class Sprockets::Preprocessor

def asset_path_from(source_line)
  source_line.source_file.find(source_line.provide, :directory)
end

def initialize(environment, options = {})
  @environment = environment
  @concatenation = Concatenation.new
  @source_files = []
  @asset_paths = []
  @options = options
end

def kind_of_require_from(source_line)
  source_line.require[/^(.)/, 1] == '"' ? :relative_require : :require
end

def location_from(source_line)
  location = source_line.require[/^.(.*).$/, 1]
  File.join(File.dirname(location), File.basename(location, ".js") + ".js")
end

def pathname_finder_from(source_line)
  "pathname_for_#{kind_of_require_from(source_line)}_from"
end

def pathname_for_relative_require_from(source_line)
  source_line.source_file.find(location_from(source_line))
end

def pathname_for_require_from(source_line)
  environment.find(location_from(source_line))
end

def pathname_from(source_line)
  pathname = send(pathname_finder_from(source_line), source_line)
  raise_load_error_for(source_line) unless pathname
  pathname
end

def provide(asset_path)
  return if !asset_path || asset_paths.include?(asset_path)
  asset_paths << asset_path
end

def provide_from_source_line(source_line)
  provide asset_path_from(source_line)
end

def raise_load_error_for(source_line)
  kind = kind_of_require_from(source_line).to_s.tr("_", " ")
  file = File.split(location_from(source_line)).last
  raise LoadError, "can't find file for #{kind} `#{file}' (#{source_line.inspect})"
end

def record_source_line(source_line)
  unless source_line.comment? && strip_comments?
    concatenation.record(source_line)
  end
end

def require(source_file)
  return if source_files.include?(source_file)
  source_files << source_file
  
  source_file.each_source_line do |source_line|
    if source_line.require?
      require_from_source_line(source_line)
    elsif source_line.provide?
      provide_from_source_line(source_line)
    else
      record_source_line(source_line)
    end
  end
end

def require_from_source_line(source_line)
  require pathname_from(source_line).source_file
end

def strip_comments?
  options[:strip_comments] != false
end