require 'net/http'
require 'net/https'
require 'uri'


#
# This list of all our protocol tests.
#
require 'custodian/protocoltests'






#
# This is a simple class which will parse a configuration file.
#
# The class peels off lines via a small number of very simple regular
# expressions - this should be flaky,  but in practice it manages to
# successfully parse each of the configuration files that we currently
# maintain @ Bytemark.
#
# If there are any lines which are not recognized the class will raise an exception.
#
#
# Steve
# --
#
module Custodian

  class Parser

    #
    # A hash of macros we found.
    #
    attr_reader :MACROS

    #
    # The filename that we're going to parse.
    #
    attr_reader :filename

    #
    # Timeout period, in seconds, that we encode into test objects.
    #
    attr_reader :timeout

    #
    # An array of test-objects, which are subclasses of our test-factory.
    #
    attr_reader :jobs



    #
    # Constructor
    #
    def initialize( )


      @MACROS  = Hash.new()
      @jobs    = Array.new()
      @timeout = 60

    end




    #
    # Retrieve a HTTP/HTTPS page from the web, which is used for macro-expansion.
    #
    def getURL (uri_str)
      begin
        uri_str = 'http://' + uri_str unless uri_str.match(/^http/)
        url = URI.parse(uri_str)
        http = Net::HTTP.new(url.host, url.port)
        http.open_timeout = @timeout
        http.read_timeout = @timeout

        if (url.scheme == "https")
          http.use_ssl = true
          http.verify_mode = OpenSSL::SSL::VERIFY_NONE
        end

        response = nil

        if nil == url.query
          response = http.start { http.get(url.path) }
        else
          response = http.start { http.get("#{url.path}?#{url.query}") }
        end


        if ( response.code.to_i != 200 )
          puts "Status code of #{uri_str} was #{response.code}"
          puts "ABORTING"
          exit( 0 )
        end

        case response
        when Net::HTTPRedirection
        then
          newURL = response['location'].match(/^http/)?
          response['Location']:uri_str+response['Location']
          return( getURL(newURL) )
        else
          return response.body
        end

      rescue Errno::EHOSTUNREACH => ex
        raise ex, "no route to host"
      rescue Timeout::Error => ex
        raise ex, "timeout"
      rescue Errno::ECONNREFUSED => ex
        raise ex, "connection refused"
      end
    end



    #
    #  Define a macro, from the configuration file.
    #
    def define_macro( line )
      name = nil
      val  = Array.new

      #
      #  Get the name of the macro.
      #
      name = $1.dup if ( line =~ /^([0-9A-Z_]+)\s+/ )


      #
      #  Get the value
      #
      if ( line =~ /fetched\s+from\s+(.*)[\r\n\.]*$/ )

        #
        #  HTTP-fetch
        #
        uri = $1.dup.chomp(".")

        text = getURL(uri)
        text.split( /[\r\n]/ ).each do |line|
          val.push( line ) if ( line.length() > 0)
        end

      elsif ( line =~ /\s(is|are)\s+(.*)\.+$/ )

        #
        #  Literal list of hosts
        #
        hosts = $2.dup

        #
        #  If there is " and " then tokenize
        #
        if ( hosts =~ /\s+and\s+/ )
          tmp = hosts.split( /\s+and\s+/ )
          tmp.each do |entry|
            val.push( entry )
          end
        else
          #
          # Otherwise a single host
          #
          val.push( hosts )
        end
      end

      if ( is_macro?( name ) )
        raise ArgumentError, "The macro #{name} is already defined"
      end

      @MACROS[name] = val

      true
    end




    #
    #  Return a hash of our current macro-definitions.
    #
    #  This is used only by the test-suite.
    #
    def macros
      @MACROS
    end




    #
    # Is the given string of text a macro?
    #
    def is_macro?( name )
      !(@MACROS[name]).nil?
    end



    #
    # Return an array of hosts if the given string was a macro identifier.
    #
    def get_macro_targets( name )
      @MACROS[name]
    end



    #
    #  Return multiple copies of a line for each macro-target
    #
    def expand_macro( input )

      r = Array.new()

      if ( input =~ /^(\S+)\s+(.*)$/ )
        macro=$1.dup
        rest=$2.dup
      end


      if ( is_macro?( macro ) )
        get_macro_targets(macro).each do |host|
          r.push( "#{host} #{rest}" )
        end
      else
        r.push( input )
      end

      r
    end


    #
    # Parse a single line from the configuration file.
    #
    def parse_line( line )

      raise ArgumentError, "Line is not a string: #{line}" unless( line.kind_of? String )

      line.chomp! if ( !line.nil? )

      #
      # A blank line, or a comment may be skipped.
      #
      return nil if ( ( line.nil? ) || ( line =~ /^#/ ) || ( line.length < 1 ) )

      #
      #  Look for macro definitions, inline
      #
      if ( line =~ /^([0-9A-Z]_+)\s+are\s+fetched\s+from\s+([^\s]+)\.?/ )
        define_macro( line )

      elsif ( line =~ /^([0-9A-Z_]+)\s+(is|are)\s+/ )
        define_macro( line )

      elsif ( line =~ /^(\S+)\s+must\s+ping(.*)/ )
        #
        #  Ping is a special case because the configuration file entry
        # would read:
        #
        #  $FOO must ping otherwise ...
        #
        #  All other tests are of the form:
        #
        #  $FOO must run XXX ... otherwise ...
        #
        #  If we clevery rewrite the line into:
        #
        #  ... must run ping ...
        #
        #  We can avoid duplicating the macro-expansion, etc.
        #
        pre  = $1.dup
        post = $2.dup
        new_line = "#{pre} must run ping #{post}"
        return( parse_line( new_line ) )

      elsif ( line =~ /^\S+\s+must(\s+not)?\s+run\s+([^\s]+)(\s+|\.|$)/i )

        #
        # Expand the macro if we should
        #
        tests = expand_macro( line )

        #
        # The array of objects we will return to the caller.
        #
        ret = Array.new()

        #
        # For each host in our possibly-macro-expanded list:
        #
        tests.each do |macro_expanded|

          job = nil

          begin
            job = Custodian::TestFactory.create( macro_expanded )
            ret.push( job )
          rescue => ex
            raise ArgumentError, "Parsing a line to a protocol test gave the error: #{ex}"
            return nil
          end
        end

        return ret
      else
        raise ArgumentError, "Unknown line: '#{line}'"
      end
    end



    #
    # Parse a text-snippet, with multiple lines.
    #
    def parse_lines( text )

      #
      # If we're given a string then split it on newline
      #
      if ( text.kind_of?( String )  )
        a    = text.split( /[\r\n]/ )
        text = a
      end

      ret = nil

      #
      # Split on newline
      #
      text.each do |line|
        ret = parse_line( line )

        #
        #  The return value from the parse_line method
        # is either:
        #
        #  Array -> An array of test-objects.
        #
        #  nil   -> The line was a macro.
        #         or
        #           The line was a comment.
        #
        #
        if ( ret.kind_of?( Array ) )
          ret.each do |probe|
            @jobs.push( probe )
          end
        end
      end

      ret
    end



    #
    # Parse the configuration file specified.
    #
    # This updates our @jobs array with the tests.
    #
    def parse_file( filename )

      raise ArgumentError, "Missing configuration file!" if ( filename.nil? )
      raise ArgumentError, "File not found: #{@file}" unless ( File.exists?( filename) )

      #
      #  Read the configuration file.
      #
      out = File.open( filename, 'r') {|file| file.readlines.collect}

      #
      #  Parse it
      #
      parse_lines( out )
    end


  end


end