invoice.rb

# coding: utf-8
$:.unshift '/home/arne/github/kramdown/lib'

require 'fileutils'
require 'prawn'
require 'kramdown'
require 'json'

CURRENCIES = {
  'EUR' => '€ %.2f',
  'USD' => 'USD %.2f'
}

PAYMENTS = {
  'bank' => 'Please make payment directly to the account of Arne Brasseur :

Arne Brasseur
IBAN: DE67100110012625668716
BIC: NTSBDEB1XXX',
  'paypal' => 'Please make payment through PayPal to the account **arne@arnebrasseur.net**.'
}

DEFAULTS = {
  'currency' => 'EUR',
  'payment' => 'bank',
  'region' => 'EU',
  'pre_message' => '',
  'description' => "Software development"
}

class Prawn::Document
  alias current_page page # :(
end

TEMPLATE = File.read('template.md')

class Invoice
  def self.from_file(infile)
    new(DEFAULTS.merge(JSON.parse(File.read(infile))))
  end

  def initialize(data)
    data.each do |k,v|
      define_singleton_method(k){v}
    end
  end

  def total
    if respond_to?(:days) && respond_to?(:day_price)
      days.to_f * day_price.to_f
    elsif respond_to?(:hours) && respond_to?(:hour_price)
      hrs = hours
      if respond_to?(:minutes)
        hrs += (minutes.to_f/60)
      end
      hrs.to_f * hour_price.to_f
    else
      line_items.map(&:last).map(&:to_f).inject(:+)
    end
  end

  def fmt_month
    %w[
    January  February  March
    April    May       June
    July     August    September
    Oktober  November  December
  ][month.to_i - 1]
  end

  def payment_info
    PAYMENTS[payment]
  end

  def fmt_price(price)
    CURRENCIES[currency.upcase] % Float(price)
  end

  def customer_vat_nr
    "VAT no.: #{customer_vat}" if respond_to?(:customer_vat)
  end

  def full_invoice_number
    if invoice_number =~ /^\d+$/
      "#{year}/#{invoice_number}"
    else
      invoice_number
    end
  end

  unless respond_to?(:post_message)
    def post_message
      "Reverse charge method; customer is responsible for the VAT." if region == 'EU'
    end
  end

  def table(data)
    data.map do |line|
      ('| ' + line.join(' | ') + ' |').gsub(/(\d) \|/, '\1|')
    end.join("\n")
  end

  def bold(str)
    '**' + str.to_s + '**'
  end

  def fmt_hours
    if respond_to?(:minutes)
      "%d:%02d hours" % [hours, minutes]
    else
      "%d hours" % [hours]
    end
  end

  def vat
    if region == "DE"
      total * 0.19
    else
      0
    end
  end

  def grand_total
    if region == "DE"
      total * 1.19
    else
      total
    end
  end

  def line_items_table
    lines = if respond_to?(:days)
              tbl = [ [ description , "#{days} days", "#{fmt_price day_price} / day" , fmt_price(total) ] ]
              if region == "DE"
                tbl << [nil, nil, "VAT 19%", fmt_price(total * 0.19)]
                tbl << [nil, nil, "Total", fmt_price(total * 1.19)]
              else
                tbl << [nil, nil, "Total", fmt_price(total)]
              end
              tbl
            elsif respond_to?(:hours)
              tbl = [ [ description , fmt_hours, "#{fmt_price hour_price} / hour" , fmt_price(total) ] ]
              if region == "DE"
                tbl << [nil, nil, "VAT 19%", fmt_price(total * 0.19)]
                tbl << [nil, nil, "Total", fmt_price(total * 1.19)]
              else
                tbl << [nil, nil, "Total", fmt_price(total)]
              end
              tbl
            else
              tbl = line_items.map do |(desc, price)|
                [ desc, fmt_price(price) ]
              end
              if region == "DE"
                tbl << ["VAT 19%", fmt_price(total * 0.19)]
                tbl << ["Total", bold(fmt_price(total * 1.19))]
              else
                tbl << ["Total", bold(fmt_price(total))]
              end
              tbl
            end
    table(lines)
  end

  def call(outfile)
    markdown = TEMPLATE.gsub(/\{\{[^\}]+\}\}/) do |token|
      token = token[2...-2]
      self.send(token)
    end

    doc = Kramdown::Document.new(markdown, input: 'GFM')

    puts outfile

    File.write(outfile, doc.to_pdf)
    dir = "/home/arne/Doku/DE/#{year}#{month}"
    FileUtils.mkdir_p(dir)
    FileUtils.cp(outfile, dir)
  end
end

mk_invoice.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

require_relative './invoice'

infile  = ARGV.shift
outfile = ARGV.shift || 'pdf/' + infile.sub(/json$/, 'pdf')

Invoice.from_file(infile).call(outfile)

template.md

INVOICE

Arne Brasseur (IT-Consult)

Date of invoice : {{invoice_date}}

Invoice number: {{full_invoice_number}}

{{customer_address}}

{{customer_vat_nr}}

{{pre_message}}

{{line_items_table}}

{{post_message}}

---

{{payment_info}}

---

Arne Brasseur Roennebergstr 8 - 12161 Berlin (DE) VAT no.: DE291146993 Telephone: +49 176 9746 8014 Email: arne@arnebrasseur.net