mfields = get_model_fields_as_dict(item)
        # map doc -> dochist
        for k, v in mfields.iteritems():
            if v == doc:
                mfields[k] = dochist
        HistModel.objects.create(**mfields)

    for item in RelatedDocument.objects.filter(source=doc):
        transfer_fields(item, RelatedDocHistory)

    for item in DocumentAuthor.objects.filter(document=doc):
        transfer_fields(item, DocHistoryAuthor)
                
    return dochist


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 = RelatedDocHistory.objects.none()
        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, rev=doc.rev, time=time)
        else:
            e = BallotDocEvent(type="created_ballot", by=by, doc=doc, rev=doc.rev)
        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, rev=doc.rev, 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()
            
        # Check for all subtypes which have 'rev' fields:
        for sub in ['newrevisiondocevent', 'submissiondocevent', ]:
            if hasattr(e, sub):
                e = getattr(e, sub)
                break
        if not hasattr(e, 'rev'):
            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

        for sub in ['newrevisiondocevent', 'submissiondocevent', ]:
            if hasattr(e, sub):
                e = getattr(e, sub)
                break

        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 add_events_message_info(events):
    for e in events:
        if not e.type == "added_message":
            continue

        e.message = e.addedmessageevent.message
        e.msgtype = e.addedmessageevent.msgtype
        e.in_reply_to = e.addedmessageevent.in_reply_to


def get_unicode_document_content(key, filename, codec='utf-8', errors='ignore'):
    try:
        with open(filename, 'rb') as f:
            raw_content = f.read().decode(codec,errors)
    except IOError:
        error = "Error; cannot read ("+key+")"
        return error

    return raw_content

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, rev=doc.rev, 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 default_consensus(doc):
    # if someone edits the consensus return that, otherwise
    # ietf stream => true and irtf stream => false
    consensus = None
    e = doc.latest_event(ConsensusDocEvent, type="changed_consensus")
    if (e):
        return e.consensus
    if doc.stream_id == "ietf":
        consensus = True
    elif doc.stream_id == "irtf":
        consensus = False
    else:                               # ise, iab, legacy
        return consensus

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'
    else:
        event_type = 'added_comment'

    e = DocEvent(type=event_type, doc=doc, rev=doc.rev, 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):
    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.rev = doc.rev
    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()

    from ietf.doc.mails import email_update_telechat
    email_update_telechat(request, doc, e.desc)

    return e

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 set_replaces_for_document(request, doc, new_replaces, by, email_subject, comment=""):
    addrs = gather_address_lists('doc_replacement_changed',doc=doc)
    to = set(addrs.to)
    cc = set(addrs.cc)

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

    events = []

    e = DocEvent(doc=doc, rev=doc.rev, 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()

    events.append(e)

    if comment:
        events.append(DocEvent.objects.create(doc=doc, rev=doc.rev, by=by, type="added_comment", desc=comment))

    for d in old_replaces:
        if d not in new_replaces:
            other_addrs = gather_address_lists('doc_replacement_changed',doc=d.document)
            to.update(other_addrs.to)
            cc.update(other_addrs.cc)
            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:
            other_addrs = gather_address_lists('doc_replacement_changed',doc=d.document)
            to.update(other_addrs.to)
            cc.update(other_addrs.cc)
            RelatedDocument.objects.create(source=doc, target=d, relationship=relationship)
            d.document.set_state(State.objects.get(type='draft', slug='repl'))

    # 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 comment:
        email_desc += "\n" + comment

    from ietf.doc.mails import html_to_text

    send_mail(request, list(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()),
              cc=list(cc))

    return events

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):
    # With the mailtrigger based changes, a document's notify should start empty
    receivers = []

    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

def extract_complete_replaces_ancestor_mapping_for_docs(names):
    """Return dict mapping all replaced by relationships of the
    replacement ancestors to docs. So if x is directly replaced by y
    and y is in names or replaced by something in names, x in
    replaces[y]."""

    replaces = defaultdict(set)

    checked = set()
    front = names
    while True:
        if not front:
            break

        relations = RelatedDocument.objects.filter(
            source__in=front, relationship="replaces"
        ).select_related("target").values_list("source", "target__document")

        if not relations:
            break

        checked.update(front)

        front = []
        for source_doc, target_doc in relations:
            replaces[source_doc].add(target_doc)

            if target_doc not in checked:
                front.append(target_doc)

    return replaces


def crawl_history(doc):
    # return document history data for inclusion in doc.json (used by timeline)
    def get_ancestors(doc):
        ancestors = []
        if hasattr(doc, 'relateddocument_set'):
            for rel in doc.relateddocument_set.filter(relationship__slug='replaces'):
                if rel.target.document not in ancestors:
                    ancestors.append(rel.target.document)
                    ancestors.extend(get_ancestors(rel.target.document))
            return ancestors

    history = {}
    docs = get_ancestors(doc)
    if docs is not None:
        docs.append(doc)
        for d in docs:
            for e in d.docevent_set.filter(type='new_revision').distinct():
                if hasattr(e, 'newrevisiondocevent'):
                    url = urlreverse("ietf.doc.views_doc.document_main", kwargs=dict(name=d)) + e.newrevisiondocevent.rev + "/"
                    history[url] = {
                        'name': d.name,
                        'rev': e.newrevisiondocevent.rev,
                        'published': e.time.isoformat(),
                        'url': url,
                    }
                    if d.history_set.filter(rev=e.newrevisiondocevent.rev).exists():
                        history[url]['pages'] = d.history_set.filter(rev=e.newrevisiondocevent.rev).first().pages

    if doc.type_id == "draft":
        e = doc.latest_event(type='published_rfc')
    else:
        e = doc.latest_event(type='iesg_approved')
    if e:
        url = urlreverse("ietf.doc.views_doc.document_main", kwargs=dict(name=e.doc))
        history[url] = {
            'name': e.doc.canonical_name(),
            'rev': e.doc.canonical_name(),
            'published': e.time.isoformat(),
            'url': url
        }
        if hasattr(e, 'newrevisiondocevent') and doc.history_set.filter(rev=e.newrevisiondocevent.rev).exists():
            history[url]['pages'] = doc.history_set.filter(rev=e.newrevisiondocevent.rev).first().pages
    history = history.values()
    return sorted(history, key=lambda x: x['published'])


def get_search_cache_key(params):
    from ietf.doc.views_search import SearchForm
    fields = set(SearchForm.base_fields) - set(['sort',])
    kwargs = dict([ (k,v) for (k,v) in params.items() if k in fields ])
    key = "doc:document:search:" + hashlib.sha512(json.dumps(kwargs, sort_keys=True)).hexdigest()
    return key
    
def label_wrap(label, items, joiner=',', max=50):
    lines = []
    if not items:
        return lines
    line = '%s: %s' % (label, items[0])
    for item in items[1:]:
        if len(line)+len(joiner+' ')+len(item) > max:
            lines.append(line+joiner)
            line = ' '*(len(label)+len(': ')) + item
        else:
            line += joiner+' '+item
    if line:
        lines.append(line)
    return lines

def join_justified(left, right, width=72):
    count = max(len(left), len(right))
    left = left + ['']*(count-len(left))
    right = right + ['']*(count-len(right))
    lines = []
    i = 0
    while True:
        l = left[i]
        r = right[i]
        if len(l)+1+len(r) > width:
            left = left + ['']
            right = right[:i] + [''] + right[i:]
            r = right[i]
            count += 1
        lines.append( l + ' ' + r.rjust(width-len(l)-1) )
        i += 1
        if i >= count:
            break
    return lines

def build_doc_meta_block(doc, path):
    def add_markup(path, doc, lines):
        is_hst = doc.is_dochistory()
        rev = doc.rev
        if is_hst:
            doc = doc.doc
        name = doc.name
        rfcnum = doc.rfc_number()
        errata_url = settings.RFC_EDITOR_ERRATA_URL.format(rfc_number=rfcnum) if not is_hst else ""
        ipr_url = "%s?submit=draft&amp;id=%s" % (urlreverse('ietf.ipr.views.search'), name)
        for i, line in enumerate(lines):
            # add draft links
            line = re.sub(r'\b(draft-[-a-z0-9]+)\b', '<a href="%s/\g<1>">\g<1></a>'%(path, ), line)
            # add rfcXXXX to RFC links
            line = re.sub(r' (rfc[0-9]+)\b', ' <a href="%s/\g<1>">\g<1></a>'%(path, ), line)
            # add XXXX to RFC links
            line = re.sub(r' ([0-9]{3,5})\b', ' <a href="%s/rfc\g<1>">\g<1></a>'%(path, ), line)
            # add draft revision links
            line = re.sub(r' ([0-9]{2})\b', ' <a href="%s/%s-\g<1>">\g<1></a>'%(path, name, ), line)
            if rfcnum:
                # add errata link
                line = re.sub(r'Errata exist', '<a class="text-warning" href="%s">Errata exist</a>'%(errata_url, ), line)
            if is_hst or not rfcnum:
                # make current draft rev bold
                line = re.sub(r'>(%s)<'%rev, '><b>\g<1></b><', line)
            line = re.sub(r'IPR declarations', '<a class="text-warning" href="%s">IPR declarations</a>'%(ipr_url, ), line)
            line = line.replace(r'[txt]', '[<a href="%s">txt</a>]' % doc.href())
            lines[i] = line
        return lines
    #
    now = datetime.datetime.now()
    draft_state = doc.get_state('draft')
    block = ''
    meta = {}
    if doc.type_id == 'draft':
        revisions = []
        ipr = doc.related_ipr()
        if ipr:
            meta['ipr'] = [ "IPR declarations" ]
        if doc.is_rfc() and not doc.is_dochistory():
            if not doc.name.startswith('rfc'):
                meta['from'] = [ "%s-%s"%(doc.name, doc.rev) ]
            meta['errata'] = [ "Errata exist" ] if doc.tags.filter(slug='errata').exists() else []
            meta['obsoletedby'] = [ alias.document.rfc_number() for alias in doc.related_that('obs') ]
            meta['obsoletedby'].sort()
            meta['updatedby'] = [ alias.document.rfc_number() for alias in doc.related_that('updates') ]
            meta['updatedby'].sort()
            meta['stdstatus'] = [ doc.std_level.name ]
        else:
            dd = doc.doc if doc.is_dochistory() else doc
            revisions += [ '(%s)%s'%(d.name, ' '*(2-((len(d.name)-1)%3))) for d in dd.replaces() ]
            revisions += doc.revisions()
            if doc.is_dochistory() and doc.doc.is_rfc():
                revisions += [ doc.doc.canonical_name() ]
            else:
                revisions += [ d.name for d in doc.replaced_by() ]
            meta['versions'] = revisions
            if not doc.is_dochistory and draft_state.slug == 'active' and now > doc.expires:
                # Active past expiration date
                meta['active'] = [ 'Document is active' ]
                meta['state' ] = [ doc.friendly_state() ]
            intended_std = doc.intended_std_level if doc.intended_std_level else None
            if intended_std:
                if intended_std.slug in ['ps', 'ds', 'std']:
                    meta['stdstatus'] = [ "Standards Track" ]
                else:
                    meta['stdstatus'] = [ intended_std.name ]
    elif doc.type_id == 'charter':
        meta['versions'] = doc.revisions()
    #
    # Add markup to items that needs it.
    if 'versions' in meta:
        meta['versions'] = label_wrap('Versions', meta['versions'], joiner="")
    for label in ['Obsoleted by', 'Updated by', 'From' ]:
        item = label.replace(' ','').lower()
        if item in meta and meta[item]:
            meta[item] = label_wrap(label, meta[item])
    #
    left = []
    right = []
    #right = [ '[txt]']
    for item in [ 'from', 'versions', 'obsoletedby', 'updatedby', ]:
        if item in meta and meta[item]:
            left += meta[item]
    for item in ['stdstatus', 'active', 'state', 'ipr', 'errata', ]:
        if item in meta and meta[item]:
            right += meta[item]
    lines = join_justified(left, right)
    block = '\n'.join(add_markup(path, doc, lines))
    #
    return block