require 'digest/sha1'
module Middleman::Extensions
  module AssetHash
    class << self
      def registered(app, options)
        exts = options[:exts] || %w(.ico .manifest .jpg .jpeg .png .gif .js .css)

        app.after_configuration do
          sitemap.reroute do |destination, page|
            if exts.include? page.ext
              # figure out the path Sprockets would use for this asset
              if page.ext == '.js'
                sprockets_path = page.path.sub(js_dir,'').sub(/^\//,'')
              elsif page.ext == '.css'
                sprockets_path = page.path.sub(css_dir,'').sub(/^\//,'')
              end

              # See if Sprockets knows about the file
              asset = sprockets.find_asset(sprockets_path) if sprockets_path

              if asset # if it's a Sprockets asset, ask sprockets for its digest
                digest = asset.digest[0..7]
              elsif page.template? # if it's a template, render it out
                digest = Digest::SHA1.hexdigest(page.render)[0..7]
              else # if it's a static file, just hash it
                digest = Digest::SHA1.file(page.source_file).hexdigest[0..7]
              end

              destination.sub(/\.(\w+)$/) { |ext| "-#{digest}#{ext}" }
            else
              destination
            end
          end

          use Middleware, :exts => exts, :middleman_app => self
        end
      end
      alias :included :registered
    end

    class Middleware
      def initialize(app, options={})
        @rack_app      = app
        @exts           = options[:exts]
        @exts_regex_text = @exts.map {|e| Regexp.escape(e) }.join('|')
        @middleman_app = options[:middleman_app]
      end

      def call(env)
        status, headers, response = @rack_app.call(env)

        path = @middleman_app.full_path(env["PATH_INFO"])
        dirpath = Pathname.new(File.dirname(path))

        if path =~ /(^\/$)|(\.(htm|html|php|css|js)$)/
          body = extract_response_text(response)

          if body
            # TODO: This regex will change some paths in plan HTML (not in a tag) - is that OK?
            body.gsub! /([=\'\"\(]\s*)([^\s\'\"\)]+(#{@exts_regex_text}))/ do |match|
              asset_path = $2
              relative_path = Pathname.new(asset_path).relative?

              asset_path = dirpath.join(asset_path).to_s if relative_path

              if asset_page = @middleman_app.sitemap.find_page_by_path(asset_path)
                replacement_path = "/#{asset_page.destination_path}"
                replacement_path = Pathname.new(replacement_path).relative_path_from(dirpath).to_s if relative_path

                "#{$1}#{replacement_path}"
              else
                match
              end
            end

            status, headers, response = Rack::Response.new(body, status, headers).finish
          end
        end
        [status, headers, response]
      end

      private

      def extract_response_text(response)
        case(response)
        when String
          response
        when Array
          response.join
        when Rack::Response
          response.body.join
        when Rack::File
          File.read(response.path)
        else
          response.to_s
        end
      end
    end
  end
  
  register :asset_hash, AssetHash
end


# =================Temp Generate Test data==============================
#   ["jpg", "png", "gif"].each do |ext|
#     [["<p>", "</p>"], ["<p><img src=", " /></p>"], ["<p>background-image:url(", ");</p>"]].each do |outer|
#       [["",""], ["'", "'"], ['"','"']].each do |inner|
#         [["", ""], ["/", ""], ["../", ""], ["../../", ""], ["../../../", ""], ["http://example.com/", ""], ["a","a"], ["1","1"], [".", "."], ["-","-"], ["_","_"]].each do |path_parts|
#           name = 'images/100px.'
#           puts outer[0] + inner[0] + path_parts[0] + name + ext + path_parts[1] + inner[1] + outer[1]
#         end
#       end
#     end
#     puts "<br /><br /><br />"
#   end