import logging
import random
import socket
import urllib2

from django import http
from django.conf import settings
from django.core.cache import cache, parse_backend_uri
from django.views.decorators.cache import never_cache
from django.views.decorators.csrf import csrf_exempt

import jingo
import phpserialize as php

from amo.urlresolvers import reverse
from api.views import render_xml
from stats.models import Contribution, ContributionError, SubscriptionEvent
from . import log

paypal_log = logging.getLogger('z.paypal')


@never_cache
def monitor(request):

    # For each check, a boolean pass/fail status to show in the template
    status_summary = {}
    status = 200

    # Check all memcached servers
    scheme, servers, _ = parse_backend_uri(settings.CACHE_BACKEND)
    memcache_results = []
    status_summary['memcache'] = True
    if 'memcached' in scheme:
        hosts = servers.split(';')
        for host in hosts:
            ip, port = host.split(':')
            try:
                s = socket.socket()
                s.connect((ip, int(port)))
            except Exception, e:
                result = False
                status_summary['memcache'] = False
                status = 500
                log.critical('Failed to connect to memcached (%s): %s' %
                                                                    (host, e))
            else:
                result = True
            finally:
                s.close()

            memcache_results.append((ip, port, result))
        if len(memcache_results) < 2:
            status = 500
            status_summary['memcache'] = False
            log.warning('You should have 2+ memcache servers.  You have %s.' %
                                                        len(memcache_results))
    if not memcache_results:
        status = 500
        status_summary['memcache'] = False
        log.info('Memcache is not configured.')

    return jingo.render(request, 'services/monitor.html',
                        {'memcache_results': memcache_results,
                         'status_summary': status_summary},
                        status=status)


@csrf_exempt
def paypal(request):
    """
    Handle PayPal IPN post-back for contribution transactions.

    IPN will retry periodically until it gets success (status=200). Any
    db errors or replication lag will result in an exception and http
    status of 500, which is good so PayPal will try again later.

    PayPal IPN variables available at:
    https://cms.paypal.com/us/cgi-bin/?cmd=_render-content
                    &content_ID=developer/e_howto_html_IPNandPDTVariables
    """
    try:
        return _paypal(request)
    except Exception, e:
        paypal_log.error('%s\n%s' % (e, request))
        return http.HttpResponseServerError('Unknown error.')


def _paypal(request):

    def _log_error_with_data(msg, request):
        """Log a message along with some of the POST info from PayPal."""

        id = random.randint(0, 99999999)
        msg = "[%s] %s (dumping data)" % (id, msg)

        paypal_log.error(msg)

        logme = {'txn_id': request.POST.get('txn_id'),
                 'txn_type': request.POST.get('txn_type'),
                 'payer_email': request.POST.get('payer_email'),
                 'receiver_email': request.POST.get('receiver_email'),
                 'payment_status': request.POST.get('payment_status'),
                 'payment_type': request.POST.get('payment_type'),
                 'mc_gross': request.POST.get('mc_gross'),
                 'item_number': request.POST.get('item_number'),
                }

        paypal_log.error("[%s] PayPal Data: %s" % (id, logme))

    if request.method != 'POST':
        return http.HttpResponseNotAllowed(['POST'])

    # Check that the request is valid and coming from PayPal.
    data = '%s&%s' % ('cmd=_notify-validate', request.raw_post_data)
    paypal_response = urllib2.urlopen(settings.PAYPAL_CGI_URL,
                                      data, 20).readline()
    if paypal_response != 'VERIFIED':
        msg = ("Expecting 'VERIFIED' from PayPal, got '%s'. "
               "Failing." % paypal_response)
        _log_error_with_data(msg, request)
        return http.HttpResponseForbidden('Invalid confirmation')

    if request.POST.get('txn_type', '').startswith('subscr_'):
        SubscriptionEvent.objects.create(post_data=php.serialize(request.POST))
        return http.HttpResponse('Success!')

    # We only care about completed transactions.
    if request.POST.get('payment_status') != 'Completed':
        return http.HttpResponse('Payment not completed')

    # Make sure transaction has not yet been processed.
    if (Contribution.objects
                   .filter(transaction_id=request.POST['txn_id']).count()) > 0:
        return http.HttpResponse('Transaction already processed')

    # Fetch and update the contribution - item_number is the uuid we created.
    try:
        c = Contribution.objects.get(uuid=request.POST['item_number'])
    except Contribution.DoesNotExist:
        key = "%s%s:%s" % (settings.CACHE_PREFIX, 'contrib',
                           request.POST['item_number'])
        count = cache.get(key, 0) + 1

        paypal_log.warning('Contribution (uuid=%s) not found for IPN request '
                           '#%s.' % (request.POST['item_number'], count))
        if count > 10:
            msg = ("Paypal sent a transaction that we don't know "
                   "about and we're giving up on it.")
            _log_error_with_data(msg, request)
            cache.delete(key)
            return http.HttpResponse('Transaction not found; skipping.')
        cache.set(key, count, 1209600)  # This is 2 weeks.
        return http.HttpResponseServerError('Contribution not found')

    c.transaction_id = request.POST['txn_id']
    c.amount = request.POST['mc_gross']
    c.uuid = None
    c.post_data = php.serialize(request.POST)
    c.save()

    # Send thankyou email.
    try:
        c.mail_thankyou(request)
    except ContributionError as e:
        # A failed thankyou email is not a show stopper, but is good to know.
        paypal_log.error('Thankyou note email failed with error: %s' % e)

    return http.HttpResponse('Success!')


def handler404(request):
    return jingo.render(request, 'amo/404.lhtml', status=404)


def handler500(request):
    return jingo.render(request, 'amo/500.lhtml', status=500)