# frozen_string_literal: true

require "redis_client/version"
require "redis_client/command_builder"
require "redis_client/url_config"
require "redis_client/config"
require "redis_client/pid_cache"
require "redis_client/sentinel_config"
require "redis_client/middlewares"

class RedisClient
  @driver_definitions = {}
  @drivers = {}

  @default_driver = nil

  class << self
    def register_driver(name, &block)
      @driver_definitions[name] = block
    end

    def driver(name)
      return name if name.is_a?(Class)

      name = name.to_sym
      unless @driver_definitions.key?(name)
        raise ArgumentError, "Unknown driver #{name.inspect}, expected one of: `#{@driver_definitions.keys.inspect}`"
      end

      @drivers[name] ||= @driver_definitions[name]&.call
    end

    def default_driver
      unless @default_driver
        @driver_definitions.each_key do |name|
          if @default_driver = driver(name)
            break
          end
        rescue LoadError
        end
      end
      @default_driver
    end

    def default_driver=(name)
      @default_driver = driver(name)
    end
  end

  register_driver :ruby do
    require "redis_client/ruby_connection"
    RubyConnection
  end

  module Common
    attr_reader :config, :id
    attr_accessor :connect_timeout, :read_timeout, :write_timeout

    def initialize(
      config,
      id: config.id,
      connect_timeout: config.connect_timeout,
      read_timeout: config.read_timeout,
      write_timeout: config.write_timeout
    )
      @config = config
      @id = id&.to_s
      @connect_timeout = connect_timeout
      @read_timeout = read_timeout
      @write_timeout = write_timeout
      @command_builder = config.command_builder
      @pid = PIDCache.pid
    end

    def timeout=(timeout)
      @connect_timeout = @read_timeout = @write_timeout = timeout
    end
  end

  Error = Class.new(StandardError)

  ProtocolError = Class.new(Error)
  UnsupportedServer = Class.new(Error)

  ConnectionError = Class.new(Error)
  CannotConnectError = Class.new(ConnectionError)

  FailoverError = Class.new(ConnectionError)

  TimeoutError = Class.new(ConnectionError)
  ReadTimeoutError = Class.new(TimeoutError)
  WriteTimeoutError = Class.new(TimeoutError)
  CheckoutTimeoutError = Class.new(TimeoutError)

  module HasCommand
    attr_reader :command

    def _set_command(command)
      @command = command
    end
  end

  class CommandError < Error
    include HasCommand

    class << self
      def parse(error_message)
        code = if error_message.start_with?("ERR Error running script")
          # On older redis servers script errors are nested.
          # So we need to parse some more.
          if (match = error_message.match(/:\s-([A-Z]+) /))
            match[1]
          end
        end
        code ||= error_message.split(' ', 2).first
        klass = ERRORS.fetch(code, self)
        klass.new(error_message)
      end
    end
  end

  AuthenticationError = Class.new(CommandError)
  PermissionError = Class.new(CommandError)
  WrongTypeError = Class.new(CommandError)
  OutOfMemoryError = Class.new(CommandError)

  ReadOnlyError = Class.new(ConnectionError)
  ReadOnlyError.include(HasCommand)

  MasterDownError = Class.new(ConnectionError)
  MasterDownError.include(HasCommand)

  CommandError::ERRORS = {
    "WRONGPASS" => AuthenticationError,
    "NOPERM" => PermissionError,
    "READONLY" => ReadOnlyError,
    "MASTERDOWN" => MasterDownError,
    "WRONGTYPE" => WrongTypeError,
    "OOM" => OutOfMemoryError,
  }.freeze

  class << self
    def config(**kwargs)
      Config.new(client_implementation: self, **kwargs)
    end

    def sentinel(**kwargs)
      SentinelConfig.new(client_implementation: self, **kwargs)
    end

    def new(arg = nil, **kwargs)
      if arg.is_a?(Config::Common)
        super
      else
        super(config(**(arg || {}), **kwargs))
      end
    end

    def register(middleware)
      Middlewares.include(middleware)
    end
  end

  include Common

  def initialize(config, **)
    super
    @middlewares = config.middlewares_stack.new(self)
    @raw_connection = nil
    @disable_reconnection = false
  end

  def inspect
    id_string = " id=#{id}" if id
    "#<#{self.class.name} #{config.server_url}#{id_string}>"
  end

  def server_url
    config.server_url
  end

  def id
    config.id
  end

  def timeout
    config.read_timeout
  end

  def db
    config.db
  end

  def host
    config.host unless config.path
  end

  def port
    config.port unless config.path
  end

  def path
    config.path
  end

  def username
    config.username
  end

  def password
    config.password
  end

  def size
    1
  end

  def with(_options = nil)
    yield self
  end
  alias_method :then, :with

  def timeout=(timeout)
    super
    @raw_connection&.read_timeout = timeout
    @raw_connection&.write_timeout = timeout
  end

  def read_timeout=(timeout)
    super
    @raw_connection&.read_timeout = timeout
  end

  def write_timeout=(timeout)
    super
    @raw_connection&.write_timeout = timeout
  end

  def pubsub
    sub = PubSub.new(ensure_connected, @command_builder)
    @raw_connection = nil
    sub
  end

  def measure_round_trip_delay
    ensure_connected do |connection|
      @middlewares.call(["PING"], config) do
        connection.measure_round_trip_delay
      end
    end
  end

  def call(*command, **kwargs)
    command = @command_builder.generate(command, kwargs)
    result = ensure_connected do |connection|
      @middlewares.call(command, config) do
        connection.call(command, nil)
      end
    end

    if block_given?
      yield result
    else
      result
    end
  end

  def call_v(command)
    command = @command_builder.generate(command)
    result = ensure_connected do |connection|
      @middlewares.call(command, config) do
        connection.call(command, nil)
      end
    end

    if block_given?
      yield result
    else
      result
    end
  end

  def call_once(*command, **kwargs)
    command = @command_builder.generate(command, kwargs)
    result = ensure_connected(retryable: false) do |connection|
      @middlewares.call(command, config) do
        connection.call(command, nil)
      end
    end

    if block_given?
      yield result
    else
      result
    end
  end

  def call_once_v(command)
    command = @command_builder.generate(command)
    result = ensure_connected(retryable: false) do |connection|
      @middlewares.call(command, config) do
        connection.call(command, nil)
      end
    end

    if block_given?
      yield result
    else
      result
    end
  end

  def blocking_call(timeout, *command, **kwargs)
    command = @command_builder.generate(command, kwargs)
    error = nil
    result = ensure_connected do |connection|
      @middlewares.call(command, config) do
        connection.call(command, timeout)
      end
    rescue ReadTimeoutError => error
      break
    end

    if error
      raise error
    elsif block_given?
      yield result
    else
      result
    end
  end

  def blocking_call_v(timeout, command)
    command = @command_builder.generate(command)
    error = nil
    result = ensure_connected do |connection|
      @middlewares.call(command, config) do
        connection.call(command, timeout)
      end
    rescue ReadTimeoutError => error
      break
    end

    if error
      raise error
    elsif block_given?
      yield result
    else
      result
    end
  end

  def scan(*args, **kwargs, &block)
    unless block_given?
      return to_enum(__callee__, *args, **kwargs)
    end

    args = @command_builder.generate(["SCAN", 0] + args, kwargs)
    scan_list(1, args, &block)
  end

  def sscan(key, *args, **kwargs, &block)
    unless block_given?
      return to_enum(__callee__, key, *args, **kwargs)
    end

    args = @command_builder.generate(["SSCAN", key, 0] + args, kwargs)
    scan_list(2, args, &block)
  end

  def hscan(key, *args, **kwargs, &block)
    unless block_given?
      return to_enum(__callee__, key, *args, **kwargs)
    end

    args = @command_builder.generate(["HSCAN", key, 0] + args, kwargs)
    scan_pairs(2, args, &block)
  end

  def zscan(key, *args, **kwargs, &block)
    unless block_given?
      return to_enum(__callee__, key, *args, **kwargs)
    end

    args = @command_builder.generate(["ZSCAN", key, 0] + args, kwargs)
    scan_pairs(2, args, &block)
  end

  def connected?
    @raw_connection&.revalidate
  end

  def close
    @raw_connection&.close
    self
  end

  def disable_reconnection(&block)
    ensure_connected(retryable: false, &block)
  end

  def pipelined
    pipeline = Pipeline.new(@command_builder)
    yield pipeline

    if pipeline._size == 0
      []
    else
      results = ensure_connected(retryable: pipeline._retryable?) do |connection|
        commands = pipeline._commands
        @middlewares.call_pipelined(commands, config) do
          connection.call_pipelined(commands, pipeline._timeouts)
        end
      end

      pipeline._coerce!(results)
    end
  end

  def multi(watch: nil, &block)
    transaction = nil

    results = if watch
      # WATCH is stateful, so we can't reconnect if it's used, the whole transaction
      # has to be redone.
      ensure_connected(retryable: false) do |connection|
        call("WATCH", *watch)
        begin
          if transaction = build_transaction(&block)
            commands = transaction._commands
            results = @middlewares.call_pipelined(commands, config) do
              connection.call_pipelined(commands, nil)
            end.last
          else
            call("UNWATCH")
            []
          end
        rescue
          call("UNWATCH") if connected? && watch
          raise
        end
      end
    else
      transaction = build_transaction(&block)
      if transaction._empty?
        []
      else
        ensure_connected(retryable: transaction._retryable?) do |connection|
          commands = transaction._commands
          @middlewares.call_pipelined(commands, config) do
            connection.call_pipelined(commands, nil)
          end.last
        end
      end
    end

    if transaction
      transaction._coerce!(results)
    else
      results
    end
  end

  class PubSub
    def initialize(raw_connection, command_builder)
      @raw_connection = raw_connection
      @command_builder = command_builder
    end

    def call(*command, **kwargs)
      raw_connection.write(@command_builder.generate(command, kwargs))
      nil
    end

    def call_v(command)
      raw_connection.write(@command_builder.generate(command))
      nil
    end

    def close
      @raw_connection&.close
      @raw_connection = nil # PubSub can't just reconnect
      self
    end

    def next_event(timeout = nil)
      unless raw_connection
        raise ConnectionError, "Connection was closed or lost"
      end

      raw_connection.read(timeout)
    rescue ReadTimeoutError
      nil
    end

    private

    attr_reader :raw_connection
  end

  class Multi
    def initialize(command_builder)
      @command_builder = command_builder
      @size = 0
      @commands = []
      @blocks = nil
      @retryable = true
    end

    def call(*command, **kwargs, &block)
      command = @command_builder.generate(command, kwargs)
      (@blocks ||= [])[@commands.size] = block if block_given?
      @commands << command
      nil
    end

    def call_v(command, &block)
      command = @command_builder.generate(command)
      (@blocks ||= [])[@commands.size] = block if block_given?
      @commands << command
      nil
    end

    def call_once(*command, **kwargs, &block)
      command = @command_builder.generate(command, kwargs)
      @retryable = false
      (@blocks ||= [])[@commands.size] = block if block_given?
      @commands << command
      nil
    end

    def call_once_v(command, &block)
      command = @command_builder.generate(command)
      @retryable = false
      (@blocks ||= [])[@commands.size] = block if block_given?
      @commands << command
      nil
    end

    def _commands
      @commands
    end

    def _blocks
      @blocks
    end

    def _size
      @commands.size
    end

    def _empty?
      @commands.size <= 2
    end

    def _timeouts
      nil
    end

    def _retryable?
      @retryable
    end

    def _coerce!(results)
      results&.each_with_index do |result, index|
        if result.is_a?(CommandError)
          result._set_command(@commands[index + 1])
          raise result
        end

        if @blocks && block = @blocks[index + 1]
          results[index] = block.call(result)
        end
      end

      results
    end
  end

  class Pipeline < Multi
    def initialize(_command_builder)
      super
      @timeouts = nil
    end

    def blocking_call(timeout, *command, **kwargs, &block)
      command = @command_builder.generate(command, kwargs)
      @timeouts ||= []
      @timeouts[@commands.size] = timeout
      (@blocks ||= [])[@commands.size] = block if block_given?
      @commands << command
      nil
    end

    def blocking_call_v(timeout, command, &block)
      command = @command_builder.generate(command)
      @timeouts ||= []
      @timeouts[@commands.size] = timeout
      (@blocks ||= [])[@commands.size] = block if block_given?
      @commands << command
      nil
    end

    def _timeouts
      @timeouts
    end

    def _empty?
      @commands.empty?
    end

    def _coerce!(results)
      return results unless results

      @blocks&.each_with_index do |block, index|
        if block
          results[index] = block.call(results[index])
        end
      end

      results
    end
  end

  private

  def build_transaction
    transaction = Multi.new(@command_builder)
    transaction.call("MULTI")
    yield transaction
    transaction.call("EXEC")
    transaction
  end

  def scan_list(cursor_index, command, &block)
    cursor = 0
    while cursor != "0"
      command[cursor_index] = cursor
      cursor, elements = call(*command)
      elements.each(&block)
    end
    nil
  end

  def scan_pairs(cursor_index, command)
    cursor = 0
    while cursor != "0"
      command[cursor_index] = cursor
      cursor, elements = call(*command)

      index = 0
      size = elements.size
      while index < size
        yield elements[index], elements[index + 1]
        index += 2
      end
    end
    nil
  end

  def ensure_connected(retryable: true)
    close if !config.inherit_socket && @pid != PIDCache.pid

    if @disable_reconnection
      if block_given?
        yield @raw_connection
      else
        @raw_connection
      end
    elsif retryable
      tries = 0
      connection = nil
      preferred_error = nil
      begin
        connection = raw_connection
        if block_given?
          yield connection
        else
          connection
        end
      rescue ConnectionError, ProtocolError => error
        preferred_error ||= error
        preferred_error = error unless error.is_a?(CircuitBreaker::OpenCircuitError)
        close

        if !@disable_reconnection && config.retry_connecting?(tries, error)
          tries += 1
          retry
        else
          raise preferred_error
        end
      end
    else
      previous_disable_reconnection = @disable_reconnection
      connection = ensure_connected
      begin
        @disable_reconnection = true
        yield connection
      rescue ConnectionError, ProtocolError
        close
        raise
      ensure
        @disable_reconnection = previous_disable_reconnection
      end
    end
  end

  def raw_connection
    if @raw_connection.nil? || !@raw_connection.revalidate
      connect
    end
    @raw_connection
  end

  def connect
    @pid = PIDCache.pid

    if @raw_connection
      @middlewares.connect(config) do
        @raw_connection.reconnect
      end
    else
      @raw_connection = @middlewares.connect(config) do
        config.driver.new(
          config,
          connect_timeout: connect_timeout,
          read_timeout: read_timeout,
          write_timeout: write_timeout,
        )
      end
    end

    prelude = config.connection_prelude.dup

    if id
      prelude << ["CLIENT", "SETNAME", id]
    end

    # The connection prelude is deliberately not sent to Middlewares
    if config.sentinel?
      prelude << ["ROLE"]
      role, = @middlewares.call_pipelined(prelude, config) do
        @raw_connection.call_pipelined(prelude, nil).last
      end
      config.check_role!(role)
    else
      unless prelude.empty?
        @middlewares.call_pipelined(prelude, config) do
          @raw_connection.call_pipelined(prelude, nil)
        end
      end
    end
  rescue FailoverError, CannotConnectError
    raise
  rescue ConnectionError => error
    raise CannotConnectError, error.message, error.backtrace
  rescue CommandError => error
    if error.message.match?(/ERR unknown command ['`]HELLO['`]/)
      raise UnsupportedServer,
        "redis-client requires Redis 6+ with HELLO command available (#{config.server_url})"
    else
      raise
    end
  end
end

require "redis_client/pooled"
require "redis_client/circuit_breaker"

RedisClient.default_driver