redmine-workflow-engine/app/models/workflow_step.rb

class WorkflowStep < ActiveRecord::Base
  belongs_to :custom_workflow
  belongs_to :issue_status, optional: true
  has_many :workflow_step_assignees, dependent: :destroy
  has_many :issue_workflow_states, foreign_key: :current_step_id

  validates :name, presence: true
  validates :custom_workflow_id, presence: true

  scope :ordered, -> { order(:position) }

  before_create :set_position

  def next_step
    custom_workflow.workflow_steps.where('position > ?', position).order(:position).first
  end

  def prev_step
    custom_workflow.workflow_steps.where('position < ?', position).order(position: :desc).first
  end

  def first_step?
    is_start || position == custom_workflow.workflow_steps.minimum(:position)
  end

  def last_step?
    is_end || position == custom_workflow.workflow_steps.maximum(:position)
  end

  # 이 단계의 모든 담당자 (사람, 역할그룹 멤버, 부서원 포함)
  def all_assignee_users
    users = []
    workflow_step_assignees.each do |assignee|
      case assignee.assignee_type
      when 'user'
        user = User.find_by(id: assignee.assignee_id)
        users << user if user
      when 'role_group'
        role_group = RoleGroup.find_by(id: assignee.assignee_id)
        users.concat(role_group.users.to_a) if role_group
      when 'department'
        department = Department.find_by(id: assignee.assignee_id)
        users.concat(department.users.to_a) if department
      end
    end
    users.uniq
  end

  # 특정 사용자가 이 단계의 담당자인지 확인
  def assignee?(user)
    all_assignee_users.include?(user)
  end

  private

  def set_position
    max_position = custom_workflow.workflow_steps.maximum(:position) || -1
    self.position = max_position + 1
  end
end