import re
import base64
import datetime
import urllib
import urllib2
import socket
from xml.dom import pulldom, Node

from django.conf import settings

from ietf.doc.models import ( Document, DocAlias, State, StateType, DocEvent, DocRelationshipName,
    DocTagName, DocTypeName, RelatedDocument )
from ietf.doc.expire import move_draft_files_to_archive
from ietf.doc.utils import add_state_change_event, prettify_std_name
from ietf.group.models import Group
from ietf.name.models import StdLevelName, StreamName
from ietf.person.models import Person
from ietf.utils.log import log
from ietf.utils.mail import send_mail_text

#QUEUE_URL = "https://www.rfc-editor.org/queue2.xml"
#INDEX_URL = "https://www.rfc-editor.org/rfc/rfc-index.xml"
#POST_APPROVED_DRAFT_URL = "https://www.rfc-editor.org/sdev/jsonexp/jsonparser.php"

MIN_QUEUE_RESULTS = 10
MIN_INDEX_RESULTS = 5000

def get_child_text(parent_node, tag_name):
    for node in parent_node.childNodes:
        if node.nodeType == Node.ELEMENT_NODE and node.localName == tag_name:
            return node.firstChild.data
    return None


def fetch_queue_xml(url):
    socket.setdefaulttimeout(30)
    return urllib2.urlopen(url)

def parse_queue(response):
    """Parse RFC Editor queue XML into a bunch of tuples + warnings."""

    events = pulldom.parse(response)
    drafts = []
    warnings = []
    stream = None

    for event, node in events:
        if event == pulldom.START_ELEMENT and node.tagName == "entry":
            events.expandNode(node)
            node.normalize()
            draft_name = get_child_text(node, "draft").strip()
            draft_name = re.sub("(-\d\d)?(.txt){1,2}$", "", draft_name)
            date_received = get_child_text(node, "date-received")
            
            state = ""
            tags = []
            missref_generation = ""
            for child in node.childNodes:
                if child.nodeType == Node.ELEMENT_NODE and child.localName == "state":
                    state = child.firstChild.data
                    # state has some extra annotations encoded, parse
                    # them out
                    if '*R' in state:
                        tags.append("ref")
                        state = state.replace("*R", "")
                    if '*A' in state:
                        tags.append("iana")
                        state = state.replace("*A", "")
                    m = re.search(r"\(([0-9]+)G\)", state)
                    if m:
                        missref_generation = m.group(1)
                        state = state.replace("(%sG)" % missref_generation, "")

            # AUTH48 link
            auth48 = ""
            for child in node.childNodes:
                if child.nodeType == Node.ELEMENT_NODE and child.localName == "auth48-url":
                    auth48 = child.firstChild.data

            # cluster link (if it ever gets implemented)
            cluster = ""
            for child in node.childNodes:
                if child.nodeType == Node.ELEMENT_NODE and child.localName == "cluster-url":
                    cluster = child.firstChild.data

            refs = []
            for child in node.childNodes:
                if child.nodeType == Node.ELEMENT_NODE and child.localName == "normRef":
                    ref_name = get_child_text(child, "ref-name")
                    ref_state = get_child_text(child, "ref-state")
                    in_queue = ref_state.startswith("IN-QUEUE")
                    refs.append((ref_name, ref_state, in_queue))

            drafts.append((draft_name, date_received, state, tags, missref_generation, stream, auth48, cluster, refs))
        
        elif event == pulldom.START_ELEMENT and node.tagName == "section":
            name = node.getAttribute('name')
            if name.startswith("IETF"):
                stream = "ietf"
            elif name.startswith("IAB"):
                stream = "iab"
            elif name.startswith("IRTF"):
                stream = "irtf"
            elif name.startswith("INDEPENDENT"):
                stream = "ise"
            else:
                stream = None
                warnings.append("unrecognized section " + name)

    return drafts, warnings

def update_drafts_from_queue(drafts):
    """Given a list of parsed drafts from the RFC Editor queue, update the
    documents in the database. Return those that were changed."""

    tag_mapping = {
        'IANA': DocTagName.objects.get(slug='iana'),
        'REF':  DocTagName.objects.get(slug='ref')
    }

    slookup = dict((s.slug, s)
                   for s in State.objects.filter(used=True, type=StateType.objects.get(slug="draft-rfceditor")))
    state_mapping = {
        'AUTH': slookup['auth'],
        'AUTH48': slookup['auth48'],
        'AUTH48-DONE': slookup['auth48-done'],
        'EDIT': slookup['edit'],
        'IANA': slookup['iana'],
        'IESG': slookup['iesg'],
        'ISR': slookup['isr'],
        'ISR-AUTH': slookup['isr-auth'],
        'REF': slookup['ref'],
        'RFC-EDITOR': slookup['rfc-edit'],
        'TO': slookup['timeout'],
        'MISSREF': slookup['missref'],
    }

    system = Person.objects.get(name="(System)")

    warnings = []

    names = [t[0] for t in drafts]

    drafts_in_db = dict((d.name, d)
                        for d in Document.objects.filter(type="draft", docalias__name__in=names))

    changed = set()

    for name, date_received, state, tags, missref_generation, stream, auth48, cluster, refs in drafts:
        if name not in drafts_in_db:
            warnings.append("unknown document %s" % name)
            continue

        if not state or state not in state_mapping:
            warnings.append("unknown state '%s' for %s" % (state, name))
            continue

        d = drafts_in_db[name]

        prev_state = d.get_state("draft-rfceditor")
        next_state = state_mapping[state]
        events = []

        # check if we've noted it's been received
        if d.get_state_slug("draft-iesg") == "ann" and not prev_state and not d.latest_event(DocEvent, type="rfc_editor_received_announcement"):
            e = DocEvent(doc=d, by=system, type="rfc_editor_received_announcement")
            e.desc = "Announcement was received by RFC Editor"
            e.save()
            send_mail_text(None, "iesg-secretary@ietf.org", None,
                           '%s in RFC Editor queue' % d.name,
                           'The announcement for %s has been received by the RFC Editor.' % d.name)
            # change draft-iesg state to RFC Ed Queue
            prev_iesg_state = State.objects.get(used=True, type="draft-iesg", slug="ann")
            next_iesg_state = State.objects.get(used=True, type="draft-iesg", slug="rfcqueue")

            d.set_state(next_iesg_state)
            e = add_state_change_event(d, system, prev_iesg_state, next_iesg_state)
            if e:
                events.append(e)
            changed.add(name)
            
        # check draft-rfceditor state
        if prev_state != next_state:
            d.set_state(next_state)

            e = add_state_change_event(d, system, prev_state, next_state)

            if auth48:
                e.desc = re.sub(r"(<b>.*</b>)", "<a href=\"%s\">\\1</a>" % auth48, e.desc)
                e.save()

            if e:
                events.append(e)

            changed.add(name)

        t = DocTagName.objects.filter(slug__in=tags)
        if set(t) != set(d.tags.all()):
            d.tags = t
            changed.add(name)

        if events:
            d.save_with_history(events)


    # remove tags and states for those not in the queue anymore
    for d in Document.objects.exclude(docalias__name__in=names).filter(states__type="draft-rfceditor").distinct():
        d.tags.remove(*tag_mapping.values())
        d.unset_state("draft-rfceditor")
        # we do not add a history entry here - most likely we already
        # have something that explains what happened
        changed.add(name)

    return changed, warnings


def fetch_index_xml(url):
    socket.setdefaulttimeout(30)
    return urllib2.urlopen(url)

def parse_index(response):
    """Parse RFC Editor index XML into a bunch of tuples."""

    def normalize_std_name(std_name):
        # remove zero padding
        prefix = std_name[:3]
        if prefix in ("RFC", "FYI", "BCP", "STD"):
            try:
                return prefix + str(int(std_name[3:]))
            except ValueError:
                pass
        return std_name

    def extract_doc_list(parentNode, tagName):
        l = []
        for u in parentNode.getElementsByTagName(tagName):
            for d in u.getElementsByTagName("doc-id"):
                l.append(normalize_std_name(d.firstChild.data))
        return l

    also_list = {}
    data = []
    events = pulldom.parse(response)
    for event, node in events:
        if event == pulldom.START_ELEMENT and node.tagName in ["bcp-entry", "fyi-entry", "std-entry"]:
            events.expandNode(node)
            node.normalize()
            bcpid = normalize_std_name(get_child_text(node, "doc-id"))
            doclist = extract_doc_list(node, "is-also")
            for docid in doclist:
                if docid in also_list:
                    also_list[docid].append(bcpid)
                else:
                    also_list[docid] = [bcpid]

        elif event == pulldom.START_ELEMENT and node.tagName == "rfc-entry":
            events.expandNode(node)
            node.normalize()
            rfc_number = int(get_child_text(node, "doc-id")[3:])
            title = get_child_text(node, "title")

            authors = []
            for author in node.getElementsByTagName("author"):
                authors.append(get_child_text(author, "name"))

            d = node.getElementsByTagName("date")[0]
            year = int(get_child_text(d, "year"))
            month = get_child_text(d, "month")
            month = ["January","February","March","April","May","June","July","August","September","October","November","December"].index(month)+1
            rfc_published_date = datetime.date(year, month, 1)

            current_status = get_child_text(node, "current-status").title()

            updates = extract_doc_list(node, "updates") 
            updated_by = extract_doc_list(node, "updated-by")
            obsoletes = extract_doc_list(node, "obsoletes") 
            obsoleted_by = extract_doc_list(node, "obsoleted-by")
            stream = get_child_text(node, "stream")
            wg = get_child_text(node, "wg_acronym")
            if wg and ((wg == "NON WORKING GROUP") or len(wg) > 15):
                wg = None
           
            l = []
            pages = ""
            for fmt in node.getElementsByTagName("format"):
                l.append(get_child_text(fmt, "file-format"))
                if get_child_text(fmt, "file-format") == "ASCII":
                    pages = get_child_text(fmt, "page-count")
            file_formats = (",".join(l)).lower()

            abstract = ""
            for abstract in node.getElementsByTagName("abstract"):
                abstract = get_child_text(abstract, "p")

            draft = get_child_text(node, "draft")
            if draft and re.search("-\d\d$", draft):
                draft = draft[0:-3]

            if len(node.getElementsByTagName("errata-url")) > 0:
                has_errata = 1
            else:
                has_errata = 0

            data.append((rfc_number,title,authors,rfc_published_date,current_status,updates,updated_by,obsoletes,obsoleted_by,[],draft,has_errata,stream,wg,file_formats,pages,abstract))

    for d in data:
        k = "RFC%04d" % d[0]
        if k in also_list:
            d[9].extend(also_list[k])
    return data


def update_docs_from_rfc_index(data, skip_older_than_date=None):
    """Given parsed data from the RFC Editor index, update the documents
    in the database. Yields a list of change descriptions for each
    document, if any."""

    std_level_mapping = {
        "Standard": StdLevelName.objects.get(slug="std"),
        "Internet Standard": StdLevelName.objects.get(slug="std"),
        "Draft Standard": StdLevelName.objects.get(slug="ds"),
        "Proposed Standard": StdLevelName.objects.get(slug="ps"),
        "Informational": StdLevelName.objects.get(slug="inf"),
        "Experimental": StdLevelName.objects.get(slug="exp"),
        "Best Current Practice": StdLevelName.objects.get(slug="bcp"),
        "Historic": StdLevelName.objects.get(slug="hist"),
        "Unknown": StdLevelName.objects.get(slug="unkn"),
        }

    stream_mapping = {
        "IETF": StreamName.objects.get(slug="ietf"),
        "INDEPENDENT": StreamName.objects.get(slug="ise"),
        "IRTF": StreamName.objects.get(slug="irtf"),
        "IAB": StreamName.objects.get(slug="iab"),
        "Legacy": StreamName.objects.get(slug="legacy"),
    }

    tag_has_errata = DocTagName.objects.get(slug='errata')
    relationship_obsoletes = DocRelationshipName.objects.get(slug="obs")
    relationship_updates = DocRelationshipName.objects.get(slug="updates")

    system = Person.objects.get(name="(System)")

    for rfc_number, title, authors, rfc_published_date, current_status, updates, updated_by, obsoletes, obsoleted_by, also, draft, has_errata, stream, wg, file_formats, pages, abstract in data:

        if skip_older_than_date and rfc_published_date < skip_older_than_date:
            # speed up the process by skipping old entries
            continue

        # we assume two things can happen: we get a new RFC, or an
        # attribute has been updated at the RFC Editor (RFC Editor
        # attributes take precedence over our local attributes)
        events = []
        changes = []
        rfc_published = False

        # make sure we got the document and alias
        doc = None
        name = "rfc%s" % rfc_number
        a = DocAlias.objects.filter(name=name).select_related("document")
        if a:
            doc = a[0].document
        else:
            if draft:
                try:
                    doc = Document.objects.get(name=draft)
                except Document.DoesNotExist:
                    pass

            if not doc:
                changes.append("created document %s" % prettify_std_name(name))
                doc = Document.objects.create(name=name, type=DocTypeName.objects.get(slug="draft"))

            # add alias
            DocAlias.objects.get_or_create(name=name, document=doc)
            changes.append("created alias %s" % prettify_std_name(name))

        # check attributes
        if title != doc.title:
            doc.title = title
            changes.append("changed title to '%s'" % doc.title)

        if abstract and abstract != doc.abstract:
            doc.abstract = abstract
            changes.append("changed abstract to '%s'" % doc.abstract)

        if pages and int(pages) != doc.pages:
            doc.pages = int(pages)
            changes.append("changed pages to %s" % doc.pages)

        if std_level_mapping[current_status] != doc.std_level:
            doc.std_level = std_level_mapping[current_status]
            changes.append("changed standardization level to %s" % doc.std_level)

        if doc.get_state_slug() != "rfc":
            doc.set_state(State.objects.get(used=True, type="draft", slug="rfc"))
            move_draft_files_to_archive(doc, doc.rev)
            changes.append("changed state to %s" % doc.get_state())

        if doc.stream != stream_mapping[stream]:
            doc.stream = stream_mapping[stream]
            changes.append("changed stream to %s" % doc.stream)

        if not doc.group: # if we have no group assigned, check if RFC Editor has a suggestion
            if wg:
                doc.group = Group.objects.get(acronym=wg)
                changes.append("set group to %s" % doc.group)
            else:
                doc.group = Group.objects.get(type="individ") # fallback for newly created doc

        if not doc.latest_event(type="published_rfc"):
            e = DocEvent(doc=doc, type="published_rfc")
            # unfortunately, rfc_published_date doesn't include the correct day
            # at the moment because the data only has month/year, so
            # try to deduce it
            d = datetime.datetime.combine(rfc_published_date, datetime.time())
            synthesized = datetime.datetime.now()
            if abs(d - synthesized) > datetime.timedelta(days=60):
                synthesized = d
            else:
                direction = -1 if (d - synthesized).total_seconds() < 0 else +1
                while synthesized.month != d.month or synthesized.year != d.year:
                    synthesized += datetime.timedelta(days=direction)
            e.time = synthesized
            e.by = system
            e.desc = "RFC published"
            e.save()
            events.append(e)

            changes.append("added RFC published event at %s" % e.time.strftime("%Y-%m-%d"))
            rfc_published = True

        for t in ("draft-iesg", "draft-stream-iab", "draft-stream-irtf", "draft-stream-ise"):
            slug = doc.get_state_slug(t)
            if slug and slug != "pub":
                new_state = State.objects.select_related("type").get(used=True, type=t, slug="pub")
                doc.set_state(new_state)
                changes.append("changed %s to %s" % (new_state.type.label, new_state))

        def parse_relation_list(l):
            res = []
            for x in l:
                if x[:3] in ("NIC", "IEN", "STD", "RTR"):
                    # try translating this to RFCs that we can handle
                    # sensibly; otherwise we'll have to ignore them
                    l = DocAlias.objects.filter(name__startswith="rfc", document__docalias__name=x.lower())
                else:
                    l = DocAlias.objects.filter(name=x.lower())

                for a in l:
                    if a not in res:
                        res.append(a)
            return res

        for x in parse_relation_list(obsoletes):
            if not RelatedDocument.objects.filter(source=doc, target=x, relationship=relationship_obsoletes):
                r = RelatedDocument.objects.create(source=doc, target=x, relationship=relationship_obsoletes)
                changes.append("created %s relation between %s and %s" % (r.relationship.name.lower(), prettify_std_name(r.source.name), prettify_std_name(r.target.name)))

        for x in parse_relation_list(updates):
            if not RelatedDocument.objects.filter(source=doc, target=x, relationship=relationship_updates):
                r = RelatedDocument.objects.create(source=doc, target=x, relationship=relationship_updates)
                changes.append("created %s relation between %s and %s" % (r.relationship.name.lower(), prettify_std_name(r.source.name), prettify_std_name(r.target.name)))

        if also:
            for a in also:
                a = a.lower()
                if not DocAlias.objects.filter(name=a):
                    DocAlias.objects.create(name=a, document=doc)
                    changes.append("created alias %s" % prettify_std_name(a))

        if has_errata:
            if not doc.tags.filter(pk=tag_has_errata.pk):
                doc.tags.add(tag_has_errata)
                changes.append("added Errata tag")
        else:
            if doc.tags.filter(pk=tag_has_errata.pk):
                doc.tags.remove(tag_has_errata)
                changes.append("removed Errata tag")

        if changes:
            events.append(DocEvent.objects.create(
                doc=doc,
                by=system,
                type="sync_from_rfc_editor",
                desc=u"Received changes through RFC Editor sync (%s)" % u", ".join(changes),
            ))

            doc.save_with_history(events)

        if changes:
            yield changes, doc, rfc_published


def post_approved_draft(url, name):
    """Post an approved draft to the RFC Editor so they can retrieve
    the data from the Datatracker and start processing it. Returns
    response and error (empty string if no error)."""

    request = urllib2.Request(url)
    request.add_header("Content-type", "application/x-www-form-urlencoded")
    request.add_header("Accept", "text/plain")
    # HTTP basic auth
    username = "dtracksync"
    password = settings.RFC_EDITOR_SYNC_PASSWORD
    request.add_header("Authorization", "Basic %s" % base64.encodestring("%s:%s" % (username, password)).replace("\n", ""))

    if settings.SERVER_MODE != "production":
        return ("OK", "")

    log("Posting RFC-Editor notifcation of approved draft '%s' to '%s'" % (name, url))
    text = error = ""
    try:
        f = urllib2.urlopen(request, data=urllib.urlencode({ 'draft': name }), timeout=20)
        text = f.read()
        status_code = f.getcode()
        f.close()
        log("RFC-Editor notification result for draft '%s': %s:'%s'" % (name, status_code, text))

        if status_code != 200:
            raise Exception("Status code is not 200 OK (it's %s)." % status_code)

        if text != "OK":
            raise Exception("Response is not \"OK\".")

    except Exception as e:
        # catch everything so we don't leak exceptions, convert them
        # into string instead
        log("Exception on RFC-Editor notification for draft '%s': '%s'" % (name, e))
        error = unicode(e)

    return text, error