#!/usr/bin/env ruby

require 'socket'
require 'optparse'

PUBLIC_HOST = '0.0.0.0'
PRIVATE_HOST = '127.0.0.1'
options = {
  :port => 7570,
  :host => PRIVATE_HOST,
  :rows => 24,
  :cols => 40,
}
OptionParser.new do |opt|
  opt.on('-pPORT', '--port PORT', Integer,
      'Port to serve on (defaults to 7570)') do |o|
    options[:port] = o
  end
  opt.on('-rROWS', '--rows ROWS', Integer,
      'The number of rows to have in the shared buffer') do |o|
    options[:rows] = o
  end
  opt.on('-cCOLS', '--cols COLS', Integer,
      'The number of columns to have in the shared buffer') do |o|
    options[:cols] = o
  end
  opt.on('-s', '--public', Boolean,
      'Serve publicly, rather than privately') do
    options[:host] = PUBLIC_HOST
  end
  opt.on('-S', '--private', Boolean,
      'Serve privately, rather than publicly (default)') do
    options[:host] = PRIVATE_HOST
  end
  opt.on('-h', '--help', 'Get help with this command') do
    puts opt
    exit
  end
end.parse!(into: options)

HOST = options[:host]
PORT = options[:port]

ROWS = options[:rows]
COLS = options[:cols]
VERSION = 0.01

server = TCPServer.new(HOST, PORT)
sockets = [server]

puts "PORT: #{PORT}"
puts "GRID SIZE: #{ROWS}r#{COLS}c"
puts 'Listening...'

pre = "#{ROWS}r#{COLS}c >>> "
buffer = pre.ljust(ROWS*COLS)[0...ROWS*COLS]
windex = pre.length # Wipe your buffer clean with your write index
windex %= buffer.length

def new_buf_wi_out(buf, wi, newtext)
  buf = buf.dup
  out = ''
  nti = 0 # New Text Index
  while nti < newtext.length
    out << "#{VERSION}|"
    out << ((wi/COLS)+1).to_s + '|'
    out << ((wi%COLS)+1).to_s + '|'
    loop do
      out << newtext[nti]
      buf[wi] = newtext[nti]
      wi += 1
      nti += 1
      break if nti >= newtext.length
      break if wi%COLS == 0
    end
    wi = 0 if wi >= (ROWS*COLS)
    wi %= ROWS*COLS
    out << "\n"
  end
  return [buf, wi, out]
end

loop do
  ready, = IO.select(sockets)
  newtext = ''

  ready.each do |sck|
    if sck == server
      client = server.accept
      sockets << client
      puts "Connection: #{client.peeraddr}"
      client.puts new_buf_wi_out(buffer,0,buffer)[2]
      if buffer.length > 1
        client.puts new_buf_wi_out(buffer,windex-1,buffer[windex-1])[2]
      end
      next
    end
    begin

      msg = sck.gets
      unless msg
        puts "Disconnect: #{sck.peeraddr}"
        sck.close
        sockets.delete(sck)
        next
      end
      ver, msg = msg.chomp.split('|',2)
      next unless ver.to_f <= VERSION
      next unless msg != nil
      newtext << msg
    rescue Errno::ECONNRESET, Errno::EPIPE
      puts "Disconnect (err): #{sck.peeraddr}"
      sck.close
      sockets.delete(sck)
    end
    buffer, windex, out = new_buf_wi_out(buffer,windex,newtext)
    clients = sockets - [server]
    clients.each { |c| c.puts out }
    #if out != ''
    #  puts "#{windex}: (#{(windex/COLS)+1},#{(windex%COLS)+1})"
    #end
  end
end