#--
# Copyright (c) 2008-2017 David Kellum
#
# rjack-logback is free software: you can redistribute it and/or
# modify it under the terms of either of following licenses:
#
#   GNU Lesser General Public License v3 or later
#   Eclipse Public License v1.0
#
# rjack-logback is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
#++

require 'rjack-slf4j'
require 'rjack-logback/base'

require 'java'

module RJack

  # Jruby wrapper module for the Logback[http://logback.qos.ch/] log writer.
  # Programmatic configuration and setting of logger output levels is supported.
  #
  # == Examples
  #
  # === High level configuration
  #
  #   require 'rjack-logback'
  #   RJack::Logback.config_console( :thread => true, :level => :info )
  #
  # === Low level configuration
  #
  #   require 'rjack-logback'
  #
  #   log = RJack::SLF4J[ 'example' ]
  #   log.info "About to reconfigure..."
  #
  #   RJack::Logback.configure do
  #     console = RJack::Logback::ConsoleAppender.new do |a|
  #       a.target = "System.err"
  #       a.layout = RJack::Logback::PatternLayout.new do |p|
  #         p.pattern = "%r %-5level %logger{35} - %msg %ex%n"
  #       end
  #     end
  #     RJack::Logback.root.add_appender( console )
  #     RJack::Logback.root.level = RJack::Logback::INFO
  #   end
  #
  #   # Adjust output levels (also works outside of configure )
  #   RJack::Logback[ 'example' ].level = RJack::Logback::DEBUG
  #
  #   log.debug "...after reconfigure."
  #
  # Configure with Logback XML configuration:
  #
  #   RJack::Logback.configure do
  #     RJack::Logback.load_xml_config( 'sample-logback.xml' )
  #   end
  #
  # == Programmatic Configuration Support
  #
  # Logback java classes implement interfaces +LifeCycle+ and
  # +ContextAware+ for configurability with Joran (XML). To simplify
  # configuration in ruby, the following classes have been extended:
  #
  # * ConsoleAppender
  # * FileAppender
  # * PatternLayout
  #
  # The extensions provide a block initializer which sets sensible
  # defaults, yields to a block for customization, and then calls
  # +start+.  Logback provides many other components not yet extended in
  # this way.  These can be created directly and or extended in a
  # similar fashion externally.  Consider providing a patch to the
  # rjack[http://rjack.gravitext.com] project with desired
  # extensions.
  #
  module Logback

    # Load logback jar.
    def self.require_jar( name )
      require File.join( LOGBACK_DIR, "#{name}-#{ LOGBACK_VERSION }.jar" )
    end

    require_jar 'logback-core'
    require_jar 'logback-classic'

    # ch.qos.logback.classic.Level
    Level = Java::ch.qos.logback.classic.Level

    # Level::TRACE
    TRACE = Level::TRACE

    # Level::DEBUG
    DEBUG = Level::DEBUG

    # Level::INFO
    INFO  = Level::INFO

    # Level::WARN
    WARN  = Level::WARN

    # Level::ERROR
    ERROR = Level::ERROR

    # Level::OFF
    OFF = Level::OFF

    DEFAULT_PATTERN = "%date [%thread] %-5level %logger{35} - %msg %ex%n" #:nodoc:

    @@context = SLF4J.linked_factory

    # Returns the LoggerContext
    def self.context
      @@context
    end

    # Utility mixin of Logback ch.qos.logback.core.spi.LifeCycle instances
    module Util
      # Start, raise if not started
      def self.start( lifecycle_obj )
        lifecycle_obj.start
        raise "#{lifecycle_obj.class.name} did not start" if ! lifecycle_obj.started?
      end
    end

    # Wrapper for
    # ch.qos.logback.classic.Logger[http://logback.qos.ch/apidocs/ch/qos/logback/classic/Logger.html]
    class Logger

      # Initialize given ch.qos.logback.classic.Logger
      def initialize( jlogger )
        @jlogger = jlogger
      end

      # Set output level
      # ==== Parameters
      # :level<Level || Symbol>:: New output Level.
      def level=( level )
        @jlogger.level = Logback.to_level( level )
      end

      # Adjust output level temporarily for block. This is not
      # internally synchronized.
      # ==== Parameters
      # :level<Level || Symbol>:: output Level.
      def with_level( level )
        orig = @jlogger.level
        self.level = level
        yield
      ensure
        self.level = orig
      end

      # Add appender to this logger
      # ==== Parameters
      # :appender<ch.qos.logback.core.Appender>:: Appender
      def add_appender( appender )
        @jlogger.add_appender( appender )
      end

      # Set additive flag ( false means events stop at attached appender )
      def additive=( is_additive )
        @jlogger.additive = is_additive
      end
    end

    # ch.qos.logback.classic.joran.JoranConfigurator
    JoranConfigurator = Java::ch.qos.logback.classic.joran.JoranConfigurator

    # Load the specified Logback (Joran) XML configuration file. Should be
    # called within a configure {...} block.
    def self.load_xml_config( file )
      cfger = JoranConfigurator.new
      cfger.context = @@context
      cfger.doConfigure( file )
    end

    # ch.qos.logback.classic.PatternLayout
    JPatternLayout = Java::ch.qos.logback.classic.PatternLayout

    # Extends
    # ch.qos.logback.classic.PatternLayout[http://logback.qos.ch/apidocs/ch/qos/logback/classic/PatternLayout.html]
    # with a block initializer.
    class PatternLayout < JPatternLayout

      # Sets context and pattern, yields self to block, and calls self.start
      def initialize( pattern=DEFAULT_PATTERN )
        super()
        self.context = Logback.context
        self.pattern = pattern
        yield( self ) if block_given?
        Util.start( self )
      end
    end

    # Utility implementation mixin for Appenders.
    module AppenderUtil
      @@default_layout = Logback::PatternLayout.new

      Charset = Java::java.nio.charset.Charset

      # Set appender defaults.
      def set_defaults
        self.context = Logback.context
        self.name = self.class.name
        self.layout = @@default_layout
      end

      # Yield to block, then start.
      def finish( &block )
        block.call( self ) unless block.nil?
        Util.start( self )
      end

      def encoding=( enc )
        self.encoder.charset = Charset::forName( enc )
      end
    end

    # ch.qos.logback.core.ConsoleAppender
    JConsoleAppender = Java::ch.qos.logback.core.ConsoleAppender

    # Extends
    # ch.qos.logback.core.ConsoleAppender[http://logback.qos.ch/apidocs/ch/qos/logback/core/ConsoleAppender.html]
    # with a block initializer.
    class ConsoleAppender < JConsoleAppender
      include AppenderUtil

      # Sets context, default name and layout, yields self to block, and
      # calls self.start
      def initialize( &block )
        super()
        set_defaults
        finish( &block )
      end
    end

    # ch.qos.logback.core.FileAppender
    JFileAppender = Java::ch.qos.logback.core.FileAppender

    # Extends
    # ch.qos.logback.core.FileAppender[http://logback.qos.ch/apidocs/ch/qos/logback/core/FileAppender.html]
    # with a block initializer.
    #
    class FileAppender < JFileAppender
      include AppenderUtil

      # Sets defaults, yields self to block, and calls self.start
      def initialize( file_name, append = true, &block )
        super()
        set_defaults
        self.file = file_name
        self.append = append
        self.encoding = "UTF-8"
        finish( &block )
      end
    end

    JLevelChangePropagator = Java::ch.qos.logback.classic.jul.LevelChangePropagator

    # Extends
    # ch.qos.logback.classic.jul.LevelChangePropagator[http://logback.qos.ch/apidocs/ch/qos/logback/classic/jul/LevelChangePropagator.html]
    # with a block initializer.
    class LevelChangePropagator < JLevelChangePropagator

      def initialize( reset_jul = true )
        super()
        self.context = Logback.context
        self.reset_jul = reset_jul
        yield( self ) if block_given?
        Util.start( self )
      end

    end

    # Configure Logback with the specified block. The Logback context is
    # +reset+, yielded to block, and then started after return
    # from the block.
    def self.configure
      @@context.reset

      yield context

      Util.start( context )
      nil
    end

    # Configure a single ConsoleAppender using options hash.
    # ==== Options
    # :stderr:: Output to standard error? (default: false)
    # :full:: Output full date? (default: false, milliseconds)
    # :thread:: Output thread name? (default: false)
    # :level<Level || Symbol>:: Set root level (default: INFO)
    # :lwidth<~to_s>:: Logger width (default: :full ? 35 : 30)
    # :mdc<String|Array[String]>:: One or more Mapped Diagnostic Context keys
    # :mdc_width<~to_s}:: MDC width (default: unspecified)
    # :propagate_to_jul:: Propagate level changes to
    #                     java.util.logging, additionally resetting
    #                     JUL levels if value is :reset (default: false)
    def self.config_console( options = {} )
      configure do |ctx|
        if options[ :propagate_to_jul ]
          r = ( options[ :propagate_to_jul ] == :reset )
          ctx.add_listener( LevelChangePropagator.new( r ) )
        end
        console = Logback::ConsoleAppender.new do |a|
          a.target = "System.err" if options[ :stderr ]
          a.layout = Logback::PatternLayout.new do |layout|
            pat = [ options[ :full ] ? '%date' : '%-4r' ]
            pat << '[%thread]' if options[ :thread ]
            pat << '%-5level'

            w = ( options[ :lwidth ] || ( options[ :full ] ? 35 : 30 ) )
            pat << "%logger{#{w}}"

            mdcs = Array( options[ :mdc ] ).map { |k| "%X{#{k}}" }
            unless mdcs.empty?
              mp = ( '\(' + mdcs.join(',') + '\)' )
              mw = options[ :mdc_width ]
              mp = "%-#{mw}(#{mp})" if mw
              pat << mp
            end

            pat += [ '-', '%msg', '%ex%n' ]
            layout.pattern = pat.join( ' ' )
          end
        end
        Logback.root.add_appender( console )
        Logback.root.level = options[ :level ] || INFO
      end
    end

    # Returns the named Logger
    def self.logger( name )
      Logger.new( @@context.getLogger( name ) )
    end

    # Synonym for logger(name)
    def self.[](name)
      logger( name )
    end

    # Returns the special "root" Logger
    def self.root
      logger( "root" )
    end

    # Converts Symbol to Level constant, or return Level unaltered.
    def self.to_level( l )
      if l.is_a?( Symbol )
        const_get( l.to_s.upcase.to_sym )
      else
        l
      end
    end

  end
end