module ViewModels
  module Helpers
    module Mapping
      
      # Construct a view_model for a collection.
      #
      # TODO Think about moving it into view_model_for, or renaming it view_models_for.
      #
      def collection_view_model_for array_or_pagination, context = self
        Collection.new array_or_pagination, context
      end
      
      # The Collection view_model helper has the purpose of presenting presentable collections.
      # * Render as list
      # * Render as table
      # * Render as collection
      # * Render a pagination
      #
      class Collection
        
        # Delegate collection relevant methods to the collection.
        #
        self.delegate *[Enumerable.instance_methods, :length, :size, :empty?, :each, :exit, { :to => :@collection }].flatten
        
        #
        #
        def initialize collection, context
          @collection, @context = collection, context
        end
        
        # Renders a list (in the broadest sense of the word).
        #
        # Options:
        #   collection => collection to iterate over
        #   context => context to render in
        #   template_name => template to render for each model element
        #   separator => separator between each element
        # By default, uses:
        #   * The collection of the collection view_model to iterate over.
        #   * The original context given to the collection view_model to render in.
        #   * Uses :list_item as the default element template.
        #   * Uses a nil separator in html.
        #
        def list options = {}
          default_options = { :collection => @collection, :template_name => :list_item, :separator => nil }
          
          render_partial :list, default_options.merge(options)
        end
        
        # Renders a collection.
        #
        # Note: The only difference between a list and a collection is the enclosing
        #       list type. While list uses ol, the collection uses ul.
        #
        # Options:
        #   collection => collection to iterate over
        #   context => context to render in
        #   template_name => template to render for each model element
        #   separator => separator between each element
        # By default, uses:
        #   * The collection of the collection view_model to iterate over.
        #   * Uses :collection_item as the default element template.
        #   * Uses a nil separator.
        #
        def collection options = {}
          default_options = { :collection => @collection, :template_name => :collection_item, :separator => nil }
          
          render_partial :collection, default_options.merge(options)
        end
        
        # Renders a table.
        #
        # Note: Each item represents a table row.
        #
        # Options:
        #   collection => collection to iterate over
        #   context => context to render in
        #   template_name => template to render for each model element
        #   separator => separator between each element
        # By default, uses:
        #   * The collection of the collection view_model to iterate over.
        #   * Uses :table_row as the default element template.
        #   * Uses a nil separator.
        #
        def table options = {}
          default_options = { :collection => @collection, :template_name => :table_row, :separator => nil }
          
          render_partial :table, default_options.merge(options)
        end
        
        # Renders a pagination.
        #
        # Options:
        #   collection => collection to iterate over
        #   context => context to render in
        #   separator => separator between pages
        # By default, uses:
        #   * The collection of the collection view_model to iterate over.
        #   * Uses | as separator.
        #
        def pagination options = {}
          default_options = { :collection => @collection, :separator => '|' }
          
          render_partial :pagination, default_options.merge(options)
        end
      end
      
    end
  end
end