module IrcServerFallback

# File lib/irc_server_fallback.rb, line 82
def apply_shared_config!(shared, primary_server:, irc_config:)
  irc_config = irc_config.is_a?(Hash) ? irc_config : {}
  shared[:irc_fallback_server] = fallback_server_for(
    primary: primary_server,
    configured: irc_config["fallback_server"]
  )
  shared[:irc_fallback_after_sec] = fallback_after_sec(
    configured: irc_config["fallback_after_sec"]
  )
  shared[:irc_connect_server] = nil
  shared.delete(:irc_unavailable_since)
end

# File lib/irc_server_fallback.rb, line 43
def connect_host(bot)
  override = bot.config.shared[:irc_connect_server]
  override = override.to_s.strip
  return override unless override.empty?

  bot.config.server
end

# File lib/irc_server_fallback.rb, line 26
def fallback_after_sec(configured: nil, env: ENV)
  env_value = env.fetch("RABBOT_IRC_FALLBACK_AFTER_SEC", "").to_s.strip
  unless env_value.empty?
    value = Integer(env_value)
    return value if value.positive?
  end

  if configured.nil?
    return DEFAULT_FALLBACK_AFTER_SEC
  end

  value = Integer(configured)
  value.positive? ? value : DEFAULT_FALLBACK_AFTER_SEC
rescue ArgumentError, TypeError
  DEFAULT_FALLBACK_AFTER_SEC
end

# File lib/irc_server_fallback.rb, line 14
def fallback_server_for(primary:, configured: nil, env: ENV)
  env_server = env.fetch("RABBOT_IRC_FALLBACK_SERVER", "").to_s.strip
  return env_server unless env_server.empty?

  configured_server = configured.to_s.strip
  return configured_server unless configured_server.empty?

  return DEFAULT_FALLBACK_SERVER if primary.to_s.match?(UNDERNET_HOST_PATTERN)

  nil
end

# File lib/irc_server_fallback.rb, line 78
def on_registered!(bot)
  bot.config.shared.delete(:irc_unavailable_since)
end

# File lib/irc_server_fallback.rb, line 55
def tick!(bot, now: Time.now)
  shared = bot.config.shared
  fallback = shared[:irc_fallback_server]
  return if fallback.to_s.strip.empty?

  if unavailable?(bot)
    shared[:irc_unavailable_since] ||= now
    elapsed = now - shared[:irc_unavailable_since]
    threshold = shared[:irc_fallback_after_sec].to_i
    return if elapsed < threshold

    current_override = shared[:irc_connect_server].to_s.strip
    return if current_override.casecmp?(fallback)

    shared[:irc_connect_server] = fallback
    bot.loggers.warn(
      "[reconnect] switching connect host to #{fallback} after #{elapsed.to_i}s unavailable"
    )
  else
    shared.delete(:irc_unavailable_since)
  end
end

# File lib/irc_server_fallback.rb, line 51
def unavailable?(bot)
  !bot.irc&.registered?
end