# CSVBuilder stores CSV configuration
# Extracted from ActiveAdmin
#
# Usage example:
#
#   csv_builder = CSVBuilder.new
#   csv_builder.column :id
#   csv_builder.column("Name") { |resource| resource.full_name }
#
#   csv_builder = CSVBuilder.new :col_sep => ";"
#   csv_builder.column :id
#
#
class CSVBuilder

  # Return a default CSVBuilder for a resource
  # The CSVBuilder's columns would be Id followed by this
  # resource's content columns
  def self.default_for_resource(resource)
    new(resource: resource).tap do |csv_builder|
      csv_builder.column(:id)
      resource.content_columns.each do |content_column|
        csv_builder.column(content_column.name.to_sym)
      end
    end
  end
  
  def self.call_method_or_proc_on(receiver, *args)
    options = { :exec => true }.merge(args.extract_options!)

    symbol_or_proc = args.shift

    case symbol_or_proc
    when Symbol, String
      receiver.send(symbol_or_proc.to_sym, *args)
    when Proc
      if options[:exec]
        instance_exec(receiver, *args, &symbol_or_proc)
      else
        symbol_or_proc.call(receiver, *args)
      end
    end
  end

  attr_reader :columns, :options

  def initialize(options={}, &block)
    @resource = options.delete(:resource)
    @columns, @options = [], options
    instance_exec &block if block_given?
  end

  # Add a column
  def column(name, &block)
    @columns << Column.new(name, @resource, block)
  end

  class Column
    attr_reader :name, :data

    def initialize(name, resource = nil, block = nil)
      @name = name.is_a?(Symbol) && resource.present? ? resource.human_attribute_name(name) : name.to_s.humanize
      @data = block || name.to_sym
    end
  end
end