# encoding: utf-8
module Mongoid
  class Criteria
    module Queryable

      # An queryable selectable is selectable, in that it has the ability to select
      # document from the database. The selectable module brings all functionality
      # to the selectable that has to do with building MongoDB selectors.
      module Selectable
        extend Macroable

        # Constant for a LineString $geometry.
        #
        # @since 2.0.0
        LINE_STRING = "LineString"

        # Constant for a Point $geometry.
        #
        # @since 2.0.0
        POINT = "Point"

        # Constant for a Polygon $geometry.
        #
        # @since 2.0.0
        POLYGON = "Polygon"

        # @attribute [rw] negating If the next spression is negated.
        # @attribute [rw] selector The query selector.
        attr_accessor :negating, :selector

        # Add the $all criterion.
        #
        # @example Add the criterion.
        #   selectable.all(field: [ 1, 2 ])
        #
        # @example Execute an $all in a where query.
        #   selectable.where(:field.all => [ 1, 2 ])
        #
        # @param [ Hash ] criterion The key value pairs for $all matching.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def all(criterion = nil)
          send(strategy || :__union__, with_array_values(criterion), "$all")
        end
        alias :all_in :all
        key :all, :union, "$all"

        # Add the $and criterion.
        #
        # @example Add the criterion.
        #   selectable.and({ field: value }, { other: value })
        #
        # @param [ Array<Hash> ] criterion Multiple key/value pair matches that
        #   all must match to return results.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def and(*criterion)
          __multi__(criterion, "$and")
        end
        alias :all_of :and

        # Add the range selection.
        #
        # @example Match on results within a single range.
        #   selectable.between(field: 1..2)
        #
        # @example Match on results between multiple ranges.
        #   selectable.between(field: 1..2, other: 5..7)
        #
        # @param [ Hash ] criterion Multiple key/range pairs.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def between(criterion = nil)
          selection(criterion) do |selector, field, value|
            selector.store(
              field,
              { "$gte" => value.min, "$lte" => value.max }
            )
          end
        end

        # Select with an $elemMatch.
        #
        # @example Add criterion for a single match.
        #   selectable.elem_match(field: { name: "value" })
        #
        # @example Add criterion for multiple matches.
        #   selectable.elem_match(
        #     field: { name: "value" },
        #     other: { name: "value"}
        #   )
        #
        # @example Execute an $elemMatch in a where query.
        #   selectable.where(:field.elem_match => { name: "value" })
        #
        # @param [ Hash ] criterion The field/match pairs.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def elem_match(criterion = nil)
          __override__(criterion, "$elemMatch")
        end
        key :elem_match, :override, "$elemMatch"

        # Add the $exists selection.
        #
        # @example Add a single selection.
        #   selectable.exists(field: true)
        #
        # @example Add multiple selections.
        #   selectable.exists(field: true, other: false)
        #
        # @example Execute an $exists in a where query.
        #   selectable.where(:field.exists => true)
        #
        # @param [ Hash ] criterion The field/boolean existence checks.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def exists(criterion = nil)
          typed_override(criterion, "$exists") do |value|
            ::Boolean.evolve(value)
          end
        end
        key :exists, :override, "$exists" do |value|
          ::Boolean.evolve(value)
        end

        # Add a $geoIntersects or $geoWithin selection. Symbol operators must
        # be used as shown in the examples to expand the criteria.
        #
        # @note The only valid geometry shapes for a $geoIntersects are:
        #   :intersects_line, :intersects_point, and :intersects_polygon.
        #
        # @note The only valid options for a $geoWithin query are the geometry
        #   shape :within_polygon and the operator :within_box.
        #
        # @note The :within_box operator for the $geoWithin query expects the
        #   lower left (south west) coordinate pair as the first argument and
        #   the upper right (north east) as the second argument.
        #   Important: When latitude and longitude are passed, longitude is
        #   expected as the first element of the coordinate pair.
        #   Source: https://docs.mongodb.com/manual/reference/operator/query/box/
        #
        # @example Add a geo intersect criterion for a line.
        #   query.geo_spacial(:location.intersects_line => [[ 1, 10 ], [ 2, 10 ]])
        #
        # @example Add a geo intersect criterion for a point.
        #   query.geo_spacial(:location.intersects_point => [[ 1, 10 ]])
        #
        # @example Add a geo intersect criterion for a polygon.
        #   query.geo_spacial(:location.intersects_polygon => [[ 1, 10 ], [ 2, 10 ], [ 1, 10 ]])
        #
        # @example Add a geo within criterion for a polygon.
        #   query.geo_spacial(:location.within_polygon => [[ 1, 10 ], [ 2, 10 ], [ 1, 10 ]])
        #
        # @example Add a geo within criterion for a box.
        #   query.geo_spacial(:location.within_box => [[ 1, 10 ], [ 2, 10 ])
        #
        # @param [ Hash ] criterion The criterion.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 2.0.0
        def geo_spacial(criterion = nil)
          __merge__(criterion)
        end
        key :intersects_line, :override, "$geoIntersects", "$geometry" do |value|
          { "type" => LINE_STRING, "coordinates" => value }
        end
        key :intersects_point, :override, "$geoIntersects", "$geometry" do |value|
          { "type" => POINT, "coordinates" => value }
        end
        key :intersects_polygon, :override, "$geoIntersects", "$geometry" do |value|
          { "type" => POLYGON, "coordinates" => value }
        end
        key :within_polygon, :override, "$geoWithin", "$geometry" do |value|
          { "type" => POLYGON, "coordinates" => value }
        end
        key :within_box, :override, "$geoWithin", "$box"

        # Add the $gt criterion to the selector.
        #
        # @example Add the $gt criterion.
        #   selectable.gt(age: 60)
        #
        # @example Execute an $gt in a where query.
        #   selectable.where(:field.gt => 10)
        #
        # @param [ Hash ] criterion The field/value pairs to check.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def gt(criterion = nil)
          __override__(criterion, "$gt")
        end
        key :gt, :override, "$gt"

        # Add the $gte criterion to the selector.
        #
        # @example Add the $gte criterion.
        #   selectable.gte(age: 60)
        #
        # @example Execute an $gte in a where query.
        #   selectable.where(:field.gte => 10)
        #
        # @param [ Hash ] criterion The field/value pairs to check.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def gte(criterion = nil)
          __override__(criterion, "$gte")
        end
        key :gte, :override, "$gte"

        # Adds the $in selection to the selectable.
        #
        # @example Add $in selection on an array.
        #   selectable.in(age: [ 1, 2, 3 ])
        #
        # @example Add $in selection on a range.
        #   selectable.in(age: 18..24)
        #
        # @example Execute an $in in a where query.
        #   selectable.where(:field.in => [ 1, 2, 3 ])
        #
        # @param [ Hash ] criterion The field/value criterion pairs.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def in(criterion = nil)
          send(strategy || :__intersect__, with_array_values(criterion), "$in")
        end
        alias :any_in :in
        key :in, :intersect, "$in"

        # Add the $lt criterion to the selector.
        #
        # @example Add the $lt criterion.
        #   selectable.lt(age: 60)
        #
        # @example Execute an $lt in a where query.
        #   selectable.where(:field.lt => 10)
        #
        # @param [ Hash ] criterion The field/value pairs to check.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def lt(criterion = nil)
          __override__(criterion, "$lt")
        end
        key :lt, :override, "$lt"

        # Add the $lte criterion to the selector.
        #
        # @example Add the $lte criterion.
        #   selectable.lte(age: 60)
        #
        # @example Execute an $lte in a where query.
        #   selectable.where(:field.lte => 10)
        #
        # @param [ Hash ] criterion The field/value pairs to check.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def lte(criterion = nil)
          __override__(criterion, "$lte")
        end
        key :lte, :override, "$lte"

        # Add a $maxDistance selection to the selectable.
        #
        # @example Add the $maxDistance selection.
        #   selectable.max_distance(location: 10)
        #
        # @param [ Hash ] criterion The field/distance pairs.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def max_distance(criterion = nil)
          __add__(criterion, "$maxDistance")
        end

        # Adds $mod selection to the selectable.
        #
        # @example Add the $mod selection.
        #   selectable.mod(field: [ 10, 1 ])
        #
        # @example Execute an $mod in a where query.
        #   selectable.where(:field.mod => [ 10, 1 ])
        #
        # @param [ Hash ] criterion The field/mod selections.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def mod(criterion = nil)
          __override__(criterion, "$mod")
        end
        key :mod, :override, "$mod"

        # Adds $ne selection to the selectable.
        #
        # @example Query for a value $ne to something.
        #   selectable.ne(field: 10)
        #
        # @example Execute an $ne in a where query.
        #   selectable.where(:field.ne => "value")
        #
        # @param [ Hash ] criterion The field/ne selections.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def ne(criterion = nil)
          __override__(criterion, "$ne")
        end
        alias :excludes :ne
        key :ne, :override, "$ne"

        # Adds a $near criterion to a geo selection.
        #
        # @example Add the $near selection.
        #   selectable.near(location: [ 23.1, 12.1 ])
        #
        # @example Execute an $near in a where query.
        #   selectable.where(:field.near => [ 23.2, 12.1 ])
        #
        # @param [ Hash ] criterion The field/location pair.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def near(criterion = nil)
          __override__(criterion, "$near")
        end
        key :near, :override, "$near"

        # Adds a $nearSphere criterion to a geo selection.
        #
        # @example Add the $nearSphere selection.
        #   selectable.near_sphere(location: [ 23.1, 12.1 ])
        #
        # @example Execute an $nearSphere in a where query.
        #   selectable.where(:field.near_sphere => [ 10.11, 3.22 ])
        #
        # @param [ Hash ] criterion The field/location pair.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def near_sphere(criterion = nil)
          __override__(criterion, "$nearSphere")
        end
        key :near_sphere, :override, "$nearSphere"

        # Adds the $nin selection to the selectable.
        #
        # @example Add $nin selection on an array.
        #   selectable.nin(age: [ 1, 2, 3 ])
        #
        # @example Add $nin selection on a range.
        #   selectable.nin(age: 18..24)
        #
        # @example Execute an $nin in a where query.
        #   selectable.where(:field.nin => [ 1, 2, 3 ])
        #
        # @param [ Hash ] criterion The field/value criterion pairs.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def nin(criterion = nil)
          send(strategy || :__intersect__, with_array_values(criterion), "$nin")
        end
        alias :not_in :nin
        key :nin, :intersect, "$nin"

        # Adds $nor selection to the selectable.
        #
        # @example Add the $nor selection.
        #   selectable.nor(field: 1, field: 2)
        #
        # @param [ Array ] criterion An array of hash criterion.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def nor(*criterion)
          __multi__(criterion, "$nor")
        end

        # Is the current selectable negating the next selection?
        #
        # @example Is the selectable negating?
        #   selectable.negating?
        #
        # @return [ true, false ] If the selectable is negating.
        #
        # @since 1.0.0
        def negating?
          !!negating
        end

        # Negate the next selection.
        #
        # @example Negate the selection.
        #   selectable.not.in(field: [ 1, 2 ])
        #
        # @example Add the $not criterion.
        #   selectable.not(name: /Bob/)
        #
        # @example Execute a $not in a where query.
        #   selectable.where(:field.not => /Bob/)
        #
        # @param [ Hash ] criterion The field/value pairs to negate.
        #
        # @return [ Selectable ] The negated selectable.
        #
        # @since 1.0.0
        def not(*criterion)
          if criterion.empty?
            tap { |query| query.negating = true }
          else
            __override__(criterion.first, "$not")
          end
        end
        key :not, :override, "$not"

        # Adds $or selection to the selectable.
        #
        # @example Add the $or selection.
        #   selectable.or(field: 1, field: 2)
        #
        # @param [ Array ] criterion An array of hash criterion.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def or(*criterion)
          __multi__(criterion, "$or")
        end
        alias :any_of :or

        # Add a $size selection for array fields.
        #
        # @example Add the $size selection.
        #   selectable.with_size(field: 5)
        #
        # @note This method is named #with_size not to conflict with any existing
        #   #size method on enumerables or symbols.
        #
        # @example Execute an $size in a where query.
        #   selectable.where(:field.with_size => 10)
        #
        # @param [ Hash ] criterion The field/size pairs criterion.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def with_size(criterion = nil)
          typed_override(criterion, "$size") do |value|
            ::Integer.evolve(value)
          end
        end
        key :with_size, :override, "$size" do |value|
          ::Integer.evolve(value)
        end

        # Adds a $type selection to the selectable.
        #
        # @example Add the $type selection.
        #   selectable.with_type(field: 15)
        #
        # @example Execute an $type in a where query.
        #   selectable.where(:field.with_type => 15)
        #
        # @note http://vurl.me/PGOU contains a list of all types.
        #
        # @param [ Hash ] criterion The field/type pairs.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def with_type(criterion = nil)
          typed_override(criterion, "$type") do |value|
            ::Integer.evolve(value)
          end
        end
        key :with_type, :override, "$type" do |value|
          ::Integer.evolve(value)
        end

        # Construct a text search selector.
        #
        # @example Construct a text search selector.
        #   selectable.text_search("testing")
        #
        # @example Construct a text search selector with options.
        #   selectable.text_search("testing", :$language => "fr")
        #
        # @note Per https://docs.mongodb.com/manual/reference/operator/query/text/
        #   it is not currently possible to supply multiple text search
        #   conditions in a query. Mongoid will build such a query but the
        #   server will return an error when trying to execute it.
        #
        # @param [ String, Symbol ] terms A string of terms that MongoDB parses
        #   and uses to query the text index.
        # @param [ Hash ] opts Text search options. See MongoDB documentation
        #   for options.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 2.2.0
        def text_search(terms, opts = nil)
          clone.tap do |query|
            if terms
              criterion = {'$text' => { '$search' => terms }}
              criterion['$text'].merge!(opts) if opts
              if query.selector['$text']
                # Per https://docs.mongodb.com/manual/reference/operator/query/text/
                # multiple $text expressions are not currently supported by
                # MongoDB server, but build the query correctly instead of
                # overwriting previous text search condition with the currently
                # given one.
                Mongoid.logger.warn('Multiple $text expressions per query are not currently supported by the server')
                query.selector = {'$and' => [query.selector]}.merge(criterion)
              else
                query.selector = query.selector.merge(criterion)
              end
            end
          end
        end

        # This is the general entry point for most MongoDB queries. This either
        # creates a standard field: value selection, and expanded selection with
        # the use of hash methods, or a $where selection if a string is provided.
        #
        # @example Add a standard selection.
        #   selectable.where(name: "syd")
        #
        # @example Add a javascript selection.
        #   selectable.where("this.name == 'syd'")
        #
        # @param [ String, Hash ] criterion The javascript or standard selection.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def where(criterion = nil)
          # We need to save the criterion in an instance variable so Modifiable methods
          # know how to create a polymorphic object.
          @criterion = criterion
          criterion.is_a?(String) ? js_query(criterion) : expr_query(criterion)
        end

        private

        # Create the standard expression query.
        #
        # @api private
        #
        # @example Create the selection.
        #   selectable.expr_query(age: 50)
        #
        # @param [ Hash ] criterion The field/value pairs.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def expr_query(criterion)
          selection(criterion) do |selector, field, value|
            selector.merge!(field.__expr_part__(value.__expand_complex__, negating?))
          end
        end

        # Force the values of the criterion to be evolved.
        #
        # @api private
        #
        # @example Force values to booleans.
        #   selectable.force_typing(criterion) do |val|
        #     Boolean.evolve(val)
        #   end
        #
        # @param [ Hash ] criterion The criterion.
        #
        # @since 1.0.0
        def typed_override(criterion, operator)
          if criterion
            criterion.update_values do |value|
              yield(value)
            end
          end
          __override__(criterion, operator)
        end

        # Create a javascript selection.
        #
        # @api private
        #
        # @example Create the javascript selection.
        #   selectable.js_query("this.age == 50")
        #
        # @param [ String ] criterion The javascript as a string.
        #
        # @return [ Selectable ] The cloned selectable
        #
        # @since 1.0.0
        def js_query(criterion)
          clone.tap do |query|
            query.selector.merge!("$where" => criterion)
          end
        end

        # Take the provided criterion and store it as a selection in the query
        # selector.
        #
        # @api private
        #
        # @example Store the selection.
        #   selectable.selection({ field: "value" })
        #
        # @param [ Hash ] criterion The selection to store.
        #
        # @return [ Selectable ] The cloned selectable.
        #
        # @since 1.0.0
        def selection(criterion = nil)
          clone.tap do |query|
            if criterion
              criterion.each_pair do |field, value|
                yield(query.selector, field.is_a?(Key) ? field : field.to_s, value)
              end
            end
            query.reset_strategies!
          end
        end

        # Convert the criterion values to $in friendly values. This means you,
        # array.
        #
        # @api private
        #
        # @example Convert all the values to arrays.
        #   selectable.with_array_values({ key: 1...4 })
        #
        # @param [ Hash ] criterion The criterion.
        #
        # @return [ Hash ] The $in friendly criterion (array values).
        #
        # @since 1.0.0
        def with_array_values(criterion)
          return nil unless criterion
          criterion.each_pair do |key, value|
            criterion[key] = value.__array__
          end
        end

        class << self

          # Get the methods on the selectable that can be forwarded to from a model.
          #
          # @example Get the forwardable methods.
          #   Selectable.forwardables
          #
          # @return [ Array<Symbol> ] The names of the forwardable methods.
          #
          # @since 1.0.0
          def forwardables
            public_instance_methods(false) -
              [ :negating, :negating=, :negating?, :selector, :selector= ]
          end
        end
      end
    end
  end
end