#!/usr/bin/env python3

from flask import Flask
from flask import request, render_template
from flask.ext.sqlalchemy import SQLAlchemy
#from flask import session, request, url_for, redirect, render_template
import netaddr
from netaddr import IPAddress
# Hack for python3
from netaddr.strategy.ipv4 import packed_to_int as unpack_v4
from netaddr.strategy.ipv6 import packed_to_int as unpack_v6
import socket
from datetime import datetime
from uuid import uuid4

app = Flask(__name__)
app.config.from_pyfile('config.py')
db = SQLAlchemy(app)


def unpack(ip):
    if len(ip) == 4:
        return unpack_v4(ip)
    elif len(ip) == 16:
        return unpack_v6(ip)

def is_valid_ip(ip):
    return netaddr.valid_ipv4(ip) or netaddr.valid_ipv6(ip)

def resolve_name(hostname):
    return list({s[4][0] for s in socket.getaddrinfo(hostname, None)})

class Target(db.Model):
    """Target IP to ping"""
    id = db.Column(db.Integer, primary_key=True)
    # Unique ID for accessing the results (privacy reasons)
    unique_id = db.Column(db.String)
    # IP addresses are encoded as their binary representation
    ip = db.Column(db.BINARY(length=16))
    # Date at which a user asked for measurements to this target
    submitted = db.Column(db.DateTime)

    def __init__(self, ip):
        self.unique_id = str(uuid4())
        self.ip = IPAddress(ip).packed
        self.submitted = datetime.now()

    def get_ip(self):
        return IPAddress(unpack(self.ip))

    def is_v4(self):
        return self.get_ip().version == 4

    def is_v6(self):
        return self.get_ip().version == 6

    def __repr__(self):
        return '%r' % self.get_ip()

    def __str__(self):
        return str(self.get_ip())


# Many-to-many table to record which target has been given to which
# participant.
handled_targets = db.Table('handled_targets',
    db.Column('target_id', db.Integer, db.ForeignKey('target.id')),
    db.Column('participant_id', db.Integer, db.ForeignKey('participant.id'))
)


class Participant(db.Model):
    """Participant in the ping network"""
    id = db.Column(db.Integer, primary_key=True)
    # Used both as identification and password
    uuid = db.Column(db.String, unique=True)
    # Name of the machine
    name = db.Column(db.String)
    # Mostly free-form (nick, mail address, ...)
    contact = db.Column(db.String)
    # Whether we accept this participant or not
    active = db.Column(db.Boolean)
    # Many-to-many relationship
    targets = db.relationship('Target',
        secondary=handled_targets,
        backref=db.backref('participants', lazy='dynamic'),
        lazy='dynamic')

    def __init__(self, name, contact):
        self.uuid = str(uuid4())
        self.name = name
        self.contact = contact
        self.active = False

    def __str__(self):
        return "{} ({})".format(self.name, self.contact)


class Result(db.Model):
    """Result of a ping measurement"""
    id = db.Column(db.Integer, primary_key=True)
    target_id = db.Column(db.Integer, db.ForeignKey('target.id'))
    target = db.relationship('Target',
                             backref=db.backref('results', lazy='dynamic'))
    participant_id = db.Column(db.Integer, db.ForeignKey('participant.id'))
    participant = db.relationship('Participant',
                                  backref=db.backref('results', lazy='dynamic'))
    # In milliseconds
    rtt = db.Column(db.Float)
    # Date at which the result was reported back to us
    date = db.Column(db.DateTime)

    def __init__(self, target_id, participant_uuid, rtt):
        target = Target.query.get_or_404(int(target_id))
        participant = Participant.query.filter_by(uuid=participant_uuid,
                                                  active=True).first_or_404()
        self.target = target
        self.participant = participant
        self.rtt = float(rtt)
        self.date = datetime.now()


def init_db():
    db.create_all()


def get_targets(uuid):
    """Returns the queryset of potential targets for the given participant
    UUID, that is, targets that have not already been handed out to this
    participant.
    """
    participant = Participant.query.filter_by(uuid=uuid, active=True).first_or_404()
    # We want to get all targets that do not have a relationship with the
    # given participant.  Note that the following lines manipulate SQL
    # queries, which are only executed at the very end.
    # This gives all targets that have already been sent to the given
    # participant.
    already_done = Target.query.join(handled_targets).filter_by(participant_id=participant.id).with_entities(Target.id)
    # This takes the negation of the previous set.
    return Target.query.filter(~Target.id.in_(already_done))


@app.route('/')
def homepage():
    return render_template('home.html')

@app.route('/robots.txt')
def robots():
    return "User-agent: *\nDisallow: /target/\nDisallow: /result/"

@app.route('/submit', methods=['POST'])
def submit_job():
    if 'target' in request.form:
        target = request.form['target']
        if is_valid_ip(target):
            # Explicit IP
            targets = [Target(target)]
        else:
            # DNS name, might give multiple IP
            targets = [Target(ip) for ip in resolve_name(target)]
        for t in targets:
            db.session.add(t)
        db.session.commit()
        return render_template('submit.html', targets=targets)
    else:
        return "Invalid arguments"

@app.route('/create/participant', methods=['POST'])
def create_participant():
    if {'name', 'contact'}.issubset(request.form) and request.form['name']:
        participant = Participant(request.form['name'], request.form['contact'])
        db.session.add(participant)
        db.session.commit()
        return render_template('participant.html', participant=participant,
                               uuid=participant.uuid)
    else:
        return "Invalid arguments"

@app.route('/target/<uuid>')
def get_next_target(uuid):
    """"Returns the next target to ping for the given participant"""
    target = get_targets(uuid).first()
    if target is not None:
        return "{} {}".format(target.id, target)
    else:
        return ""

@app.route('/target/<uuid>/<family>')
def get_next_target_family(uuid, family):
    """Same as above, but for a specific family ("ipv4" or "ipv6")"""
    if family not in ("ipv4", "ipv6"):
        return "Invalid family, should be ipv4 or ipv6\n"
    predicate = lambda t: t.is_v4() if family == "ipv4" else t.is_v6()
    targets = [t for t in get_targets(uuid).all() if predicate(t)]
    if not targets:
        return ""
    return "{} {}".format(targets[0].id, targets[0])

@app.route('/result/report/<uuid>', methods=['POST'])
def report_result(uuid):
    if {'rtt', 'target'}.issubset(request.form):
        target_id = request.form['target']
        rtt = request.form['rtt']
        result = Result(target_id, uuid, rtt)
        db.session.add(result)
        # Record that the participant has returned a result
        participant = result.participant
        participant.targets.append(result.target)
        db.session.commit()
        return "OK\n"
    else:
        return "Invalid arguments\n"

@app.route('/result/show/<target_uniqueid>')
def show_results(target_uniqueid):
    target = Target.query.filter_by(unique_id=target_uniqueid).first_or_404()
    results = target.results.order_by('rtt').all()
    return render_template('results.html', target=target, results=results)


if __name__ == '__main__':
    init_db()
    app.run(host='0.0.0.0', port=8888)