module Gbdev
  
  module PdfOperations
  
    class FillTemplate

      # Fills a PDF form based on the options specified.
      # 
      # Hash pdf_options : A hash of parameters for filling the PDF form. 
      #                    [data] Hash of fields to fill and what to fill them with. Example: {:field => 'value'}.
      #                    [template] The full path to the PDF form to fill.
      #                    [dir] The directory to write filled form to.
      #                    [file_name] (optional) The name of the output file to create. If not specified a random
      #                                file name will be used.
      #
      # Exceptons : 
      #   1) If any of the required hash options from pdf_options is missing.
      def initialize(pdf_options = {})
        if !pdf_options.has_key?(:data) or !pdf_options.has_key?(:template) or !pdf_options.has_key?(:dir)
          raise 'Option parameters data, template, dir are required'
        end
  
        unless File.exist?(pdf_options[:template])
          raise 'Template file does not exist or path is wrong'
        end
  
        if ['Hash'].index(pdf_options[:data].class.to_s).nil?
          raise 'Data must be a hash'
        end
  
        unless File.directory?(pdf_options[:dir])
          raise 'Output directory does not exist or path is wrong'
        end
    
        @data      = pdf_options[:data]
        @template  = pdf_options[:template]
        @dir       = pdf_options[:dir]
        @file_name = pdf_options.has_key?(:file_name) ? pdf_options[:file_name] : build_random_file_name
      end  
    
      # Compiles the new PDF from the template and data given
      def compile_pdf
        field_cache = HashMap.new
        reader = PdfReader.new(@template)
        stamper = PdfStamper.new( reader, FileOutputStream.new([@dir, @file_name].join('/')) )
        form = stamper.getAcroFields()
        form.setFieldCache(field_cache)
      
        @data.each do |field,value|
          form.setField(field.to_s, value.to_s)
        end
    
        stamper.setFormFlattening(true)
        stamper.close        
      end
    
      private
    
        include Gbdev::Utils::PrivateMethods
    
    end # End FillTemplate
    
  end # End PdfOperations
  
end # End Gbdev