require 'json'
require 'stringio'

# Node shim calls this class to process both controllers and jobs
class Jets::Processors::MainProcessor
  attr_reader :event, :context, :handler
  def initialize(event, context, handler)
    # assume valid json from Lambda
    @event = JSON.parse(event)
    @context = JSON.parse(context)
    @handler = handler
  end

  def run
    # Use the handler to deduce app code to run.
    # Example handlers: handlers/controllers/posts.create, handlers/jobs/sleep.perform
    #
    #   deducer = Jets::Processors::Deducer.new("handlers/controllers/posts.create")
    #
    deducer = Jets::Processors::Deducer.new(handler)
    begin
      # Examples:
      #   deducer.code => PostsController.process(event, context, "show")
      #   deducer.path => app/controllers/posts_controller.rb
      #
      #   deducer.code => HardJob.process(event, context, "dig")
      #   deducer.path => app/jobs/hard_job.rb
      #
      #   deducer.code => HelloFunction.process(event, context, "world")
      #   deducer.path => app/functions/hello.rb
      deducer.load_class
      result = instance_eval(deducer.code, deducer.path)
      # result = PostsController.process(event, context, "create")

      Jets.increase_call_count
      if result.is_a?(Hash) && result["headers"]
        result["headers"]["x-jets-call-count"] = Jets.call_count
        result["headers"]["x-jets-prewarm-count"] = Jets.prewarm_count
      end

      # Puts the return value of project code to stdout because this is
      # what eventually gets used by API Gateway.
      # Explicitly using $stdout since puts has been redirected to $stderr.
      #
      # JSON.dump is pretty robust.  If it cannot dump the structure into a
      # json string, it just dumps it to a plain text string.
      resp = Jets::Util.normalize_result(result) # String
    rescue Exception => e
      # Customize error message slightly so nodejs shim can process the
      # returned error message.
      # The "RubyError: " is a marker that the javascript shim scans for.
      $stderr.puts("RubyError: #{e.class}: #{e.message}") # js needs this as the first line
      backtrace = e.backtrace.map {|l| "  #{l}" }
      $stderr.puts(backtrace)
      # No need to having error in stderr above anymore because errors are handled in memory
      # at ruby_server.rb but keeping around for posterity.

      raise # raise error to ruby_server.rb to rescue and handle

      # $stderr.puts("END OF RUBY OUTPUT") # uncomment for debugging
    end
  end
end