require 'logger'

# A simple wrapper arround the Ruby logger. Mainly for 
# compatibility purposes.
#
#--
# TODO: implement as mixin that can be added to Log4R.
#++

class Logger
	alias_method :devel, :debug
	alias_method :fine, :debug
	
	# Prints a trace message to DEBUGLOG (at debug level).  
	# Useful for emitting the value of variables, etc.  Use 
	# like this:
	#
	#   x = y = 5
	#   trace 'x'        # -> 'x = 5'
	#   trace 'x ** y'   # -> 'x ** y = 3125'
	#
	# If you have a more complicated value, like an array of 
	# hashes, then you'll probably want to use an alternative 
	# output format.  For instance:
	#
	#   trace 'value', :yaml
	#
	# Valid output format values (the _style_ parameter) are:
	#
	#   :p :inspect
	#   :pp                     (pretty-print, using 'pp' library)
	#   :s :to_s
	#   :y :yaml :to_yaml       (using the 'yaml' library')
	#
	# The default is <tt>:p</tt>.
	#
	# CREDITS:
	# 
	# This code comes straight from the dev-utils Gem.
	# Author: Gavin Sinclair <gsinclair@soyabean.com.au>
	
  def trace(expr, style=:p)
    unless expr.respond_to? :to_str
      warn "trace: Can't evaluate the given value: #{caller.first}"
    else
			require 'facet/binding-of-caller'

      Binding.of_caller do |b|
        value = b.eval(expr.to_str)
        formatter = TRACE_STYLES[style] || :inspect
        case formatter
        when :pp then require 'pp'
        when :y, :yaml, :to_yaml then require 'yaml'
        end
        value_s = value.send(formatter)
        message = "#{expr} = #{value_s}"
        lines = message.split(/\n/)
        indent = "   "
        debug(lines.shift)            					
        lines.each do |line|
          debug(indent + line)
        end
      end
    end
  end

  TRACE_STYLES = {}  # :nodoc:
  TRACE_STYLES.update( 
		:pp => :pp_s, :s => :to_s, :p => :inspect, 
		:y => :to_yaml, :yaml => :to_yaml, 
		:inspect => :inspect, :to_yaml => :to_yaml 
	)

	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
	# Global logger interface. 
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

	# Override the logger with your custom version.
	
	@@global_logger = Logger.new(STDERR)

	# Set the global Logger.
	
	def self.set(logger)
		if logger.is_a?(String)
			@@global_logger = Logger.new(logger)
		elsif logger.is_a?(Logger)
			@@global_logger = logger
		else
			raise ArgumentError.new
		end
	end

	def self.get
		@@global_logger
	end
	
	def self.warn(str)
		@@global_logger.warn(str)
	end

	def self.info(str)
		@@global_logger.info(str)
	end

	def self.debug(str)
		@@global_logger.debug(str)
	end
	
	def self.error(str)
		@@global_logger.error(str)
	end

	#--
	# Saddly have to duplicate the code to make
	# Binding.of_caller work.
	#++
  def self.trace(expr, style=:p)
    unless expr.respond_to? :to_str
      warn "trace: Can't evaluate the given value: #{caller.first}"
    else
			require 'facet/binding-of-caller'

      Binding.of_caller do |b|
        value = eval(expr.to_str, b)
        formatter = TRACE_STYLES[style] || :inspect
        case formatter
        when :pp then require 'pp'
        when :y, :yaml, :to_yaml then require 'yaml'
        end
        value_s = value.send(formatter)
        message = "#{expr} = #{value_s}"
        lines = message.split(/\n/)
        indent = "   "
        debug(lines.shift)            					
        lines.each do |line|
          debug(indent + line)
        end
      end
    end
  end
	
	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
	
	private
		
	# the default Ruby logger has a hardwired silly format.
	# we use some Ruby magic to fix it!

	remove_const "Format"

	Format = "%5s: %s\n"

	def format_message(severity, timestamp, msg, progname)
		Format % [severity, msg]
	end

end

module Glue

# Add logging capabilities to the including class.
# When using the log/logger variables always check 
# for nil:
#
# log.info "your #{expensive_calculation} comes here" if @log
#
# This way the expensive calculation is avoided if the 
# logger is dissabled (@log == nil).

module Logging 
	attr_accessor :logger
	alias_method :log, :logger
end

end

# * George Moschovitis  <gm@navel.gr>