# coding: utf-8

import hashlib
import uuid
from datetime import timedelta as td

from django.conf import settings
from django.contrib.auth.models import User
from django.core.urlresolvers import reverse
from django.db import models
from django.utils import timezone
from hc.api import transports
from hc.lib import emails

STATUSES = (
    ("up", "Up"),
    ("down", "Down"),
    ("new", "New"),
    ("paused", "Paused")
)
DEFAULT_TIMEOUT = td(days=1)
DEFAULT_GRACE = td(hours=1)
CHANNEL_KINDS = (("email", "Email"), ("webhook", "Webhook"),
                 ("hipchat", "HipChat"),
                 ("slack", "Slack"), ("pd", "PagerDuty"), ("po", "Pushover"))

PO_PRIORITIES = {
    -2: "lowest",
    -1: "low",
    0: "normal",
    1: "high",
    2: "emergency"
}


class Check(models.Model):

    class Meta:
        # sendalerts command will query using these
        index_together = ["status", "user", "alert_after"]

    name = models.CharField(max_length=100, blank=True)
    tags = models.CharField(max_length=500, blank=True)
    code = models.UUIDField(default=uuid.uuid4, editable=False, db_index=True)
    user = models.ForeignKey(User, blank=True, null=True)
    created = models.DateTimeField(auto_now_add=True)
    timeout = models.DurationField(default=DEFAULT_TIMEOUT)
    grace = models.DurationField(default=DEFAULT_GRACE)
    n_pings = models.IntegerField(default=0)
    last_ping = models.DateTimeField(null=True, blank=True)
    alert_after = models.DateTimeField(null=True, blank=True, editable=False)
    status = models.CharField(max_length=6, choices=STATUSES, default="new")

    def name_then_code(self):
        if self.name:
            return self.name

        return str(self.code)

    def url(self):
        return settings.PING_ENDPOINT + str(self.code)

    def email(self):
        return "%s@%s" % (self.code, settings.PING_EMAIL_DOMAIN)

    def send_alert(self):
        if self.status not in ("up", "down"):
            raise NotImplementedError("Unexpected status: %s" % self.status)

        for channel in self.channel_set.all():
            channel.notify(self)

    def get_status(self):
        if self.status in ("new", "paused"):
            return self.status

        now = timezone.now()

        if self.last_ping + self.timeout > now:
            return "up"

        if self.last_ping + self.timeout + self.grace > now:
            return "grace"

        return "down"

    def assign_all_channels(self):
        if self.user:
            channels = Channel.objects.filter(user=self.user)
            self.channel_set.add(*channels)

    def tags_list(self):
        return [t.strip() for t in self.tags.split(" ") if t.strip()]


class Ping(models.Model):
    n = models.IntegerField(null=True)
    owner = models.ForeignKey(Check)
    created = models.DateTimeField(auto_now_add=True)
    scheme = models.CharField(max_length=10, default="http")
    remote_addr = models.GenericIPAddressField(blank=True, null=True)
    method = models.CharField(max_length=10, blank=True)
    ua = models.CharField(max_length=200, blank=True)


class Channel(models.Model):
    code = models.UUIDField(default=uuid.uuid4, editable=False)
    user = models.ForeignKey(User)
    created = models.DateTimeField(auto_now_add=True)
    kind = models.CharField(max_length=20, choices=CHANNEL_KINDS)
    value = models.CharField(max_length=200, blank=True)
    email_verified = models.BooleanField(default=False)
    checks = models.ManyToManyField(Check)

    def make_token(self):
        seed = "%s%s" % (self.code, settings.SECRET_KEY)
        seed = seed.encode("utf8")
        return hashlib.sha1(seed).hexdigest()

    def send_verify_link(self):
        args = [self.code, self.make_token()]
        verify_link = reverse("hc-verify-email", args=args)
        verify_link = settings.SITE_ROOT + verify_link
        emails.verify_email(self.value, {"verify_link": verify_link})

    @property
    def transport(self):
        if self.kind == "email":
            return transports.Email(self)
        elif self.kind == "webhook":
            return transports.Webhook(self)
        elif self.kind == "slack":
            return transports.Slack(self)
        elif self.kind == "hipchat":
            return transports.HipChat(self)
        elif self.kind == "pd":
            return transports.PagerDuty(self)
        elif self.kind == "po":
            return transports.Pushover()
        else:
            raise NotImplementedError("Unknown channel kind: %s" % self.kind)

    def notify(self, check):
        # Make 3 attempts--
        for x in range(0, 3):
            error = self.transport.notify(check) or ""
            if error in ("", "no-op"):
                break  # Success!

        if error != "no-op":
            n = Notification(owner=check, channel=self)
            n.check_status = check.status
            n.error = error
            n.save()

    def test(self):
        return self.transport().test()

    @property
    def po_value(self):
        assert self.kind == "po"
        user_key, prio = self.value.split("|")
        prio = int(prio)
        return user_key, prio, PO_PRIORITIES[prio]


class Notification(models.Model):
    owner = models.ForeignKey(Check)
    check_status = models.CharField(max_length=6)
    channel = models.ForeignKey(Channel)
    created = models.DateTimeField(auto_now_add=True)
    error = models.CharField(max_length=200, blank=True)