module Scrivito
  # This class allows you to retrieve CMS objects from a specific working copy.
  # You can get an instance by accessing {Workspace#objs}.
  # @api public
  class ObjCollection
    attr_reader :workspace

    def initialize(workspace)
      @workspace = workspace
    end

    # Find an {BasicObj Obj} by its id.
    # If the parameter is an Array containing ids, return a list of the
    # corresponding {Scrivito::BasicObj Obj}s.
    # @param [String, Integer, Array<String, Integer>]id_or_list
    # @return [Obj, Array<Obj>]
    # @api public
    def find(id_or_list)
      find_using(id_or_list, :find_by)
    end

    # Find a {BasicObj Obj} by its id.
    # If the parameter is an Array containing ids, return a list of the
    # corresponding {Scrivito::BasicObj Obj}s. The results include deleted objects as well.
    # @param [String, Integer, Array<String, Integer>]id_or_list
    # @return [Obj, Array<Obj>]
    # @api public
    def find_including_deleted(id_or_list)
      find_using(id_or_list, :find_by_including_deleted)
    end

    #
    # Find the {Scrivito::BasicObj Obj} that has the given +path+.
    #
    # @api public
    #
    # @note If there is more than one {Scrivito::BasicObj Obj} with the given +path+,
    #   then the {Scrivito::BasicObj Obj} with the smallest +id+ will be returned.
    #
    # @param [String] path Path of the {Scrivito::BasicObj Obj}.
    #
    # @return [Scrivito::BasicObj] if an {Scrivito::BasicObj Obj} with the given +path+ exists.
    # @return [NilClass] if no {Scrivito::BasicObj Obj} with the given +path+ exists.
    #
    def find_by_path(path)
      find_by(:path, [path]).first.min_by(&:id)
    end

    #
    # Returns the {Scrivito::BasicObj Obj} that has the given +permalink+.
    #
    # @api public
    #
    # @note If there is more than one {Scrivito::BasicObj Obj} with the given +permalink+,
    #   then the {Scrivito::BasicObj Obj} with the smallest +id+ will be returned.
    #
    # @param [String] permalink The permalink of the {BasicObj Obj}.
    #
    # @return [Scrivito::BasicObj] if an {Scrivito::BasicObj Obj} with the given +permalink+ exists.
    # @return [NilClass] if no {Scrivito::BasicObj Obj} with the given +permalink+ exists.
    #
    def find_by_permalink(permalink)
      find_by(:permalink, [permalink]).first.min_by(&:id)
    end

    # Returns an {ObjSearchEnumerator} with the given initial subquery consisting of the four arguments.
    #
    # Note that +field+ and +value+ may also be arrays for searching several fields or searching for several values.
    #
    # {ObjSearchEnumerator}s can be chained using one of the chainable methods
    # (e.g. {ObjSearchEnumerator#and} and {ObjSearchEnumerator#and_not}).
    #
    # @param [Symbol, String, Array<Symbol, String>] field See {ObjSearchEnumerator#and} for details
    # @param [Symbol, String] operator See {ObjSearchEnumerator#and} for details
    # @param [String, Array<String>] value See {ObjSearchEnumerator#and} for details
    # @param [Hash] boost See {ObjSearchEnumerator#and} for details
    # @return [ObjSearchEnumerator]
    # @api public
    def where(field, operator, value, boost = nil)
      ObjSearchEnumerator.new(workspace)
        .and(field, operator, value, boost)
    end

    # Returns an {ObjSearchEnumerator} of all {BasicObj Obj}s.
    # @return [ObjSearchEnumerator]
    # @api public
    def all
      ObjSearchEnumerator.new(workspace).batch_size(1000)
    end

    # Returns an {ObjSearchEnumerator} of all {BasicObj Obj}s with the given +obj_class+.
    # @param [String] obj_class name of the object class.
    # @return [ObjSearchEnumerator]
    # @api public
    def find_all_by_obj_class(obj_class)
      all.and(:_obj_class, :equals, obj_class)
    end

    def find_by_parent_path(path)
      find_by(:ppath, [path]).first
    end

    def find_by_id(id)
      find_by(:id, [id]).first.first
    end

    def find_by_paths(paths)
      find_by(:path, paths).map(&:first)
    end

    def changes(offset, batch_size)
      where('_modification', 'equals', ['new', 'edited', 'deleted'])
          .batch_size(batch_size)
          .offset(offset)
          .include_deleted
    end

    private

    def find_using(id_or_list, method)
      case id_or_list
      when Array
        send(method, :id, id_or_list).map(&:first).compact
      else
        obj = send(method, :id, [id_or_list.to_s]).first.first

        obj or raise ResourceNotFound, "Could not find Obj with id #{id_or_list}"
      end
    end

    def find_by(view, keys)
      find_by_including_deleted(view, keys).map do |list|
        list.reject(&:deleted?)
      end
    end

    # Accepts the name of an "obj_by" view, a list of keys.
    # Returns a list of lists of Objs: a list of Objs for each given key.
    def find_by_including_deleted(view, keys)
      result = CmsBackend.instance.find_obj_data_by(
        workspace.revision,
        view,
        keys)

      result.map do |list|
        list.map do |obj_data|
          obj = BasicObj.instantiate(obj_data)
          obj.revision = workspace.revision

          obj
        end
      end
    end
  end
end