#!/usr/bin/env ruby
#
# Fetch list of methods from Telegram docs.
# Use it to update client.rb.

require 'net/http'
require 'nokogiri'

DOCS_URL = 'https://core.telegram.org/bots/api'.freeze

page_html = Net::HTTP.get(URI(DOCS_URL))
doc = Nokogiri::HTML(page_html)

# Select `h4`s, but use `h3`s to group them.
headers = doc.css('h3, h4').
  chunk_while { |_, x| x.name == 'h4' }.
  map { |g| g.select { |x| x.name == 'h4' } }.
  map { |g| g.map(&:text) }

# Method starts with lowercase and does not have spaces.
NOT_METHOD_REGEXP = /(\A[^a-z])|\s/

# Filter method names.
method_list = headers.
  map { |g| g.reject { |x| x.match?(NOT_METHOD_REGEXP) } }.
  reject(&:empty?)

api_version = doc.text.match(/^(Bot API ([\d\.]+))\.?$/)

result = ['# Generated with bin/fetch-telegram-methods']
result << "# #{api_version[1]}" if api_version
result << ''
result << method_list.map { |g| g.join("\n") }.join("\n\n")
result << ''
result_txt = result.join("\n")

puts result_txt

API_METHODS_FILE = File.expand_path('../lib/telegram/bot/client/api_methods.txt', __dir__).freeze
File.write(API_METHODS_FILE, result_txt)
puts '', "Updated #{API_METHODS_FILE}"