PDF Invoice generation script

invoice.rb

#!/usr/bin/env ruby

# Usage:
# Save this to a file invoice.rb, and set the values from L#185 on to your needs.
# Then run
# $ ruby invoice.rb

require 'bundler/inline'
require "date"

gemfile true do
 source "https://rubygems.org"
 gem 'prawn-table', "~> 0.2.2"
end

module TwoColumnHelper
  def two_columns(ratio: 0.5, left_width: nil)
    left_column_width = left_width || ratio * bounds.width
    right_column_width = bounds.width - left_column_width
    start_y = cursor

    bounding_box([0, start_y], :width => left_column_width) do
      yield :left
    end

    bounding_box([left_column_width, start_y], :width => right_column_width) do
      yield :right
    end
  end
end

class LineItem
  attr_reader :description, :rate, :quantity

  def initialize(description:, rate:, quantity:)
    @description = description
    @rate = rate
    @quantity = quantity
  end

  def amount
    quantity * rate
  end
end

BankDetails = Struct.new(:name, :account_number)
Supplier = Struct.new(:name, :address, :phone_number, :gst_number, :bank_account)
Recipient = Struct.new(:name, :address)

class Invoice
  attr_reader :supplier, :recipient, :date, :id, :line_items, :extra_information

  def initialize(supplier:, recipient:, date:, id:, line_items:, **extra_information)
    @supplier = supplier
    @recipient = recipient
    @date = date
    @id = id
    @line_items = line_items
    @extra_information = extra_information
  end

  def name
    "#{recipient.name}-#{id}"
  end
end

class InvoiceDocument
  include Prawn::View
  include TwoColumnHelper

  attr_reader :invoice

  def initialize(invoice)
    @invoice = invoice
  end

  def build
    text "TAX INVOICE", size: 20, align: :center

    hr

    supplier_details

    hr

    recipient_details

    move_down 30

    items

    move_down 30
    payment_info
  end

  private

  def hr
    move_down 10
    horizontal_rule
    move_down 10
  end

  def supplier_details
    two_columns do |side|
      if side == :left
        text "GST Number: #{supplier.gst_number}"
        text "Date: #{invoice.date.strftime('%e %b %Y')}"
        text "Invoice Number: #{invoice.id}"
      else
        text supplier.name, align: :right
        text supplier.address, align: :right
      end
    end
  end

  def recipient_details
    two_columns(left_width: 40) do |side|
      if side == :left
        text "To:"
      else
        text recipient.name
        text recipient.address
      end
    end

    if invoice.extra_information.size > 0
      move_down 20
      invoice.extra_information.each { |name, value| text "#{name}: #{value}" }
    end
  end

  def items
    subtotal = invoice.line_items.sum(&:amount).round(2)
    gst = (subtotal * 0.15).round(2)
    total = (subtotal + gst).round(2)
    data = [
      ["Description", "Hours", "Rate", "Amount"],
      *invoice.line_items.map { |li| [li.description, right_aligned(li.quantity), right_aligned(li.rate), right_aligned(li.amount)] },
      [nil]*4,
      [nil, {content: "Subtotal", colspan: 2, align: :right, font_style: :bold}, right_aligned("%.2f" % subtotal)],
      [nil, {content: "GST", colspan: 2, align: :right, font_style: :bold}, right_aligned("%.2f" % gst)],
      [nil, {content: "Total Due (NZD)", colspan: 2, align: :right, font_style: :bold}, right_aligned("%.2f" % total)],
    ]

    column_widths = [0.55, 0.15, 0.15, 0.15].map { |r| r * bounds.width }
    items_offset = invoice.line_items.count + 1

    table(data, column_widths: column_widths) do
      cells.padding = 5

      row(0).font_style = :bold

      row(items_offset).borders = []
      rows(items_offset..(items_offset + 4)).borders = []

      row(items_offset+3).columns(1..3).borders = [:top]
    end
  end

  def right_aligned(content)
    { content: content.to_s, align: :right }
  end

  def payment_info
    if (bank_account = invoice.supplier.bank_account)
      text "Please pay by direct credit to"
      move_down 5
      text "Name: #{bank_account.name}"
      text "Account Number: #{bank_account.account_number}"
    end
  end

  def supplier
    invoice.supplier
  end

  def recipient
    invoice.recipient
  end
end

if __FILE__ == $0
  # Generate and save the invoice PDF"

  invoice_date = Date.new(2024, 1, 31)
  bank_details = BankDetails.new("J SMITH", "01-1234-0000567-000")
  supplier = Supplier.new("Jean Smith", "1 Sample Ave\nSumner\nChristchurch", "021 111 1111", "000-000-000", bank_details)
  recipient = Recipient.new("Company Being Billed Co", "PO Box 20 123\nAuckland")
  id = invoice_date.strftime("%Y%m%d")

  line_items = [
    LineItem.new(
      description: "Technical services (January 2024)",
      quantity: 75,
      rate: 50
    )
  ]

  invoice = Invoice.new(
    supplier: supplier,
    recipient: recipient,
    date: invoice_date,
    id: id,
    line_items: line_items,
    "Purchase Order Number": "1234-5678",
    "Custom Attribute": "ABC123"
  )

  invoice_file_name = "invoice-#{invoice.id}.pdf"
  invoice_document = InvoiceDocument.new(invoice)
  invoice_document.build
  invoice_document.save_as(invoice_file_name)

  puts "\nGenerated #{invoice_file_name}"
end