form_letter.rb

require_relative "helper"

### Parse the sections of the document into a params dictionary

parser = FormLetter::Parser.new

parser.rewrite(:emails, :deadline) 
parser.rewrite(:date) { Date.today.strftime("%b %d, %Y") }

# this would come from a database or other source,
# but you get the idea
parser.rewrite(:customer_name) do
  ["Gregory", "Brad", "James", "Daniel", "Jonathan" ].sample 
end

params = parser.parse(File.read("letter.txt"))

## Set relevant formatting for different sections

formatting = {
  :company            => { :styles => [:bold] },
  :company_subtext    => { :size => 8 },
  :company_header     => { :align => :center, :leading => 4, :color => "555555" },
  :company_address    => { :align => :center, :color => "555555", :size => 10 },
  :from               => { :align => :left, :color => "555555", :size => 10 },
  :contact            => { :align => :right, :color => "555555", :size => 10 },
  :body               => { :size => 10, :inline_format => true },
  :footer             => { :size => 8, :color => "555555" }
}

### Generate the letter

letter = FormLetter.new(params, formatting)

letter.update do
  font "Helvetica"

  header_box(:left) do
    move_down 0.75.in
    text(:from)
  end

  header_box(:center) do
    text_group [:company, :company_subtext], :company_header

    text(:company_address)
  end

  header_box(:right) do
    move_down 0.75.in
    text(:contact)
  end

  font "Times-Roman"

  move_down 2.in

  body do
    letter.text(:body) # NOTE: nbsp in content
  end

  move_cursor_to 0.5.in

  font "Helvetica"

  text(:footer)
end

letter.save_as("letter.pdf")

helper.rb

require "ostruct"

require "bundler"
Bundler.require

require "prawn/measurement_extensions"

Prawn.debug = true

module PrawnDSL
  def document
    @document ||= Prawn::Document.new
  end

  def method_missing(m, *a, &b)
    document.send(m, *a, &b)
  end

  def update(&b)
    instance_eval(&b)
  end

  def save_as(filename)
    document.render_file(filename)
  end
end

class FormLetter
  include PrawnDSL
   
  def initialize(params, styles)
    @params   = params
    @styles   = styles
  end


  def text(content_key)
    document.text(@params[content_key].strip + "\n",
                  @styles.fetch(content_key, {}))
  end

  def text_group(fragments, style_key=nil)
    document.formatted_text(
      fragments.map { |e| fragment(e) },
      @styles.fetch(style_key, {}))
  end

  def header_box(position)
    float do
      span(bounds.width / 3.0, :position => position) do
        yield
      end
    end
  end

  def body
    span(6.5.in, :position => :center) { yield }
  end

  private

  def fragment(content_key)
    { :text => @params[content_key].strip + "\n" }
    .merge(@styles.fetch(content_key, {}))
  end
end

class FormLetter::Parser
  def initialize
    @rewrites = {}
  end

  def rewrite(*patterns, &block)
    return rewrite_dynamic(patterns.first, &block) if block

    patterns.each do |pattern|
      key = ":#{pattern}:"

      @rewrites[key] = ->(e) { e[pattern.to_s] }
    end
  end

  def parse(text)
    params = OpenStruct.new

    section         = nil

    text.lines.each do |e| 
      
      if e[/^::(.*)/, 1]
        section = $1
      elsif section
        @rewrites.select { |k,v| e.include?(k) }
                 .each   { |k,v| e.gsub!(k, v.call(params).strip) }

        (params[section] ||= "") << e
      else
        warn "Section not set!"
      end
    end

    params
  end

  private

  def rewrite_dynamic(pattern, &block)
    key = ":#{pattern}:"

    @rewrites[key] = block
  end
end

letter.pdf

letter.txt

::from
Enrico O'Keefe
Florine Grant

::contact
Phone: 203-555-1234
Fax: 203-555-4321

::company
O'KEEFE AND GRANT, P.C.

::company_subtext
CERTIFIED PUBLIC ACCOUNTANTS

::company_address
24410 Rice Meadow Road • Suite A
New Haven, Connecticut 06512

::deadline
March 31, 2014

::emails
        <u>enrico@okgracpas.com</u>
        <u>florine@okgracpas.com</u>

::footer
Members:
American Institute of Certified Public Accountants
Connecticut Society of Certified Public Accountants

::body
:date:

Dear :customer_name:,

It's that time of year again and in order to assist you in gathering the necessary records needed to prepare your 2013 tax returns, we have compiled the enclosed cheklist for you to complete.

Just a reminder, your 2013 returns must be electronically filed as required by the Internal Revenue Service. Also, our fee is expected to be paid at the time your tax return is completed. <strong>Fee must be paid before return is filed. For your convenience, we accept credit cards.</strong>

If you receive a refund we recommend that you have it direct deposited. This results in a quicker and dafer way to receive your refund. Please complete and return the enclosed information and return it to us when you send in your tax information.

When you send in your information, also give us your email address if you have one so that we may contact you should we need any additional information. Also, please let us know if you would like to pick up your return when it is completed or if you would like it mailed to you.

Please send in your information before :deadline:. If we receive your information after that date, there is no guarantee that your returns will be processed by the tax filing deadline and an extension will be filed for you.


If you have any questions, please do not heasitate to give us a call, or email us at:

:emails:

Sincerely,

O'KEEFE AND GRANT, P.C.
Certified Public Accountants