module Sass::Plugin

def check_for_updates
  return unless !Sass::Plugin.checked_for_updates ||
      Sass::Plugin.options[:always_update] || Sass::Plugin.options[:always_check]
  update_stylesheets
end

def css_filename(name, path)
  "#{path}/#{name}.css"
end

def css_locations
  if options[:template_location] && !options[:template_location].is_a?(String)
    options[:template_location].to_a.map { |l| l.last }
  else
    [options[:css_location]]
  end
end

def dependencies(filename)
  File.readlines(filename).grep(/^@import /).map do |line|
    line[8..-1].split(',').map do |inc|
      Sass::Files.find_file_to_import(inc.strip, [File.dirname(filename)] + load_paths)
    end
  end.flatten.grep(/\.sass$/)
end

def dependency_updated?(css_mtime)
  lambda do |dep|
    File.mtime(dep) > css_mtime ||
      dependencies(dep).any?(&dependency_updated?(css_mtime))
  end
end

def engine_options(additional_options = {})
  opts = options.dup.merge(additional_options)
  opts[:load_paths] = load_paths(opts)
  opts
end

def exact_stylesheet_needs_update?(css_file, template_file)
  return true unless File.exists?(css_file)
  css_mtime = File.mtime(css_file)
  File.mtime(template_file) > css_mtime ||
    dependencies(template_file).any?(&dependency_updated?(css_mtime))
end

def exception_string(e)
  e_string = "#{e.class}: #{e.message}"
  if e.is_a? Sass::SyntaxError
    e_string << "\non line #{e.sass_line}"
    if e.sass_filename
      e_string << " of #{e.sass_filename}"
      if File.exists?(e.sass_filename)
        e_string << "\n\n"
        min = [e.sass_line - 5, 0].max
        begin
          File.read(e.sass_filename).rstrip.split("\n")[
            min .. e.sass_line + 5
          ].each_with_index do |line, i|
            e_string << "#{min + i + 1}: #{line}\n"
          end
        rescue
          e_string << "Couldn't read sass file: #{e.sass_filename}"
        end
      end
    end
  end
  <<END
string}
trace:\n#{e.backtrace.join("\n")}
:before {
ite-space: pre;
nt-family: monospace;
ntent: "#{e_string.gsub('"', '\"').gsub("\n", '\\A ')}"; }
  # Fix an emacs syntax-highlighting hiccup: '
end

def forbid_update?(name)
  name.sub(/^.*\//, '')[0] == ?_
end

def load_paths(opts = options)
  (opts[:load_paths] || []) + template_locations
end

def mkpath(base, name)
  dirs = [base]
  name.split(File::SEPARATOR)[0...-1].each { |dir| dirs << File.join(dirs[-1],dir) }
  dirs.each { |dir| Dir.mkdir(dir) unless File.exist?(dir) }
end

def options=(value)
  @options.merge!(value)
end

def stylesheet_needs_update?(name, template_path, css_path)
  css_file = css_filename(name, css_path)
  template_file = template_filename(name, template_path)
  exact_stylesheet_needs_update?(css_file, template_file)
end

def template_filename(name, path)
  "#{path}/#{name}.sass"
end

def template_locations
  location = (options[:template_location] || File.join(options[:css_location],'sass'))
  if location.is_a?(String)
    [location]
  else
    location.to_a.map { |l| l.first }
  end
end

def update_stylesheet(name, template_location, css_location)
  css = css_filename(name, css_location)
  File.delete(css) if File.exists?(css)
  filename = template_filename(name, template_location)
  result = begin
             Sass::Files.tree_for(filename, engine_options(:css_filename => css, :filename => filename)).render
           rescue Exception => e
             raise e unless options[:full_exception]
             exception_string(e)
           end
  # Create any directories that might be necessary
  mkpath(css_location, name)
  # Finally, write the file
  flag = 'w'
  flag = 'wb' if RbConfig::CONFIG['host_os'] =~ /mswin|windows/i && options[:unix_newlines]
  File.open(css, flag) {|file| file.print(result)}
end

def update_stylesheets
  return if options[:never_update]
  @checked_for_updates = true
  template_locations.zip(css_locations).each do |template_location, css_location|
    Dir.glob(File.join(template_location, "**", "*.sass")).each do |file|
      # Get the relative path to the file with no extension
      name = file.sub(template_location.sub(/\/*$/, '/'), "")[0...-5]
      if !forbid_update?(name) && (options[:always_update] || stylesheet_needs_update?(name, template_location, css_location))
        update_stylesheet(name, template_location, css_location)
      end
    end
  end
end