# coding: utf-8

import hashlib
import json
import time
import uuid
from datetime import datetime, timedelta as td

from croniter import croniter
from django.conf import settings
from django.contrib.auth.models import User
from django.db import models
from django.urls import reverse
from django.utils import timezone
from hc.api import transports
from hc.lib import emails
import requests
import pytz

STATUSES = (
    ("up", "Up"),
    ("down", "Down"),
    ("new", "New"),
    ("paused", "Paused")
)
DEFAULT_TIMEOUT = td(days=1)
DEFAULT_GRACE = td(hours=1)
NEVER = datetime(3000, 1, 1, tzinfo=pytz.UTC)
CHECK_KINDS = (("simple", "Simple"),
               ("cron", "Cron"))

CHANNEL_KINDS = (("email", "Email"),
                 ("webhook", "Webhook"),
                 ("hipchat", "HipChat"),
                 ("slack", "Slack"),
                 ("pd", "PagerDuty"),
                 ("pagertree", "PagerTree"),
                 ("po", "Pushover"),
                 ("pushbullet", "Pushbullet"),
                 ("opsgenie", "OpsGenie"),
                 ("victorops", "VictorOps"),
                 ("discord", "Discord"),
                 ("telegram", "Telegram"),
                 ("sms", "SMS"),
                 ("zendesk", "Zendesk"),
                 ("trello", "Trello"))

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


def isostring(dt):
    """Convert the datetime to ISO 8601 format with no microseconds. """

    if dt:
        return dt.replace(microsecond=0).isoformat()


class Check(models.Model):
    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)
    desc = models.TextField(blank=True)
    user = models.ForeignKey(User, models.CASCADE, blank=True, null=True)
    created = models.DateTimeField(auto_now_add=True)
    kind = models.CharField(max_length=10, default="simple",
                            choices=CHECK_KINDS)
    timeout = models.DurationField(default=DEFAULT_TIMEOUT)
    grace = models.DurationField(default=DEFAULT_GRACE)
    schedule = models.CharField(max_length=100, default="* * * * *")
    tz = models.CharField(max_length=36, default="UTC")
    n_pings = models.IntegerField(default=0)
    last_ping = models.DateTimeField(null=True, blank=True)
    last_start = models.DateTimeField(null=True, blank=True)
    last_ping_was_fail = models.NullBooleanField(default=False)
    has_confirmation_link = models.BooleanField(default=False)
    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 details_url(self):
        return settings.SITE_ROOT + reverse("hc-details", args=[self.code])

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

    def send_alert(self, flip):
        if flip.new_status == "up" and flip.old_status in ("new", "paused"):
            # Don't send alerts on new->up and paused->up transitions
            return []

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

        errors = []
        for channel in self.channel_set.all():
            error = channel.notify(self)
            if error not in ("", "no-op"):
                errors.append((channel, error))

        return errors

    def get_grace_start(self):
        """ Return the datetime when the grace period starts.

        If the check is currently new, paused or down, return None.

        """

        # NEVER is a constant sentinel value (year 3000).
        # Using None instead would make the logic clunky.
        result = NEVER

        if self.kind == "simple" and self.status == "up":
            result = self.last_ping + self.timeout
        elif self.kind == "cron" and self.status == "up":
            # The complex case, next ping is expected based on cron schedule.
            # Don't convert to naive datetimes (and so avoid ambiguities around
            # DST transitions). Croniter will handle the timezone-aware datetimes.

            zone = pytz.timezone(self.tz)
            last_local = timezone.localtime(self.last_ping, zone)
            it = croniter(self.schedule, last_local)
            result = it.next(datetime)

        if self.last_start:
            result = min(result, self.last_start)

        if result != NEVER:
            return result

    def is_down(self):
        """ Return True if the check is currently in alert state. """

        alert_after = self.get_alert_after()
        if alert_after is None:
            return False

        return timezone.now() >= self.get_alert_after()

    def get_status(self, now=None):
        """ Return current status for display. """

        if now is None:
            now = timezone.now()

        if self.last_start:
            if now >= self.last_start + self.grace:
                return "down"
            else:
                return "started"

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

        grace_start = self.get_grace_start()
        grace_end = grace_start + self.grace
        if now >= grace_end:
            return "down"

        if now >= grace_start:
            return "grace"

        return "up"

    def get_alert_after(self):
        """ Return the datetime when check potentially goes down. """

        grace_start = self.get_grace_start()
        if grace_start is not None:
            return grace_start + self.grace

    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()]

    def matches_tag_set(self, tag_set):
        return tag_set.issubset(self.tags_list())

    def to_dict(self):
        update_rel_url = reverse("hc-api-update", args=[self.code])
        pause_rel_url = reverse("hc-api-pause", args=[self.code])
        channel_codes = [str(ch.code) for ch in self.channel_set.all()]

        result = {
            "name": self.name,
            "ping_url": self.url(),
            "update_url": settings.SITE_ROOT + update_rel_url,
            "pause_url": settings.SITE_ROOT + pause_rel_url,
            "tags": self.tags,
            "grace": int(self.grace.total_seconds()),
            "n_pings": self.n_pings,
            "status": self.get_status(),
            "channels": ",".join(sorted(channel_codes)),
            "last_ping": isostring(self.last_ping),
            "next_ping": isostring(self.get_grace_start())
        }

        if self.kind == "simple":
            result["timeout"] = int(self.timeout.total_seconds())
        elif self.kind == "cron":
            result["schedule"] = self.schedule
            result["tz"] = self.tz

        return result

    def ping(self, remote_addr, scheme, method, ua, body, action):
        if action == "start":
            # If we receive multiple start events in a row,
            # we remember the first one, not the last one
            if self.last_start is None:
                self.last_start = timezone.now()
            # DOn't update "last_ping" field.
        else:
            self.last_start = None
            self.last_ping = timezone.now()
            self.last_ping_was_fail = action == "fail"

            new_status = "down" if action == "fail" else "up"
            if self.status != new_status:
                flip = Flip(owner=self)
                flip.created = self.last_ping
                flip.old_status = self.status
                flip.new_status = new_status
                flip.save()

                self.status = new_status

        self.alert_after = self.get_alert_after()
        self.n_pings = models.F("n_pings") + 1
        self.has_confirmation_link = "confirm" in str(body).lower()
        self.save()
        self.refresh_from_db()

        ping = Ping(owner=self)
        ping.n = self.n_pings
        ping.start = action == "start"
        ping.fail = action == "fail"
        ping.remote_addr = remote_addr
        ping.scheme = scheme
        ping.method = method
        # If User-Agent is longer than 200 characters, truncate it:
        ping.ua = ua[:200]
        ping.body = body[:10000]
        ping.save()


class Ping(models.Model):
    id = models.BigAutoField(primary_key=True)
    n = models.IntegerField(null=True)
    owner = models.ForeignKey(Check, models.CASCADE)
    created = models.DateTimeField(auto_now_add=True)
    start = models.NullBooleanField(default=False)
    fail = models.NullBooleanField(default=False)
    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)
    body = models.CharField(max_length=10000, blank=True, null=True)


class Channel(models.Model):
    name = models.CharField(max_length=100, blank=True)
    code = models.UUIDField(default=uuid.uuid4, editable=False)
    user = models.ForeignKey(User, models.CASCADE)
    created = models.DateTimeField(auto_now_add=True)
    kind = models.CharField(max_length=20, choices=CHANNEL_KINDS)
    value = models.TextField(blank=True)
    email_verified = models.BooleanField(default=False)
    checks = models.ManyToManyField(Check)

    def __str__(self):
        if self.name:
            return self.name
        if self.kind == "email":
            return "Email to %s" % self.value
        elif self.kind == "sms":
            return "SMS to %s" % self.sms_number
        elif self.kind == "slack":
            return "Slack %s" % self.slack_channel
        elif self.kind == "telegram":
            return "Telegram %s" % self.telegram_name

        return self.get_kind_display()

    def to_dict(self):
        return {
            "id": str(self.code),
            "name": self.name,
            "kind": self.kind
        }

    def assign_all_checks(self):
        checks = Check.objects.filter(user=self.user)
        self.checks.add(*checks)

    def make_token(self):
        seed = "%s%s" % (self.code, settings.SECRET_KEY)
        seed = seed.encode()
        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})

    def get_unsub_link(self):
        args = [self.code, self.make_token()]
        verify_link = reverse("hc-unsubscribe-alerts", args=args)
        return settings.SITE_ROOT + 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 == "pagertree":
            return transports.PagerTree(self)
        elif self.kind == "victorops":
            return transports.VictorOps(self)
        elif self.kind == "pushbullet":
            return transports.Pushbullet(self)
        elif self.kind == "po":
            return transports.Pushover(self)
        elif self.kind == "opsgenie":
            return transports.OpsGenie(self)
        elif self.kind == "discord":
            return transports.Discord(self)
        elif self.kind == "telegram":
            return transports.Telegram(self)
        elif self.kind == "sms":
            return transports.Sms(self)
        elif self.kind == "trello":
            return transports.Trello(self)
        else:
            raise NotImplementedError("Unknown channel kind: %s" % self.kind)

    def notify(self, check):
        if self.transport.is_noop(check):
            return "no-op"

        n = Notification(owner=check, channel=self)
        n.check_status = check.status
        n.error = "Sending"
        n.save()

        if self.kind == "email":
            error = self.transport.notify(check, n.bounce_url()) or ""
        else:
            error = self.transport.notify(check) or ""

        n.error = error
        n.save()

        return error

    def icon_path(self):
        return 'img/integrations/%s.png' % self.kind

    @property
    def po_priority(self):
        assert self.kind == "po"
        parts = self.value.split("|")
        prio = int(parts[1])
        return PO_PRIORITIES[prio]

    @property
    def url_down(self):
        assert self.kind == "webhook"
        if not self.value.startswith("{"):
            parts = self.value.split("\n")
            return parts[0]

        doc = json.loads(self.value)
        return doc.get("url_down")

    @property
    def url_up(self):
        assert self.kind == "webhook"
        if not self.value.startswith("{"):
            parts = self.value.split("\n")
            return parts[1] if len(parts) > 1 else ""

        doc = json.loads(self.value)
        return doc.get("url_up")

    @property
    def post_data(self):
        assert self.kind == "webhook"
        if not self.value.startswith("{"):
            parts = self.value.split("\n")
            return parts[2] if len(parts) > 2 else ""

        doc = json.loads(self.value)
        return doc.get("post_data")

    @property
    def headers(self):
        assert self.kind == "webhook"
        if not self.value.startswith("{"):
            return {}

        doc = json.loads(self.value)
        return doc.get("headers", {})

    @property
    def slack_team(self):
        assert self.kind == "slack"
        if not self.value.startswith("{"):
            return None

        doc = json.loads(self.value)
        return doc["team_name"]

    @property
    def slack_channel(self):
        assert self.kind == "slack"
        if not self.value.startswith("{"):
            return None

        doc = json.loads(self.value)
        return doc["incoming_webhook"]["channel"]

    @property
    def slack_webhook_url(self):
        assert self.kind == "slack"
        if not self.value.startswith("{"):
            return self.value

        doc = json.loads(self.value)
        return doc["incoming_webhook"]["url"]

    @property
    def discord_webhook_url(self):
        assert self.kind == "discord"
        doc = json.loads(self.value)
        return doc["webhook"]["url"]

    @property
    def discord_webhook_id(self):
        assert self.kind == "discord"
        doc = json.loads(self.value)
        return doc["webhook"]["id"]

    @property
    def telegram_id(self):
        assert self.kind == "telegram"
        doc = json.loads(self.value)
        return doc.get("id")

    @property
    def telegram_type(self):
        assert self.kind == "telegram"
        doc = json.loads(self.value)
        return doc.get("type")

    @property
    def telegram_name(self):
        assert self.kind == "telegram"
        doc = json.loads(self.value)
        return doc.get("name")

    def refresh_hipchat_access_token(self):
        assert self.kind == "hipchat"
        if not self.value.startswith("{"):
            return  # Don't have OAuth credentials

        doc = json.loads(self.value)
        if time.time() < doc.get("expires_at", 0):
            return  # Current access token is still valid

        url = "https://api.hipchat.com/v2/oauth/token"
        auth = (doc["oauthId"], doc["oauthSecret"])
        r = requests.post(url, auth=auth, data={
            "grant_type": "client_credentials",
            "scope": "send_notification"
        })

        doc.update(r.json())
        doc["expires_at"] = int(time.time()) + doc["expires_in"] - 300
        self.value = json.dumps(doc)
        self.save()

    @property
    def hipchat_webhook_url(self):
        assert self.kind == "hipchat"
        if not self.value.startswith("{"):
            return self.value

        doc = json.loads(self.value)
        tmpl = "https://api.hipchat.com/v2/room/%s/notification?auth_token=%s"
        return tmpl % (doc["roomId"], doc.get("access_token"))

    @property
    def pd_service_key(self):
        assert self.kind == "pd"
        if not self.value.startswith("{"):
            return self.value

        doc = json.loads(self.value)
        return doc["service_key"]

    @property
    def pd_account(self):
        assert self.kind == "pd"
        if self.value.startswith("{"):
            doc = json.loads(self.value)
            return doc["account"]

    def latest_notification(self):
        return Notification.objects.filter(channel=self).latest()

    @property
    def sms_number(self):
        assert self.kind == "sms"
        if self.value.startswith("{"):
            doc = json.loads(self.value)
            return doc["value"]
        return self.value

    @property
    def sms_label(self):
        assert self.kind == "sms"
        if self.value.startswith("{"):
            doc = json.loads(self.value)
            return doc["label"]

    @property
    def trello_token(self):
        assert self.kind == "trello"
        if self.value.startswith("{"):
            doc = json.loads(self.value)
            return doc["token"]

    @property
    def trello_board_list(self):
        assert self.kind == "trello"
        if self.value.startswith("{"):
            doc = json.loads(self.value)
            return doc["board_name"], doc["list_name"]

    @property
    def trello_list_id(self):
        assert self.kind == "trello"
        if self.value.startswith("{"):
            doc = json.loads(self.value)
            return doc["list_id"]


class Notification(models.Model):
    class Meta:
        get_latest_by = "created"

    code = models.UUIDField(default=uuid.uuid4, null=True, editable=False)
    owner = models.ForeignKey(Check, models.CASCADE)
    check_status = models.CharField(max_length=6)
    channel = models.ForeignKey(Channel, models.CASCADE)
    created = models.DateTimeField(auto_now_add=True)
    error = models.CharField(max_length=200, blank=True)

    def bounce_url(self):
        return settings.SITE_ROOT + reverse("hc-api-bounce", args=[self.code])


class Flip(models.Model):
    owner = models.ForeignKey(Check, models.CASCADE)
    created = models.DateTimeField()
    processed = models.DateTimeField(null=True, blank=True, db_index=True)
    old_status = models.CharField(max_length=8, choices=STATUSES)
    new_status = models.CharField(max_length=8, choices=STATUSES)