# encoding: UTF-8
#
# Copyright (c) 2010-2017 GoodData Corporation. All rights reserved.
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree.

module GoodData
  module Mixin
    module MdObjectQuery
      # Method intended to get all objects of that type in a specified project
      #
      # @param options [Hash] the options hash
      # @option options [Boolean] :full if passed true the subclass can decide
      # to pull in full objects. This is desirable from the usability POV
      # but unfortunately has negative impact on performance so it is not
      # the default.
      # @return [Array<GoodData::MdObject> | Array<Hash>] Return the appropriate metadata objects or their representation
      def all(_options = { :client => GoodData.connection, :project => GoodData.project })
        fail NotImplementedError, 'Method should be implemented in subclass. Currently there is no way how to get all metadata objects on API.'
      end

      # Method intended to be called by individual classes in their all
      # implementations. It abstracts the way interacting with query resources.
      # It either returns the array of hashes from query. If asked it also
      # goes and brings the full objects. Due to performance reasons
      # :full => false is the default. This will most likely change
      #
      # @param query_obj_type [String] string used in URI to distinguish different query resources for different objects
      # @param klass [Class] A class used for instantiating the returned data
      # @param options [Hash] the options hash
      # @option options [Boolean] :full if passed true the subclass can
      # decide to pull in full objects. This is desirable from the usability
      # POV but unfortunately has negative impact on performance so it is
      # not the default.
      # @return [Array<GoodData::MdObject> | Array<Hash>] Return the appropriate metadata objects or their representation
      def query(query_obj_type, klass, options = { :client => GoodData.connection, :project => GoodData.project })
        client = options[:client]
        fail ArgumentError, 'No :client specified' if client.nil?

        p = options[:project]
        fail ArgumentError, 'No :project specified' if p.nil?

        project = GoodData::Project[p, options]
        fail ArgumentError, 'Wrong :project specified' if project.nil?

        offset = 0
        page_limit = 50
        Enumerator.new do |y|
          loop do
            result = client.get(project.md['objects'] + '/query', params: { category: query_obj_type, limit: page_limit, offset: offset })
            result['objects']['items'].each do |item|
              y << (klass ? client.create(klass, item, project: project) : item)
            end
            break if result['objects']['paging']['count'] < page_limit
            offset += page_limit
          end
        end
      end

      def dependency(uri, key = nil, opts = { :client => GoodData.connection })
        c = opts[:client]
        fail ArgumentError, 'No :client specified' if c.nil?

        result = c.get(uri)['entries']
        if key.nil?
          result
        elsif key.respond_to?(:category)
          result = result.select { |item| item['category'] == key.category }
        else
          result = result.select { |item| item['category'] == key }
        end

        if opts[:full]
          result = result.map do |res|
            GoodData::MdObject[res['link'], :client => c, :project => opts[:project]]
          end
        end

        result
      end

      # Checks for dependency
      def dependency?(type, uri, target_uri, opts = { :client => GoodData.connection, :project => GoodData.project })
        uri = uri.respond_to?(:uri) ? uri.uri : uri
        objs = case type
               when :usedby
                 usedby(uri, nil, opts)
               when :using
                 using(uri, nil, opts)
               end

        target_uri = target_uri.respond_to?(:uri) ? target_uri.uri : target_uri
        objs.any? do |obj|
          obj['link'] == target_uri
        end
      end

      # Returns which objects uses this MD resource
      def usedby(uri, key = nil, opts = { :client => GoodData.connection, :project => GoodData.project })
        p = opts[:project]
        fail ArgumentError, 'No :project specified' if p.nil?

        project = GoodData::Project[p, opts]
        fail ArgumentError, 'No :project specified' if project.nil?

        dependency("#{project.md['usedby2']}/#{uri_obj_id(uri)}", key, opts)
      end

      alias_method :used_by, :usedby

      # Returns which objects this MD resource uses
      def using(uri, key = nil, opts = { :client => GoodData.connection, :project => GoodData.project })
        p = opts[:project]
        fail ArgumentError, 'No :project specified' if p.nil?

        project = GoodData::Project[p, opts]
        fail ArgumentError, 'No :project specified' if project.nil?

        dependency("#{project.md['using2']}/#{uri_obj_id(uri)}", key, opts)
      end

      def usedby?(uri, target_uri, opts = { :client => GoodData.connection, :project => GoodData.project })
        dependency?(:usedby, uri, target_uri, opts)
      end

      alias_method :used_by?, :usedby?

      # Checks if obj is using this MD resource
      def using?(uri, target_uri, opts = { :client => GoodData.connection, :project => GoodData.project })
        dependency?(:using, uri, target_uri, opts)
      end
    end
  end
end