# frozen_string_literal: true

module GraphQL
  class Schema
    class Visibility
      # This class filters the types, fields, arguments, enum values, and directives in a schema
      # based on the given `context`.
      #
      # It's like {Warden}, but has some differences:
      #
      # - It doesn't use {Schema}'s top-level caches (eg {Schema.references_to}, {Schema.possible_types}, {Schema.types})
      # - It doesn't hide Interface or Union types when all their possible types are hidden. (Instead, those types should implement `.visible?` to hide in that case.)
      # - It checks `.visible?` on root introspection types
      #
      # In the future, {Subset} will support lazy-loading types as needed during execution and multi-request caching of subsets.
      class Subset
        # @return [Schema::Visibility::Subset]
        def self.from_context(ctx, schema)
          if ctx.respond_to?(:types) && (types = ctx.types).is_a?(self)
            types
          else
            # TODO use a cached instance from the schema
            self.new(context: ctx, schema: schema)
          end
        end

        def self.pass_thru(context:, schema:)
          subset = self.new(context: context, schema: schema)
          subset.instance_variable_set(:@cached_visible, Hash.new { |h,k| h[k] = true })
          subset
        end

        def initialize(context:, schema:)
          @context = context
          @schema = schema
          @all_types = {}
          @all_types_loaded = false
          @unvisited_types = []
          @referenced_types = Hash.new { |h, type_defn| h[type_defn] = [] }.compare_by_identity
          @cached_directives = {}
          @all_directives = nil
          @cached_visible = Hash.new { |h, member|
            h[member] = @schema.visible?(member, @context)
          }.compare_by_identity

          @cached_visible_fields = Hash.new { |h, owner|
            h[owner] = Hash.new do |h2, field|
              h2[field] = if @cached_visible[field] &&
                  (ret_type = field.type.unwrap) &&
                  @cached_visible[ret_type] &&
                  (owner == field.owner || (!owner.kind.object?) || field_on_visible_interface?(field, owner))

                if !field.introspection?
                  # The problem is that some introspection fields may have references
                  # to non-custom introspection types.
                  # If those were added here, they'd cause a DuplicateNamesError.
                  # This is basically a bug -- those fields _should_ reference the custom types.
                  add_type(ret_type, field)
                end
                true
              else
                false
              end
            end.compare_by_identity
          }.compare_by_identity

          @cached_visible_arguments = Hash.new do |h, arg|
            h[arg] = if @cached_visible[arg] && (arg_type = arg.type.unwrap) && @cached_visible[arg_type]
              add_type(arg_type, arg)
              true
            else
              false
            end
          end.compare_by_identity

          @cached_parent_fields = Hash.new do |h, type|
            h[type] = Hash.new do |h2, field_name|
              h2[field_name] = type.get_field(field_name, @context)
            end
          end.compare_by_identity

          @cached_parent_arguments = Hash.new do |h, arg_owner|
            h[arg_owner] = Hash.new do |h2, arg_name|
              h2[arg_name] = arg_owner.get_argument(arg_name, @context)
            end
          end.compare_by_identity

          @cached_possible_types = Hash.new do |h, type|
            h[type] = case type.kind.name
            when "INTERFACE"
              load_all_types
              pts = []
              @unfiltered_interface_type_memberships[type].each { |itm|
                if @cached_visible[itm] && (ot = itm.object_type) && @cached_visible[ot] && referenced?(ot)
                  pts << ot
                end
              }
              pts
            when "UNION"
              pts = []
              type.type_memberships.each { |tm|
                if @cached_visible[tm] &&
                    (ot = tm.object_type) &&
                    @cached_visible[ot] &&
                    referenced?(ot)
                  pts << ot
                end
              }
              pts
            when "OBJECT"
              load_all_types
              if @all_types[type.graphql_name] == type
                [type]
              else
                EmptyObjects::EMPTY_ARRAY
              end
            else
              GraphQL::EmptyObjects::EMPTY_ARRAY
            end
          end.compare_by_identity

          @cached_enum_values = Hash.new do |h, enum_t|
            values = non_duplicate_items(enum_t.all_enum_value_definitions, @cached_visible)
            if values.size == 0
              raise GraphQL::Schema::Enum::MissingValuesError.new(enum_t)
            end
            h[enum_t] = values
          end.compare_by_identity

          @cached_fields = Hash.new do |h, owner|
            h[owner] = non_duplicate_items(owner.all_field_definitions.each(&:ensure_loaded), @cached_visible_fields[owner])
          end.compare_by_identity

          @cached_arguments = Hash.new do |h, owner|
            h[owner] = non_duplicate_items(owner.all_argument_definitions, @cached_visible_arguments)
          end.compare_by_identity
        end

        def field_on_visible_interface?(field, owner)
          ints = owner.interface_type_memberships.map(&:abstract_type)
          field_name = field.graphql_name
          filtered_ints = interfaces(owner)
          any_interface_has_field = false
          any_interface_has_visible_field = false
          ints.each do |int_t|
            if (_int_f_defn = @cached_parent_fields[int_t][field_name])
              any_interface_has_field = true

              if filtered_ints.include?(int_t) # TODO cycles, or maybe not necessary since previously checked? && @cached_visible_fields[owner][field]
                any_interface_has_visible_field = true
                break
              end
            end
          end

          if any_interface_has_field
            any_interface_has_visible_field
          else
            true
          end
        end

        def type(type_name)
          t = if (loaded_t = @all_types[type_name])
            loaded_t
          elsif !@all_types_loaded
            load_all_types
            @all_types[type_name]
          end
          if t
            if t.is_a?(Array)
              vis_t = nil
              t.each do |t_defn|
                if @cached_visible[t_defn]
                  if vis_t.nil?
                    vis_t = t_defn
                  else
                    raise_duplicate_definition(vis_t, t_defn)
                  end
                end
              end
              vis_t
            else
              if t && @cached_visible[t]
                t
              else
                nil
              end
            end
          end
        end

        def field(owner, field_name)
          f = if owner.kind.fields? && (field = @cached_parent_fields[owner][field_name])
            field
          elsif owner == query_root && (entry_point_field = @schema.introspection_system.entry_point(name: field_name))
            entry_point_field
          elsif (dynamic_field = @schema.introspection_system.dynamic_field(name: field_name))
            dynamic_field
          else
            nil
          end
          if f.is_a?(Array)
            visible_f = nil
            f.each do |f_defn|
              if @cached_visible_fields[owner][f_defn]

                if visible_f.nil?
                  visible_f = f_defn
                else
                  raise_duplicate_definition(visible_f, f_defn)
                end
              end
            end
            visible_f.ensure_loaded
          elsif f && @cached_visible_fields[owner][f.ensure_loaded]
            f
          else
            nil
          end
        end

        def fields(owner)
          @cached_fields[owner]
        end

        def arguments(owner)
          @cached_arguments[owner]
        end

        def argument(owner, arg_name)
          arg = @cached_parent_arguments[owner][arg_name]
          if arg.is_a?(Array)
            visible_arg = nil
            arg.each do |arg_defn|
              if @cached_visible_arguments[arg_defn]
                if visible_arg.nil?
                  visible_arg = arg_defn
                else
                  raise_duplicate_definition(visible_arg, arg_defn)
                end
              end
            end
            visible_arg
          else
            if arg && @cached_visible_arguments[arg]
              arg
            else
              nil
            end
          end
        end

        def possible_types(type)
          @cached_possible_types[type]
        end

        def interfaces(obj_or_int_type)
          ints = obj_or_int_type.interface_type_memberships
            .select { |itm| @cached_visible[itm] && @cached_visible[itm.abstract_type] }
            .map!(&:abstract_type)
          ints.uniq! # Remove any duplicate interfaces implemented via other interfaces
          ints
        end

        def query_root
          add_if_visible(@schema.query)
        end

        def mutation_root
          add_if_visible(@schema.mutation)
        end

        def subscription_root
          add_if_visible(@schema.subscription)
        end

        def all_types
          load_all_types
          @all_types.values
        end

        def all_types_h
          load_all_types
          @all_types
        end

        def enum_values(owner)
          @cached_enum_values[owner]
        end

        def directive_exists?(dir_name)
          if (dir = @schema.directives[dir_name]) && @cached_visible[dir]
            !!dir
          else
            load_all_types
            !!@cached_directives[dir_name]
          end
        end

        def directives
          @all_directives ||= begin
            load_all_types
            dirs = []
            @schema.directives.each do |name, dir_defn|
              if !@cached_directives[name] && @cached_visible[dir_defn]
                dirs << dir_defn
              end
            end
            dirs.concat(@cached_directives.values)
          end
        end

        def loadable?(t, _ctx)
          !@all_types[t.graphql_name] && @cached_visible[t]
        end

        def loaded_types
          @all_types.values
        end

        def reachable_type?(name)
          load_all_types
          !!@all_types[name]
        end

        private

        def add_if_visible(t)
          (t && @cached_visible[t]) ? (add_type(t, true); t) : nil
        end

        def add_type(t, by_member)
          if t && @cached_visible[t]
            n = t.graphql_name
            if (prev_t = @all_types[n])
              if !prev_t.equal?(t)
                raise_duplicate_definition(prev_t, t)
              end
              false
            else
              @referenced_types[t] << by_member
              @all_types[n] = t
              @unvisited_types << t
              true
            end
          else
            false
          end
        end

        def non_duplicate_items(definitions, visibility_cache)
          non_dups = []
          definitions.each do |defn|
            if visibility_cache[defn]
              if (dup_defn = non_dups.find { |d| d.graphql_name == defn.graphql_name })
                raise_duplicate_definition(dup_defn, defn)
              end
              non_dups << defn
            end
          end
          non_dups
        end

        def raise_duplicate_definition(first_defn, second_defn)
          raise DuplicateNamesError.new(duplicated_name: first_defn.path, duplicated_definition_1: first_defn.inspect, duplicated_definition_2: second_defn.inspect)
        end

        def referenced?(t)
          load_all_types
          @referenced_types[t].any? { |reference| (reference == true) || @cached_visible[reference] }
        end

        def load_all_types
          return if @all_types_loaded
          @all_types_loaded = true
          entry_point_types = [
            query_root,
            mutation_root,
            subscription_root,
            *@schema.introspection_system.types.values,
          ]

          # Don't include any orphan_types whose interfaces aren't visible.
          @schema.orphan_types.each do |orphan_type|
            if @cached_visible[orphan_type] &&
              orphan_type.interface_type_memberships.any? { |tm| @cached_visible[tm] && @cached_visible[tm.abstract_type] }
              entry_point_types << orphan_type
            end
          end

          @schema.directives.each do |_dir_name, dir_class|
            if @cached_visible[dir_class]
              arguments(dir_class).each do |arg|
                entry_point_types << arg.type.unwrap
              end
            end
          end

          entry_point_types.compact! # TODO why is this necessary?!
          entry_point_types.flatten! # handle multiple defns
          entry_point_types.each { |t| add_type(t, true) }

          @unfiltered_interface_type_memberships = Hash.new { |h, k| h[k] = [] }.compare_by_identity
          @add_possible_types = Set.new

          while @unvisited_types.any?
            while t = @unvisited_types.pop
              # These have already been checked for `.visible?`
              visit_type(t)
            end
            @add_possible_types.each do |int_t|
              itms = @unfiltered_interface_type_memberships[int_t]
              itms.each do |itm|
                if @cached_visible[itm] && (obj_type = itm.object_type) && @cached_visible[obj_type]
                  add_type(obj_type, itm)
                end
              end
            end
            @add_possible_types.clear
          end

          @all_types.delete_if { |type_name, type_defn| !referenced?(type_defn) }
          nil
        end

        def visit_type(type)
          visit_directives(type)
          case type.kind.name
          when "OBJECT", "INTERFACE"
            if type.kind.object?
              type.interface_type_memberships.each do |itm|
                @unfiltered_interface_type_memberships[itm.abstract_type] << itm
              end
              # recurse into visible implemented interfaces
              interfaces(type).each do |interface|
                add_type(interface, type)
              end
            else
              type.orphan_types.each { |t| add_type(t, type)}
            end

            # recurse into visible fields
            t_f = type.all_field_definitions
            t_f.each do |field|
              field.ensure_loaded
              if @cached_visible[field]
                visit_directives(field)
                field_type = field.type.unwrap
                if field_type.kind.interface?
                  @add_possible_types.add(field_type)
                end
                add_type(field_type, field)

                # recurse into visible arguments
                arguments(field).each do |argument|
                  visit_directives(argument)
                  add_type(argument.type.unwrap, argument)
                end
              end
            end
          when "INPUT_OBJECT"
            # recurse into visible arguments
            arguments(type).each do |argument|
              visit_directives(argument)
              add_type(argument.type.unwrap, argument)
            end
          when "UNION"
            # recurse into visible possible types
            type.type_memberships.each do |tm|
              if @cached_visible[tm]
                obj_t = tm.object_type
                if obj_t.is_a?(String)
                  obj_t = Member::BuildType.constantize(obj_t)
                  tm.object_type = obj_t
                end
                if @cached_visible[obj_t]
                  add_type(obj_t, tm)
                end
              end
            end
          when "ENUM"
            enum_values(type).each do |val|
              visit_directives(val)
            end
          when "SCALAR"
            # pass
          end
        end

        def visit_directives(member)
          member.directives.each { |dir|
            dir_class = dir.class
            if @cached_visible[dir_class]
              dir_name = dir_class.graphql_name
              if (existing_dir = @cached_directives[dir_name])
                if existing_dir != dir_class
                  raise ArgumentError, "Two directives for `@#{dir_name}`: #{existing_dir}, #{dir.class}"
                end
              else
                @cached_directives[dir.graphql_name] = dir_class
              end
            end
          }
        end
      end
    end
  end
end