=begin
  Copyright (c) 2020 Marek Küthe
  This program is free software. It comes without any warranty, to
  the extent permitted by applicable law. You can redistribute it
  and/or modify it under the terms of the Do What The Fuck You Want
  To Public License, Version 2, as published by Sam Hocevar. See
  http://www.wtfpl.net/ for more details.
=end

module SAMHelper
  def self.samcmd fircmd, seccmd = nil, args = {}
    cmd = "#{fircmd}#{seccmd ? " #{seccmd}" : ""}"
    args.each_pair { |arg, value|
      cmd << " #{arg}=\"#{value.to_s}\""
    }
    return cmd
  end

  def self.parsesamcmd ans
    ans.chomp!
    ans += " "
    f = ans.index " "
    s = ans.index " ", f + 1
    w = ans[f+1...s]

    args = Hash.new
    loop do
      g1 = ans.index "=", s+1
      break if g1 == nil
      g2 = nil
      if ans[g1+1] == "\""
        g2 = ans.index "\"", g1+2
        args[ans[s+1..g1-1]] = ans[g1+2..g2-1]
      else
        g2 = ans.index " ", g1+1
        args[ans[s+1..g1-1]] = ans[g1+1..g2-1]
      end
      s = g2
    end

    return [ans[0...f], w, args]
  end
end

module I2PLookuper
  require "socket"
  
  def self.samlookup name, **args
    host = args.include?(:host) ? args[:host] : "127.0.0.1"
    port = args.include?(:port) ? args[:port] : 7656
    
    puts "Connect to the SAM API ..." if $verbose
    begin
      sock = TCPSocket.new host, port
    rescue Exception => e
      return false, e
    end
    
    # hello version
    puts "Handshake with the SAM API is carried out ..." if $verbose
    sock.puts SAMHelper.samcmd "HELLO", "VERSION", {
      "MIN" => "1.0"
    }
    res = SAMHelper.parsesamcmd sock.gets
    if res[2]["RESULT"] != "OK"
      return false, res
    end
    
    # lookup request
    puts "Lookup the name ..." if $verbose
    sock.puts SAMHelper.samcmd "NAMING", "LOOKUP", {
      "NAME" => name
    }
    res = SAMHelper.parsesamcmd sock.gets
    if res[2]["RESULT"] != "OK" or res[2]["NAME"] != name
      return false, res
    end
    
    return true, res[2]["VALUE"]
  end
  
  def self.boblookup name, **args
    host = args.include?(:host) ? args[:host] : "127.0.0.1"
    port = args.include?(:port) ? args[:port] : 2827
    
    puts "Connect to the BOB API ..." if $verbose
    begin
      sock = TCPSocket.new host, port
    rescue Exception => e
      return false, e
    end
    
    # welcome response
    puts "Handshake with the BOB API is carried out ..." if $verbose
    res = sock.gets.chomp
    unless res =~ /(BOB) (\d{2}.\d{2}.\d{2})/
      return false, res
    end
    
    res = sock.gets.chomp
    if res != "OK"
      return false, res
    end
    
    # lookup request
    puts "Lookup the name ..." if $verbose
    sock.puts "lookup #{name}"
    res = sock.gets.chomp
    spl = res.split
    if spl[0] != "OK"
      return false, res
    end
    
    return true, spl[1]
  end
  
  def self.wclookup name, **args
    host = args.include?(:host) ? args[:host] : "127.0.0.1"
    port = args.include?(:port) ? args[:port] : 7657
    uagent = args.include?(:uagent) ? args[:uagent] : "mi2pdig"
    
    puts "Connect to the web console and send the HTTP request ..." if $verbose
    begin
      sock = TCPSocket.new host, port
    rescue Exception => e
      return false, e
    end
    sock.puts "GET /susidns/details?h=#{name} HTTP/1.1"
    sock.puts "Host: 127.0.0.1"
    sock.puts "Connection: close"
    sock.puts "User-Agent: #{uagent}"
    sock.puts
    
    puts "Evaluate the received data ..." if $verbose
    res = sock.read.split "\n"
    resstat = res[0].chomp.split
    if resstat[1] != "200" || resstat[2] != "OK"
      return false, res
    end
    sock.close
    
    require "base64"
    begin
      l = res[59].scan(/\<input type="hidden" name="destination" value="(.*)">/)[0][0]
    rescue Exception => e
      return false, "The name could not be found or the data structure in the received code was changed."
    end
    if Base64.decode64(l) == ""
      return false, res[59]
    end
    
    return true, l
  end
end

# argument parsing

if ARGV.length == 0
  puts "No argument was given. If you need help you can call \"ruby #{__FILE__} --help\"."
  exit
end

name = nil
args = {}
$verbose = false
$norout = true
i = 0
while i < ARGV.length
  if ARGV[i].index "-"
    if ARGV[i] == "-s" or ARGV[i] == "--sam"
      args[:sam] = nil
    elsif ARGV[i] == "-b" or ARGV[i] == "--bob"
      args[:bob] = nil
    elsif ARGV[i] == "-c" or ARGV[i] == "--console"
      args[:wc] = nil
    elsif ARGV[i] == "-a" or ARGV[i] == "--auto"
      args[:auto] = nil
    elsif ARGV[i] == "-u" or ARGV[i] == "--uagent"
      args[:uagent] = nil
    elsif ARGV[i] == "-v" or ARGV[i] == "--verbose"
      $verbose = true
    elsif ARGV[i] == "-l" or ARGV[i] == "--lookup"
      $norout = false
    elsif ARGV[i] == "-p" or ARGV[i] == "--port"
      args[:port] = ARGV[i + 1]
      i += 1
    elsif ARGV[i] == "-o" or ARGV[i] == "--host"
      args[:host] = ARGV[i + 1]
      i += 1
    elsif ARGV[i] == "-h" or ARGV[i] == "--help"
      puts <<~EOH
mi2pdig resolves an I2P name into a base64.
It was written by Marek Küthe on 23/07/2020 in the programming language Ruby and published under the WTFPL license.

Usage:
  -s, --sam         Use the SAM API to resolve the name.
  -b, --bob         Use the BOB API to resolve the name.
  -c, --console     Accesses the I2P web console to resolve a name.
  -a, --auto        Try out all three options offered to resolve the name. First the SAM API, then the BOB API and then the Web Console.
  -p, --port        Specifies the port for the the possibility. If you choose automatic, all three options will be tried on this port.
  -s, --host        Specifies the host for the the possibility. If you choose automatic, all three options will be tried on this host.
  -l, --lookup      If the resolution is successful, only outputs the base64.
  -u, --uagent      Specifies the HTTP user agent in the web console option. If none is specified, "mi2pdig" is used.
  -h, --help        Displays this help page.
  -v, --verbose     Activates verbose output

Example:
    ruby #{__FILE__} -s -o 127.0.0.1 -p 7656 stats.i2p
    ruby #{__FILE__} --sam --host 127.0.0.1 --port 7656 stats.i2p
    ruby #{__FILE__} stats.i2p -s -o 127.0.0.1 -p 7656
EOH
      exit
    end
  else
    if name == nil
      name = ARGV[i]
    else
      $stderr << "Error: Only one name may be specified, which should be resolved."
      exit
    end
  end
  i += 1
end

if args.has_key? :sam
  res = I2PLookuper.samlookup name, **args
  if res[0] == true
    puts "The name was successfully resolved using the SAM API." if $norout
    puts res[1]
  else
    $stderr << "Error: #{res.inspect}"
  end
elsif args.has_key? :bob
  res = I2PLookuper.boblookup name, **args
  if res[0] == true
    puts "The name was successfully resolved using the BOB API." if $norout
    puts res[1]
  else
    $stderr << "Error: #{res.inspect}"
  end
elsif args.has_key? :wc
  res = I2PLookuper.wclookup name, **args
  if res[0] == true
    puts "The name was successfully resolved using the I2P Web Console." if $norout
    puts res[1]
  else
    $stderr << "Error: #{res.inspect}"
  end
else
  res1 = I2PLookuper.samlookup name, **args
  if res1[0] == true
    puts "The name was successfully resolved using the SAM API." if $norout
    puts res1[1]
    exit
  end
  
  res2 = I2PLookuper.boblookup name, **args
  if res2[0] == true
    puts "The name was successfully resolved using the BOB API." if $norout
    puts res2[1]
    exit
  end
  
  res3 = I2PLookuper.wclookup name, **args
  if res3[0] == true
    puts "The name was successfully resolved using the I2P Web Console." if $norout
    puts res3[1]
    exit
  end
  
  puts "The name could not be lookeped."
  puts "#{res1[1].inspect}"
  puts "#{res2[1].inspect}"
  puts "#{res3[1].inspect}"
end