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

-- Joseph Weizenbaum's classic Eliza ported to TinyBrain.de

-- Kein-Hong Man <khman@users.sf.net> 20060905

-- Stefan Reich <stefan.reich.maker.of.eye@gmail.com>

-- This program is hereby placed into PUBLIC DOMAIN

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

-- HOW TO USE

-- * This program is for recreational purposes only. :-)

-- * ClassicEliza function will open a new buffer, then type away...

-- * Eliza recognizes one line of input only (if you are typing very

--   long lines, please consider seeing a real person.)

-- * Eliza will not interfere with other buffers or handlers, and is

--   compatible with extman.

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

-- Original ELIZA paper:

--   ELIZA--A Computer Program For the Study of Natural Language

--   Communication Between Man and Machine,

--   Joseph Weizenbaum, 1966, Communications of the ACM Volume 9,

--   Number 1 (January 1966): 36-35.

--   URL: http://i5.nyu.edu/~mm64/x52.9265/january1966.html

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

-- A copy of the original BASIC source of this Lua version of ELIZA can

-- be found at Josep Subirana's ELIZA download page.

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

-- Redefine a Lua 5.0 function still used in this script

table.getn = function (t)

        if t.n then

            return t.n

        else

            local n = 0

            for i in pairs(t) do

                if type(i) == "number" then

                    n = math.max(n, i)

                end

            end

        return n

        end

    end

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

-- Eliza main routine, processes user input

-- * Input is case insensitive. No punctuation except apostrophes,

--   as in: don't you're i'm i've you've.

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

local function Eliza(text)

  local response = ""

  local user = string.upper(text)

  local userOrig = user

  -- randomly selected replies if no keywords

  local randReplies = {

    "WHAT DOES THAT SUGGEST TO YOU?",

    "I SEE...",

    "I'M NOT SURE I UNDERSTAND YOU FULLY.",

    "CAN YOU ELABORATE ON THAT?",

    "THAT IS QUITE INTERESTING!",

    "THAT'S SO... PLEASE CONTINUE...",

    "I UNDERSTAND...",

    "WELL, WELL... DO GO ON",

    "WHY ARE YOU SAYING THAT?",

    "PLEASE EXPLAIN THE BACKGROUND TO THAT REMARK...",

    "COULD YOU SAY THAT AGAIN, IN A DIFFERENT WAY?",

  }

  -- keywords, replies

  local replies = {

    [" CAN YOU"] = "PERHAPS YOU WOULD LIKE TO BE ABLE TO",

    [" DO YOU"] = "YES, I",

    [" CAN I"] = "PERHAPS YOU DON'T WANT TO BE ABLE TO",

    [" YOU ARE"] = "WHAT MAKES YOU THINK I AM",

    [" YOU'RE"] = "WHAT IS YOUR REACTION TO ME BEING",

    [" I DON'T"] = "WHY DON'T YOU",

    [" I FEEL"] = "TELL ME MORE ABOUT FEELING",

    [" WHY DON'T YOU"] = "WHY WOULD YOU WANT ME TO",

    [" WHY CAN'T I"] = "WHAT MAKES YOU THINK YOU SHOULD BE ABLE TO",

    [" ARE YOU"] = "WHY ARE YOU INTERESTED IN WHETHER OR NOT I AM",

    [" I CAN'T"] = "HOW DO YOU KNOW YOU CAN'T",

    [" SEX"] = "I FEEL YOU SHOULD DISCUSS THIS WITH A HUMAN.",

    [" I AM"] = "HOW LONG HAVE YOU BEEN",

    [" I'M"] = "WHY ARE YOU TELLING ME YOU'RE",

    [" I WANT"] = "WHY DO YOU WANT",

    [" WHAT"] = "WHAT DO YOU THINK?",

    [" HOW"] = "WHAT ANSWER WOULD PLEASE YOU THE MOST?",

    [" WHO"] = "HOW OFTEN DO YOU THINK OF SUCH QUESTIONS?",

    [" WHERE"] = "WHY DID YOU THINK OF THAT?",

    [" WHEN"] = "WHAT WOULD YOUR BEST FRIEND SAY TO THAT QUESTION?",

    [" WHY"] = "WHAT IS IT THAT YOU REALLY WANT TO KNOW?",

    [" PERHAPS"] = "YOU'RE NOT VERY FIRM ON THAT!",

    [" DRINK"] = "MODERATION IN ALL THINGS SHOULD BE THE RULE.",

    [" SORRY"] = "WHY ARE YOU APOLOGIZING?",

    [" DREAMS"] = "WHY DID YOU BRING UP THE SUBJECT OF DREAMS?",

    [" I LIKE"] = "IS IT GOOD THAT YOU LIKE",

    [" MAYBE"] = "AREN'T YOU BEING A BIT TENTATIVE?",

    [" NO"] = "WHY ARE YOU BEING NEGATIVE?",

    [" YOUR"] = "WHY ARE YOU CONCERNED ABOUT MY",

    [" ALWAYS"] = "CAN YOU THINK OF A SPECIFIC EXAMPLE?",

    [" THINK"] = "DO YOU DOUBT",

    [" YES"] = "YOU SEEM QUITE CERTAIN. WHY IS THIS SO?",

    [" FRIEND"] = "WHY DO YOU BRING UP THE SUBJECT OF FRIENDS?",

    [" COMPUTER"] = "WHY DO YOU MENTION COMPUTERS?",

    [" AM I"] = "YOU ARE",

  }

  -- conjugate

  local conjugate = {

    [" I "] = "YOU",

    [" ARE "] = "AM",

    [" WERE "] = "WAS",

    [" YOU "] = "ME",

    [" YOUR "] = "MY",

    [" I'VE "] = "YOU'VE",

    [" I'M "] = "YOU'RE",

    [" ME "] = "YOU",

    [" AM I "] = "YOU ARE",

    [" AM "] = "ARE",

  }

  -- random replies, no keyword

  local function replyRandomly()

    response = randReplies[math.random(table.getn(randReplies))].."\n"

  end

  -- find keyword, phrase

  local function processInput()

    for keyword, reply in pairs(replies) do

      local d, e = string.find(user, keyword, 1, 1)

      if d then

        -- process keywords

        response = response..reply.." "

        if string.byte(string.sub(reply, -1)) < 65 then -- "A"

          response = response.."\n"; return

        end

        local h = string.len(user) - (d + string.len(keyword))

        if h > 0 then

          user = string.sub(user, -h)

        end

        for cFrom, cTo in pairs(conjugate) do

          local f, g = string.find(user, cFrom, 1, 1)

          if f then

            local j = string.sub(user, 1, f - 1).." "..cTo

            local z = string.len(user) - (f - 1) - string.len(cTo)

            response = response..j.."\n"

            if z > 2 then

              local l = string.sub(user, -(z - 2))

              if not string.find(userOrig, l) then return end

            end

            if z > 2 then response = response..string.sub(user, -(z - 2)).."\n" end

            if z < 2 then response = response.."\n" end

            return

          end--if f

        end--for

        response = response..user.."\n"

        return

      end--if d

    end--for

    replyRandomly()

    return

  end

  -- main()

  -- accept user input

  if string.sub(user, 1, 3) == "BYE" then

    response = "BYE, BYE FOR NOW.\nSEE YOU AGAIN SOME TIME.\n"

    return response

  end

  if string.sub(user, 1, 7) == "BECAUSE" then

    user = string.sub(user, 8)

  end

  user = " "..user.." "

  -- process input, print reply

  processInput()

  return response

end

if input == '' then

  return "I'm Eliza, your virtual psychiatrist. Please tell me about your worries."

else

  return Eliza(input):gsub('\n+$', '')

end