--[[
IRCCC v 0.9.2 ComputerCraft IRC Client
Matti Vapa, 2014
https://github.com/mattijv/IRCCC/
http://pastebin.com/gaSL8HZC

This is a ComputerCraft IRC client, or more specifically a client for the qwebirc backend server.
Unfortunately the HTTP API in ComputerCraft doesn't allow for a true IRC client (even though the
HTTP protocol can in theory be used to communicate with an IRC server[1]). This client provides
a work-around by interfacing with the qwebirc backend. qwebirc is a popular webchat interface and
is relatively straightforward to work with. In addition, several IRC servers already host a webchat
server, so there's no need to set up your own, although that remains a possibility if you can't
find a webchat for your favourite server to connect to.

How to use:

        * Download with: pastebin get gaSL8HZC irc
        * Check that the baseUrl and dynamicUrl parameters are correct. Examples are provided for espernet
          and quakenet. By default the client connects to espernet.
        * Start the client with:
                irc

You can also supply an optional nick argument to set your nickname, or you can change your nick within the client with the standard /nick command.
Currently supported commands are:

/window N                       - switch to window N
/join CHANNEL           - join CHANNEL
/part                           - part the current channel or private chat
/quit                           - disconnect and quit
/nick NICK                      - change nickname to NICK
/query USER             - start a private chat with user USER
/help                           - list available commands


1. https://www.youtube.com/watch?v=2ctRfWnisSk#t=343

TODO:
                - color support
                - better handling of the IRC protocol
                - use window API where available

This program is released under the MIT license.

]]--


-- look at the source of the qwebirc webchat login page and take the values
-- for baseUrl and dynamicBaseUrl for use here
-- examples for espernet and quakenet

local baseUrl = "http://irc.freenode.net/"
local dynamicUrl = ""
--local baseUrl = "http://webchat.quakenet.org/"
--local dynamicUrl = "dynamic/leibniz/"


--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
-- JSON4Lua: JSON encoding / decoding support for the Lua language.
-- json Module.
-- Author: Craig Mason-Jones
-- Homepage: http://json.luaforge.net/
-- Version: 0.9.40
-- This module is released under the MIT License (MIT).

-- edited for brevity

local base = _G
local decode_scanArray
local decode_scanComment
local decode_scanConstant
local decode_scanNumber
local decode_scanObject
local decode_scanString
local decode_scanWhitespace
local encodeString
local isArray
local isEncodable

local function encode (v)
  -- Handle nil values
  if v==nil then
    return "null"
  end

  local vtype = base.type(v)

  -- Handle strings
  if vtype=='string' then
    return '"' .. encodeString(v) .. '"'            -- Need to handle encoding in string
  end

  -- Handle booleans
  if vtype=='number' or vtype=='boolean' then
    return base.tostring(v)
  end

  -- Handle tables
  if vtype=='table' then
    local rval = {}
    -- Consider arrays separately
    local bArray, maxCount = isArray(v)
    if bArray then
      for i = 1,maxCount do
        table.insert(rval, encode(v[i]))
      end
    else        -- An object, not an array
      for i,j in base.pairs(v) do
        if isEncodable(i) and isEncodable(j) then
          table.insert(rval, '"' .. encodeString(i) .. '":' .. encode(j))
        end
      end
    end
    if bArray then
      return '[' .. table.concat(rval,',') ..']'
    else
      return '{' .. table.concat(rval,',') .. '}'
    end
  end

  -- Handle null values
  if vtype=='function' and v==null then
    return 'null'
  end

  base.assert(false,'encode attempt to encode unsupported type ' .. vtype .. ':' .. base.tostring(v))
end

local function decode(s, startPos)
  startPos = startPos and startPos or 1
  startPos = decode_scanWhitespace(s,startPos)
  base.assert(startPos<=string.len(s), 'Unterminated JSON encoded object found at position in [' .. s .. ']')
  local curChar = string.sub(s,startPos,startPos)
  -- Object
  if curChar=='{' then
    return decode_scanObject(s,startPos)
  end
  -- Array
  if curChar=='[' then
    return decode_scanArray(s,startPos)
  end
  -- Number
  if string.find("+-0123456789.e", curChar, 1, true) then
    return decode_scanNumber(s,startPos)
  end
  -- String
  if curChar==[["]] or curChar==[[']] then
    return decode_scanString(s,startPos)
  end
  if string.sub(s,startPos,startPos+1)=='/*' then
    return decode(s, decode_scanComment(s,startPos))
  end
  -- Otherwise, it must be a constant
  return decode_scanConstant(s,startPos)
end

local function null()
  return null -- so json.null() will also return null ;-)
end


function decode_scanArray(s,startPos)
  local array = {}      -- The return value
  local stringLen = string.len(s)
  base.assert(string.sub(s,startPos,startPos)=='[','decode_scanArray called but array does not start at position ' .. startPos .. ' in string:\n'..s )
  startPos = startPos + 1
  -- Infinite loop for array elements
  repeat
    startPos = decode_scanWhitespace(s,startPos)
    base.assert(startPos<=stringLen,'JSON String ended unexpectedly scanning array.')
    local curChar = string.sub(s,startPos,startPos)
    if (curChar==']') then
      return array, startPos+1
    end
    if (curChar==',') then
      startPos = decode_scanWhitespace(s,startPos+1)
    end
    base.assert(startPos<=stringLen, 'JSON String ended unexpectedly scanning array.')
    object, startPos = decode(s,startPos)
    table.insert(array,object)
  until false
end

function decode_scanComment(s, startPos)
  base.assert( string.sub(s,startPos,startPos+1)=='/*', "decode_scanComment called but comment does not start at position " .. startPos)
  local endPos = string.find(s,'*/',startPos+2)
  base.assert(endPos~=nil, "Unterminated comment in string at " .. startPos)
  return endPos+2
end

function decode_scanConstant(s, startPos)
  local consts = { ["true"] = true, ["false"] = false, ["null"] = nil }
  local constNames = {"true","false","null"}

  for i,k in base.pairs(constNames) do
    --print ("[" .. string.sub(s,startPos, startPos + string.len(k) -1) .."]", k)
    if string.sub(s,startPos, startPos + string.len(k) -1 )==k then
      return consts[k], startPos + string.len(k)
    end
  end
  base.assert(nil, 'Failed to scan constant from string ' .. s .. ' at starting position ' .. startPos)
end

function decode_scanNumber(s,startPos)
  local endPos = startPos+1
  local stringLen = string.len(s)
  local acceptableChars = "+-0123456789.e"
  while (string.find(acceptableChars, string.sub(s,endPos,endPos), 1, true)
        and endPos<=stringLen
        ) do
    endPos = endPos + 1
  end
  local stringValue = 'return ' .. string.sub(s,startPos, endPos-1)
  local stringEval = base.loadstring(stringValue)
  base.assert(stringEval, 'Failed to scan number [ ' .. stringValue .. '] in JSON string at position ' .. startPos .. ' : ' .. endPos)
  return stringEval(), endPos
end

function decode_scanObject(s,startPos)
  local object = {}
  local stringLen = string.len(s)
  local key, value
  base.assert(string.sub(s,startPos,startPos)=='{','decode_scanObject called but object does not start at position ' .. startPos .. ' in string:\n' .. s)
  startPos = startPos + 1
  repeat
    startPos = decode_scanWhitespace(s,startPos)
    base.assert(startPos<=stringLen, 'JSON string ended unexpectedly while scanning object.')
    local curChar = string.sub(s,startPos,startPos)
    if (curChar=='}') then
      return object,startPos+1
    end
    if (curChar==',') then
      startPos = decode_scanWhitespace(s,startPos+1)
    end
    base.assert(startPos<=stringLen, 'JSON string ended unexpectedly scanning object.')
    -- Scan the key
    key, startPos = decode(s,startPos)
    base.assert(startPos<=stringLen, 'JSON string ended unexpectedly searching for value of key ' .. key)
    startPos = decode_scanWhitespace(s,startPos)
    base.assert(startPos<=stringLen, 'JSON string ended unexpectedly searching for value of key ' .. key)
    base.assert(string.sub(s,startPos,startPos)==':','JSON object key-value assignment mal-formed at ' .. startPos)
    startPos = decode_scanWhitespace(s,startPos+1)
    base.assert(startPos<=stringLen, 'JSON string ended unexpectedly searching for value of key ' .. key)
    value, startPos = decode(s,startPos)
    object[key]=value
  until false   -- infinite loop while key-value pairs are found
end

function decode_scanString(s,startPos)
  base.assert(startPos, 'decode_scanString(..) called without start position')
  local startChar = string.sub(s,startPos,startPos)
  base.assert(startChar==[[']] or startChar==[["]],'decode_scanString called for a non-string')
  local escaped = false
  local endPos = startPos + 1
  local bEnded = false
  local stringLen = string.len(s)
  repeat
    local curChar = string.sub(s,endPos,endPos)
    -- Character escaping is only used to escape the string delimiters
    if not escaped then
      if curChar==[[\]] then
        escaped = true
      else
        bEnded = curChar==startChar
      end
    else
      -- If we're escaped, we accept the current character come what may
      escaped = false
    end
    endPos = endPos + 1
    base.assert(endPos <= stringLen+1, "String decoding failed: unterminated string at position " .. endPos)
  until bEnded
  local stringValue = 'return ' .. string.sub(s, startPos, endPos-1)
  local stringEval = base.loadstring(stringValue)
  base.assert(stringEval, 'Failed to load string [ ' .. stringValue .. '] in JSON4Lua.decode_scanString at position ' .. startPos .. ' : ' .. endPos)
  return stringEval(), endPos
end

function decode_scanWhitespace(s,startPos)
  local whitespace=" \n\r\t"
  local stringLen = string.len(s)
  while ( string.find(whitespace, string.sub(s,startPos,startPos), 1, true)  and startPos <= stringLen) do
    startPos = startPos + 1
  end
  return startPos
end

function encodeString(s)
  s = string.gsub(s,'\\','\\\\')
  s = string.gsub(s,'"','\\"')
  s = string.gsub(s,'\n','\\n')
  s = string.gsub(s,'\t','\\t')
  return s
end

function isArray(t)
  -- Next we count all the elements, ensuring that any non-indexed elements are not-encodable
  -- (with the possible exception of 'n')
  local maxIndex = 0
  for k,v in base.pairs(t) do
    if (base.type(k)=='number' and math.floor(k)==k and 1<=k) then      -- k,v is an indexed pair
      if (not isEncodable(v)) then return false end     -- All array elements must be encodable
      maxIndex = math.max(maxIndex,k)
    else
      if (k=='n') then
        if v ~= table.getn(t) then return false end  -- False if n does not hold the number of elements
      else -- Else of (k=='n')
        if isEncodable(v) then return false end
      end  -- End of (k~='n')
    end -- End of k,v not an indexed pair
  end  -- End of loop across all pairs
  return true, maxIndex
end

function isEncodable(o)
  local t = base.type(o)
  return (t=='string' or t=='boolean' or t=='number' or t=='nil' or t=='table') or (t=='function' and o==null)
end

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

-- ComputerCraft IRC client code begins here

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

local defaultNick = "cc-irc-client"..tostring(math.random(1,1000))
local nick = Verti_
local password = nil
local newNick = "Verti__"

local counter = 0 -- used by the qwebirc protocol for something
local sessionID = "" -- as is this, although a bit more self evident

local currentChannel = "status"
local quitReason = ""

local BUFFERSIZE = 100 -- keep this many lines in each windows history
local offset = 0 -- for scrolling, not implemented

local w,h = term.getSize()
local legacy = true --(window == nil) CC v < 1.6 doesn't have the window API which would be useful, but maybe later
local windows = {}
local winnumbers = {}
local seen = {}
if not legacy then
        local origTerm = term.current()
        windows["input"] = window.create(origTerm,1,h-1,w,2)
        windows["status"] = window.create(origTerm,1,1,w,h-2)
        windows["current"] = windows["status"]
else
        windows["status"] = {}
        windows["current"] = windows["status"]
end
table.insert(winnumbers,"status")
seen[windows["status"]] = true
local lock = "off"

local win2num = function(win)
        for k,v in pairs(winnumbers) do
                if v == win then return k end
        end
        return nil
end

--os.loadAPI("json")

local post = function(url,data)
        local cacheAvoidance = "abc"..tostring(math.random(0,10000)) -- not sure if this is needed...
        local resp = http.post(baseUrl..dynamicUrl.."e/"..url,"r="..cacheAvoidance.."&t="..tostring(counter)..data)
        counter = counter + 1
        return resp
end

-- better responsiveness with asynchronous methods as we usually let the recv couroutine handle the responses
local request = function(url,data)
        local cacheAvoidance = "abc"..tostring(math.random(0,10000)) -- not sure if this is needed...
        http.request(baseUrl..dynamicUrl.."e/"..url,"r="..cacheAvoidance.."&t="..tostring(counter)..data)
        counter = counter + 1
end

-- these special URLs are used by the webchat server for different methods
local send = function(data)
        return request("p","&s="..sessionID.."&c="..textutils.urlEncode(data))
end

local recv = function()
        return post("s","&s="..sessionID)
end

local connect = function(password)
  if password ~= nil then
        return post("n","&nick="..nick.."&password="..password)
  else
    return post("n","&nick="..nick)
  end
end

-- some helper functions
local pong = function(data)
        return send("PONG :"..data)
end

local quit = function(_reason)
        local reason = _reason or ""
        return send("QUIT :"..reason)
end

-- lua default string methods suck :/
local split = function(str,sep)
        local sep, fields = sep or ":", {}
        local pattern = string.format("([^%s]+)", sep)
        str:gsub(pattern, function(c) fields[#fields+1] = c end)
        return fields
end

local exit = function(reason)
        local r = reason or ""
        term.clear()
        term.setCursorPos(1,1)
        print(r)
end

-- for debug
local writeLine
writeLine = function(data,line)
        if not (type(data) == "table") then
                return tostring(data)
        end
        for i=1,#data do
                if type(data[i]) == "table" then
                        line = writeLine(data[i],line)
                elseif data[i] ~= nick then
                        line = line..data[i].." "
                end
        end
        return line
end

-- some IRC protocol codes we handle "properly"
local codes = {}
codes["371"] = "RPL_INFO"
codes["374"] = "RPL_ENDINFO"
codes["375"] = "RPL_MOTDSTART"
codes["372"] = "RPL_MOTD"
codes["376"] = "RPL_ENDOFMOTD"
codes["352"] = "RPL_WHOREPLY"

-- add lines to window
local writeToWin = function(win, s)
        if win ~= windows["current"] then
                seen[win] = false
        end
        if legacy then
                while #s > w do
                        table.insert(win,s:sub(1,w))
                        s = s:sub(w+1)
                end
                table.insert(win,s)
                while #win > BUFFERSIZE do
                        table.remove(win,1)
                end
        end
end

-- helper
local errormsg = function(msg)
        if legacy then
                writeToWin(windows["status"],msg)
        end
end

-- draw the current window to the screen
local drawWin = function(win)
        if legacy then
                local x,y = term.getCursorPos()
                for i = 2,h-2 do
                        term.setCursorPos(1,i)
                        term.clearLine()
                end
                if #win > 0 then
                        local i = math.max(1,#win-h+4)
                        iend = #win
                        local row = 2
                        while i <= iend do
                                term.setCursorPos(1,row)
                                local line = win[i]
                                --[[
                                local n = 0
                                while #line > w do
                                        term.write(line:sub(1,w))
                                        row = row + 1
                                        n = n + 1
                                        term.setCursorPos(1,row)
                                        line = line:sub(w+1)
                                end
                                ]]--
                                term.write(line)
                                row = row + 1
                                i = i + 1
                        end
                end
                term.setCursorPos(x,y)
        end
end

-- draw the separator with list of windows and indicators of activity

local drawSeparator = function()
        if legacy then
                local x,y = term.getCursorPos()
                local nwin = #winnumbers
                --local left = math.floor(0.5*(w-2*nwin+1))
                --local right = w-left-2*nwin-1
                term.setCursorPos(1,h-1)
                term.write(string.rep("-",w))
                local newcount = 0
                for i = 1,nwin do
                        if not seen[windows[winnumbers[i]]] then
                                newcount = newcount + 1
                        end
                end
                local start = math.ceil(0.5*(w-(2*nwin+1+newcount)))
                term.setCursorPos(start,h-1)
                for i=1,nwin do
                        term.write(" ")
                        if winnumbers[i] == currentChannel then
                                term.setBackgroundColor(colors.white)
                                term.setTextColor(colors.black)
                        end
                        term.write(string.format("%d",i))
                        if not seen[windows[winnumbers[i]]] then
                                term.write("+")
                        end
                        term.setBackgroundColor(colors.black)
                        term.setTextColor(colors.white)
                end
                term.write(" ")
                term.setCursorPos(x,y)
        end
end

-- top banner with channel name
local drawBanner = function()
        local x,y = term.getCursorPos()
        term.setCursorPos(1,1)
        term.clearLine()
        --local banner = "["..currentChannel.."]"
        local banner = currentChannel
        local start = math.ceil(0.5*(w-#banner))
        term.setCursorPos(start,1)
        term.write(banner)
        term.setCursorPos(x,y)
end

local drawInput = function()
        if legacy then
                term.setCursorPos(1,h)
                term.clearLine()
                term.write("> ")
        end
end

local handleResponse = function(data)
        for i = 1, #data do
                local id = data[i][2]
                if id == "PING" then
                        pong(data[i][4][1])
                elseif id == "PRIVMSG" then
                        local senderDetails = data[i][3]
                        local sender = senderDetails:sub(1,senderDetails:find("!")-1)
                        local channel = data[i][4][1]:lower()
      --print(textutils.serialize(data[i]))
      --print(channel)
                        if channel == nick then
                                channel = sender
                                if not windows[sender] then
                                        if legacy then
                                                windows[channel] = {}
                                        end
                                        table.insert(winnumbers,channel)
                                        seen[windows[channel]] = false
                                end
                        end
                        local msg = data[i][4][2]
                        if legacy then
                                writeToWin(windows[channel],"<"..sender.."> "..msg)
                        end
                        --print("<"..sender.."> "..msg)
                elseif id == "NICK" then
                        if newNick ~= "" then
                                local name = data[i][3]:sub(1,data[i][3]:find("!")-1)
                                if name == nick then
                                        nick = newNick
                                        newNick = ""
                                end
                        end
                elseif id == "433" then
                        writeToWin(windows["status"],"Nickname already in use!")
                        newNick = ""
                elseif codes[id] then
                        if legacy then
                                writeToWin(windows["status"],writeLine(data[i][4],""))
                                --print(data[i][4][2])
                        end
                        --print(data[i][4][2])
                else
                        errormsg(writeLine(data[i],""))
                end
        end
end

commands = {}
commands["join"] = function(input)
  if not input[2] then
    errormsg("No channel specified!")
    return true
  end
        local channel = input[2]:lower()
        if channel:sub(1,1) ~= "#" then
                errormsg("Invalid channel name!")
                return true
        end
        currentChannel = channel
        if legacy then
                windows[channel] = {}
        end
        windows["current"] = windows[currentChannel]
        table.insert(winnumbers,channel)
        seen[windows[channel]] = true
        send("JOIN "..channel)
        return true
end

commands["who"] = function(input)
        local channel = input[2]
        send("WHO "..channel)
        return true
end

commands["whois"] = function(input)
        local user = input[2]
        send("WHOIS "..user)
        return true
end

commands["part"] = function(input)
        local channel = currentChannel
        if channel == "status" then
                errormsg("Can't part status window!")
        else
                local nwin
                for i,v in pairs(winnumbers) do
                        if v == channel then
                                nwin = i
                                break
                        end
                end
                table.remove(winnumbers,nwin)
                seen[windows[channel]] = nil
                windows[channel] = nil
                currentChannel = winnumbers[#winnumbers]
                print(currentChannel)
                windows["current"] = windows[currentChannel]
                seen[windows["current"]] = true
                if channel:sub(1,1) == "#" then
                        send("PART "..channel)
                end
        end
        return true
end

commands["quit"] = function(input)
        quit(input[2])
        return false
end

commands["window"] = function(input)
        local nwin = tonumber(input[2])
        if not nwin then
                errormsg("Invalid window number!")
        elseif nwin > #winnumbers or nwin < 1 then
                errormsg("Invalid window number!")
        else
                windows["current"] = windows[winnumbers[nwin]]
                seen[windows["current"]] = true
                currentChannel = winnumbers[nwin]
        end
        return true
end

commands["nick"] = function(input)
        local nickname = input[2]
        if nickname then
                send("NICK "..nickname)
                newNick = nickname
                writeToWin(windows["status"],"Changed nick to: "..newNick)
        else
                errormsg("No nickname given.")
        end
        return true
end

commands["query"] = function(input)
        local user = input[2]
        if user then
                currentChannel = user
                if legacy then
                        windows[user] = {}
                end
                windows["current"] = windows[currentChannel]
                table.insert(winnumbers,user)
                seen[windows[user]] = true
                --send("JOIN "..channel)
        else
                errormsg("No username given.")
        end
        return true
end

commands["help"] = function(input)
        writeToWin(windows["status"],"Available commands:")
        for k,v in pairs(commands) do
                writeToWin(windows["status"],"- "..k)
        end
        return true
end

local alias = {}
alias["w"] = "window"
alias["j"] = "join"
alias["p"] = "part"
alias["q"] = "quit"
alias["exit"] = "quit"
alias["e"] = "quit"
alias["n"] = "nick"
alias["qr"] = "query"
alias["h"] = "help"


local changeWindow = function(nwin)
        windows["current"] = windows[winnumbers[nwin]]
        seen[windows["current"]] = true
        currentChannel = winnumbers[nwin]
        return true
end

local handeInput = function(input)
        if not input then return true end
        if input:sub(1,1) == "/" then
                input = split(input," ")
                local cmd = input[1]:sub(2)
                if commands[cmd] then
                        return commands[cmd](input)
                elseif alias[cmd] then
                        return commands[alias[cmd]](input)
                else
                        errormsg("Invalid command!")
                end
        elseif currentChannel ~= "status" then
                        send("PRIVMSG "..currentChannel.." :"..input)
                        writeToWin(windows["current"],"<"..nick.."> "..input)
        else
                writeToWin(windows["status"],input)
        end
        return true
end

local keys = {}

-- arrow keys cause problems with read() :/

--[[
keys[203] = function() -- LEFT
        local n = win2num(currentChannel)
        if n > 1 then
                changeWindow(n-1)
        end
        return true
end

keys[205] = function() -- RIGHT
        local n = win2num(currentChannel)
        if n < #winnumbers then
                changeWindow(n+1)
        end
        return true
end
]]--

-- TAB to cycle through windows
keys[15] = function()
        local n = win2num(currentChannel)
        if n < #winnumbers then
                changeWindow(n+1)
        else
                changeWindow(1)
        end
        return true
end

local receive = function()
        resp = recv()
        while resp do
                _data = resp.readAll()
                if #_data > 0 then
                        data = decode(_data)
                        handleResponse(data)
                        while lock == "on" do
                                sleep(0.1)
                        end
                        lock = "on"
                        drawBanner()
                        drawWin(windows["current"])
                        drawSeparator()
                        --drawInput()
                        lock = "off"
                end
                resp = recv()
        end
        quitReason = "Disconnected!"
end

local interface = function()
        input = read()
        while handeInput(input) do
                while lock == "on" do
                        sleep(0.1)
                end
                lock = "on"
                drawBanner()
                drawWin(windows["current"])
                drawSeparator()
                drawInput()
                lock = "off"
                input = read()
        end
        quitReason = "Bye!"
end

local specialKeys = function()
        while true do
                local ev, key = os.pullEvent("key")
                if keys[key] then
                        if not keys[key]() then break end
                        while lock == "on" do
                                sleep(0.1)
                        end
                        lock = "on"
                        drawBanner()
                        drawWin(windows["current"])
                        drawSeparator()
                        --drawInput()
                        lock = "off"
                end
        end
        quitReason = "Bye!"
end

local args = {...}
if #args > 0 then
        if args[1] == "help" then
                print("Usage: irc [nick] [password]")
                print("Edit the file to change servers.")
                return
        else
                nick = args[1]
    password = args[2]
        end
end
drawBanner()
drawWin(windows["current"])
drawSeparator()
drawInput()
errormsg("Connecting...")
resp = connect(password)
if not resp then exit("Unable to connect!") return end
_data = resp.readAll()
data = decode(_data)
sessionID = data[2]
errormsg("Got sessionID: "..sessionID)
--sleep(1)
parallel.waitForAny(receive,interface,specialKeys)
exit(quitReason)