class GdsApi::Validators::BasePathValidator

def ends_with_a_period?
  base_path[-1] == "."
end

def errors
  return {} unless base_path
  errors = []
  errors << [:base_path_invalid, "must start with a /"] if no_leading_slash?
  errors << [:base_path_too_long, "must not be longer than #{MAX_PATH_LENGTH} bytes"] if too_long?
  errors << [:base_path_invalid, "must not include runs of . and or / characters, which could be penetration attempts"] if potential_path_traversal?
  errors << [:base_path_invalid, "must not end with a ."] if ends_with_a_period?
  errors << [:base_path_invalid, "must not include characters that are not lowercase letters, numbers, -, ., or /"] if invalid_chars?
  errors.each_with_object({}) do |err, memo|
    memo[err[0]] ||= []
    memo[err[0]] << err[1]
  end
end

def initialize(base_path)
  @base_path = base_path
end

def invalid_chars?
  base_path !~ /^([\/a-z0-9.-])+$/
end

def no_leading_slash?
  base_path[0] != "/"
end

def potential_path_traversal?
  base_path =~ /([\/.]{2,})/
end

def too_long?
  base_path.length > MAX_PATH_LENGTH
end

def valid?
  return true unless base_path
  !(no_leading_slash? || too_long? || potential_path_traversal? || ends_with_a_period? || invalid_chars?)
end