code-mancers/invoker

module Invoker
  module Parsers
    # rip off from foreman
    class Procfile
      # Initialize a Procfile
      #
      # @param [String] filename (nil)  An optional filename to read from
      #
      def initialize(filename=nil)
        @entries = []
        load(filename) if filename
      end

      # Yield each +Procfile+ entry in order
      #
      def entries
        return @entries unless block_given?
        @entries.each do |(name, command)|
          yield name, command
        end
      end

      # Retrieve a +Procfile+ command by name
      #
      # @param [String] name  The name of the Procfile entry to retrieve
      #
      def [](name)
        @entries.detect { |n,c| name == n }.last
      end

      # Create a +Procfile+ entry
      #
      # @param [String] name     The name of the +Procfile+ entry to create
      # @param [String] command  The command of the +Procfile+ entry to create
      #
      def []=(name, command)
        delete name
        @entries << [name, command]
      end

      # Remove a +Procfile+ entry
      #
      # @param [String] name  The name of the +Procfile+ entry to remove
      #
      def delete(name)
        @entries.reject! { |n,c| name == n }
      end

      # Load a Procfile from a file
      #
      # @param [String] filename  The filename of the +Procfile+ to load
      #
      def load(filename)
        @entries.replace parse(filename)
      end

      # Save a Procfile to a file
      #
      # @param [String] filename  Save the +Procfile+ to this file
      #
      def save(filename)
        File.open(filename, 'w') do |file|
          file.puts self.to_s
        end
      end

      # Get the +Procfile+ as a +String+
      #
      def to_s
        @entries.map do |name, command|
          [ name, command ].join(": ")
        end.join("\n")
      end

      private

      def parse(filename)
        File.read(filename).gsub("\r\n","\n").split("\n").map do |line|
          if line =~ /^([A-Za-z0-9_-]+):\s*(.+)$/
            [$1, $2]
          end
        end.compact
      end
    end
  end
end