class Email < Sequel::Model($db)
  many_to_one :mailinglist

  def before_create
    self.created_at ||= Time.now
    super
  end

  def before_save
    self.updated_at ||= Time.now
    super
  end

  module Permissions
    NONE  = 0    # 0
    READ  = 2**0 # 1
    WRITE = 2**1 # 2
    OP    = 2**2 # 4
    MODO  = 2**3 # 8
    ALL   = READ | WRITE | OP | MODO
    WORDS = {
      READ  => "reader",
      WRITE => "writer",
      OP    => "operator",
      MODO  => "modo",
    }.freeze
    FROM_SYMBOLS = {
      reader:   READ,
      writer:   WRITE,
      operator: OP,
      modo:     MODO,
      none:     NONE,
    }
    def self.from_symbols(*syms)
      syms.map { FROM_SYMBOLS[_1] }.sum
    end

    def self.op?(perm)
      perm & OP == OP
    end
  end

  def permissions?(ask)
    (permissions & ask) == ask
  end

  def reader?
    permissions?(Permissions::READ)
  end

  def writer?
    permissions?(Permissions::WRITE)
  end

  def op?
    permissions?(Permissions::OP)
  end

  def modo?
    permissions?(Permissions::MODO)
  end

  def permissions_words
    words = Permissions::WORDS.filter { permissions?(_1) }.values
    words << "none" if words.empty?
    words
  end

  # Adds a new email to a ML, and respect the ML strategy.
  # Registers with full permissions if first subscribe.
  #
  # @param name
  # @param email
  # @param mailinglist required if mailinglist.nil?
  # @param mailinglist_id required if mailinglist.nil?
  def self.register!(name:, email:, mailinglist: nil, mailinglist_id: nil)
    mailinglist = Mailinglist.first(id: mailinglist_id) if mailinglist.nil?
    if mailinglist.nil?
      $logger.error "No mailing list found with id=#{mailinglist_id}"
      raise "No mailinglist #{mailinglist_id}"
    end

    permissions =
      if mailinglist.emails.count == 0
        Permissions::ALL
      elsif mailinglist.registration == "free"
        Permissions::READ | Permissions::WRITE
      elsif mailinglist.registration == "validated"
        Permissions::NONE
      elsif mailinglist.registration == "closed"
        $logger.warn "Forbidden register for #{mailinglist.id}"
        return nil # not valid
      end

    $logger.debug { "Existing users: #{mailinglist.emails.map(&:email).join(', ')}" }
    new(
      name: name,
      email: email,
      mailinglist: mailinglist,
      permissions: permissions,
    ).save
  end

  def self.unregister!(mailinglist:, email:)
    Email.where(mailinglist: mailinglist, email: email).delete
  end
end