dot_params.rb

module DotParams
  class Middleware
    def initialize(app)
      @app = app
    end

    def call(env)
      reparse_query(env["rack.request.query_hash"])
      reparse_query(env["rack.request.form_hash"])

      @app.call(env)
    end

    def reparse_query params
      return unless params
      params.each do |key, value|
        normalize_params params, key, value
      end
    end

    def normalize_params(params, name, v = nil)
      name =~ %r(\A[\[\]\.]*([^\[\]\.]+)\]*)
      k = $1 || ''
      after = $' || ''

      return if k.empty?

      if after == ""
        params[k] = v
      elsif after == "[]" || after == "."
        params[k] ||= []
        raise TypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        params[k] << v
      elsif after =~ %r(^\[\]\[([^\[\]]+)\]$) || after =~ %r(^\[\](.+)$) || after =~ %r(^\.\.(.+)$)
        child_key = $1
        params[k] ||= []
        raise TypeError, "expected Array (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Array)
        if params[k].last.is_a?(Hash) && !params[k].last.key?(child_key)
          normalize_params(params[k].last, child_key, v)
        else
          params[k] << normalize_params({}, child_key, v)
        end
      else
        params[k] ||= {}
        raise TypeError, "expected Hash (got #{params[k].class.name}) for param `#{k}'" unless params[k].is_a?(Hash)
        params[k] = normalize_params(params[k], after, v)
      end

      return params
    end
  end
end