# encoding: utf-8
# TAKEN FROM WIIBAA
require "logstash/config/mixin"
require "time"
require "date"
require_relative "value_tracking"
require_relative "statement_handler"

java_import java.util.concurrent.locks.ReentrantLock

# Tentative of abstracting JDBC logic to a mixin
# for potential reuse in other plugins (input/output)
module LogStash  module PluginMixins module Jdbc
  module Jdbc
    # This method is called when someone includes this module
    def self.included(base)
      # Add these methods to the 'base' given.
      base.extend(self)
      base.setup_jdbc_config
    end


    public
    def setup_jdbc_config
      # JDBC driver library path to third party driver library. In case of multiple libraries being
      # required you can pass them separated by a comma.
      #
      # If not provided, Plugin will look for the driver class in the Logstash Java classpath.
      config :jdbc_driver_library, :validate => :string

      # JDBC driver class to load, for exmaple, "org.apache.derby.jdbc.ClientDriver"
      # NB per https://github.com/logstash-plugins/logstash-input-jdbc/issues/43 if you are using
      # the Oracle JDBC driver (ojdbc6.jar) the correct `jdbc_driver_class` is `"Java::oracle.jdbc.driver.OracleDriver"`
      config :jdbc_driver_class, :validate => :string, :required => true

      # JDBC connection string
      config :jdbc_connection_string, :validate => :string, :required => true

      # JDBC user
      config :jdbc_user, :validate => :string, :required => true

      # JDBC password
      config :jdbc_password, :validate => :password

      # JDBC password filename
      config :jdbc_password_filepath, :validate => :path

      # JDBC enable paging
      #
      # This will cause a sql statement to be broken up into multiple queries.
      # Each query will use limits and offsets to collectively retrieve the full
      # result-set. The limit size is set with `jdbc_page_size`.
      #
      # Be aware that ordering is not guaranteed between queries.
      config :jdbc_paging_enabled, :validate => :boolean, :default => false

      # Which pagination mode to use, automatic pagination or explicitly defined in the query.
      config :jdbc_paging_mode, :validate => [ "auto", "explicit" ], :default => "auto"

      # JDBC page size
      config :jdbc_page_size, :validate => :number, :default => 100000

      # JDBC fetch size. if not provided, respective driver's default will be used
      config :jdbc_fetch_size, :validate => :number

      # Connection pool configuration.
      # Validate connection before use.
      config :jdbc_validate_connection, :validate => :boolean, :default => false

      # Connection pool configuration.
      # How often to validate a connection (in seconds)
      config :jdbc_validation_timeout, :validate => :number, :default => 3600

      # Connection pool configuration.
      # The amount of seconds to wait to acquire a connection before raising a PoolTimeoutError (default 5)
      config :jdbc_pool_timeout, :validate => :number, :default => 5

      # Timezone conversion.
      # SQL does not allow for timezone data in timestamp fields.  This plugin will automatically
      # convert your SQL timestamp fields to Logstash timestamps, in relative UTC time in ISO8601 format.
      #
      # Using this setting will manually assign a specified timezone offset, instead
      # of using the timezone setting of the local machine.  You must use a canonical
      # timezone, *America/Denver*, for example.
      config :jdbc_default_timezone, :validate => :string

      # General/Vendor-specific Sequel configuration options.
      #
      # An example of an optional connection pool configuration
      #    max_connections - The maximum number of connections the connection pool
      #
      # examples of vendor-specific options can be found in this
      # documentation page: https://github.com/jeremyevans/sequel/blob/master/doc/opening_databases.rdoc
      config :sequel_opts, :validate => :hash, :default => {}

      # Log level at which to log SQL queries, the accepted values are the common ones fatal, error, warn,
      # info and debug. The default value is info.
      config :sql_log_level, :validate => [ "fatal", "error", "warn", "info", "debug" ], :default => "info"

      # Maximum number of times to try connecting to database
      config :connection_retry_attempts, :validate => :number, :default => 1
      # Number of seconds to sleep between connection attempts
      config :connection_retry_attempts_wait_time, :validate => :number, :default => 0.5

      # give users the ability to force Sequel application side into using local timezone
      config :plugin_timezone, :validate => ["local", "utc"], :default => "utc"
    end

    private
    def jdbc_connect
      sequel_opts = complete_sequel_opts(:pool_timeout => @jdbc_pool_timeout, :keep_reference => false)
      retry_attempts = @connection_retry_attempts
      loop do
        retry_attempts -= 1
        begin
          return Sequel.connect(@jdbc_connection_string, sequel_opts)
        rescue Sequel::PoolTimeout => e
          if retry_attempts <= 0
            @logger.error("Failed to connect to database. #{@jdbc_pool_timeout} second timeout exceeded. Tried #{@connection_retry_attempts} times.")
            raise e
          else
            @logger.error("Failed to connect to database. #{@jdbc_pool_timeout} second timeout exceeded. Trying again.")
          end
        rescue Java::JavaSql::SQLException, ::Sequel::Error => e
          if retry_attempts <= 0
            log_java_exception(e.cause)
            @logger.error("Unable to connect to database. Tried #{@connection_retry_attempts} times", error_details(e, trace: true))
            raise e
          else
            @logger.error("Unable to connect to database. Trying again", error_details(e, trace: false))
          end
        end
        sleep(@connection_retry_attempts_wait_time)
      end
    end

    def error_details(e, trace: false)
      details = { :message => e.message, :exception => e.class }
      details[:cause] = e.cause if e.cause
      details[:backtrace] = e.backtrace if trace || @logger.debug?
      details
    end

    def log_java_exception(e)
      return unless e.is_a?(java.lang.Exception)
      # @logger.name using the same convention as LS does
      logger = self.class.name.gsub('::', '.').downcase
      logger = org.apache.logging.log4j.LogManager.getLogger(logger)
      logger.error('', e) # prints nested causes
    end

    def open_jdbc_connection
      # at this point driver is already loaded
      Sequel.application_timezone = @plugin_timezone.to_sym

      @database = jdbc_connect()
      @database.extension(:pagination)
      if @jdbc_default_timezone
        @database.extension(:named_timezones)
        @database.timezone = @jdbc_default_timezone
      end
      if @jdbc_validate_connection
        @database.extension(:connection_validator)
        @database.pool.connection_validation_timeout = @jdbc_validation_timeout
      end
      @database.fetch_size = @jdbc_fetch_size unless @jdbc_fetch_size.nil?
      begin
        @database.test_connection
      rescue Java::JavaSql::SQLException => e
        @logger.warn("Failed test_connection with java.sql.SQLException.", :exception => e)
      rescue Sequel::DatabaseConnectionError => e
        @logger.warn("Failed test_connection.", :exception => e)
        #TODO return false and let the plugin raise a LogStash::ConfigurationError
        raise e
      end

      @database.sql_log_level = @sql_log_level.to_sym
      @database.logger = @logger

      @database.extension :identifier_mangling

      if @lowercase_column_names
        @database.identifier_output_method = :downcase
      else
        @database.identifier_output_method = :to_s
      end
    end

    public
    def prepare_jdbc_connection
      @connection_lock = ReentrantLock.new
    end

    public
    def close_jdbc_connection
      begin
        # pipeline restarts can also close the jdbc connection, block until the current executing statement is finished to avoid leaking connections
        # connections in use won't really get closed
        @connection_lock.lock
        @database.disconnect if @database
      rescue => e
        @logger.warn("Failed to close connection", :exception => e)
      ensure
        @connection_lock.unlock
      end
    end

    public
    def execute_statement
      success = false
      begin
        @connection_lock.lock
        open_jdbc_connection
        sql_last_value = @use_column_value ? @value_tracker.value : Time.now.utc
        @tracking_column_warning_sent = false
        @statement_handler.perform_query(@database, @value_tracker.value) do |row|
          sql_last_value = get_column_value(row) if @use_column_value
          yield extract_values_from(row)
        end
        success = true
      rescue Sequel::DatabaseConnectionError, Sequel::DatabaseError, Java::JavaSql::SQLException => e
        details = { exception: e.class, message: e.message }
        details[:cause] = e.cause.inspect if e.cause
        details[:backtrace] = e.backtrace if @logger.debug?
        @logger.warn("Exception when executing JDBC query", details)
      else
        @value_tracker.set_value(sql_last_value)
      ensure
        close_jdbc_connection
        @connection_lock.unlock
      end
      return success
    end

    public
    def get_column_value(row)
      if !row.has_key?(@tracking_column.to_sym)
        if !@tracking_column_warning_sent
          @logger.warn("tracking_column not found in dataset.", :tracking_column => @tracking_column)
          @tracking_column_warning_sent = true
        end
        # If we can't find the tracking column, return the current value in the ivar
        @value_tracker.value
      else
        # Otherwise send the updated tracking column
        row[@tracking_column.to_sym]
      end
    end

    private
    #Stringify row keys and decorate values when necessary
    def extract_values_from(row)
      Hash[row.map { |k, v| [k.to_s, decorate_value(v)] }]
    end

    private
    def decorate_value(value)
      case value
      when Time
        # transform it to LogStash::Timestamp as required by LS
        LogStash::Timestamp.new(value)
      when Date, DateTime
        LogStash::Timestamp.new(value.to_time)
      else
        value
      end
    end
  end
end end end


