# Copyright (c) 2023 Contrast Security, Inc. See https://www.contrastsecurity.com/enduser-terms-0317a for more details.
# frozen_string_literal: true

require 'fiber'
require 'contrast/agent/scope'
require 'cs__scope/cs__scope'

# This is the Scope component.
#
# It tracks /Contrast/ scope.  That is, "are we currently doing assess or protect stuff within a patched method?" --
# this is how we avoid doing Contrast stuff on Contrast code or creating infinite loops -- or "are we in some other
# execution context for which we need to special case?".
module Contrast
  module Components
    # Constants defined in C:
    #
    # MONITOR = Mutex.new This was replaced from Monitor to Mutex.
    # EXECUTION_CONTEXT = {} Hash containing all of the current ecs as keys pointing to their scope instances.
    # EC_KEYS = [] set while we get the current ec, and used for sweeping the dead fibers in C.
    #
    # Methods defined in C:
    #
    # class Interface
    #   initializes the scope for the current fiber context.
    #   def initialize end;
    #
    #     This returns the scope governing the current execution context. Use this sparingly, preferring the instance
    #    & class methods to access and query scope, rather than interacting with the scope object directly.
    #   def scope_for_current_ec end;
    # end
    #
    # module Scope
    #   Singleton method for cleaning the dead fibers and unused scope instances, scope GC.
    #   def self.sweep_dead_ecs end;
    # end
    module Scope
      # Methods defined in C:
      #
      # For each instance method on a scope, define a forwarder to the scope on the
      # current execution context's scope.
      # def scope_for_current_ec end;
      #
      # all the methods bellow are used as forwarders to be executed in the current ec.
      # exp: in_contrast_scope? => scope_for_current_ec.enter_contrast_scope!
      #
      # Check if we are in contrast scope.
      # def in_contrast_scope? end;
      # @return [Boolean] check if we are in contrast scope
      #                   if the scope is above 0 return true.
      #
      # check if we are in deserialization scope.
      # def in_deserialization_scope? end;
      # @return [Boolean] check if we are in contrast scope
      #                   if the scope is above 0 return true.
      #
      # check if we are in split scope.
      # def in_split_scope? end;
      # @return [Boolean] check if we are in contrast scope
      #                   if the scope is above 0 return true.
      #
      # enter contrast scope.
      # def enter_contrast_scope! end;
      # @return @contrast_scope [Integer] contrast scope increased.
      #
      # enter deserialization scope.
      # def enter_deserialization_scope! end;
      # @return @deserialization_scope [Integer] deserialization scope increased.
      #
      # enter split scope.
      # def enter_split_scope! end;
      # @return @split_scope [Integer] split scope increased.
      #
      # check split scope depth.
      # def split_scope_depth end;
      # @return @split_scope [Integer] split scope depth.
      #
      # exit contrast scope.
      # def exit_contrast_scope! end;
      # @return @contrast_scope [Integer] contrast scope decreased.
      #
      # exit deserialization scope.
      # def exit_deserialization_scope! end;
      # @return @deserialization_scope [Integer] deserialization scope decreased.
      #
      # exit split scope.
      # def exit_split_scope! end;
      # @return @split_scope [Integer] split scope decreased.
      #
      # Static methods to be used, the cases are defined by the usage from the above methods
      #
      # check if are in specific scope.
      # def in_scope? name end;
      # @param name [Symbol] scope symbol representing scope to check.
      # @return [Boolean] check if we are in passed scope.
      #
      # enter specific scope.
      # def enter_scope! name end;
      # @param name [Symbol] scope symbol representing scope to enter.
      # @return scope [Integer] entered scope value increased.
      #
      # exit specific scope.
      # def exit_cope! name end;
      # @param name [Symbol] scope symbol representing scope to exit.
      # @return scope [Integer] entered scope value decreased.
      module InstanceMethods
        # Forwarder to execute block in contrast scope under current
        # method execution context. On completion exits scope.
        def with_contrast_scope
          scope_for_current_ec.enter_contrast_scope!
          yield
        ensure
          scope_for_current_ec.exit_contrast_scope!
        end

        # Forwarder to execute block in deserialization scope under current
        # method execution context. On completion exits scope.
        def with_deserialization_scope
          scope_for_current_ec.enter_deserialization_scope!
          yield
        ensure
          scope_for_current_ec.exit_deserialization_scope!
        end

        # Forwarder to execute block in split scope under current
        # method execution context. On completion exits scope.
        def with_split_scope
          scope_for_current_ec.enter_split_scope!
          yield
        ensure
          scope_for_current_ec.exit_split_scope!
        end

        # Enter app scope
        def with_app_scope
          scope_for_current_ec.exit_contrast_scope!
          yield
        ensure
          scope_for_current_ec.enter_contrast_scope!
        end
      end

      ClassMethods = InstanceMethods
    end
  end
end