require 'colorize'
require 'chronic_duration'

class Chronicle::ETL::Runner
  def initialize(job)
    @job = job
    @job_logger = Chronicle::ETL::JobLogger.new(@job)
  end

  def run!
    validate_job
    instantiate_connectors
    prepare_job
    prepare_ui
    run_extraction
    finish_job
  end

  private

  def validate_job
    @job.job_definition.validate!
  end

  def instantiate_connectors
    @extractor = @job.instantiate_extractor
    @loader = @job.instantiate_loader
  end

  def prepare_job
    Chronicle::ETL::Logger.info(tty_log_job_start)
    @job_logger.start
    @loader.start
    @extractor.prepare
  end

  def prepare_ui
    total = @extractor.results_count
    @progress_bar = Chronicle::ETL::Utils::ProgressBar.new(title: 'Running job', total: total)
    Chronicle::ETL::Logger.attach_to_progress_bar(@progress_bar)
  end

  # TODO: refactor this further
  def run_extraction
    @extractor.extract do |extraction|
      unless extraction.is_a?(Chronicle::ETL::Extraction)
        raise Chronicle::ETL::RunnerTypeError, "Extracted should be a Chronicle::ETL::Extraction"
      end

      transformer = @job.instantiate_transformer(extraction)
      record = transformer.transform

      Chronicle::ETL::Logger.info(tty_log_transformation(transformer))
      @job_logger.log_transformation(transformer)

      @loader.load(record) unless @job.dry_run?
    rescue Chronicle::ETL::TransformationError => e
      Chronicle::ETL::Logger.error(tty_log_transformation_failure(e, transformer))
    ensure
      @progress_bar.increment
    end

    @progress_bar.finish
    @loader.finish
    @job_logger.finish
  rescue Interrupt
    Chronicle::ETL::Logger.error("\n#{'Job interrupted'.red}")
    @job_logger.error
  rescue StandardError => e
    raise e
  end

  def finish_job
    @job_logger.save
    @progress_bar&.finish
    Chronicle::ETL::Logger.detach_from_progress_bar
    Chronicle::ETL::Logger.info(tty_log_completion)
  end

  def tty_log_job_start
    output = "Beginning job "
    output += "'#{@job.name}'".bold if @job.name
    output
  end

  def tty_log_transformation(transformer)
    output = "  ✓".green
    output += " #{transformer}"
  end

  def tty_log_transformation_failure(exception, transformer)
    output = "  ✖".red
    output += " Failed to build #{transformer}. #{exception.message}"
  end

  def tty_log_completion
    status = @job_logger.success ? 'Success' : 'Failed'
    output = "\nCompleted job "
    output += "'#{@job.name}'".bold if @job.name
    output += " in #{ChronicDuration.output(@job_logger.duration)}" if @job_logger.duration
    output += "\n  Status:\t".light_black + status
    output += "\n  Completed:\t".light_black + "#{@job_logger.job_log.num_records_processed}"
    output += "\n  Latest:\t".light_black + "#{@job_logger.job_log.highest_timestamp.iso8601}" if @job_logger.job_log.highest_timestamp
    output
  end
end