# encoding: utf-8
require "logstash/outputs/base"
require "logstash/namespace"
require "stud/buffer"
require "java"
require "logstash-output-jdbc_jars"

class LogStash::Outputs::Jdbc < LogStash::Outputs::Base
  # Adds buffer support
  include Stud::Buffer

  config_name "jdbc"

  # Driver class - No longer required
  config :driver_class, :obsolete => "driver_class is no longer required and can be removed from your configuration"

  # Where to find the jar
  # Defaults to not required, and to the original behaviour
  config :driver_jar_path, :validate => :string, :required => false

  # jdbc connection string
  config :connection_string, :validate => :string, :required => true

  # jdbc username - optional, maybe in the connection string
  config :username, :validate => :string, :required => false

  # jdbc password - optional, maybe in the connection string
  config :password, :validate => :string, :required => false

  # [ "insert into table (message) values(?)", "%{message}" ]
  config :statement, :validate => :array, :required => true

  # If this is an unsafe statement, use event.sprintf
  # This also has potential performance penalties due to having to create a 
  # new statement for each event, rather than adding to the batch and issuing
  # multiple inserts in 1 go
  config :unsafe_statement, :validate => :boolean, :default => false

  # Number of connections in the pool to maintain
  config :max_pool_size, :validate => :number, :default => 5

  # Connection timeout
  config :connection_timeout, :validate => :number, :default => 2800

  # We buffer a certain number of events before flushing that out to SQL.
  # This setting controls how many events will be buffered before sending a
  # batch of events.
  config :flush_size, :validate => :number, :default => 1000

  # The amount of time since last flush before a flush is forced.
  #
  # This setting helps ensure slow event rates don't get stuck in Logstash.
  # For example, if your `flush_size` is 100, and you have received 10 events,
  # and it has been more than `idle_flush_time` seconds since the last flush,
  # Logstash will flush those 10 events automatically.
  #
  # This helps keep both fast and slow log streams moving along in
  # a timely manner.
  #
  # If you change this value please ensure that you change
  # max_repeat_exceptions_time accordingly.
  config :idle_flush_time, :validate => :number, :default => 1

  # Maximum number of repeating (sequential) exceptions, before we stop retrying
  # If set to < 1, then it will infinitely retry.
  config :max_repeat_exceptions, :validate => :number, :default => 4

  # The max number of seconds since the last exception, before we consider it
  # a different cause.
  # This value should be carefully considered in respect to idle_flush_time.
  config :max_repeat_exceptions_time, :validate => :number, :default => 30

  public
  def register
    @logger.info("JDBC - Starting up")

    load_jar_files!

    @pool = Java::ComZaxxerHikari::HikariDataSource.new
    @pool.setJdbcUrl(@connection_string)

    @pool.setUsername(@username) if @username
    @pool.setPassword(@password) if @password

    @pool.setMaximumPoolSize(@max_pool_size)
    @pool.setConnectionTimeout(@connection_timeout)

    if (@flush_size > 1000)
      @logger.warn("JDBC - Flush size is set to > 1000")
    end

    @repeat_exception_count = 0
    @last_exception_time = Time.now

    if (@max_repeat_exceptions > 0) and ((@idle_flush_time * @max_repeat_exceptions) > @max_repeat_exceptions_time)
      @logger.warn("JDBC - max_repeat_exceptions_time is set such that it may still permit a looping exception. You probably changed idle_flush_time. Considering increasing max_repeat_exceptions_time.")
    end

    buffer_initialize(
      :max_items => @flush_size,
      :max_interval => @idle_flush_time,
      :logger => @logger
    )
  end

  def receive(event)
    return unless output?(event) or event.cancelled?
    return unless @statement.length > 0

    buffer_receive(event)
  end

  def flush(events, teardown=false)
    if @unsafe_statement == true
      unsafe_flush(events, teardown)
    else
      safe_flush(events, teardown)
    end
  end

  def on_flush_error(e)
    return if @max_repeat_exceptions < 1

    if @last_exception == e.to_s
      @repeat_exception_count += 1
    else
      @repeat_exception_count = 0
    end

    if (@repeat_exception_count >= @max_repeat_exceptions) and (Time.now - @last_exception_time) < @max_repeat_exceptions_time
      @logger.error("JDBC - Exception repeated more than the maximum configured", :exception => e, :max_repeat_exceptions => @max_repeat_exceptions, :max_repeat_exceptions_time => @max_repeat_exceptions_time)
      raise e
    end

    @last_exception_time = Time.now
    @last_exception = e.to_s
  end

  def teardown
    buffer_flush(:final => true)
    @pool.close()
    super
  end

  private

  def load_jar_files!
    # Load jar from driver path
    unless @driver_jar_path.nil?
      raise Exception.new("JDBC - Could not find jar file at given path. Check config.") unless File.exists? @driver_jar_path
      require @driver_jar_path
      return
    end

    # Revert original behaviour of loading from vendor directory
    # if no path given
    if ENV['LOGSTASH_HOME']
      jarpath = File.join(ENV['LOGSTASH_HOME'], "/vendor/jar/jdbc/*.jar")
    else
      jarpath = File.join(File.dirname(__FILE__), "../../../vendor/jar/jdbc/*.jar")
    end

    @logger.debug("JDBC - jarpath", path: jarpath)

    jars = Dir[jarpath]
    raise Exception.new("JDBC - No jars found in jarpath. Have you read the README?") if jars.empty?

    jars.each do |jar|
      @logger.debug("JDBC - Loaded jar", :jar => jar)
      require jar
    end
  end

  def safe_flush(events, teardown=false)
    connection = @pool.getConnection()
    statement = connection.prepareStatement(@statement[0])

    events.each do |event|
      next if event.cancelled?
      next if @statement.length < 2
      statement = add_statement_event_params(statement, event)

      statement.addBatch()
    end

    begin
      statement.executeBatch()
      statement.close()
    rescue => e
      # Raising an exception will incur a retry from Stud::Buffer.
      # Since the exceutebatch failed this should mean any events failed to be
      # inserted will be re-run. We're going to log it for the lols anyway.
      log_jdbc_exception(e)
    ensure
      connection.close();
    end
  end

  def unsafe_flush(events, teardown=false)
    connection = @pool.getConnection()

    events.each do |event|
      next if event.cancelled?
      
      statement = connection.prepareStatement(event.sprintf(@statement[0]))
      statement = add_statement_event_params(statement, event) if @statement.length > 1

      begin
        statement.execute()
        
        # cancel the event, since we may end up outputting the same event multiple times
        # if an exception happens later down the line
        event.cancel
      rescue => e
        # Raising an exception will incur a retry from Stud::Buffer.
        # We log for the lols.
        log_jdbc_exception(e)
      ensure
        statement.close()
        connection.close()
      end
    end
  end

  def add_statement_event_params(statement, event)
    @statement[1..-1].each_with_index do |i, idx|
      case event[i]
      when Time, LogStash::Timestamp
        # Most reliable solution, cross JDBC driver
        statement.setString(idx + 1, event[i].iso8601())
      when Fixnum, Integer
        statement.setInt(idx + 1, event[i])
      when Float
        statement.setFloat(idx + 1, event[i])
      when String
        statement.setString(idx + 1, event[i])
      when true
        statement.setBoolean(idx + 1, true)
      when false
        statement.setBoolean(idx + 1, false)
      else
        statement.setString(idx + 1, event.sprintf(i))
      end
    end

    statement
  end

  def log_jdbc_exception(e)
    ce = e
    loop do
      @logger.error("JDBC Exception encountered: Will automatically retry.", :exception => ce)
      ce = e.getNextException()
      break if ce == nil
    end
  end
end # class LogStash::Outputs::jdbc