# encoding: UTF-8
require 'log4r'
require 'ipaddress'
require 'uri'
require 'mauve/mauve_time'
require 'mauve/mauve_resolv'
require 'mauve/generic_http_api_client'
require 'mauve/configuration'

module Mauve

  # A simple construct to match sources.
  #
  # One can ask if an IPv4, IPv6, hostname or url (match on hostname only) is
  # contained within a list.  If the query is not an IP address, it will be
  # converted into one as the checks are made.
  #
  # Note that the matching is greedy.  When a hostname maps to several IP
  # addresses and only one of tbhose is included in the list, a match 
  # will occur.
  #
  class SourceList

    include GenericHttpApiClient

    attr_reader :label, :last_resolved_at

    ## Default contructor.
    def initialize (label, url = nil)
      @label            = label
      @last_resolved_at = nil
      @list = []
      @resolved_list = []
      @url = url
    end

    alias username label

    # Adds a source onto the list.
    #
    # The source can be a string, or array of strings.  Each one can be an IPv6
    # or IPv4 address or range, or a hostname.
    #
    # Hostnames can have *, or numeric ranges in their name.  A '*' represents
    # any character except ".".  A range can be specified as 1..4, meaning 1,
    # 2, 3 or 4.
    #
    # e.g.  1.2.3.4/24
    #       2001:dead::beef/64
    #       app1..10.my-customer.com
    #       *.db.my-customer.com
    #
    # Hostnames are also resolved into IP addresses, and re-resolved every 30
    # minutes.
    #
    # @param [String or Array] l The source(s) to add.
    # @return [SourceList]
    #
    def +(l)
      arr = [l].flatten.collect do |h|
        do_parse_source(h)
      end.flatten.compact

      arr.each do |source|
        ##
        # I would use include? here, but IPAddr tries to convert "foreign"
        # classes to intgers, and RegExp doesn't have a to_i method..
        #
        if @list.any?{|e| source.is_a?(e.class) and source == e}
          logger.warn "#{source} is already on the #{self.label} list"
        else
          @list << source
        end
      end

      @resolved_list    = [] 
      @last_resolved_at = nil

      self
    end

    alias add_to_list +

    # @return [Log4r::Logger]
    def logger
      @logger ||= Log4r::Logger.new self.class.to_s
    end

    def list
      #
      # Redo resolution every thirty minutes
      #
      resolve if @resolved_list.empty? or @last_resolved_at.nil? or (Time.now - 1800) > @last_resolved_at

      @resolved_list
    end

    # 
    # Return whether or not a list contains a source.
    #
    # First the hostname is checked for a URI, using URI#parse, and then the
    # hostname is extracted from there.  If that fails, the original hostname
    # is used.
    #
    # Next we check against our list, including all IPs for any hostnames in
    # that list.
    #
    # If nothing is found, the hostname is then resolved to its IPs, and we
    # check to see if those IPs are in our list. 
    #
    # @param [String] host The host to look for.
    # @return [Boolean]
    def includes?(host)
      #
      # Pick out hostnames from URIs.
      #
      if host =~ /^[a-z][a-z0-9+-]+:\/\//
        begin      
          uri = URI.parse(host)
          host = uri.host unless uri.host.nil?
          host = $1 if host =~ /^\[([0-9a-f:]+)\]$/i
        rescue URI::InvalidURIError => ex
          # ugh
          logger.warn "Did not recognise URI #{host}"
        end
      end

      host_as_ip = nil

      begin
        host_as_ip = IPAddress.parse(host)
      rescue ArgumentError
        # Rescue IPAddress argument errors, i.e. host is not an IP address.
      end

      return true if self.list.any? do |l|
        case l
          when String
            host == l
          when Regexp
            host =~ l
          when IPAddress 
            host_as_ip.is_a?(l.class) and l.include?(host_as_ip)
          else
            false
        end
      end

      #
      # To cut down the amount of DNS queries, we'll bail out at this point.
      #
      return false if true == Configuration.current.minimal_dns_lookups

      return false unless self.list.any?{|l| l.is_a?(IPAddress)}

      ips = MauveResolv.get_ips_for(host).collect{|i| IPAddress.parse(i)}

      return false if ips.empty?

      return self.list.select{|i| i.is_a?(IPAddress)}.any? do |list_ip|
        ips.any?{|ip| ip.is_a?(list_ip.class) and list_ip.include?(ip) }
      end
      
      return false
    end

    # 
    # Resolve all hostnames in the list to IP addresses.
    #
    # @return [Array] The new list.
    #
    def resolve
      @last_resolved_at = Time.now

      if true == Configuration.current.minimal_dns_lookups

        new_list = [] + @list

      else

        url_list = []
        if @url
          url_list_s = do_get(@url)
          if url_list_s.is_a?(String)
            url_list = url_list_s.split("\n").collect{|s| do_parse_source(s)}.flatten.compact
          end
        end

        new_list = (url_list + @list).collect do |host| 
          if host.is_a?(String)
            [host] + MauveResolv.get_ips_for(host).collect{|i| IPAddress.parse(i)}
          else
            host
          end
        end

      end

      @resolved_list = new_list.flatten
    end

    private

    def do_parse_source(h)
      # "*"              means [^\.]+
      # "(\d+)\.\.(\d+)" is expanded to every integer between $1 and $2
      #                  joined by a pipe, e.g. 1..5 means 1|2|3|4|5
      #  "."              is literal, not a single-character match
      if h.is_a?(String) and (h =~ /[\[\]\*]/ or h =~ /(\d+)\.\.(\d+)/)
        Regexp.new(
            h.
            gsub(/(\d+)\.\.(\d+)/) { |a,b|
              ($1.to_i..$2.to_i).collect.join("|")
            }.
            gsub(/\./, "\\.").
            gsub(/\*/, "[0-9a-z\\-]+") +
            "\\.?$")
      elsif h.is_a?(String) and h =~ /^[0-9a-f\.:]+(\/\d+)?$/i
        IPAddress.parse(h)
      elsif h.is_a?(String) and h =~ /^\/(.*)\/$/
        Regexp.new($1)
      elsif h.is_a?(String) or h.is_a?(Regexp)
        h
      else
        logger.warn "Cannot parse source line #{h.inspect} for source list #{@label}."
        nil
      end

    end

  end

end