require 'active_support/inflector' # for the sake of pluralizing

module Rabl
  module Helpers
    # data_object(data) => <AR Object>
    # data_object(@user => :person) => @user
    # data_object(:user => :person) => @_object.send(:user)
    def data_object(data)
      data = data.keys.first if data.is_a?(Hash) && data.keys.size == 1
      data = @_object.__send__(data) if data.is_a?(Symbol) && defined?(@_object) && @_object && @_object.respond_to?(data)
      data
    end

    # data_object_attribute(data) => @_object.send(data)
    def data_object_attribute(data)
      attribute = @_object.__send__(data)
      attribute = attribute.as_json if is_collection?(attribute, false) && attribute.respond_to?(:as_json)
      attribute
    end

    # data_name(data) => "user"
    # data_name(@user => :person) => :person
    # data_name(@users) => :user
    # data_name([@user]) => "users"
    # data_name([]) => "array"
    def data_name(data_token)
      return unless data_token # nil or false

      return data_token.values.first if data_token.is_a?(Hash) # @user => :user

      data = data_object(data_token)

      if is_collection?(data) # data is a collection
        object_name = collection_root_name if collection_root_name
        object_name ||= data.table_name if data.respond_to?(:table_name)

        if object_name.nil? && data.respond_to?(:first)
          first = data.first
          object_name = data_name(first).to_s.pluralize if first.present?
        end

        object_name ||= data_token if data_token.is_a?(Symbol)
        object_name
      elsif is_object?(data) # data is an object
        object_name = object_root_name if object_root_name
        object_name ||= data if data.is_a?(Symbol)
        object_name ||= collection_root_name.to_s.singularize if collection_root_name
        object_name ||= data.class.respond_to?(:model_name) ? data.class.model_name.element : data.class.to_s.downcase
        object_name
      else
        data_token
      end
    end

    # Returns the object rootname based on if the root should be included
    # Can be called with data as a collection or object
    # determine_object_root(@user, :user, true) => "user"
    # determine_object_root(@user, :person) => "person"
    # determine_object_root([@user, @user]) => "user"
    def determine_object_root(data_token, data_name = nil, include_root = true)
      return if object_root_name == false

      root_name = data_name.to_s if include_root
      if is_object?(data_token) || data_token.nil?
        root_name
      elsif is_collection?(data_token)
        object_root_name || (root_name.singularize if root_name)
      end
    end

    # Returns true if obj is not a collection
    # is_object?(@user) => true
    # is_object?([]) => false
    # is_object?({}) => false
    def is_object?(obj, follow_symbols = true)
      obj && !is_collection?(obj, follow_symbols)
    end

    # Returns true if the obj is a collection of items
    # is_collection?(@user) => false
    # is_collection?([]) => true
    def is_collection?(obj, follow_symbols = true)
      data_obj = follow_symbols ? data_object(obj) : obj
      data_obj && data_obj.respond_to?(:map) && data_obj.respond_to?(:each) &&
        !(data_obj.is_a?(Struct) || defined?(Hashie::Mash) && data_obj.is_a?(Hashie::Mash))
    end

    # Returns the context_scope wrapping this engine, used for retrieving data, invoking methods, etc
    # In Rails, this is the controller and in Padrino this is the request context
    def context_scope
      defined?(@_context_scope) ? @_context_scope : nil
    end

    def view_path
      defined?(@_view_path) ? @_view_path : nil
    end

    # Returns the root (if any) name for an object within a collection
    # Sets the name of the object i.e "person"
    # => { "users" : [{ "person" : {} }] }
    def object_root_name
      defined?(@_object_root_name) ? @_object_root_name : nil
    end

    # Returns the root for the collection
    # Sets the name of the collection i.e "people"
    #  => { "people" : [] }
    def collection_root_name
      defined?(@_collection_name) ? @_collection_name : nil
    end

    # Returns true if the value is a name value (symbol or string)
    def is_name_value?(val)
      val.is_a?(String) || val.is_a?(Symbol)
    end

    # Returns an Engine based representation of any data object given ejs template block
    # object_to_engine(@user) { attribute :full_name } => { ... }
    # object_to_engine(@user, :source => "...") { attribute :full_name } => { ... }
    # object_to_engine([@user], :source => "...") { attribute :full_name } => { ... }
    # options must have :source (rabl file contents)
    # options can have :source_location (source filename)
    def object_to_engine(object, options = {}, &block)
      return if object.nil?

      options.reverse_merge!({
        :format     => "hash".freeze,
        :view_path  => view_path,
        :root       => (options[:root] || false)
      })

      Engine.new(options[:source], options).apply(context_scope, :object => object, :locals => options[:locals], &block)
    end

    # Fetches a key from the cache and stores rabl template result otherwise
    # fetch_from_cache('some_key') { ...rabl template result... }
    def fetch_result_from_cache(cache_key, cache_options = {}, &block)
      expanded_cache_key = ActiveSupport::Cache.expand_cache_key(cache_key, :rabl)
      Rabl.configuration.cache_engine.fetch(expanded_cache_key, cache_options, &block)
    end

    def write_result_to_cache(cache_key, cache_options = {}, &block)
      expanded_cache_key = ActiveSupport::Cache.expand_cache_key(cache_key, :rabl)
      result = yield
      Rabl.configuration.cache_engine.write(expanded_cache_key, result, cache_options)
      result
    end

    # Returns true if the cache has been enabled for the application
    def template_cache_configured?
      if defined?(Rails)
        defined?(ActionController::Base) && ActionController::Base.perform_caching
      else
        Rabl.configuration.perform_caching
      end
    end

    module Escaper
      def escape_output(response)
        case response
        when Hash
          response.each{|k,v| response[k] = escape_value(v) }
        when Array
          response.map!{|v| escape_value(v) }
        else
          response
        end
      end

      def escape_value(value)
        case value
        when String
          ERB::Util.h(value)
        when Array, Hash
          escape_output(value)
        else
          value
        end
      end
    end
  end
end