require "pathname"

module ActionView
  class Template
  # Abstract super class
    class Path
      def initialize(options)
        @cache  = options[:cache]
        @cached = {}
      end
    
      # Normalizes the arguments and passes it on to find_template
      def find_by_parts(*args)
        find_all_by_parts(*args).first
      end
      
      def find_all_by_parts(name, details = {}, prefix = nil, partial = nil)
        details[:locales] = [I18n.locale]
        name = name.to_s.gsub(handler_matcher, '').split("/")
        find_templates(name.pop, details, [prefix, *name].compact.join("/"), partial)
      end
    
    private
      
      # This is what child classes implement. No defaults are needed
      # because Path guarentees that the arguments are present and
      # normalized.
      def find_templates(name, details, prefix, partial)
        raise NotImplementedError
      end
      
      def valid_handlers
        @valid_handlers ||= TemplateHandlers.extensions
      end
      
      def handler_matcher
        @handler_matcher ||= begin
          e = valid_handlers.join('|')
          /\.(?:#{e})$/
        end
      end
       
      def handler_glob
        e = TemplateHandlers.extensions.map{|h| ".#{h},"}.join
        "{#{e}}"
      end
      
      def formats_glob
        @formats_glob ||= begin
          formats = Mime::SET.map { |m| m.symbol }
          '{' + formats.map { |l| ".#{l}," }.join + '}'
        end
      end
      
      def cached(key)
        return yield unless @cache
        return @cached[key] if @cached.key?(key)
        @cached[key] = yield
      end
    end
  
    class FileSystemPath < Path
    
      def initialize(path, options = {})
        raise ArgumentError, "path already is a Path class" if path.is_a?(Path)
        super(options)
        @path = Pathname.new(path).expand_path
      end

      # TODO: This is the currently needed API. Make this suck less
      # ==== <suck>
      attr_reader :path
    
      def to_s
        path.to_s
      end

      def to_str
        path.to_s
      end

      def ==(path)
        to_str == path.to_str
      end

      def eql?(path)
        to_str == path.to_str
      end
      # ==== </suck>
    
      def find_templates(name, details, prefix, partial, root = "#{@path}/")
        if glob = details_to_glob(name, details, prefix, partial, root)
          cached(glob) do
            Dir[glob].map do |path|
              next if File.directory?(path)
              source = File.read(path)
              identifier = Pathname.new(path).expand_path.to_s
              
              Template.new(source, identifier, *path_to_details(path))
            end.compact
          end
        end
      end
    
    private
  
      # :api: plugin
      def details_to_glob(name, details, prefix, partial, root)
        path = ""
        path << "#{prefix}/" unless prefix.empty?
        path << (partial ? "_#{name}" : name)
      
        extensions = ""
        [:locales, :formats].each do |k|
          extensions << if exts = details[k]
            '{' + exts.map {|e| ".#{e},"}.join + '}'
          else
            k == :formats ? formats_glob : ''
          end
        end
        
        "#{root}#{path}#{extensions}#{handler_glob}"
      end
      
      # TODO: fix me
      # :api: plugin
      def path_to_details(path)
        # [:erb, :format => :html, :locale => :en, :partial => true/false]
        if m = path.match(%r'/(_)?[\w-]+(\.[\w-]+)*\.(\w+)$')
          partial = m[1] == '_'
          details = (m[2]||"").split('.').reject { |e| e.empty? }
          handler = Template.handler_class_for_extension(m[3])

          format  = Mime[details.last] && details.pop.to_sym
          locale  = details.last && details.pop.to_sym
          
          return handler, :format => format, :locale => locale, :partial => partial
        end
      end
    end

    class FileSystemPathWithFallback < FileSystemPath
      
      def find_templates(name, details, prefix, partial)
        templates = super
        return super(name, details, prefix, partial, '') if templates.empty?
        templates
      end
      
    end
  end
end