Ruby script to download latest Crystal tagged Debian package

download_latest_crystal_tagged_deb.rb

#!/usr/bin/env ruby
# vim: ft=ruby syn=ruby fileencoding=utf-8 sw=2 ts=2 ai eol et si
#
# download_latest_crystal_tagged_deb.rb: this script looks up the latest
# successfull tagged build of crystal on Circle CI, extracts the build number
# of `dist_artifacts` job and retrieves it's Debian artifacts, depending of
# ARCH environment variable (default: 'amd64')
#
# (c) 2018 Laurent Vallar <val@zbla.net>, WTFPL license v2 see below.
#
# This program is free software. It comes without any warranty, to
# the extent permitted by applicable law. You can redistribute it
# and/or modify it under the terms of the Do What The Fuck You Want
# To Public License, Version 2, as published by Sam Hocevar. See
# http://www.wtfpl.net/ for more details.
#
# frozen_string_literal: true

require 'json'
require 'open-uri'

ARCH = ENV['ARCH'] || 'amd64' # 'amd64' or 'i386'
raise "invalid arch #{ARCH}" unless %w[amd64 i386].include?(ARCH)
URL_BASE = "https://circleci.com/api/v1.1/project/github/crystal-lang/crystal"

def last_tagged_build_with_artifacts(limit: 100, offset: 0)
  location = "?filter=successful&limit=#{limit}&branch=master&offset=#{offset}"

  puts "requesting page ##{offset} of #{limit} items"
  open("#{URL_BASE}#{location}") do |body|
    JSON.parse(body.read, symbolize_names: true)
        .sort_by { |hash| - hash[:build_num] }
        .find do |hash|
      hash[:vcs_tag] && hash[:build_parameters][:CIRCLE_JOB] == 'dist_artifacts'
    end
  end
end

def find_last_tagged_build_with_artifacts(depth: 10)
  0.upto(depth) do |offset|
    current = last_tagged_build_with_artifacts

    break current if current
  end
end

def artifact_url
  build = find_last_tagged_build_with_artifacts
  build_num = build[:build_num]
  puts "found build ##{build_num}, tags: #{build[:vcs_tag]}"

  open("#{URL_BASE}/#{build[:build_num]}/artifacts") do |file|
    file.read.scan(%r{https://[^"]*#{ARCH}\.deb}m).first
  end
end

@total = nil
CONTENT_LENGTH_PROC = lambda { |content_length| @total = content_length }
PROGRESS_PROC = lambda { |transferred|
  print("\r#{transferred}/#{@total || 'unknown'}")
}

def get(source, dest)
  open(dest, 'w') do |target|
    open(source,
         content_length_proc: CONTENT_LENGTH_PROC,
         progress_proc: PROGRESS_PROC) do |file|
      content = file.read
      @total = content.size
      target.write(content)
    end

    puts
  end
end

def download(url: artifact_url)
  basename = File.basename(url)
  raise("#{basename} already present!") if File.exist?(basename)

  get(url, basename)

  puts "#{basename} downloaded #{@total} bytes"
end

download