--[[
Author: theoriginalbit
Version: 1.2 for ComputerCraft 1.6+
Created: 26 APR 2013
Last Update: 18 OCT 2014

Licensed under the MIT License [http://opensource.org/licenses/MIT]
Copyright © 2013 Joshua Asbury a.k.a theoriginalbit [theoriginalbit@gmail.com]
--]]

-- make sure that its only a computer terminal that is displaying
local sw, sh = term.getSize()

if sw ~= 51 and sh ~= 19 then
  error("Sorry this game can only run on computers", 0)
end

-- the wining directions
local winCombos = {
  -- horizontal
  {1,2,3}, {4,5,6}, {7,8,9},
  -- vertical
  {1,4,7}, {2,5,8}, {3,6,9},
  -- diagonal
  {1,5,9}, {3,5,7}
}

local players = {x = 'Player', o = 'The Computer'}
-- whether an AI is active, could be used later to allow SP
local activeAI = true
local currentPlayer
local opposites = { x = 'o', o = 'x' }
local board
local winner
local move
local allowedBgColors = { colors.orange, colors.lightBlue, colors.gray, colors.cyan, colors.purple, colors.blue, colors.brown, colors.green, colors.red, colors.black }
local bg

local function clear(col)
  term.setBackgroundColor(col or colors.black)
  term.clear()
  term.setCursorPos(1,1)
end

-- function thanks to Mads... found here: http://www.computercraft.info/forums2/index.php?/topic/11771-print-coloured-text-easily/page__p__105389#entry105389
local function writeWithFormat(...)
  local s = "&0"
  for k, v in ipairs(arg) do
    s = s .. v
  end
  s = s .. "&0"
  local fields = {}
  local lastcolor, lastpos = "0", 0
  for pos, clr in s:gmatch"()&(%x)" do
    table.insert(fields, {s:sub(lastpos + 2, pos - 1), lastcolor})
    lastcolor, lastpos = clr , pos
  end
  for i = 2, #fields do
    term.setTextColor(2 ^ (tonumber(fields[i][2], 16)))
    write(fields[i][1])
  end
end

-- modification of Mads' function to get the length of the string without the color modifiers
local function countFormatters(text)
  return #(text:gsub("()&(%x)", ''))
end

-- print a color formatted string in the center of the screen
local function cwriteWithFormat(text, y)
  local sw,sh = term.getSize()
  local _,cy = term.getCursorPos()
  term.setCursorPos(math.floor((sw-countFormatters(text))/2)+(countFormatters(text) % 2 == 0 and 1 or 0), y or cy)
  writeWithFormat(text)
end

-- writes the text at the give location
local function writeAt(text, x, y)
  local _,cy = term.getCursorPos()
  term.setCursorPos(x or 1, y or cy)
  write(text)
end

local function reset()
  bg = allowedBgColors[math.random(1, #allowedBgColors)]
  currentPlayer = 'x'
  board = {}
  for i = 1, 9 do
    board[i] = ' '
  end
  winner = nil
  move = nil
end

local function search(match)
  for _, check in ipairs(winCombos) do
    if board[check[1]] == board[check[2]] and board[check[1]] == match and board[check[3]] == ' ' then
      return check[3]
    elseif board[check[1]] == board[check[3]] and board[check[1]] == match and board[check[2]] == ' ' then
      return check[2]
    elseif board[check[2]] == board[check[3]] and board[check[2]] == match and board[check[1]] == ' ' then
      return check[1]
    end
  end
end

local function getAIMove()
  -- make it seem like the computer actually has to think about its move
  sleep(0.8)
  
  -- check if AI can win and return the 3rd tile to create a win, if it cannot, check for a human attempt at winning and stop it, if there is none, return a random
  return (search(currentPlayer) or search(opposites[currentPlayer])) or math.random(1,9)
end

local function modread( _mask, _history, _limit )
  term.setCursorBlink(true)

  local input = ""
  local pos = 0
  if _mask then
    _mask = _mask:sub(1,1)
  end
  local historyPos = nil

  local sw, sh = term.getSize()
  local sx, sy = term.getCursorPos()

  local function redraw( _special )
    local scroll = (sx + pos >= sw and (sx + pos) - sw or 0)
    local replace = _special or _mask
    term.setCursorPos( sx, sy )
    term.write( replace and string.rep(replace, #input - scroll) or input:sub(scroll + 1) )
    term.setCursorPos( sx + pos - scroll, sy )
  end

  while true do
    local event = {os.pullEvent()}
    if event[1] == 'char' and (not _limit or #input < _limit) then
      input = input:sub(1, pos)..event[2]..input:sub(pos + 1)
      pos = pos + 1
    elseif event[1] == 'key' then
      if event[2] == keys.enter then
        break
      elseif event[2] == keys.backspace and pos > 0 then
        redraw(' ')
        input = input:sub(1, pos - 1)..input:sub(pos + 1)
        pos = pos - 1
      elseif event[2] == keys.delete and pos < #input then
        redraw(' ')
        input = input:sub(1, pos)..input:sub(pos + 2)
      elseif event[2] == keys.home then
        pos = 0
      elseif event[2] == keys['end'] then
        pos = #input
      elseif event[2] == keys.left and pos > 0 then
        pos = pos - 1
      elseif event[2] == keys.right and pos < #input then
        pos = pos + 1
      elseif _history and event[2] == keys.up or event[2] == keys.down then
        redraw(' ')
        if event[2] == keys.up then
          if not historyPos then
            historyPos = #_history 
          elseif historyPos > 1 then
            historyPos = historyPos - 1
          end
        else
          if historyPos ~= nil and historyPos < #_history then
            historyPos = historyPos + 1
          elseif historyPos == #_history then
            historyPos = nil
          end
        end

        if historyPos then
          input = string.sub(_history[historyPos], 1, _limit) or ""
          pos = #input
        else
          input = ""
          pos = 0
        end
      end
    elseif event[1] == 'mouse_click' then
      local xPos, yPos = event[3], event[4]
      if xPos == sw and yPos == 1 then
        -- exit and make sure to fool the catch-all
        error('Terminated', 0)
      end
      local row = (xPos >= 16 and xPos <= 21) and 1 or (xPos >= 23 and xPos <= 28) and 2 or (xPos >= 30 and xPos <= 35) and 3 or 10
      local col = (yPos >= 4 and yPos <= 6) and 1 or (yPos >= 8 and yPos <= 10) and 2 or (yPos >= 12 and yPos <= 16) and 3 or 10
      local ret = (col - 1) * 3 + row
      if ret >= 1 and ret <= 9 then
        return ret
      end
    end

    redraw(_mask)
  end

  term.setCursorBlink(false)
  term.setCursorPos(1, sy + 1)

  return input
end

local function getHumanMove()
  writeWithFormat('&b[1-9] >>&f ')
  return modread()
end

local function processInput()
  -- set the cursor pos ready for the input
  term.setCursorPos(3, sh-1)
  move = (currentPlayer == 'x' and getHumanMove or getAIMove)()
end

local function output(msg)
  -- if the player is not an AI, print the error
  if not (activeAI and currentPlayer == 'o') then
    term.setCursorPos(3, sh-1)
    writeWithFormat('&eERROR >> '..msg)
    sleep(2)
  end
end

local function checkMove()
  -- if the user typed exit
  if not tonumber(move) and move:lower() == 'exit' then
    -- exit and make sure to fool the catch-all
    error('Terminated', 0)
  end

  -- attempt to convert the move to a number
  local nmove = tonumber(move)
  -- if it wasn't a number
  if not nmove then
    output(tostring(move)..' is not a number between 1 and 9!')
    return false
  end
  -- if it is not within range of the board
  if nmove > 9 or nmove < 1 then
    output('Must be a number between 1 and 9!')
    return false
  end
  -- if the space is already taken
  if board[nmove] ~= ' ' then
    output('Position already taken!')
    return false
  end
  -- keep the conversion
  move = tonumber(move)
  return true
end

local function checkWin()
  for _, check in ipairs(winCombos) do
    if board[check[1]] ~= ' ' and board[check[1]] == board[check[2]] and board[check[1]] == board[check[3]] then
      return board[check[1]]
    end
  end

  for _, tile in ipairs(board) do
    if tile == ' ' then
      return nil
    end
  end

  return 'tie'
end

local function update()
  if checkMove() then
    board[move] = currentPlayer
    winner = checkWin()

    currentPlayer = currentPlayer == 'x' and 'o' or 'x'
  end
end

local function render()
  -- clear the screen light blue
  clear(bg)

  -- draw the ascii borders
  term.setTextColor(colors.white)
  for i = 2, sh-1 do
    writeAt('|', 1, i)
    writeAt('|', sw, i)
  end
  writeAt('+'..string.rep('-', sw-2)..'+', 1, 1)
  writeAt('+'..string.rep('-', sw-2)..'+', 1, 3)
  writeAt('+'..string.rep('-', sw-2)..'+', 1, sh-2)
  writeAt('+'..string.rep('-', sw-2)..'+', 1, sh)
  
  if term.isColor and term.isColor() then
    term.setCursorPos(sw, 1)
    term.setBackgroundColor(colors.red)
    term.setTextColor(colors.black)
    writeWithFormat('X')
  end
  
  -- set our colours
  term.setBackgroundColor(colors.white)
  term.setTextColor(colors.black)

  -- clear an area for the title
  writeAt(string.rep(' ', sw-2), 2, 2)
  writeAt('Tic-Tac-Toe!', sw/2-5, 2)

  -- clear an area for the input
  writeAt(string.rep(' ', sw-2), 2, sh-1)

  -- clear the area for the board
  local h = sh - 6
  for i = 0, h - 1 do
    writeAt(string.rep(' ', sw - 2), 2, 4+i)
  end

  -- draw the grid
  for i = 0, 10 do
    writeAt(((i == 3 or i == 7) and '------+------+------' or '      |      |      '), 16, i + 4)
  end

  -- draw the first line moves
  for i = 1, 3 do
    if board[i] ~= ' ' then
      writeAt((board[i] == 'x' and '\\/' or '/\\'), 18+((i-1)*7), 5)
      writeAt((board[i] == 'x' and '/\\' or '\\/'), 18+((i-1)*7), 6)
    end
  end
  -- draw the second line moves
  for i = 1, 3 do
    if board[i + 3] ~= ' ' then
      writeAt((board[i + 3] == 'x' and '\\/' or '/\\'), 18+((i-1)*7), 9)
      writeAt((board[i + 3] == 'x' and '/\\' or '\\/'), 18+((i-1)*7), 10)
    end
  end
  -- draw the third line moves
  for i = 1, 3 do
    if board[i + 6] ~= ' ' then
      writeAt((board[i + 6] == 'x' and '\\/' or '/\\'), 18+((i-1)*7), 13)
      writeAt((board[i + 6] == 'x' and '/\\' or '\\/'), 18+((i-1)*7), 14)
    end
  end
  
  -- draw the current player
  term.setCursorPos(3, sh - 3)
  if not winner then
    writeWithFormat('&bCurrent Player: &f'..players[currentPlayer])
  end
end

local function main(arc, argv)
  clear()
  writeWithFormat('&0Welcome to CCTicTacToe by &8TheOriginal&3BIT&0\n\nPlease enter your name\n\n&4>>&0 ')
  players.x = read() or 'Player'

  -- setup the game, will later be used to
  reset()

  -- initial render
  render()

  -- game loop
  while not winner do
    processInput()
    update()
    render()

    -- highly unorthodox having something that isn't in input, update, render!
    -- print the winner info
    if winner then
      writeWithFormat('&f'..(winner == 'tie' and 'There was no winner :(&f' or players[winner]..'&f is the winner!'))
      -- allow the player to start a new game or quit
      writeAt("Press 'R' to play again, 'Q' to quit...", 3, sh - 1)
      while true do
        local _, k = os.pullEvent('key')
        if k == 16 then
          break
        elseif k == 19 then
          reset() -- reset the game
          render() -- render the new game ready to wait for input
          break
        end
      end
      os.pullEvent() -- remove the char event that would be waiting
    end
  end

  return true
end

-- create a terminal object with a non-advanced computer safe version of setting colors
local oldTermObj = term.current()
local termObj = {
  setTextColor = function(n) if term.isColor and term.isColor() then local ok, err = pcall(oldTermObj.setTextColor , n) if not ok then error(err, 2) end end end,
  setBackgroundColor = function(n) if term.isColor and term.isColor() then local ok, err = pcall(oldTermObj.setBackgroundColor , n) if not ok then error(err, 2) end end end
}
-- also override the English spelling of the colour functions
termObj.setTextColour = termObj.setTextColor
termObj.setBackgroundColour = termObj.setBackgroundColor

-- make the terminal object refer to the native terminal for every other function
termObj.__index = oldTermObj
setmetatable(termObj, termObj)

-- redirect the terminal to the new object
term.redirect(termObj)

-- run the program
local ok, err = pcall(main, #{...}, {...})

-- catch-all
if not ok and err ~= 'Terminated' then
  clear()
  print('Error in runtime!')
  print(err)
  sleep(5)
end

-- print thank you message
clear()
cwriteWithFormat('&4Thank you for playing CCTicTacToe v1.0', 1)
cwriteWithFormat('&4By &8TheOriginal&3BIT\n', 2)

-- restore the default terminal object
term.redirect( oldTermObj )