#!/usr/bin/python3

import argparse
import flask
import sys
import subprocess
import os
import datetime
import secrets

import ldaptools
import messagetools

from sqlalchemy import Column, Integer, String, Boolean, or_, and_
from sqlalchemy.orm import sessionmaker
from sqlalchemy.exc import IntegrityError
from sqlalchemy.sql import func
import sqlalchemy
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.sql.expression import func


HOST = "icinga.atlantishq.de"
app = flask.Flask("Signal Notification Gateway")
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///sqlite.db"
db = SQLAlchemy(app)

BAD_DISPATCH_ACCESS_TOKEN = "Invalid or missing dispatch-access-token parameter in URL"

def _apply_substitution(string):

    for replace, match in app.config["SUBSTITUTIONS"].items():
        string = string.replace(match, replace)

    return string

class WebHookPaths(db.Model):

    __tablename__ = "webhook_paths"

    username = Column(String, primary_key=True)
    path = Column(String, primary_key=True)

class UserSettings(db.Model):

    __tablename__ = "user_settings"

    username = Column(String, primary_key=True)
    signal_priority = Column(Integer)
    email_priority = Column(Integer)
    ntfy_priority = Column(Integer)

    def get_highest_prio_method(self):

        if self.signal_priority >= max(self.email_priority, self.ntfy_priority):
            return "signal"
        elif self.email_priority >= max(self.signal_priority, self.ntfy_priority):
            return "email"
        else:
            return "ntfy"

    def serizalize(self):
        return {
            "username" : self.username,
            "signal_priority" : self.signal_priority,
            "email_priority" : self.email_priority,
            "ntfy_priority" : self.ntfy_priority,
        }
        

class DispatchObject(db.Model):

    __tablename__ = "dispatch_queue"

    username = Column(String, primary_key=True)
    timestamp = Column(Integer, primary_key=True)
    phone = Column(String)
    email = Column(String)

    title = Column(String)
    message = Column(String, primary_key=True)
    method = Column(String)

    dispatch_secret = Column(String)
    dispatch_error = Column(String)

    def serialize(self):

        ret = {
            "person" : self.username, # legacy field TODO remove at some point
            "username" : self.username,
            "timestamp" : self.timestamp,
            "phone" : self.phone,
            "email" : self.email,
            "title" : _apply_substitution(self.title),
            "message" : _apply_substitution(self.message),
            "uuid" : self.dispatch_secret,
            "method" : self.method,
            "error" : self.dispatch_error,
        }

        # fix bytes => string from LDAP #
        for key, value in ret.items():
            if type(value) == bytes:
                ret[key] = value.decode("utf-8")

        if ret["method"] == "any":
            user_settings = db.session.query(UserSettings).filter(
                                UserSettings.username == ret["username"]).first()

            if not user_settings and self.phone:
                ret["method"] = "signal"
            elif not user_settings and self.email:
                ret["method"] = "email"
            elif user_settings:
                ret["method"] = user_settings.get_highest_prio_method()
            else:
                ret["method"] = "ntfy"

        return ret

@app.route('/get-dispatch-status')
def get_dispatch_status():
    '''Retrive the status of a specific dispatch by it's secret'''

    secret = flask.request.args.get("secret")
    do = db.session.query(DispatchObject).filter(DispatchObject.dispatch_secret == secret).first()
    if not do:
        return ("Not in Queue",  200)
    else:
        return ("Waiting for dispatch", 200)


@app.route('/webhooks', methods=["GET", "POST", "DELETE"])
def webhooks():

    # check static access token #
    token = flask.request.args.get("token")
    if token != app.config["SETTINGS_ACCESS_TOKEN"]:
        return ("SETTINGS_ACCESS_TOKEN incorrect. Refusing to access webhooks", 401)

    user = flask.request.args.get("user")
    if not user:
        return ("Missing user paramter in URL", 500)

    if flask.request.method == "POST":
        posted = WebHookPaths(username=user, path=secrets.token_urlsafe(20))
        db.session.merge(posted)
        db.session.commit()
        return ("", 204)
    elif flask.request.method == "GET":
        webhooks = db.session.query(WebHookPaths).filter(WebHookPaths.username==user).all()
        if not webhooks:
            return flask.jsonify([])
        else:
            return flask.jsonify([ wh.path for wh in webhooks])
    elif flask.request.method == "DELETE":
        path = flask.request.json["path"]
        webhook_to_be_deleted = db.session.query(WebHookPaths).filter(WebHookPaths.username==user,
                                    WebHookPaths.path==path).first()
        if not webhook_to_be_deleted:
            return ("Webhook to be deleted was not found ({}, {})".format(user, path), 404)
        else:
            db.session.delete(webhook_to_be_deleted)
            db.session.commit()
            return ("", 204)

@app.route('/settings', methods=["GET", "POST"])
def settings():

    # check static access token #
    token = flask.request.args.get("token")
    if token != app.config["SETTINGS_ACCESS_TOKEN"]:
        return ("SETTINGS_ACCESS_TOKEN incorrect. Refusing to access settings", 401)

    user = flask.request.args.get("user")
    if not user:
        return ("Missing user paramter in URL", 500)

    if flask.request.method == "POST":
        posted = UserSettings(username=user,
                        signal_priority=flask.request.json.get("signal_priority") or 0,
                        email_priority=flask.request.json.get("email_priority") or 0,
                        ntfy_priority=flask.request.json.get("ntfy_priority") or 0)
        db.session.merge(posted)
        db.session.commit()
        return ('', 204)

    if flask.request.method == "GET":
        user_settings = db.session.query(UserSettings).filter(UserSettings.username==user).first()
        if not user_settings:
            posted = UserSettings(username=user, signal_priority=5, email_priority=7, ntfy_priority=3)
            db.session.merge(posted)
            db.session.commit()
            user_settings = posted
        return flask.jsonify(user_settings.serizalize())


@app.route('/get-dispatch')
def get_dispatch():
    '''Retrive consolidated list of dispatched objects'''

    method = flask.request.args.get("method")
    timeout = flask.request.args.get("timeout") or 5 # timeout in seconds
    timeout = int(timeout)

    dispatch_acces_token = flask.request.args.get("dispatch-access-token") or ""
    if dispatch_acces_token != app.config["DISPATCH_ACCESS_TOKEN"]:
        return (BAD_DISPATCH_ACCESS_TOKEN, 401)

    if not method:
        return (500, "Missing Dispatch Target (signal|email|phone|ntfy|all|any)")

    # prevent message floods #
    timeout_cutoff = datetime.datetime.now() - datetime.timedelta(seconds=timeout)
    timeout_cutoff_timestamp = timeout_cutoff.timestamp()

    lines_unfiltered = db.session.query(DispatchObject)
    lines_timeout = lines_unfiltered.filter(DispatchObject.timestamp < timeout_cutoff_timestamp)

    if method != "all":

        dispatch_objects = lines_timeout.filter(DispatchObject.method==method).all()

        dispatch_objects_any = lines_timeout.filter(DispatchObject.method=="any").all()
        for d in dispatch_objects_any:
            user_str = str(d.username, "utf-8")
            user_settings = db.session.query(UserSettings).filter(UserSettings.username==user_str).first()
            if user_settings and user_settings.get_highest_prio_method() == method:
                dispatch_objects += [d]
    else:
        dispatch_objects = lines_timeout.all()

    # TODO THIS IS THE NEW MASTER PART
    if method and method != "signal":
        debug = [ d.serialize() for d in dispatch_objects]
        if debug:
            print(debug)
        return flask.jsonify([ d.serialize() for d in dispatch_objects])
    else:
        # TODO THIS PART WILL BE REMOVED ##
        # accumulate messages by person #
        dispatch_by_person = dict()
        dispatch_secrets = []
        for dobj in dispatch_objects:
            if dobj.username not in dispatch_by_person:
                dispatch_by_person.update({ dobj.username : dobj.message })
                dispatch_secrets.append(dobj.dispatch_secret)
            else:
                dispatch_by_person[dobj.username] += "\n{}".format(dobj.message)
                dispatch_secrets.append(dobj.dispatch_secret)

        # legacy hack #
        if method == "any":
            method = "signal"

        response = [ { "person" : tupel[0].decode("utf-8"),
                        "message" : tupel[1],
                        "method" : method,
                        "uids" : dispatch_secrets 
                      } for tupel in dispatch_by_person.items() ]

        # add phone numbers and emails #
        for obj in response:
            for person in dispatch_objects:
                if obj["person"] == person.username.decode("utf-8"):
                    if person.email:
                        obj.update({ "email" : person.email.decode("utf-8") })
                    if person.phone:
                        obj.update({ "phone" : person.phone.decode("utf-8") })

        return flask.jsonify(response)

@app.route('/report-dispatch-failed', methods=["POST"])
def reject_dispatch():
    '''Inform the server that a dispatch has failed'''

    rejects = flask.request.json

    for r in rejects:

        uuid = r["uuid"]
        error = r["error"]
        dpo = db.session.query(DispatchObject).filter(
                        DispatchObject.dispatch_secret == uuid).first()

        if not dpo:
            return ("No pending dispatch for this UID/Secret", 404)

        dpo.dispatch_error = error
        db.session.merge(dpo)
        db.session.commit()

    return ("", 204)

@app.route('/confirm-dispatch', methods=["POST"])
def confirm_dispatch():
    '''Confirm that a message has been dispatched by replying with its dispatch secret/uid'''

    confirms = flask.request.json

    for c in confirms:

        uuid = c["uuid"]
        dpo = db.session.query(DispatchObject).filter(
                        DispatchObject.dispatch_secret == uuid).first()

        if not dpo:
            return ("No pending dispatch for this UID/Secret", 404)

        db.session.delete(dpo)
        db.session.commit()

    return ("", 204)


@app.route('/smart-send/<path:path>', methods=["POST"])
@app.route('/smart-send', methods=["POST"])
def smart_send_to_clients(path=None):
    '''Send to clients based on querying the LDAP
        requests MAY include:
            - list of usernames under key "users"
            - list of groups    under key "groups"
            - neither of the above to automatically target the configured administrators group"
        retuest MUST include:
            - message as STRING in field "msg"
            OR
            - supported struct of type "ICINGA|ZABBIX|GENERIC" (see docs) in field "data"
    '''

    instructions = flask.request.json

    users = instructions.get("users")
    groups = instructions.get("groups")
    message = instructions.get("msg")
    title = instructions.get("title")
    method = instructions.get("method")

    # authenticated by access token or webhook path #
    dispatch_acces_token = flask.request.args.get("dispatch-access-token") or ""
    print(path)
    if path:
        webhook_path = db.session.query(WebHookPaths).filter(WebHookPaths.path==path).first()
        if webhook_path:
            users = webhook_path.username
            groups = None
        else:
            return ("Invalid Webhook path", 401)
    elif dispatch_acces_token != app.config["DISPATCH_ACCESS_TOKEN"]:
        return (BAD_DISPATCH_ACCESS_TOKEN, 401)

    # allow single use string instead of array #
    if type(users) == str:
        users = [users]

    struct = instructions.get("data")
    if struct:
        try:
            message = messagetools.load_struct(struct)
        except messagetools.UnsupportedStruct as e:
            print(str(e), file=sys.stderr)
            return (e.response(), 408)

    if method in ["debug", "debug-fail"]:
        persons = [ldaptools.Person(cn="none", username=users[0], name="Mr. Debug",
                        email="invalid@nope.notld", phone="0")]
    else:
        persons = ldaptools.select_targets(users, groups, app.config["LDAP_ARGS"])

    dispatch_secrets = save_in_dispatch_queue(persons, title, message, method)
    return flask.jsonify(dispatch_secrets)


def save_in_dispatch_queue(persons, title, message, method):


    dispatch_secrets = []
    for p in persons:

        if not p:
            continue

        # this secret will be needed to confirm the message as dispatched #
        dispatch_secret = secrets.token_urlsafe(32)

        master_method = "any"
        obj = DispatchObject(username=p.username,
                        phone=p.phone,
                        email=p.email,
                        method=method or master_method,
                        timestamp=datetime.datetime.now().timestamp(),
                        dispatch_secret=dispatch_secret,
                        title=title,
                        message=message)

        db.session.merge(obj)
        db.session.commit()

        dispatch_secrets.append(dispatch_secret)

    return dispatch_secrets

@app.route("/")
@app.route("/health")
def health():

    return ("Not Iplemented, but at least it's running", 200)

def create_app():

    db.create_all()

    if not app.config.get("LDAP_NO_READ_ENV"):
        ldap_args = {
            "LDAP_SERVER"  : os.environ["LDAP_SERVER"],
            "LDAP_BIND_DN" : os.environ["LDAP_BIND_DN"],
            "LDAP_BIND_PW" : os.environ["LDAP_BIND_PW"],
            "LDAP_BASE_DN" : os.environ["LDAP_BASE_DN"]
        }
        app.config["LDAP_ARGS"] = ldap_args
        app.config["SETTINGS_ACCESS_TOKEN"] = os.environ["SETTINGS_ACCESS_TOKEN"]
        app.config["DISPATCH_ACCESS_TOKEN"] = os.environ["DISPATCH_ACCESS_TOKEN"]

    substitution_config_file = app.config.get("SUBSTITUTION_MAP") or "substitutions.yaml"
    app.config["SUBSTITUTIONS"] = {}
    if os.path.isfile(substitution_config_file):
        with open(substitution_config_file) as f:
            app.config["SUBSTITUTIONS"] = yaml.safe_load(f)


if __name__ == "__main__":

    parser = argparse.ArgumentParser(description='Simple Telegram Notification Interface',
                        formatter_class=argparse.ArgumentDefaultsHelpFormatter)

    parser.add_argument('--interface', default="localhost", help='Interface on which to listen')
    parser.add_argument('--port', default="5000", help='Port on which to listen')
    parser.add_argument("--signal-cli-bin", default=None, type=str,
                            help="Path to signal-cli binary if no in $PATH")

    parser.add_argument('--ldap-server')
    parser.add_argument('--ldap-base-dn')
    parser.add_argument('--ldap-manager-dn')
    parser.add_argument('--ldap-manager-password')

    parser.add_argument('--settings-access-token')
    parser.add_argument('--dispatch-access-token')

    args = parser.parse_args()

    # define ldap args #
    ldap_args = {
        "LDAP_SERVER" : args.ldap_server,
        "LDAP_BIND_DN" : args.ldap_manager_dn,
        "LDAP_BIND_PW" : args.ldap_manager_password,
        "LDAP_BASE_DN" : args.ldap_base_dn,
    }
    app.config["LDAP_NO_READ_ENV"] = True

    app.config["SETTINGS_ACCESS_TOKEN"] = args.settings_access_token
    app.config["DISPATCH_ACCESS_TOKEN"] = args.dispatch_access_token

    if not any([value is None for value in ldap_args.values()]):
        app.config["LDAP_ARGS"] = ldap_args
    else:
        app.config["LDAP_ARGS"] = None

    with app.app_context():
        create_app()

    app.run(host=args.interface, port=args.port, debug=True)