Converting markdown to pdf in Python

Vitaly Bogomolov — Thu, 12 Oct 2023 11:48:42 +0000

There are many solutions for the task of automatically converting text in markdown format into a printable pdf file. These solutions based on Pandoc, LaTex, wkhtmltopdf, etc.

I want to share a new (at least for me) solution to this problem in Python.

This solution has the following advantages.

All dependencies are in requrments.txt, no external binaries.
There are no problems with non-standard encoding, pictures and the most popular markup elements.
Ability to use different page sizes within one pdf.
Customizable mode for creating a table of contents (bookmarks).

This method is based on the use of the libraries markdown-it-py (conversion from markdown to html) and PyMuPDF (conversion from html to pdf). A small Python class links them together.

Install

pip install markdown-pdf

Create a pdf with TOC (bookmarks) from headings up to level 2.

from markdown_pdf import MarkdownPdf

pdf = MarkdownPdf(toc_level=2)

Add three sections of markdown to the pdf. Each section starts on a new page. Headings from the first section are not included in the TOC.

from markdown_pdf import Section

pdf.add_section(Section("# Title\n", toc=False))
pdf.add_section(Section("# Head1\n\nbody\n"))
pdf.add_section(Section("## Head2\n\n### Head3\n\n"))

Set the properties of the pdf document.

pdf.meta["title"] = "User Guide"

Save to file.

pdf.save("guide.pdf")

Done!

Accepting cryptocurrency payments in the Telegram bot via WalletPay and Python/Flask.

Vitaly Bogomolov — Wed, 02 Aug 2023 11:21:20 +0000

Hi all!

The Telegram @wallet bot recently provided an API for accepting payments in third-party Telegram bots. Of the cryptocurrencies, BTC, TON, USDT are supported.

You need to register on the site, provide information about the bot, that will be connected to the API, go through the identification procedure (biometrics for individuals), wait for the application to be approved and setting the amount of commission for your payments. My procedure took a little over a day.

After the application is approved, you get access to your personal account, where you need to generate a key to access the WalletPay API.

After that, you can start selling. The buyer needs a link to pay the invoice for the goods/services of your bot through WalletPay. The code to get this link could be like this.

import requests

def get_pay_link():
    headers = {
     'Wpay-Store-Api-Key': 'YOUR-API-KEY',
     'Content-Type': 'application/json',
     'Accept': 'application/json',
    }

    payload = {
      'amount': {
        'currencyCode': 'USD',  # invoice in US dollars
        'amount': '1.00',
      },
      'description': 'Goods and service.',
      'externalId': 'XXX-YYY-ZZZ',  # invoice ID (in your bot) for payment
      'timeoutSeconds': 60 * 60 * 24,  # invoice expiration time in seconds
      'customerTelegramUserId': '999666999',  # buyer's Telegram account ID
      'returnUrl': 'https://t.me/mybot',  # after successful payment redirect the buyer to your bot
      'failReturnUrl': 'https://t.me/wallet',  # leave the buyer in @wallet if there is no payment
    }

    response = requests.post(
      "https://pay.wallet.tg/wpay/store-api/v1/order",
      json=payload, headers=headers, timeout=10
    )
    data = response.json()

    if (response.status_code != 200) or (data['status'] not in ["SUCCESS", "ALREADY"]):
        logging.warning("# code: %s json: %s", response.status_code, data)
        return ''

    return data['data']['payLink']

The invoice can be issued in US dollars or euros. Conversion to BTC, TON, USDT will be performed at the WalletPay rate.

To ensure that the payment of an invoice was made, WalletPay provides two options:

periodic polling of the invoice status
POST request at the https address you specified in your WalletPay dashboard (webhook in terms of WalletPay)

I used the second option. The webhook handler code could look like this.

from flask import Flask, request

app = Flask(__name__)

@app.route('/tgwallet/ipn', methods=['POST'])
def ipn_tgwallet():
    for event in request.get_json():
        if event["type"] == "ORDER_PAID":
            data = event["payload"]
            print("Paid invoice N {} for the amount {} {}. Payment {} {}.".format(
              data["externalId"],  # Invoice ID (in your bot), which we specified when creating the payment link
              data["orderAmount"]["amount"],  # Invoice amount specified when creating the payment link
              data["orderAmount"]["currencyCode"],  # Invoice currency
              data["selectedPaymentOption"]["amount"]["amount"],  # How much did the buyer pay
              data["selectedPaymentOption"]["amount"]["currencyCode"]  # In what cryptocurrency
            ))

    # should always return code 200 to prevent WalletPay from calling the webhook again
    return 'OK'

Before transferring a paid product or service, you need to make sure that the webhook call came from WalletPay, and not from attackers who are eager to get our goods for free.

To do this, WalletPay offers two options:

checking whether the IP call belongs to the pool of WalletPay IP addresses
verifying the hash calculated from the webhook call data and your API key

The list of WalletPay IP addresses can be found in the documentation, and the following code can be used to verify the hash.

import base64, hashlib, hmac

ENCODING = 'utf-8'

def is_valid(flask_request):
    text = '.'.join([
      flask_request.method,  # 'POST'
      flask_request.path,  # you need to use part of the address without the domain name, '/tgwallet/ipn' in our case
      flask_request.headers.get('WalletPay-Timestamp'),
      base64.b64encode(flask_request.get_data()).decode(ENCODING),
    ])
    signature = base64.b64encode(hmac.new(
      bytes('YOUR-API-KEY', ENCODING),
      msg=bytes(text, ENCODING),
      digestmod=hashlib.sha256
    ).digest())

    return flask_request.headers.get('Walletpay-Signature') == signature.decode(ENCODING)

Then use the is_valid function to validate call in the webhook handler.

Thank you for your attention.

DEV Community: Vitaly Bogomolov

Converting markdown to pdf in Python

Accepting cryptocurrency payments in the Telegram bot via WalletPay and Python/Flask.