#!/usr/bin/env python3
""" A small donation service so that users can request ln invoices

This plugin spins up a small flask server that provides a form to
users who wish to donate some money to the owner of the lightning
node. The server can run on an arbitrary port and returns an invoice.
Also a list of previously paid invoices (only those that used this
service) will be displayed. Displaying paid invoices could be made
optionally in a future version.

Author: Rene Pickhardt (https://ln.rene-pickhardt.de)

you can see a demo of the plugin (and leave a tip) directly at:
       https://ln.rene-pickhardt.de/donation

LICENSE: MIT / APACHE
"""
import base64
import multiprocessing
import qrcode


from flask import Flask, render_template
from flask_bootstrap import Bootstrap
from flask_wtf import FlaskForm
from io import BytesIO
from pyln.client import Plugin
from random import random
from wtforms import StringField, SubmitField, IntegerField
from wtforms.validators import Required, NumberRange


plugin = Plugin()


class DonationForm(FlaskForm):
    """Form for donations """
    amount = IntegerField("Enter how many Satoshis you want to donate!",
                          validators=[Required(), NumberRange(min=1, max=16666666)])
    description = StringField("Leave a comment (displayed publically)")
    submit = SubmitField('Donate')


def make_base64_qr_code(bolt11):
    qr = qrcode.QRCode(
        version=1,
        error_correction=qrcode.constants.ERROR_CORRECT_H,
        box_size=4,
        border=4,
    )

    qr.add_data(bolt11)
    qr.make(fit=True)
    img = qr.make_image()

    buffered = BytesIO()
    img.save(buffered, format="PNG")
    img_str = base64.b64encode(buffered.getvalue()).decode("utf-8")
    return img_str


def ajax(label):
    global plugin
    msg = plugin.rpc.listinvoices(label)["invoices"][0]
    if msg["status"] == "paid":
        return "Your donation has been received and is well appricated."
    return "waiting"


def donation_form():
    global plugin
    form = DonationForm()
    b11 = None
    qr = None
    label = None
    if form.validate_on_submit():
        amount = form.amount.data
        description = form.description.data
        label = "ln-plugin-donation-{}".format(random())
        invoice = plugin.rpc.invoice(int(amount) * 1000, label, description)
        b11 = invoice["bolt11"]
        qr = make_base64_qr_code(b11)

    invoices = plugin.rpc.listinvoices()["invoices"]
    donations = []
    for invoice in invoices:
        if invoice["label"].startswith("ln-plugin-donation-"):
            # FIXME: change to paid after debugging
            if invoice["status"] == "paid":
                bolt11 = plugin.rpc.decodepay(invoice["bolt11"])
                satoshis = int(bolt11["msatoshi"]) // 1000
                description = bolt11["description"]
                ts = bolt11["created_at"]
                donations.append((ts, satoshis, description))

    if b11 is not None:
        return render_template("donation.html", donations=sorted(donations, reverse=True), form=form, bolt11=b11, qr=qr, label=label)
    else:
        return render_template("donation.html", donations=sorted(donations, reverse=True), form=form)


def worker(port):
    app = Flask(__name__)
    # FIXME: use hexlified hsm secret or something else
    app.config['SECRET_KEY'] = 'you-will-never-guess-this'
    app.add_url_rule('/donation', 'donation',
                     donation_form, methods=["GET", "POST"])
    app.add_url_rule('/is_invoice_paid/<label>', 'ajax', ajax)
    Bootstrap(app)
    app.run(host="0.0.0.0", port=port)
    return


jobs = {}


def start_server(port):
    if port in jobs:
        return False, "server already running"

    p = multiprocessing.Process(
        target=worker, args=[port], name="server on port {}".format(port))
    p.daemon = True

    jobs[port] = p
    p.start()

    return True


def stop_server(port):
    if port in jobs:
        jobs[port].terminate()
        jobs[port].join()
        del jobs[port]
        return True
    else:
        return False


@plugin.method('donationserver')
def donationserver(request, command="start", port=8088):
    """Starts a donationserver with {start/stop/restart} on {port}.

    A Simple HTTP Server is created that can serve a donation webpage and
    allow to issue invoices.  The plugin takes one of the following three
    commands {start/stop/restart} as the first agument By default the plugin
    starts the server on port 8088. This can however be changed with the port
    argument.

    """
    commands = {"start", "stop", "restart", "list"}

    # if command unknown make start our default command
    if command not in commands:
        command = "start"

    # if port not an integer make 8088 as default
    try:
        port = int(port)
    except Exception:
        port = int(plugin.options['donation-web-port']['value'])

    if command == "list":
        return "servers running on the following ports: {}".format(list(jobs.keys()))

    if command == "start":
        if port in jobs:
            return "Server already running on port {}. Maybe restart the server?".format(port)
        suc = start_server(port)
        if suc:
            return "started server successfully on port {}".format(port)
        else:
            return "Could not start server on port {}".format(port)

    if command == "stop":
        if stop_server(port):
            return "stopped server on port {}".format(port)
        else:
            return "could not stop the server"

    if command == "restart":
        stop_server(port)
        suc = start_server(port)
        if suc:
            return "started server successfully on port {}".format(port)
        else:
            return "Could not start server on port {}".format(port)


plugin.add_option(
    'donation-autostart',
    'true',
    'Should the donation server start automatically'
)

plugin.add_option(
    'donation-web-port',
    '8088',
    'Which port should the donation server listen to?'
)


@plugin.init()
def init(options, configuration, plugin):
    port = int(options['donation-web-port'])

    if options['donation-autostart'].lower() in ['true', '1']:
        start_server(port)


plugin.run()