#!/usr/bin/env ruby

require 'socket'
require 'io/console'
require 'optparse'

PUBLIC_HOST = '0.0.0.0'
PRIVATE_HOST = '127.0.0.1'
DEFAULT_CLIENT_HOST = '127.0.0.1'
VERSION = {
  :SRV_TXT => '0.01',
  :CLN_TXT => '0.01',
  :CLN_ARO => '0.02',
  :SRV_CO8 => '0.30', # 8-color
  :CLN_CO8 => '0.30', # 8-color
  :SRV_GSZ => '0.40',

  :FIL_TXT => '0.01',
  :FIL_CUP => '0.02',
  :FIL_CO8 => '0.30',
}

options = {
  :port => 7570,
  :server => false,
  :host => DEFAULT_CLIENT_HOST,
  :server_host => PRIVATE_HOST,
  :rows => 24,
  :cols => 40,
  :file => nil,
  :file_lockout => false,
  :file_interval => 600,
}
OptionParser.new do |opt|
  opt.on('-pPORT', '--port PORT', Integer,
         'Port to serve/listen on (defaults to 7570)') do |o|
    options[:port] = o
  end
  opt.on('-S', '--server',
         'Make this instance function as a server'
        ) do
    options[:server] = true
  end
  opt.on('-s', '--client',
         'Make this instance function as a client'
        ) do
    options[:server] = false
  end
  opt.on('-HHOST', '--host HOST', String,
         '(client only) Host to connect to (defaults to `localhost`)') do |o|
    options[:host] = o
  end
  opt.on('-tSECONDS', '--save-interval SECONDS', Float,
         '(server only) How long to wait between file writes in seconds. (defaults to 600 which is 10 minutes)'
        ) do |o|
    options[:file_interval] = o
  end
  opt.on('-rROWS', '--rows ROWS', Integer,
         '(server only) The number of rows to have in the shared buffer'
        ) do |o|
    options[:rows] = o
  end
  opt.on('-cCOLS', '--cols COLS', Integer,
         '(server only) The number of columns to have in the shared buffer'
        ) do |o|
    options[:cols] = o
  end
  opt.on('--expose-this-instance-for-the-world-to-see-because-I-know-what-I\'m-doing [please]',
         # X -- eXposed
         '(server only) Serve publicly, rather than privately. Please ONLY add this option if you entierly know what you\'re doing and have permission from/are the server owner. Say please to expose.'
        ) do |o|
    if o == "please"
      options[:server_host] = PUBLIC_HOST
    end
  end
  opt.on('-x', '--private',
         # x -- not visible
         '(server only) Serve privately, rather than publicly (default)'
        ) do
    options[:server_host] = PRIVATE_HOST
  end
  opt.on('-f FILE', '--save-file FILE',
         '(server only) File to read initial state from and save state to.'
        ) do |f|
    break if options[:file_lockout]
    options[:file_lockout] = true
    file_stuff = {
      :name => f,
      :text => '',
      :color => [],
      :cursor => 0,
      :writeme => false
    }
    unless File.exist? f
      file_stuff[:writeme] = true
      options[:file] = file_stuff
      options[:file_lockout] = false
      next
    end
    File.readlines(f, chomp: true).each do |msg|
      ver, msg = msg.chomp.split('|',2)
      next unless msg != nil
      case ver
      when VERSION[:FIL_TXT]
        file_stuff[:text] = msg
      when VERSION[:FIL_CO8]
        msg.each_char.with_index do |c, i|
          next unless c =~ /[0-7]/
          file_stuff[:color] << {
            :co8 => 7
          } until file_stuff[:color].length > i
          file_stuff[:color][i][:co8] = c.to_i.clamp(0,7)
        end
      when VERSION[:FIL_CUP]
        file_stuff[:cursor] = msg.to_i
      end
    end
    options[:file] = file_stuff
  end
  opt.on('-h', '--help', 'Get help with this command') do
    puts opt
    exit
  end
end.parse!

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

ROWS = options[:rows]
COLS = options[:cols]
FILE_INTERVAL = options[:file_interval]

def do_server(file_opts)
  def write_current(wi, buffer, cobuf, file_opts)
    return if file_opts.nil?
    File.open(file_opts[:name], 'w') do |f|
      f.puts("#{VERSION[:FIL_TXT]}|#{clean_chars(buffer)}\n")
      f.write("#{VERSION[:FIL_CO8]}|")
      cobuf.each do |color|
        f.write(color[:co8].to_s)
      end
      f.puts ''
      f.puts("#{VERSION[:FIL_CUP]}|#{wi}")
    end
  end

  server = TCPServer.new(SRV_HOST, PORT)
  sockets = [server]
  sockats = {
    server => {
      :color => {
        :co8 => 7
      }
    }
  }
  if file_opts.nil? || file_opts[:writeme]
    pre = "#{ROWS}r#{COLS}c >>> "
    buffer = pre.ljust(ROWS*COLS)[0...ROWS*COLS]
    cobuf = Array.new(ROWS*COLS, {
                        :co8 => 7
                      })
    windex = pre.length # Wipe your buffer clean with your write index
  else
    buffer = file_opts[:text].ljust(ROWS*COLS)[0...ROWS*COLS]
    cobuf = file_opts[:color]
    if cobuf.length < ROWS*COLS
      cobuf += Array.new(ROWS*COLS - cobuf.length ) { {:co8 => 7} }
    else
      cobuf = cobuf.first(ROWS*COLS)
    end
    windex = file_opts[:cursor]
  end
  windex = windex%buffer.length
  if not file_opts.nil?
    write_current(windex, buffer, cobuf, file_opts)
  end

  puts "PORT: #{PORT}"
  puts "GRID SIZE: #{ROWS}r#{COLS}c"
  if SRV_HOST == PUBLIC_HOST then puts "EXPOSED" end
  puts 'Listening...'

  motions = []

  def new_buf_cob_wi_out(buf, cob, wi, newtext, newcolors, motions: [])
    buf = buf.dup
    cob = cob.dup
    out = ''
    nti = 0 # New Text Index
    wco = {} #Writing Color
    cur = motions.length > 0 #Update cursor at end
    while (nti < newtext.length) || (motions.length > 0)
      if motions.length > 0 && nti >= motions[0][:nti]
        case motions[0][:dir]
        when 'u'
          wi -= COLS
        when 'd'
          wi += COLS
        when 'l'
          wi -= 1
        when 'r'
          wi += 1
        end
        wi = wi%(ROWS*COLS)
        motions.shift # remove first motion
      end
      next if nti >= newtext.length
      if newcolors[nti] != wco
        wco = newcolors[nti]
        if wco.has_key? :co8
          out << "#{VERSION[:SRV_CO8]}|#{wco[:co8]}\n"
        end
      end
      out << "#{VERSION[:SRV_TXT]}|"
      out << ((wi/COLS)+1).to_s + '|'
      out << ((wi%COLS)+1).to_s + '|'
      loop do
        out << newtext[nti]
        buf[wi] = newtext[nti]
        cob[wi] = wco
        wi += 1
        nti += 1
        break if newcolors[nti] != wco
        break if motions.length > 0 && nti >= motions[0][:nti]
        break if nti >= newtext.length
        break if wi%COLS == 0
      end
      wi = wi%(ROWS*COLS)
      out << "\n"
    end
    if cur
      out << "#{VERSION[:SRV_TXT]}|"
      out << ((wi/COLS)+1).to_s + '|'
      out << ((wi%COLS)+1).to_s + "|\n"
    end
    [buf, cob, wi, out]
  end

  begin
    old = {
      :windex => windex.dup,
      :buffer => buffer.dup,
      :cobuf => cobuf.dup,
      :lastsave => Time.now,
    }
    Thread.new do
      loop do
        time_since_next_save = Time.now - old[:lastsave]
        time_till_next_save = FILE_INTERVAL - time_since_next_save
        # To ensure thread doesn't bog down cpu too much.....
        sleep [
          [
            [1.0, # Wait a second
             time_till_next_save/2 # or half the remaining time
            ].max, # Whichever's longer
            time_till_next_save].min, # Unless the remaining time is shorter than a second
          1.0].max # But don't wait longer than no time at all
        unless (old[:windex] == windex &&
                old[:buffer] == buffer &&
                old[:cobuf] == cobuf)
          next if file_opts.nil?
          next if time_since_next_save < FILE_INTERVAL
          old = {
            :lastsave => Time.now,
            :windex => windex.dup,
            :buffer => buffer.dup,
            :cobuf => cobuf.dup
          }
          write_current(windex, buffer, cobuf, file_opts)
          puts "[#{Time.now.strftime("%Y-%m-%d %H:%M:%S")}] File autosaved."
        end
      end
    end
    loop do
      ready, = IO.select(sockets)
      newtext = ''
      newcolors = []

      ready.each do |sck|
        if sck == server
          client = server.accept
          sockats[client] = {
            :color => {
              :co8 => 7
            }
          }
          sockets << client
          puts "Connection: #{client.peeraddr}"
          client.puts "#{VERSION[:SRV_GSZ]}|#{ROWS}|#{COLS}"
          client.puts new_buf_cob_wi_out(buffer,cobuf,0,buffer,cobuf)[3]
          if buffer.length > 1
            client.puts new_buf_cob_wi_out(
                          buffer,cobuf,windex-1,
                          buffer[windex-1],[cobuf[windex-1]])[3]
          end
          next
        end
        begin
          msg = sck.gets
          unless msg
            puts "Disconnect: #{sck.peeraddr}"
            sck.close
            sockets.delete(sck)
            sockats.delete(sck)
            next
          end
          ver, msg = msg.chomp.split('|',2)
          next unless msg != nil
          case ver
          when VERSION[:CLN_TXT]
            newtext << clean_chars(msg)
            msg.length.times do
              newcolors << sockats[sck][:color].dup
            end
          when  VERSION[:CLN_ARO]
            dir = 'l'
            case msg
            when 'A'
              dir = 'u'
            when 'B'
              dir = 'd'
            when 'C'
              dir = 'r'
            when 'D'
              dir = 'l'
            else
              next
            end
            motions << {
              :nti => newtext.length - 1,
              :dir => dir,
            }
          when VERSION[:CLN_CO8]
            sockats[sck][:color][:co8] = msg.to_i.clamp(0,7)
          end
        rescue Errno::ECONNRESET, Errno::EPIPE
          puts "Disconnect (err): #{sck.peeraddr}"
          sck.close
          sockets.delete(sck)
        end
        buffer, cobuf, windex, out = new_buf_cob_wi_out(buffer,cobuf,windex,newtext,newcolors,motions:motions)
        motions = []
        clients = sockets - [server]
        clients.each do |c|
          begin
            c.puts out
          rescue Errno::ECONNRESET, Errno::EPIPE
            puts "Disconnect (err): #{c.peeraddr}"
            c.close
            sockets.delete(c)
          end
        end
        #if out != ''
        #  puts "#{windex}: (#{(windex/COLS)+1},#{(windex%COLS)+1})"
        #end
      end
    end
  ensure
    write_current(windex, buffer, cobuf, file_opts)
    puts "File saved on exit."
  end
end

def clean_chars(chars)
  out = ''
  chars.each_char do |char|
    if char.ord < 0x20 # Non printing
      out << '^'+(char.ord + 0x40).chr
    elsif char.ord == 0x7F # DEL (Non print)
      out << '^?'
    else
      out << char
    end
  end
  out
end


def do_client
  socket = TCPSocket.new(HOST, PORT)
  grid_rows = 24
  grid_cols = 40

  puts "PORT: #{PORT}"
  puts "HOST: #{HOST}"

  def print_mode(mode,gridrows)
    return if ENV["TERM"].downcase == "dumb"
    #print ("\x1b[s"+               # Save cursor
    #       "\x1b[m"+               # Reset color
    #       "\x1b[#{gridrows+1};1H"+# Cursor pos
    #       "\x1b[2K"+              # Clear line
    #       mode+                   # Print mode
    #       "\x1b[u")               # Restore cursor
    print "\e[s\e[m\e[#{gridrows+1};1H\e[2K#{mode}\e[u"
  end

  def parse_esckey(gridrows)
    begin
      char2 = STDIN.read_nonblock(1)
      return [:RAW, "\e#{char2}"] unless char2 == '['
    rescue
      return [:KEY_ESCAPE, '']
    end
    begin
      char3 = STDIN.read_nonblock(1)
    rescue
      return [:RAW, "\e#{char2}"]
    end
    case char3
    when 'A'
      return [:ARROW, 'A']
    when 'B'
      return [:ARROW, 'B']
    when 'C'
      return [:ARROW, 'C']
    when 'D'
      return [:ARROW, 'D']
    else
      loop do
        begin
          char3 << STDIN.read_nonblock(1)
          break unless char3[-1] =~ /[0-9:;\<=\>\?]/
        rescue
          break
        end
      end
      print_mode "#{clean_chars("\e"+char2+char3)} -- I'm unfamiliar with that key.",gridrows
      return [:RAW, "\e#{char2}#{char3}"]
    end
  end

  begin
    print "\x1b[?1049h\x1b[2J\x1b[3J" # Open and clear alternate buffer
    print "\x1b[m" # Reset color

    #reader = Thread.new do
    Thread.new do
      loop do
        msg = socket.gets
        exit 0 unless msg
        ver, msg = msg.split('|',2)
        next unless msg != nil
        case ver
        when VERSION[:SRV_TXT]
          row,col,chars = msg.split('|',3)
          print "\x1b[#{row};#{col}H#{chars.chomp}"
        when VERSION[:SRV_CO8]
          next if ENV["TERM"].downcase == "dumb"
          print "\x1b[3#{msg.to_i.clamp(0,7)}m"
        when VERSION[:SRV_GSZ]
          grid_rows, grid_cols = msg.split('|',2).map { |p| p.to_i }
          print_mode ":3",grid_rows
        end
      end
    end

    socket.puts "#{VERSION[:CLN_CO8]}|#{rand(1..7)}"
    while (char = STDIN.noecho(&:getch))
      print_mode ":3",grid_rows
      exit if char == "\x04" # ^D
      if char == "\x0F" # (^O) Color change
        if /[0-7]/.match? (char2 = STDIN.noecho(&:getch).upcase)
          socket.puts "#{VERSION[:CLN_CO8]}|#{char2}"
          next
        else
          char << char2
        end
      elsif char == "\x1b" # Detect arrows
        keytype, keytext = parse_esckey(grid_rows)
        if keytype == :ARROW
          socket.puts "#{VERSION[:CLN_ARO]}|#{keytext}"
          next
        elsif keytype != :KEY_ESCAPE
          char = keytext
        end
      elsif (char == "\x08" || # backspace
             char == "\x7F"  ) # delete
        socket.puts "#{VERSION[:CLN_ARO]}|D"
        socket.puts "#{VERSION[:CLN_TXT]}| "
        socket.puts "#{VERSION[:CLN_ARO]}|D"
        next
      end
      socket.puts "#{VERSION[:CLN_TXT]}|#{clean_chars(char)}"
    end
  ensure
    print "\x1b[m" # Reset color
    print "\x1b[?1049l" # Back to regular buffer
  end
end

if options[:server]
  do_server(options[:file])
else
  do_client
end