from django.conf import settings
from django.contrib.auth.models import User
from zephyr.lib.context_managers import lockfile
from zephyr.models import Realm, Stream, UserProfile, \
    Subscription, Recipient, Message, UserMessage, \
    DefaultStream, \
    MAX_MESSAGE_LENGTH, get_client
from django.db import transaction, IntegrityError
from zephyr.lib.initial_password import initial_password
from zephyr.lib.cache import cache_with_key
from zephyr.lib.message_cache import cache_save_message
from django.utils import timezone
from django.contrib.auth.models import UserManager

import subprocess
import simplejson
import time
import traceback
import re
import requests
import hashlib
import base64

# Store an event in the log for re-importing messages
def log_event(event):
    if "timestamp" not in event:
        event["timestamp"] = time.time()
    with lockfile(settings.MESSAGE_LOG + '.lock'):
        with open(settings.MESSAGE_LOG, 'a') as log:
            log.write(simplejson.dumps(event) + '\n')

# create_user_hack is the same as Django's User.objects.create_user,
# except that we don't save to the database so it can used in
# bulk_creates
def create_user_hack(username, password, email, active):
    now = timezone.now()
    email = UserManager.normalize_email(email)
    user = User(username=username, email=email,
                is_staff=False, is_active=active, is_superuser=False,
                last_login=now, date_joined=now)

    if active:
        user.set_password(password)
    else:
        user.set_unusable_password()
    return user

def create_user_base(email, password, active=True):
    # NB: the result of Base32 + truncation is not a valid Base32 encoding.
    # It's just a unique alphanumeric string.
    # Use base32 instead of base64 so we don't have to worry about mixed case.
    # Django imposes a limit of 30 characters on usernames.
    email_hash = hashlib.sha256(settings.HASH_SALT + email).digest()
    username = base64.b32encode(email_hash)[:30]
    return create_user_hack(username, password, email, active)

def create_user(email, password, realm, full_name, short_name,
                active=True):
    user = create_user_base(email=email, password=password,
                            active=active)
    user.save()
    return UserProfile.create(user, realm, full_name, short_name)

def do_create_user(email, password, realm, full_name, short_name,
                   active=True):
    log_event({'type': 'user_created',
               'timestamp': time.time(),
               'full_name': full_name,
               'short_name': short_name,
               'user': email})
    return create_user(email, password, realm, full_name, short_name, active)

def compute_mit_user_fullname(email):
    try:
        # Input is either e.g. starnine@mit.edu or user|CROSSREALM.INVALID@mit.edu
        match_user = re.match(r'^([a-zA-Z0-9_.-]+)(\|.+)?@mit\.edu$', email.lower())
        if match_user and match_user.group(2) is None:
            dns_query = "%s.passwd.ns.athena.mit.edu" % (match_user.group(1),)
            proc = subprocess.Popen(['host', '-t', 'TXT', dns_query],
                                    stdout=subprocess.PIPE,
                                    stderr=subprocess.PIPE)
            out, _err_unused = proc.communicate()
            if proc.returncode == 0:
                # Parse e.g. 'starnine:*:84233:101:Athena Consulting Exchange User,,,:/mit/starnine:/bin/bash'
                # for the 4th passwd entry field, aka the person's name.
                hesiod_name = out.split(':')[4].split(',')[0].strip()
                if hesiod_name == "":
                    return email
                return hesiod_name
        elif match_user:
            return match_user.group(1).lower() + "@" + match_user.group(2).upper()[1:]
    except:
        print ("Error getting fullname for %s:" % (email,))
        traceback.print_exc()
    return email.lower()

def create_mit_user_if_needed(realm, email):
    try:
        return UserProfile.objects.get(user__email=email)
    except UserProfile.DoesNotExist:
        try:
            # Forge a user for this person
            return create_user(email, initial_password(email), realm,
                               compute_mit_user_fullname(email), email.split("@")[0],
                               active=False)
        except IntegrityError:
            # Unless we raced with another thread doing the same
            # thing, in which case we should get the user they made
            transaction.commit()
            return UserProfile.objects.get(user__email=email)

def log_message(message):
    if not message.sending_client.name.startswith("test:"):
        log_event(message.to_log_dict())

user_hash = {}
def get_user_profile_by_id(uid):
    if uid in user_hash:
        return user_hash[uid]
    return UserProfile.objects.select_related().get(id=uid)

def do_send_message(message, no_log=False):
    # Log the message to our message log for populate_db to refill
    if not no_log:
        log_message(message)

    if message.recipient.type == Recipient.PERSONAL:
        recipients = list(set([get_user_profile_by_id(message.recipient.type_id),
                               get_user_profile_by_id(message.sender_id)]))
        # For personals, you send out either 1 or 2 copies of the message, for
        # personals to yourself or to someone else, respectively.
        assert((len(recipients) == 1) or (len(recipients) == 2))
    elif (message.recipient.type == Recipient.STREAM or
          message.recipient.type == Recipient.HUDDLE):
        recipients = [s.user_profile for
                      s in Subscription.objects.select_related().filter(recipient=message.recipient, active=True)]
    else:
        raise ValueError('Bad recipient type')

    # Save the message receipts in the database
    # TODO: Use bulk_create here
    with transaction.commit_on_success():
        message.save()
        for user_profile in recipients:
            # Only deliver messages to "active" user accounts
            if user_profile.user.is_active:
                UserMessage(user_profile=user_profile, message=message).save()

    cache_save_message(message)

    # We can only publish messages to longpolling clients if the Tornado server is running.
    if settings.TORNADO_SERVER:
        # Render Markdown etc. here, so that the single-threaded Tornado server doesn't have to.
        # TODO: Reduce duplication in what we send.
        rendered = { 'text/html':       message.to_dict(apply_markdown=True),
                     'text/x-markdown': message.to_dict(apply_markdown=False) }
        requests.post(settings.TORNADO_SERVER + '/notify_new_message', data=dict(
            secret   = settings.SHARED_SECRET,
            message  = message.id,
            rendered = simplejson.dumps(rendered),
            users    = simplejson.dumps([str(user.id) for user in recipients])))

def create_stream_if_needed(realm, stream_name):
    (stream, created) = Stream.objects.get_or_create(
        realm=realm, name__iexact=stream_name,
        defaults={'name': stream_name})
    if created:
        Recipient.objects.create(type_id=stream.id, type=Recipient.STREAM)
    return stream

def internal_send_message(sender_email, recipient_type, recipient_name,
                          subject, content):
    if len(content) > MAX_MESSAGE_LENGTH:
        content = content[0:3900] + "\n\n[message was too long and has been truncated]"
    message = Message()
    message.sender = UserProfile.objects.get(user__email=sender_email)
    message.recipient = Recipient.objects.get(type_id=create_stream_if_needed(
        message.sender.realm, recipient_name).id, type=recipient_type)
    message.subject = subject
    message.content = content
    message.pub_date = timezone.now()
    message.sending_client = get_client("Internal")

    do_send_message(message)

def do_add_subscription(user_profile, stream, no_log=False):
    recipient = Recipient.objects.get(type_id=stream.id,
                                      type=Recipient.STREAM)
    (subscription, created) = Subscription.objects.get_or_create(
        user_profile=user_profile, recipient=recipient,
        defaults={'active': True})
    did_subscribe = created
    if not subscription.active:
        did_subscribe = True
        subscription.active = True
        subscription.save()
    if did_subscribe and not no_log:
        log_event({'type': 'subscription_added',
                   'user': user_profile.user.email,
                   'name': stream.name,
                   'domain': stream.realm.domain})
    return did_subscribe

def do_remove_subscription(user_profile, stream, no_log=False):
    recipient = Recipient.objects.get(type_id=stream.id,
                                      type=Recipient.STREAM)
    maybe_sub = Subscription.objects.filter(user_profile=user_profile,
                                    recipient=recipient)
    if len(maybe_sub) == 0:
        return False
    subscription = maybe_sub[0]
    did_remove = subscription.active
    subscription.active = False
    subscription.save()
    if did_remove and not no_log:
        log_event({'type': 'subscription_removed',
                   'user': user_profile.user.email,
                   'name': stream.name,
                   'domain': stream.realm.domain})
    return did_remove

def log_subscription_property_change(user_email, property, property_dict):
    event = {'type': 'subscription_property',
             'property': property,
             'user': user_email}
    event.update(property_dict)
    log_event(event)

def do_activate_user(user, log=True, join_date=timezone.now()):
    user.is_active = True
    user.set_password(initial_password(user.email))
    user.date_joined = join_date
    user.save()
    if log:
        log_event({'type': 'user_activated',
                   'user': user.email})

def do_change_password(user, password, log=True, commit=True):
    user.set_password(password)
    if commit:
        user.save()
    if log:
        log_event({'type': 'user_change_password',
                   'user': user.email,
                   'pwhash': user.password})

def do_change_full_name(user_profile, full_name, log=True):
    user_profile.full_name = full_name
    user_profile.save()
    if log:
        log_event({'type': 'user_change_full_name',
                   'user': user_profile.user.email,
                   'full_name': full_name})

def do_create_realm(domain, replay=False):
    realm, created = Realm.objects.get_or_create(domain=domain)
    if created and not replay:
        # Log the event
        log_event({"type": "realm_created",
                   "domain": domain})

        # Sent a notification message
        message = Message()
        message.sender = UserProfile.objects.get(user__email="humbug+signups@humbughq.com")
        message.recipient = Recipient.objects.get(type_id=create_stream_if_needed(
                message.sender.realm, "signups").id, type=Recipient.STREAM)
        message.subject = domain
        message.content = "Signups enabled."
        message.pub_date = timezone.now()
        message.sending_client = get_client("Internal")

        do_send_message(message)
    return (realm, created)

def do_change_enable_desktop_notifications(user_profile, enable_desktop_notifications, log=True):
    user_profile.enable_desktop_notifications = enable_desktop_notifications
    user_profile.save()
    if log:
        log_event({'type': 'enable_desktop_notifications_changed',
                   'user': user_profile.user.email,
                   'enable_desktop_notifications': enable_desktop_notifications})

def set_default_streams(realm, stream_names):
    DefaultStream.objects.filter(realm=realm).delete()
    for stream_name in stream_names:
        stream = create_stream_if_needed(realm, stream_name)
        DefaultStream.objects.create(stream=stream, realm=realm)

def add_default_subs(user_profile):
    for default in DefaultStream.objects.filter(realm=user_profile.realm):
        do_add_subscription(user_profile, default.stream)