local IAC, SB, SE = 0xFF, 0xFA, 0xF0
local GMCP = 201

function gmcp_send(data)
  SendPkt(string.char(IAC, SB, GMCP) .. string.gsub(data, "\255", "\255\255") .. string.char(IAC, SE))
end

function gmcp_handshake()
  gmcp_send('Core.Hello {"client": "MUSHclient", "version": "'..Version()..'"}')
  gmcp_send('Core.Supports.Set ["Char 1", "Char.Skills 1", "Char.Items 1", "Char.Defences 1", "Char.Afflictions 1", "Comm.Channel 1", "Room 1", "Redirect 1", "IRE.Rift 1", "IRE.Composer 1", "IRE.Time 1", "IRE.Target 1"]')
end


function OnPluginTelnetRequest(protocol, cmd)
  if (protocol == GMCP) and (cmd == "WILL") then
    return true
  end

  if (protocol == GMCP) and (cmd == "SENT_DO") then
    gmcp_handshake()
    return true
  end

  return false
end


function OnPluginTelnetSubnegotiation(protocol, data)
  if (protocol ~= GMCP) then
    return
  end

  local cmd, jd = string.match(data, "^([A-za-z%.]+)%s*(.*)$")

  if not cmd then
    return
  end

  if jd then
    if not string.match(jd, "^[%[%{]") then
      jd = "["..jd.."]"
    end
  end

  -- The following line has been commented out so as to allow you to handle the data as you wish (and to prevent accidentally spamming yourself out of your gourd in an infinite Char.Vitals loop as has happened to us all).
  -- Instead, I've added in echoes to display the data.
  -- Execute("parsegmcp "..cmd.." "..jd)
  Note("GMCP command: "..cmd)
  Note("GMCP data: "..jd)
  return false
end