module Spinebox
  class RenderError < StandardError; end
  
  module ERBContext
    
    # Includes javascript tags in the erb. If concatenation is disabled it returns multiple tags,
    # otherwise it returns a single application tag.
    def javascript_include_tag source
      if Spinebox.config.concatenate
        javascript_tag_for(asset_for(source, 'js'))
      else
        asset_for(source, 'js').to_a.map{ |asset| javascript_tag_for asset, :body => 1 }.join("\n")
      end
    end
    
    # Includes javascript tags in the erb. If concatenation is disabled it returns multiple tags,
    # otherwise it returns a single application tag.
    def stylesheet_link_tag source, options = {}
      if Spinebox.config.concatenate
        stylesheet_tag_for(asset_for(source, 'css'), options)
      else
        asset_for(source, 'css').to_a.map{ |asset| stylesheet_tag_for asset, options.merge!({ :body => 1 }) }.join("\n")
      end
    end
    
    # Renders, e.g. a partial into another view
    def render params = {}
      raise RenderError, "Render without :partial called" if params[:partial].nil?
      raise RenderError, "Partial needs a file extension" if params[:partial].split(".").size == 0
      
      partial = Spinebox.views["_#{params[:partial]}"]
      
      raise RenderError, "Partial not found" if partial.nil?
      
      partial.to_s
    end
    
    private
    
    # Access an asset from the assets
    def asset_for source, extension
      Spinebox.assets[source.include?(".#{extension}") ? source : "#{source}.#{extension}"]
    end
    
    # Build a javascript tag with body options
    def javascript_tag_for asset, options = {}
      "<script src='/assets/#{asset.logical_path}#{"?body=1" if options[:body]}' type='text/javascript'></script>"
    end
    
    # Build a stylesheet link with body options
    def stylesheet_tag_for asset, new_options = {}
      options = { :media => "all", :rel => "stylesheet" }.merge!(new_options)
      "<link href='/assets/#{asset.logical_path}#{"?body=1" if options[:body]}' media='#{options[:media]}' rel='#{options[:rel]}' type='text/css'>"
    end
    
  end
  
  class << self
    
    # Load helpers and include into sprockets context
    def load_helpers!
      Spinebox::ERBContext.class_eval do
        Dir["app/helpers/*"].each do |helper|
          require("./#{helper}")
          include Spinebox.const_get(File.basename(helper, ".rb").classify)
        end
      end
      
      ::Sprockets::Context.instance_eval do
        include Spinebox::ERBContext
      end
    end
  end
  
end