require 'sinatra'
require 'liquid'
require 'yaml'

# :nodoc:
module Noumenon
  # The base of all Noumenon sites, responsible for building the URL structure, and providing
  # access to the content repository.
  #
  # By default any request will be routed to the content repository to find an item of content
  # using #locate_content, which will then be rendered using the template specified by the content
  # file.
  #
  # A piece of content takes the form of a YAML file, which should provide any fields required by
  # template specified. If any required fields are missing then a MissingContentError will be raised.
  #
  class Core < Sinatra::Base
    def config
      Noumenon.config
    end
    
    # Get the path to a file in the content repository.
    def content_path(path)
      File.join(config.content_repository_path, path)
    end
    
    # Get the path to a file provided by the current theme.
    def theme_path(path)
      File.join(Noumenon.themes[config.theme][:path], path)
    end
    
    # Render a template, surrounding it with the theme layout if a theme has been set, and 
    # it provides a layout.
    #
    # Any locals provided will be passed onto Liquid for use in the template.
    #
    # Valid options:
    #
    #   layout: If set to a string, an attempt will be made to use that layout.
    #           If set to false no layout will be used.
    #           If set to true (the default) the default layout will be used.
    def render_template(path, locals = {}, options = {})
      options[:layout] = "layout" if options[:layout] == true || options[:layout].nil?
      
      template = Template.from_file(path)
      body = template.render(locals)
      
      if options[:layout]
        begin
          body = render_template(theme_path("templates/#{options[:layout]}.html"), { 'body' => body }, :layout => false)
        rescue Noumenon::Template::NotFoundError => ignore_missing_layouts
        end
      end
      
      body
    end
    
    # Render a piece of content from the content repository, using the template specified within
    # the content item.
    #
    # If no template was specified then the template "default" will be used.
    def render_content(path)
      content = File.read(content_path(path))
      item = YAML.load( content )
      
      [ 200, render_template( theme_path("templates/#{item["template"]}.html"), item ) ]
    end
    
    # Locate a piece of content in the content repository based on the URL it is being accessed from.
    #
    # The following files will satisfy a request for "/example", in the order shown:
    #
    # 1. "repository/example.yml
    # 2. "repository/example/index.yml
    #
    def locate_content_for(path)
      if File.exists?(content_path("#{path}.yml"))
        return "#{path}.yml"
      else
        if File.exists?(content_path(path)) && File.exists?(content_path("#{path}/index.yml"))
          return "#{path}/index.yml"
        end
      end

      nil
    end

    get '*' do |path|
      path = locate_content_for(path)
      path ? render_content(path) : [ 404, "Not Found" ]
    end
  end
end