"""Everything to do with Apps"""

import os
import base64

from sqlalchemy import ForeignKey, Integer, String, Boolean
from sqlalchemy.orm import relationship
from database import db
import helpers.kubernetes as k8s

from flask import current_app

from constants import APP_NOT_INSTALLED_STATUS

DEFAULT_APP_SUBDOMAINS = {
    "nextcloud": "files",
    "wordpress": "www",
    "monitoring": "grafana",
}

class App(db.Model):
    """
    The App object, interact with the App database object. Data is stored in
    the local database.
    """

    id = db.Column(Integer, primary_key=True)
    name = db.Column(String(length=64))
    slug = db.Column(String(length=64), unique=True)
    external = db.Column(Boolean, unique=False, nullable=False, default=True, server_default='0')
    # The URL is only stored in the DB for external applications; otherwise the
    # URL is stored in a configmap (see get_url)
    url = db.Column(String(length=128), unique=False)

    def __repr__(self):
        return f"{self.id} <{self.name}>"

    def get_url(self):
        """
        Returns the URL where this application is running

        For external applications: the URL is stored in the database

        For internal applications: the URL is stored in a configmap named
        `stackspin-{self.slug}-kustomization-variables under
        `{self.slug_domain}`. This function reads that configmap. If the
        configmap does not contain a URL for the application (which is
        possible, if the app is not installed yet, for example), we return a
        default URL.
        """

        if self.external:
            return self.url

        # Get domain name from configmap
        ks_config_map = k8s.get_kubernetes_config_map_data(
                f"stackspin-{self.slug}-kustomization-variables",
                "flux-system")
        domain_key = f"{self.slug}_domain"
        # No config map found, or configmap not configured to contain the
        # domain (yet). Return the default for this app
        if ks_config_map is None or domain_key not in ks_config_map.keys():
            domain_secret = k8s.get_kubernetes_secret_data(
                    "stackspin-cluster-variables",
                    "flux-system")
            domain = base64.b64decode(domain_secret['domain']).decode()
            # See if there is another default subdomain for this app than just
            # "slug.{domain}"
            if self.slug in DEFAULT_APP_SUBDOMAINS:
                return f"https://{DEFAULT_APP_SUBDOMAINS[self.slug]}.{domain}"
            # No default known
            return f"https://{self.slug}.{domain}"
        return f"https://{ks_config_map[domain_key]}"


    def get_status(self):
        """Returns a string that describes the app state in the cluster"""

        if self.external:
            return "External app"


        # TODO: Get some kind of caching for those values, as this is called
        #       on every app list, causing significant delays in the interface

        kustomization = self.kustomization
        if kustomization is not None and "status" in kustomization:
            ks_ready, ks_message = App.check_condition(kustomization['status'])
        else:
            ks_ready = None
        for helmrelease in self.helmreleases['items']:
            hr_status = helmrelease['status']
            hr_ready, hr_message = App.check_condition(hr_status)

            # For now, only show the message of the first HR that isn't ready
            if not hr_ready:
                break

        if ks_ready is None:
            return APP_NOT_INSTALLED_STATUS
        # *Should* not happen, but just in case:
        if (ks_ready is None and hr_ready is not None) or \
                (hr_ready is None and ks_ready is not None):
            return ("This app is in a strange state. Contact a Stackspin"
                " administrator if this status stays for longer than 5 minutes")
        if ks_ready and hr_ready:
            return "App installed and running"
        if not hr_ready:
            return f"App HelmRelease status: {hr_message}"
        if not ks_ready:
            return f"App Kustomization status: {ks_message}"
        return "App is installing..."


    def install(self):
        """Creates a Kustomization in the Kubernetes cluster that installs this application"""
        # Generate the necessary passwords, etc. from a template
        self.__generate_secrets()
        # Create add-<app> kustomization
        self.__create_kustomization()

    def uninstall(self):
        """
        Delete the app kustomization.

        This triggers a deletion of the app's PVCs (so deletes all data), as
        well as any other Kustomizations and HelmReleases related to the app
        """
        self.__delete_kustomization()

    def delete(self):
        """
        Fully deletes an application

        This includes user roles, all kubernetes objects and also PVCs, so your
        data will be *gone*
        """
        # Delete all roles first
        for role in self.roles:
            db.session.delete(role)
        db.session.commit()

        db.session.delete(self)
        return db.session.commit()

    def __generate_secrets(self):
        """Generates passwords for app installation"""
        # Create app variables secret
        if self.variables_template_filepath:
            k8s.create_variables_secret(self.slug, self.variables_template_filepath)

    def __create_kustomization(self):
        """Creates the `add-{app_slug}` kustomization in the Kubernetes cluster"""
        kustomization_template_filepath = \
            os.path.join(self.__get_templates_dir(),
                "add-app-kustomization.yaml.jinja")
        k8s.store_kustomization(kustomization_template_filepath, self.slug)

    def __delete_kustomization(self):
        """Deletes kustomization for this app"""
        k8s.delete_kustomization(f"add-{self.slug}")


    @property
    def variables_template_filepath(self):
        """Path to the variables template used to generate secrets the app needs"""
        variables_template_filepath = os.path.join(self.__get_templates_dir(),
                f"stackspin-{self.slug}-variables.yaml.jinja")
        if os.path.exists(variables_template_filepath):
            return variables_template_filepath
        return None

    @property
    def namespace(self):
        """
        Returns the Kubernetes namespace of this app

        FIXME: This should probably become a database field.
        """
        if self.slug in ['nextcloud', 'wordpress', 'wekan', 'zulip']:
            return 'stackspin-apps'
        return 'stackspin'

    @property
    def roles(self):
        """
        All roles that are linked to this app
        """
        return AppRole.query.filter_by(
            app_id=self.id
        ).all()

    @property
    def kustomization(self):
        """Returns the kustomization object for this app"""
        return k8s.get_kustomization(self.slug)


    @property
    def helmreleases(self):
        """Returns the helmreleases associated with the kustomization for this app"""
        return k8s.list_helmreleases(self.namespace,
                f"kustomize.toolkit.fluxcd.io/name={self.slug}")

    @staticmethod
    def __get_templates_dir():
        """Returns directory that contains the Jinja templates used to create app secrets."""
        return os.path.join(os.path.dirname(os.path.realpath(__file__)), "templates")

    @staticmethod
    def check_condition(status):
        """
        Returns a tuple that has true/false for readiness and a message

        Ready, in this case means that the condition's type == "Ready" and its
        status == "True". If the condition type "Ready" does not occur, the
        status is interpreted as not ready.

        The message that is returned is the message that comes with the
        condition with type "Ready"

        :param status: Kubernetes resource's "status" object.
        :type status: dict
        """
        for condition in status["conditions"]:
            if condition["type"] == "Ready":
                return condition["status"] == "True", condition["message"]
        return False, "Condition with type 'Ready' not found"

    def to_json(self):
        """
        represent this object as a json object. Return JSON object
        """

        return {"id": self.id,
                "name": self.name,
                "slug": self.slug,
                "external": self.external,
                "url": self.get_url(),
                "status": self.get_status()}


class AppRole(db.Model):  # pylint: disable=too-few-public-methods
    """
    The AppRole object, stores the roles Users have on Apps
    """

    user_id = db.Column(String(length=64), primary_key=True)
    app_id = db.Column(Integer, ForeignKey("app.id"), primary_key=True)
    role_id = db.Column(Integer, ForeignKey("role.id"))

    role = relationship("Role")

    def __repr__(self):
        return (f"role_id: {self.role_id}, user_id: {self.user_id},"
                f" app_id: {self.app_id}, role: {self.role}")