require 'fileutils'
require 'qasim/map/generic'
require 'qasim/map/smb'
require 'qasim/map/ssh'
require 'qasim/map/webdav'

module Qasim ; module Map

	class ParseError < RuntimeError ; end
	class ConnectError < RuntimeError ; end

  def class_for type
    plugin = nil
    ObjectSpace.each_object(Class) do |cls|
      
      if cls < Qasim::Map::Generic then
        puts "Searching #{type} in " + cls.handles.inspect
        plugin = cls if cls.handles.include? type.to_sym
      end 
    end
    plugin
  end

  #
  # replace magic values withing map lines
  #
  # Allowed values :
  #
  # $(var) => variable value from environment
  # ${var} => variable value from environment
  # 
  def env_substitute text
    seek = true
    str = text

		while seek do
      seek = false
			case str
			when /^(.*)\${([^}]+?)}(.*)$/ then
        before, pattern, after = [$1, $2, $3]
        pattern_value = env_substitute(pattern)
        pattern_value = (ENV[pattern_value] || "")
				str = before + pattern_value + after
        seek = true
			when /^(.*)\$(\w+)(.*)$/ then
        before, pattern, after = [$1, $2, $3]
        pattern_value = (ENV[pattern] || "")
				str = before + pattern_value + after
        seek = true
			end
		end
    str
  end

	#
	# Load description from file and create a Map object
	#
	def from_file appcfg, filename
    params = {
      type: :ssh  # for params V1, we assume SSHFS by default
    }
    map = nil

		f = File.open filename
		linect = 0
		f.each do |line|
			line = line.strip
			linect += 1

      line = env_substitute(line)
      params[:filename] = filename
			case line
			when /^\s*REMOTE_USER\s*=\s*(.*)\s*$/ then
        params[:ssh_user] = $1
			when /^\s*REMOTE_PORT\s*=\s*(.*)\s*$/ then
        params[:ssh_port] = $1.to_i
			when /^\s*REMOTE_HOST\s*=\s*(.*)\s*$/ then
				params[:ssh_host] = $1
			when /^\s*REMOTE_CYPHER\s*=\s*(.*)\s*$/ then
				if CYPHERS.map(&:to_s).include? $1 then
					params[:ssh_cypher] = $1.to_sym
				end
			when /^\s*MAP\s*=\s*(.*)\s+(.*)\s*$/ then
        params[:links] ||= {}
        params[:links][$1] = $2
      when /^\s*([A-Z_]+)\s*=\s*(.*)\s*$/ then
        key = $1.downcase.to_sym
        params[key] = $2
			when /^\s*$/,/^\s*#/ then
			else
        STDERR.puts line
				raise ParseError, "parse error at #{filename}:#{linect}"
			end
		end
		f.close
		map_class = class_for params[:type]
    if map_class.nil? then
      raise ParseError, "no plugin found for type « #{params[:type]} »"
    end
    map = map_class.new appcfg, params
    return map
	end


	#
	# Write map description to file
	#
	def to_file path=nil
		@path=path unless path.nil?

		File.open(@path, "w") do |f|
			f.puts "REMOTE_USER=%s" % @user
			f.puts "REMOTE_PORT=%s" % @port
			f.puts "REMOTE_HOST=%s" % @host
			f.puts "REMOTE_CYPHER=%s" % @cypher
		end
	end

  module_function :from_file
  module_function :env_substitute
  module_function :class_for
  module_function :select

end ; end