class Devise::ParamFilter

def filter(conditions)
  conditions = stringify_params(conditions.dup)
  @case_insensitive_keys.each do |k|
    value = conditions[k]
    next unless value.respond_to?(:downcase)
    conditions[k] = value.downcase
  end
  @strip_whitespace_keys.each do |k|
    value = conditions[k]
    next unless value.respond_to?(:strip)
    conditions[k] = value.strip
  end
  conditions
end

def initialize(case_insensitive_keys, strip_whitespace_keys)
  @case_insensitive_keys = case_insensitive_keys || []
  @strip_whitespace_keys = strip_whitespace_keys || []
end

def param_requires_string_conversion?(value)
  [Fixnum, TrueClass, FalseClass, Regexp].none? {|clz| value.is_a? clz }
end

def stringify_params(conditions)
  return conditions unless conditions.is_a?(Hash)
  conditions.each do |k, v|
    conditions[k] = v.to_s if param_requires_string_conversion?(v)
  end
end