#!/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 json
import multiprocessing
import qrcode
import sys


from flask import Flask, render_template
from flask_bootstrap import Bootstrap
from flask_wtf import FlaskForm
from io import BytesIO
from lightning import LightningRpc, Plugin
from os.path import join
from random import random
from time import time
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 = Bootstrap(app)
    app.run("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()
        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:
        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',
    '33506',
    '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()