module Sprockets::Utils

def self.normalize_extension(extension)
  extension = extension.to_s
  if extension[/^\./]
    extension
  else
    ".#{extension}"
  end
end

def self.read_unicode(pathname, external_encoding = Encoding.default_external)
  pathname.open("r:#{external_encoding}") do |f|
    f.read.tap do |data|
      # Eager validate the file's encoding. In most cases we
      # expect it to be UTF-8 unless `default_external` is set to
      # something else. An error is usually raised if the file is
      # saved as UTF-16 when we expected UTF-8.
      if !data.valid_encoding?
        raise EncodingError, "#{pathname} has a invalid " +
          "#{data.encoding} byte sequence"
      # If the file is UTF-8 and theres a BOM, strip it for safe concatenation.
      elsif data.encoding.name == "UTF-8" && data =~ UTF8_BOM_PATTERN
        data.sub!(UTF8_BOM_PATTERN, "")
      end
    end
  end
end

def self.read_unicode(pathname)
  pathname.read.tap do |data|
    # If the file is UTF-8 and theres a BOM, strip it for safe concatenation.
    if data =~ UTF8_BOM_PATTERN
      data.sub!(UTF8_BOM_PATTERN, "")
    # If we find a UTF-16 BOM, theres nothing we can do on
    # 1.8. Only UTF-8 is supported.
    elsif data =~ UTF16_BOM_PATTERN
      raise EncodingError, "#{pathname} has a UTF-16 BOM. " +
        "Resave the file as UTF-8 or upgrade to Ruby 1.9."
    end
  end
end