require "sprockets/helpers/version"
require "sprockets"

module Sprockets
  module Helpers
    autoload :AssetPath, "sprockets/helpers/asset_path"
    autoload :FilePath,  "sprockets/helpers/file_path"
    
    # Pattern for checking if a given path is an external URI.
    URI_MATCH = %r(^[-a-z]+://|^cid:|^//)
    
    class << self
      # When true, the asset paths will return digest paths.
      attr_accessor :digest
      
      # The base URL the Sprocket environment is mapped to.
      # This defaults to "/assets".
      def prefix
        @prefix ||= "/assets"
      end
      attr_writer :prefix
      
      # The path to the public directory, where the assets
      # not managed by Sprockets will be located.
      # Defaults to "./public"
      def public_path
        @public_path ||= "./public"
      end
      attr_writer :public_path
    end
    
    # Returns the path to an asset either in the Sprockets environment
    # or the public directory. External URIs are untouched.
    #
    # ==== Options
    #
    # * <tt>:ext</tt> - The extension to append if the source does not have one.
    # * <tt>:dir</tt> - The directory to prepend if the file is in the public directory.
    # * <tt>:digest</tt> - Wether or not use the digest paths for assets. Set Sprockets::Helpers.digest for global configuration.
    # * <tt>:prefix</tt> - Use a custom prefix for the Sprockets environment. Set Sprockets::Helpers.prefix for global configuration.
    #
    #
    # ==== Examples
    #
    # For files within Sprockets:
    #
    #   asset_path "xmlhr.js"                       # => "/assets/xmlhr.js"
    #   asset_path "xmlhr", :ext => "js"            # => "/assets/xmlhr.js"
    #   asset_path "xmlhr.js", :digest => true      # => "/assets/xmlhr-27a8f1f96afd8d4c67a59eb9447f45bd.js"
    #   asset_path "xmlhr.js", :prefix => "/themes" # => "/themes/xmlhr.js"
    #
    # For files outside of Sprockets:
    #
    #   asset_path "xmlhr"                                # => "/xmlhr"
    #   asset_path "xmlhr", :ext => "js"                  # => "/xmlhr.js"
    #   asset_path "dir/xmlhr.js", :dir => "javascripts"  # => "/javascripts/dir/xmlhr.js"
    #   asset_path "/dir/xmlhr.js", :dir => "javascripts" # => "/dir/xmlhr.js"
    #   asset_path "http://www.example.com/js/xmlhr"      # => "http://www.example.com/js/xmlhr"
    #   asset_path "http://www.example.com/js/xmlhr.js"   # => "http://www.example.com/js/xmlhr.js"
    # 
    def asset_path(source, options = {})
      return source if source =~ URI_MATCH
      
      # Append extension if necessary
      if options[:ext] && File.extname(source).empty?
        source << ".#{options[:ext]}"
      end
        
      # If the source points to an asset in the Sprockets
      # environment use AssetPath to generate the full path.
      environment.resolve(source) do |path|
        return AssetPath.new(environment.find_asset(path), options).to_s
      end
      
      # Use FilePath for normal files on the file system
      FilePath.new(source, options).to_s
    end
    
    # Computes the path to a javascript asset either in the Sprockets
    # environment or the public directory. If the +source+ filename has no extension,
    # <tt>.js</tt> will be appended. External URIs are untouched.
    #
    # ==== Examples
    #
    # For files within Sprockets:
    #
    #   javascript_path "xmlhr"        # => "/assets/xmlhr.js"
    #   javascript_path "dir/xmlhr.js" # => "/assets/dir/xmlhr.js"
    #   javascript_path "/dir/xmlhr"   # => "/assets/dir/xmlhr.js"
    #
    # For files outside of Sprockets:
    #
    #   javascript_path "xmlhr"                              # => "/javascripts/xmlhr.js"
    #   javascript_path "dir/xmlhr.js"                       # => "/javascripts/dir/xmlhr.js"
    #   javascript_path "/dir/xmlhr"                         # => "/dir/xmlhr.js"
    #   javascript_path "http://www.example.com/js/xmlhr"    # => "http://www.example.com/js/xmlhr"
    #   javascript_path "http://www.example.com/js/xmlhr.js" # => "http://www.example.com/js/xmlhr.js"
    #
    def javascript_path(source, options = {})
      asset_path source, { :dir => "javascripts", :ext => "js" }.merge(options)
    end
    
    # Computes the path to a stylesheet asset either in the Sprockets
    # environment or the public directory. If the +source+ filename has no extension,
    # <tt>.css</tt> will be appended. External URIs are untouched.
    #
    # ==== Examples
    #
    # For files within Sprockets:
    #
    #   stylesheet_path "style"          # => "/assets/style.css"
    #   stylesheet_path "dir/style.css"  # => "/assets/dir/style.css"
    #   stylesheet_path "/dir/style.css" # => "/assets/dir/style.css"
    #
    # For files outside of Sprockets:
    #
    #   stylesheet_path "style"                                  # => "/stylesheets/style.css"
    #   stylesheet_path "dir/style.css"                          # => "/stylesheets/dir/style.css"
    #   stylesheet_path "/dir/style.css"                         # => "/dir/style.css"
    #   stylesheet_path "http://www.example.com/css/style"       # => "http://www.example.com/css/style"
    #   stylesheet_path "http://www.example.com/css/style.css"   # => "http://www.example.com/css/style.css"
    #
    def stylesheet_path(source, options = {})
      asset_path source, { :dir => "stylesheets", :ext => "css" }.merge(options)
    end
    
    # Computes the path to an image asset either in the Sprockets environment
    # or the public directory. External URIs are untouched.
    #
    # ==== Examples
    #
    # With files within Sprockets:
    #
    #   image_path "edit.png"        # => "/assets/edit.png"
    #   image_path "icons/edit.png"  # => "/assets/icons/edit.png"
    #   image_path "/icons/edit.png" # => "/assets/icons/edit.png"
    #
    # With files outside of Sprockets:
    #
    #   image_path "edit"                                # => "/images/edit"
    #   image_path "edit.png"                            # => "/images/edit.png"
    #   image_path "icons/edit.png"                      # => "/images/icons/edit.png"
    #   image_path "/icons/edit.png"                     # => "/icons/edit.png"
    #   image_path "http://www.example.com/img/edit.png" # => "http://www.example.com/img/edit.png"
    #
    def image_path(source, options = {})
      asset_path source, { :dir => "images" }.merge(options)
    end
  end
  
  class Context
    include Helpers
  end
end