# typed: ignore

# Copyright (c) 2015 Sqreen. All Rights Reserved.
# Please refer to our terms for more information: https://www.sqreen.com/terms.html

# TODO: => Sqreen::JS:MiniRacer
# TODO: remove class vars

require 'sqreen/log'

module Sqreen
  module Js
    class MiniRacerExecutableJs < ExecutableJs
      @@ctx_defined = false # rubocop:disable Style/ClassVars

      def ctx_defined?
        @@ctx_defined
      end

      def define_ctx!
        @@ctx_defined = true # rubocop:disable Style/ClassVars
      end

      def initialize(pool, code, vendored)
        @pool = pool
        @code = code
        @code_id = self.class.code_id(code)

        @module = vendored ? Sqreen::MiniRacer : MiniRacer

        mod = vendored ? Sqreen::MiniRacer : MiniRacer

        return if ctx_defined?

        self.class.define_sqreen_context(mod)
        define_ctx!
      end

      def run_js_cb(cb_name, budget, arguments)
        Sqreen.log.debug { "js:#{self.class} callback:#{cb_name} pool:#{@pool.inspect}" }
        @pool.with_context do |ctx|
          Sqreen.log.debug { "js:#{self.class} callback:#{cb_name} context:#{ctx.inspect}" }
          if ctx.code_failed?(@code_id)
            Sqreen.log.debug do
              "Skipping execution of callback #{cb_name} (code md5 #{@code_id})" \
              " due to prev failure of definition evaluation"
            end
            return nil
          end

          ctx.add_code(@code_id, @code) unless ctx.code?(@code_id)

          # mini_racer expects timeout to be in ms
          ctx.timeout = budget ? budget * 1000.0 : nil
          begin
            ctx.call("sqreen_#{@code_id}_#{cb_name}", *arguments)
          rescue @module::ScriptTerminatedError
            Sqreen.log.debug "ScriptTerminatedError/#{cb_name}"
            nil
          end
        end
      end

      def self.code_id(code)
        Digest::MD5.hexdigest(code)
      end

      class << self
        def define_sqreen_context(modoole)
          # Context specialized for Sqreen usage
          Sqreen::Js.const_set 'SqreenContext', Class.new(modoole.const_get('Context'))
          SqreenContext.class_eval do
            attr_accessor :gc_threshold_in_bytes
            attr_accessor :gc_load
            attr_writer   :timeout

            def code?(code_id)
              return false unless @code_ids
              @code_ids.include?(code_id)
            end

            def code_failed?(code_id)
              return false unless @failed_code_ids
              @failed_code_ids.include?(code_id)
            end

            def add_code(code_id, code)
              # It's important that the definition is run in its own scope (by executing it inside an anonymous function)
              # Otherwise some auxiliary functions that the backend server sends will collide the name
              # Because they're defined with `var`, running the definitions inside a function is enough
              eval_unsafe "(function() { #{code} })()"
              transf_global_funcs code_id
              @code_ids ||= Set.new
              @code_ids << code_id
            rescue StandardError
              @failed_code_ids ||= Set.new
              @failed_code_ids << code_id
              raise
            end

            def eval_unsafe(str, filename = nil, timeoutv = nil)
              # Beware, timeout could be kept in the context
              # if perf cap is removed after having been activated
              # As it's unused by execjscb we are not cleaning it
              return super(str, filename) if timeoutv.nil?
              return if timeoutv <= 0.0
              timeoutv *= 1000 # Timeout are currently expressed in seconds
              @timeout = timeoutv
              @eval_thread = Thread.current
              timeout do
                super(str, filename)
              end
            end

            def possibly_gc
              @gc_threshold_in_bytes ||= DEFAULT_GC_THRESHOLD
              @gc_load ||= 0

              # garbage collections max 1 in every 4 calls (avg)
              if heap_stats[:total_heap_size] > @gc_threshold_in_bytes
                low_memory_notification
                @gc_load += 4
              else
                @gc_load = [0, @gc_load - 1].max
              end
            end

            private

            def transf_global_funcs(code_id)
              # Multiple callbacks may share the same name. In order to avoid collisions, we rename them here.
              eval_unsafe <<-JS
                Object.keys(this).forEach(name => {
                  if (typeof this[name] === "function" && !name.startsWith("sqreen_")) {
                    this['sqreen_#{code_id}_' + name] = this[name];
                    this[name] = undefined;
                  }
                });
              JS
            end
          end
        end
      end
    end
  end
end