#!/usr/bin/python3

import argparse
import flask
import sys
import subprocess
import os
from functools import wraps
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"
SIGNAL_USER_FILE = "signal_targets.txt"
app = flask.Flask("Signal Notification Gateway")
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///sqlite.db"
db = SQLAlchemy(app)

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

def login_required(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        auth = flask.request.authorization
        print(auth.password)
        print(type(auth.password))
        if not auth or not auth.lower() == app.config["PASSWORD"]:
            return (flask.jsonify({ 'message' : 'Authentication required' }), 401)
        return f(*args, **kwargs)
    return decorated_function


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

    method = flask.request.args.get("method")
    if not method:
        return (500, "Missing Dispatch Target (signal|email|phone)")

    # prevent message floods #
    timeout_cutoff = datetime.datetime.now() - datetime.timedelta(seconds=5)
    timeout_cutoff_timestamp = timeout_cutoff.timestamp()

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

    # 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)

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

    return flask.jsonify(response)


@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:

        uid = c["uid"]
        dpo = db.session.query(DispatchObject).filter(DispatchObject.dispatch_secret == uid).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', methods=["POST"])
@login_required
def smart_send_to_clients():
    '''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")

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


    persons = ldaptools.select_targets(users, groups, app.config["LDAP_ARGS"])
    save_in_dispatch_queue(persons, message)
    return ("OK", 200)


def save_in_dispatch_queue(persons, message):

    for p in persons:

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

        obj = DispatchObject(username=p.username,
                        phone=p.phone,
                        email=p.email,
                        method="signal",
                        timestamp=datetime.datetime.now().timestamp(),
                        dispatch_secret=dispatch_secret,
                        message=message)
        db.session.merge(obj)
        db.session.commit()

def create_app():
    db.create_all()
    app.config["PASSWORD"] = os.environ.get("SIGNAL_GATEWAY_PASS")
    if not app.config["PASSWORD"]:
        print("Missing ENV Variable SIGNAL_GATEWAY_PASS", file=sys.stderr)
        sys.exit(1)

    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

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')

    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,
    }

    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)