meeat/app.py

import datetime
import email.message
import logging
import os
import smtplib

import psycopg
import psycopg.rows

from flask import (
    Flask, session, redirect, url_for, request, render_template,
    g, abort
)

import config

logging.basicConfig(format="%(asctime)s %(levelname)s %(name)s %(lineno)d | %(message)s", level=logging.DEBUG)

app = Flask(__name__)
app.secret_key = config.secret_key
app.config["PERMANENT_SESSION_LIFETIME"] = datetime.timedelta(days=92)

log = logging.getLogger(__name__)

@app.route("/")
def home():
    log.debug("in home")
    log.debug("session = %s", session)
    if "user" not in session:
        return redirect(url_for("register", target="/"))
    return render_template("home.html")

@app.route("/register", methods=["GET", "POST"])
def register():
    log.debug("in register")
    if request.method == "GET":
        return render_template("register.html")
    email_address = request.form.get("email", "")
    if "@" not in email_address:
        flash("Das schaut nicht wie eine E-Mail-Adresse aus")
    csr = get_cursor()
    csr.execute("select * from bod where email = %s", (email_address,))
    r = csr.fetchone()
    if r:
        if r.key:
            key = r.key
        else:
            key = os.urandom(8).hex()
            csr.execute(
                    "update bod set key = %s, keychange = now() where email = %s",
                    (key, email_address,))
    else:
        key = os.urandom(8).hex()
        csr.execute(
                "insert into bod(email, key, keychange) values(%s, %s, now())",
                (email_address, key,))
    log.debug("request.scheme = %s", request.scheme)
    log.debug("request.server = %s", request.server)
    log.debug("request.root_url = %s", request.root_url)
    confirmation_url = \
        request.root_url + \
        url_for("confirm",
                target=request.form["target"],
                key=key)
    send_mail(email_address, confirmation_url)
    return render_template("wait_for_confirmation.html")

@app.route("/confirm")
def confirm():
    csr = get_cursor()
    csr.execute("select * from bod where key = %s", (request.args["key"],))
    bod = csr.fetchone()
    if not bod:
        return render_template("wrong_key.html")
    session["user"] = { "id": bod.id, "email": bod.email}
    return redirect(request.args["target"])

@app.route("/vote/<string:key>")
def vote(key):
    log.debug("session = %s", session)
    if "user" not in session:
        return redirect(url_for("register", target=request.url))
    csr = get_cursor()
    csr.execute("select * from meet where key = %s", (key,))
    meet = csr.fetchone()
    if not meet:
        abort(404)

    csr.execute(
            """
            select d.id, d.date, d.display, position
            from date d left join date_vote v on d.id = v.date and v.bod = %s
            where meet = %s order by position, d.date
            """,
            (session["user"]["id"], meet.id,))
    dates = csr.fetchall()

    csr.execute(
            """
            select d.id, d.time, d.display, position
            from time d left join time_vote v on d.id = v.time and v.bod = %s
            where meet = %s order by position, d.time
            """,
            (session["user"]["id"], meet.id,))
    times = csr.fetchall()

    csr.execute(
            """
            select d.id, d.name, position
            from place d left join place_vote v on d.id = v.place and v.bod = %s
            where meet = %s order by position, d.name
            """,
            (session["user"]["id"], meet.id,))
    places = csr.fetchall()

    return render_template("vote.html",
                meet=meet, dates=dates, times=times, places=places)

@app.post("/vote/date")
def vote_date():
    log.debug("form = %s", request.form)
    date_ids = request.form.getlist("date")

    csr = get_cursor()
    # Retrieve the meet.id from the date ids. This also ensures that all the
    # dates refer to the same meet.
    csr.execute("select distinct meet from date where id = any (%s)",
        (date_ids,))
    r = csr.fetchall()
    if len(r) != 1:
        # this should never happen. Is the client messing around?
        log.warning("Date ids %s map to meets %s", date_ids, r)
        abort(400)
    meet_id = r[0].meet

    csr.execute(
            "delete from date_vote where date = any (%s) and bod = %s",
            (date_ids, session["user"]["id"]))
    for pos, date_id in enumerate(date_ids):
        csr.execute(
                "insert into date_vote(date, bod, position) values(%s, %s, %s)",
                (date_id, session["user"]["id"], pos)
            )
    # XXX - (almost) duplicate
    csr.execute(
            """
            select d.id, d.date, d.display, position
            from date d left join date_vote v on d.id = v.date and v.bod = %s
            where meet = %s order by position, d.date
            """,
            (session["user"]["id"], meet_id,))
    dates = csr.fetchall()

    result = instantrunoff_forward(meet_id, "date")
    log.debug("result = %s", result)

    return render_template("date_vote_fragment.html", dates=dates, result=result)

@app.get("/result/<int:meet_id>/date")
def result_date(meet_id):
    result = instantrunoff_forward(meet_id, "date")
    log.debug("result = %s", result)

    return render_template("date_result_fragment.html", result=result)



@app.post("/vote/time")
def vote_time():
    log.debug("form = %s", request.form)
    time_ids = request.form.getlist("time")

    csr = get_cursor()
    # Retrieve the meet.id from the time ids. This also ensures that all the
    # times refer to the same meet.
    csr.execute("select distinct meet from time where id = any (%s)",
        (time_ids,))
    r = csr.fetchall()
    if len(r) != 1:
        # this should never happen. Is the client messing around?
        log.warning("Time ids %s map to meets %s", time_ids, r)
        abort(400)
    meet_id = r[0].meet

    csr.execute(
            "delete from time_vote where time = any (%s) and bod = %s",
            (time_ids, session["user"]["id"]))
    for pos, time_id in enumerate(time_ids):
        csr.execute(
                "insert into time_vote(time, bod, position) values(%s, %s, %s)",
                (time_id, session["user"]["id"], pos)
            )
    # XXX - (almost) duplicate
    csr.execute(
            """
            select d.id, d.time, d.display, position
            from time d left join time_vote v on d.id = v.time and v.bod = %s
            where meet = %s order by position, d.time
            """,
            (session["user"]["id"], meet_id,))
    times = csr.fetchall()

    result = instantrunoff_forward(meet_id, "time")
    log.debug("result = %s", result)

    return render_template("time_vote_fragment.html", times=times, result=result)

@app.get("/result/<int:meet_id>/time")
def result_time(meet_id):
    result = instantrunoff_forward(meet_id, "time")
    log.debug("result = %s", result)

    return render_template("time_result_fragment.html", result=result)

@app.post("/vote/place")
def vote_place():
    log.debug("form = %s", request.form)
    place_ids = request.form.getlist("place")

    csr = get_cursor()
    # Retrieve the meet.id from the place ids. This also ensures that all the
    # places refer to the same meet.
    csr.execute("select distinct meet from place where id = any (%s)",
        (place_ids,))
    r = csr.fetchall()
    if len(r) != 1:
        # this should never happen. Is the client messing around?
        log.warning("Place ids %s map to meets %s", place_ids, r)
        abort(400)
    meet_id = r[0].meet

    csr.execute(
            "delete from place_vote where place = any (%s) and bod = %s",
            (place_ids, session["user"]["id"]))
    for pos, place_id in enumerate(place_ids):
        csr.execute(
                "insert into place_vote(place, bod, position) values(%s, %s, %s)",
                (place_id, session["user"]["id"], pos)
            )
    # XXX - (almost) duplicate
    csr.execute(
            """
            select d.id, d.name, position
            from place d left join place_vote v on d.id = v.place and v.bod = %s
            where meet = %s order by position, d.name
            """,
            (session["user"]["id"], meet_id,))
    places = csr.fetchall()

    result = instantrunoff_forward(meet_id, "place")
    log.debug("result = %s", result)

    return render_template("place_vote_fragment.html", places=places, result=result)


@app.get("/result/<int:meet_id>/place")
def result_place(meet_id):
    result = instantrunoff_forward(meet_id, "place")
    log.debug("result = %s", result)

    return render_template("place_result_fragment.html", result=result)


def send_mail(email_address, confirmation_url):
    msg = email.message.EmailMessage()
    msg["From"] ="noreply@hjp.at"
    msg["To"] = email_address
    msg["Subject"] = "MEEAT confirmation"
    body = confirmation_url # Really minimalistic
    msg.set_content(body)
    mta = smtplib.SMTP(host="localhost")
    mta.send_message(msg)

def get_ballots(meet_id, kind):
    csr = get_cursor()

    q = f"""
         select {kind}.*, bod, position
         from {kind} join {kind}_vote on {kind}.id = {kind}_vote.{kind}
         where meet = %s
         order by bod, position
         """
    csr.execute(q, (meet_id,))

    last_bod = None
    ballots = []
    for r in csr:
        if r.bod != last_bod:
            ballot = []
            ballots.append(ballot)
            last_bod = r.bod
        ballot.append(r)
    return ballots

def dump_ballots(ballots):
    for ballot in ballots:
        log.debug ("---")
        for r in ballot:
            log.debug(r)

def runoff(ballots):
    count = {}
    candidates = {}
    for ballot in ballots:
        for r in ballot:
            count[r.id] = [0] * len(ballot)
            candidates[r.id] = r
    for ballot in ballots:
        for pos, r in enumerate(ballot):
            count[r.id][pos] += 1
    result = sorted(count.keys(), key=lambda i: count[i])
    log.debug("result of this round:")
    for r in result:
        log.debug("%s %s", r, count[r])
    log.debug("striking %d", result[0])
    loser = candidates[result[0]]
    new_ballots = [
        [
            r for r in ballot if r.id != loser.id
        ] for ballot in ballots
    ]
    return loser, new_ballots

def instantrunoff_forward(meet_id, kind):
    ballots = get_ballots(meet_id, kind)

    result = []
    while max(len(b) for b in ballots):
        dump_ballots(ballots)
        loser, ballots = runoff(ballots)
        result.append(loser)
    result = list(reversed(result))
    log.debug("final result")
    for r in result:
        log.debug(r)
    return result

def get_cursor():
    db = get_db()
    csr = db.cursor(row_factory=psycopg.rows.namedtuple_row)
    return csr

def get_db():
    if "db" not in g:
        g.db = psycopg.connect(dbname=config.dbname)
    return g.db

@app.teardown_appcontext
def teardown_db(exception):
    log.debug("in teardown_db: exception = %s", exception)
    db = g.pop('db', None)
    if db is not None:
        if not exception:
            try:
                db.commit()
            except:
                pass
        db.rollback()
        db.close()