#
# Copyright (C) 2006 SIPfoundry Inc.
# Licensed by SIPfoundry under the LGPL license.
# 
# Copyright (C) 2006 Pingtel Corp.
# Licensed to SIPfoundry under a Contributor Agreement.
#
##############################################################################

# The Configure class reads in config params from a standard sipX config file
# and creates a map of param-values that is publicly available via the "[]"
# operator.  This class is generic, it is not specifically for Call Resolver.
# We would have used the name "Config" for this class, but "Config" is the name
# of an existing Ruby module.
# There is also a config subdirectory of this project.  That contains Rails
# code that is only used for unit testing.

# system requires
require 'logger'              # writes log messages to a file or stream

# application requires
require 'exceptions'


class Configure

  # Config file syntax
  COMMENT_CHAR = ?#
  SEPARATOR_CHAR = ':'    # separate param names from values
  
public
  
  # String constants
  DISABLE = 'DISABLE'
  ENABLE = 'ENABLE'

  # Initialize inputs:
  #   config_file - relative or absolute path to config file (String)
  #   log - Logger instance to log to
  def initialize(config_file = nil, log = nil)
    @config_file = config_file
    
    if !log
      @log = Logger.new(STDOUT)
      @log.level = Logger::ERROR
    end
    
    # create a Hash to hold the config param name to value map
    @map = {}
    
    # parse the config file and fill in the map
    parse_config(@config_file) if @config_file
  end

  # Return the value for the named parameter, or nil if no such parameter exists
  def [](param_name)
    return @map[param_name]
  end

  attr_reader :config_file

private

  # Set param values, mainly for testing.
  def []=(param_name, param_value)
    @map[param_name] = param_value
  end

  # Parse the config file and construct a hash mapping param names to values.
  def parse_config(config_file)
    begin
      File.open(config_file, 'r') do |file|
        @log.debug("Parsing config file #{config_file}")  
        
        line_num = 1
        file.each_line do |line|
          line.strip!   # trim leading and trailing whitespace
          if line.length > 0 and                  # ignore empty lines
             line[0] != COMMENT_CHAR              # ignore comment lines
            # discard any trailing comments
            comment = line.index(COMMENT_CHAR)
            if comment
              line = line[0...comment]
            end
            
            # split the line into name and value
            sep = line.index(SEPARATOR_CHAR)
            if !sep
              msg = "Missing \"#{SEPARATOR_CHAR}\" on line #{line_num}: #{line}"
              @log.error(msg)
              raise(ConfigException, msg)
            end
            name = line[0...sep]
            name.strip!
            value = line[(sep + 1)..-1]
            value.strip!
            @log.debug do
              "Name = #{name}, value=#{value}, line number #{line_num}"
            end
            if value.length > 0
              @map[name] = value
            end
          end
          line_num += 1
        end
      end
    rescue SystemCallError
      @log.error("Error opening \"#{config_file}\": #{$!}")
      raise   # unrecoverable, so rethrow
    end
  end

end