module Senf
  VERSION = {{ `shards version`.stringify.chomp.downcase }}

  class SafeEnv
    private property keys

    def initialize(@keys = {} of String => String?)
    end

    def initialize(keys : Array(String))
      @keys = {} of String => String?
      keys.each { |k| self.<< k }
    end

    def <<(key : String) : self
      @keys[key] = ENV[key]?

      self
    end

    def []?(key : String) : String?
      if @keys.has_key?(key)
        @keys[key]?
      end
    end

    def [](key : String) : String
      if @keys.has_key?(key)
        val = @keys[key]?
        raise "ENV[#{key}] is nil" unless val

        val
      else
        raise "No such key: #{key}"
      end
    end
  end
end