class Sprockets::Asset

def self.from_hash(environment, hash)
  return unless hash.is_a?(Hash)
  klass = case hash['class']
    when 'BundledAsset'
      BundledAsset
    when 'ProcessedAsset'
      ProcessedAsset
    when 'StaticAsset'
      StaticAsset
    else
      nil
    end
  if klass
    asset = klass.allocate
    asset.init_with(environment, hash)
    asset
  end
rescue UnserializeError
  nil
end

def body
  source
end

def dependencies
  []
end

def dependency_fresh?(environment, dep)
  path, mtime, hexdigest = dep.pathname.to_s, dep.mtime, dep.digest
  stat = environment.stat(path)
  # If path no longer exists, its definitely stale.
  if stat.nil?
    return false
  end
  # Compare dependency mtime to the actual mtime. If the
  # dependency mtime is newer than the actual mtime, the file
  # hasn't changed since we created this `Asset` instance.
  #
  # However, if the mtime is newer it doesn't mean the asset is
  # stale. Many deployment environments may recopy or recheckout
  # assets on each deploy. In this case the mtime would be the
  # time of deploy rather than modified time.
  #
  # Note: to_i is used in eql? and write_to we assume fidelity of 1 second
  #  if people save files more frequently than 1 second sprockets may
  #  not pick it up, by design
  if mtime.to_i >= stat.mtime.to_i
    return true
  end
  digest = environment.file_digest(path)
  # If the mtime is newer, do a full digest comparsion. Return
  # fresh if the digests match.
  if hexdigest == digest.hexdigest
    return true
  end
  # Otherwise, its stale.
  false
end

def dependency_paths
  @dependency_paths ||= []
end

def digest_path
  logical_path.sub(/\.(\w+)$/) { |ext| "-#{digest}#{ext}" }
end

def each
  yield to_s
end

def encode_with(coder)
  coder['class']        = self.class.name.sub(/Sprockets::/, '')
  coder['logical_path'] = logical_path
  coder['pathname']     = relativize_root_path(pathname).to_s
  coder['content_type'] = content_type
  coder['mtime']        = mtime.to_i
  coder['length']       = length
  coder['digest']       = digest
end

def eql?(other)
  other.class == self.class &&
    other.logical_path == self.logical_path &&
    other.mtime.to_i == self.mtime.to_i &&
    other.digest == self.digest
end

def expand_root_path(path)
  path.to_s.sub(/^\$root/, @root)
end

def fresh?(environment)
  # Check current mtime and digest
  dependency_fresh?(environment, self)
end

def hash
  digest.hash
end

def init_with(environment, coder)
  @root = environment.root
  @logical_path = coder['logical_path']
  @content_type = coder['content_type']
  @digest       = coder['digest']
  if pathname = coder['pathname']
    # Expand `$root` placeholder and wrapper string in a `Pathname`
    @pathname = Pathname.new(expand_root_path(pathname))
  end
  if mtime = coder['mtime']
    @mtime = Time.at(mtime)
  end
  if length = coder['length']
    # Convert length to an `Integer`
    @length = Integer(length)
  end
end

def initialize(environment, logical_path, pathname)
  raise ArgumentError, "Asset logical path has no extension: #{logical_path}" if File.extname(logical_path) == ""
  @root         = environment.root
  @logical_path = logical_path.to_s
  @pathname     = Pathname.new(pathname)
  @content_type = environment.content_type_of(pathname)
  # drop precision to 1 second, same pattern followed elsewhere
  @mtime        = Time.at(environment.stat(pathname).mtime.to_i)
  @length       = environment.stat(pathname).size
  @digest       = environment.file_digest(pathname).hexdigest
end

def inspect
  "#<#{self.class}:0x#{object_id.to_s(16)} " +
    "pathname=#{pathname.to_s.inspect}, " +
    "mtime=#{mtime.inspect}, " +
    "digest=#{digest.inspect}" +
    ">"
end

def relative_pathname
  @relative_pathname ||= Pathname.new(relativize_root_path(pathname))
end

def relativize_root_path(path)
  path.to_s.sub(/^#{Regexp.escape(@root)}/, '$root')
end

def required_assets
  @required_assets ||= []
end

def stale?(environment)
  !fresh?(environment)
end

def to_a
  [self]
end

def to_s
  source
end

def write_to(filename, options = {})
  # Gzip contents if filename has '.gz'
  options[:compress] ||= File.extname(filename) == '.gz'
  FileUtils.mkdir_p File.dirname(filename)
  File.open("#{filename}+", 'wb') do |f|
    if options[:compress]
      # Run contents through `Zlib`
      gz = Zlib::GzipWriter.new(f, Zlib::BEST_COMPRESSION)
      gz.mtime = mtime.to_i
      gz.write to_s
      gz.close
    else
      # Write out as is
      f.write to_s
    end
  end
  # Atomic write
  FileUtils.mv("#{filename}+", filename)
  # Set mtime correctly
  File.utime(mtime, mtime, filename)
  nil
ensure
  # Ensure tmp file gets cleaned up
  FileUtils.rm("#{filename}+") if File.exist?("#{filename}+")
end