class Redis::Cluster

def _scan(command, &block)
  input_cursor = Integer(command[1])
  client_index = input_cursor % 256
  raw_cursor = input_cursor >> 8
  clients = @node.scale_reading_clients
  client = clients[client_index]
  return ['0', []] unless client
  command[1] = raw_cursor.to_s
  result_cursor, result_keys = client.call(command, &block)
  result_cursor = Integer(result_cursor)
  if result_cursor == 0
    client_index += 1
  end
  [((result_cursor << 8) + client_index).to_s, result_keys]
end

def assign_asking_node(err_msg)
  _, _, node_key = err_msg.split(' ')
  find_node(node_key)
end

def assign_node(command)
  node_key = find_node_key(command)
  find_node(node_key)
end

def assign_redirection_node(err_msg)
  _, slot, node_key = err_msg.split(' ')
  slot = slot.to_i
  @slot.put(slot, node_key)
  find_node(node_key)
end

def call(command, &block)
  send_command(command, &block)
end

def call_loop(command, timeout = 0, &block)
  node = assign_node(command)
  try_send(node, :call_loop, command, timeout, &block)
end

def call_pipeline(pipeline)
  node_keys = pipeline.commands.map { |cmd| find_node_key(cmd, primary_only: true) }.compact.uniq
  if node_keys.size > 1
    raise(CrossSlotPipeliningError,
          pipeline.commands.map { |cmd| @command.extract_first_key(cmd) }.reject(&:empty?).uniq)
  end
  try_send(find_node(node_keys.first), :call_pipeline, pipeline)
end

def call_with_timeout(command, timeout, &block)
  node = assign_node(command)
  try_send(node, :call_with_timeout, command, timeout, &block)
end

def call_without_timeout(command, &block)
  call_with_timeout(command, 0, &block)
end

def connected?
  @node.any?(&:connected?)
end

def connection_info
  @node.sort_by(&:id).map do |client|
    {
      host: client.host,
      port: client.port,
      db: client.db,
      id: client.id,
      location: client.location
    }
  end
end

def db
  0
end

def db=(_db); end

def disconnect
  @node.each(&:disconnect)
  true
end

def fetch_cluster_info!(option)
  node = Node.new(option.per_node_key)
  available_slots = SlotLoader.load(node)
  node_flags = NodeLoader.load_flags(node)
  option.update_node(available_slots.keys.map { |k| NodeKey.optionize(k) })
  [Node.new(option.per_node_key, node_flags, option.use_replica?),
   Slot.new(available_slots, node_flags, option.use_replica?)]
ensure
  node&.each(&:disconnect)
end

def fetch_command_details(nodes)
  details = CommandLoader.load(nodes)
  Command.new(details)
end

def find_node(node_key)
  return @node.sample if node_key.nil?
  @node.find_by(node_key)
rescue Node::ReloadNeeded
  update_cluster_info!(node_key)
  @node.find_by(node_key)
end

def find_node_key(command, primary_only: false)
  key = @command.extract_first_key(command)
  return if key.empty?
  slot = KeySlotConverter.convert(key)
  return unless @slot.exists?(slot)
  if @command.should_send_to_master?(command) || primary_only
    @slot.find_node_key_of_master(slot)
  else
    @slot.find_node_key_of_slave(slot)
  end
end

def id
  @node.map(&:id).sort.join(' ')
end

def initialize(options = {})
  @option = Option.new(options)
  @node, @slot = fetch_cluster_info!(@option)
  @command = fetch_command_details(@node)
end

def process(commands, &block)
  if commands.size == 1 &&
     %w[unsubscribe punsubscribe].include?(commands.first.first.to_s.downcase) &&
     commands.first.size == 1
    # Node is indeterminate. We do just a best-effort try here.
    @node.process_all(commands, &block)
  else
    node = assign_node(commands.first)
    try_send(node, :process, commands, &block)
  end
end

def send_client_command(command, &block)
  case command[1].to_s.downcase
  when 'list' then @node.call_all(command, &block).flatten
  when 'pause', 'reply', 'setname'
    @node.call_all(command, &block).first
  else assign_node(command).call(command, &block)
  end
end

def send_cluster_command(command, &block)
  subcommand = command[1].to_s.downcase
  case subcommand
  when 'addslots', 'delslots', 'failover', 'forget', 'meet', 'replicate',
       'reset', 'set-config-epoch', 'setslot'
    raise OrchestrationCommandNotSupported, 'cluster', subcommand
  when 'saveconfig' then @node.call_all(command, &block).first
  else assign_node(command).call(command, &block)
  end
end

def send_command(command, &block)
  cmd = command.first.to_s.downcase
  case cmd
  when 'acl', 'auth', 'bgrewriteaof', 'bgsave', 'quit', 'save'
    @node.call_all(command, &block).first
  when 'flushall', 'flushdb'
    @node.call_master(command, &block).first
  when 'wait'     then @node.call_master(command, &block).reduce(:+)
  when 'keys'     then @node.call_slave(command, &block).flatten.sort
  when 'dbsize'   then @node.call_slave(command, &block).reduce(:+)
  when 'scan'     then _scan(command, &block)
  when 'lastsave' then @node.call_all(command, &block).sort
  when 'role'     then @node.call_all(command, &block)
  when 'config'   then send_config_command(command, &block)
  when 'client'   then send_client_command(command, &block)
  when 'cluster'  then send_cluster_command(command, &block)
  when 'readonly', 'readwrite', 'shutdown'
    raise OrchestrationCommandNotSupported, cmd
  when 'memory'   then send_memory_command(command, &block)
  when 'script'   then send_script_command(command, &block)
  when 'pubsub'   then send_pubsub_command(command, &block)
  when 'discard', 'exec', 'multi', 'unwatch'
    raise AmbiguousNodeError, cmd
  else
    node = assign_node(command)
    try_send(node, :call, command, &block)
  end
end

def send_config_command(command, &block)
  case command[1].to_s.downcase
  when 'resetstat', 'rewrite', 'set'
    @node.call_all(command, &block).first
  else assign_node(command).call(command, &block)
  end
end

def send_memory_command(command, &block)
  case command[1].to_s.downcase
  when 'stats' then @node.call_all(command, &block)
  when 'purge' then @node.call_all(command, &block).first
  else assign_node(command).call(command, &block)
  end
end

def send_pubsub_command(command, &block)
  case command[1].to_s.downcase
  when 'channels' then @node.call_all(command, &block).flatten.uniq.sort
  when 'numsub'
    @node.call_all(command, &block).reject(&:empty?).map { |e| Hash[*e] }
         .reduce({}) { |a, e| a.merge(e) { |_, v1, v2| v1 + v2 } }
  when 'numpat' then @node.call_all(command, &block).reduce(:+)
  else assign_node(command).call(command, &block)
  end
end

def send_script_command(command, &block)
  case command[1].to_s.downcase
  when 'debug', 'kill'
    @node.call_all(command, &block).first
  when 'flush', 'load'
    @node.call_master(command, &block).first
  else assign_node(command).call(command, &block)
  end
end

def timeout
  @node.first.timeout
end

def try_send(node, method_name, *args, retry_count: 3, &block)
  node.public_send(method_name, *args, &block)
rescue CommandError => err
  if err.message.start_with?('MOVED')
    raise if retry_count <= 0
    node = assign_redirection_node(err.message)
    retry_count -= 1
    retry
  elsif err.message.start_with?('ASK')
    raise if retry_count <= 0
    node = assign_asking_node(err.message)
    node.call(%i[asking])
    retry_count -= 1
    retry
  else
    raise
  end
rescue CannotConnectError
  update_cluster_info!
  raise
end

def update_cluster_info!(node_key = nil)
  unless node_key.nil?
    host, port = NodeKey.split(node_key)
    @option.add_node(host, port)
  end
  @node.map(&:disconnect)
  @node, @slot = fetch_cluster_info!(@option)
end

def with_reconnect(val = true, &block)
  try_send(@node.sample, :with_reconnect, val, &block)
end