# Copyright (C) 2012-2024 Zammad Foundation, https://zammad-foundation.org/

class Sequencer::Unit
  extend ::Sequencer::Mixin::PrefixedConstantize

  PREFIX = 'Sequencer::Unit::'.freeze

  # Convenience wrapper for processing a single Unit.
  #
  # ATTENTION: This should only be used for development, testing or debugging purposes.
  # There might be a check in the future to prevent using this method in other scopes.
  #
  # @see #initialize
  # @see #process
  def self.process(unit, parameters, &)
    new(unit).process(parameters, &)
  end

  # Initializes a new Sequencer::Unit for processing it.
  #
  # ATTENTION: This should only be used for development, testing or debugging purposes.
  # There might be a check in the future to prevent using this method in other scopes.
  #
  # @param [String] unit the name String for the Unit that should get processed
  def initialize(unit)
    @unit = self.class.constantize(unit)
  end

  # Processes the Sequencer::Unit that the instance was initialized with.
  #
  # ATTENTION: This should only be used for development, testing or debugging purposes.
  # There might be a check in the future to prevent using this method in other scopes.
  #
  # @param [Hash{Symbol => Object}] parameters the parameters for initializing the Sequencer::State
  # @yield [instance] optional block to access the Unit instance
  # @yieldparam instance [Object] the Unit instance for e.g. adding expectations
  def process(parameters)
    @parameters = parameters
    instance    = @unit.new(state)

    # yield instance to apply expectations
    yield instance if block_given?

    state.process do
      instance.process
    end

    state.to_h
  end

  private

  def state
    @state ||= begin
      units = Sequencer::Units.new(
        @unit.name
      )

      sequence = Sequencer::Sequence.new(
        units:     units,
        expecting: @unit.provides,
      )

      Sequencer::State.new(sequence,
                           parameters: @parameters)
    end
  end
end