class Participant < ApplicationRecord
  # Associations
  belongs_to :employer, optional: true
  has_many :employments
  has_many :workers, through: :employments
  has_many :service_contracts
  has_many :vendors, through: :service_contracts
  has_many :employer_records
  has_many :employers, through: :employer_records
  has_and_belongs_to_many :programs

  # Validations
  validates :first_name, :last_name, :ssn, presence: true
  validate :ssn_must_be_unique_across_models

  def full_name
    "#{first_name} #{last_name}"
  end

  private

  def ssn_must_be_unique_across_models
    if Participant.where.not(id: id).exists?(ssn: ssn) || Employer.exists?(ssn: ssn)
      errors.add(:ssn, 'SSN is already taken by another participant or employer')
    end
  end
end