LZW

local fls = require("filesystem")
local shl = require("shell")
local b32 = require("bit32")
local args = shl.parse(...)
frompath, topath = args[1], args[2]

VALUE = 0 LEN = 0
function AddBite(value, len)
  VALUE = b32.lshift(VALUE, len) + value
  LEN = LEN + len
  while LEN > 7 do
    file:write(string.char(b32.rshift(VALUE, LEN - 8)))
    VALUE = VALUE % (2 ^ (LEN - 8))
    LEN = LEN - 8
  end
end


function inflate()
  OUTPUT = {}
  local dict = {}
  for i=0, 255 do
    dict[string.char(i)] = i
  end
  INDEX = 255

  file = io.open(frompath, "r")
  STR = file:read("*a")
  file:close()

  file = io.open(topath, "wb")
  word = STR:sub(1, 1)
  for i=2, #STR do
    if dict[word] == nil then
      OUTPUT[#OUTPUT + 1] = dict[word:sub(1, -2)]
      AddBite(OUTPUT[#OUTPUT], math.ceil(math.log(INDEX + 1, 2)))

      dict[word] = INDEX + 1
      INDEX = INDEX + 1
      word = word:sub(-1)..STR:sub(i, i)
    else
      word = word..STR:sub(i, i)
    end
  end
  if dict[word] == nil then
    OUTPUT[#OUTPUT + 1] = dict[word:sub(1, -2)]
    AddBite(OUTPUT[#OUTPUT], math.ceil(math.log(INDEX + 1, 2)))
    dict[word] = INDEX + 1
    INDEX = INDEX + 1
    word = word:sub(-1)
  end
  OUTPUT[#OUTPUT + 1] = dict[word]
  AddBite(OUTPUT[#OUTPUT], math.ceil(math.log(INDEX + 1, 2)))
  if LEN ~= 0 then
    file:write(string.char(b32.lshift(VALUE, 8 - LEN)))
  end

  file:close()
end

function PutBite() local len = math.ceil(math.log(INDEX, 2))
  while LEN < len do
    if POS > #STR1 then return false
    end
    VALUE = VALUE * 256 + STR1:byte(POS)
    POS = POS + 1
    LEN = LEN + 8
  end
  LEN = LEN - len
  local tmp = b32.rshift(VALUE, LEN)
  VALUE = VALUE % (2 ^ LEN)
  return tmp
end


function deflate()
  dict1 = {}
  for i=0, 255 do
    dict1[i] = string.char(i)
  end
  INDEX = 256
  INPUT = ""
  VALUE, POS, LEN = 0, 1, 0
  file = io.open(topath, "rb")
  STR1 = file:read("*a")
  file:close()

  local TEMP = PutBite()
  INPUT = dict1[TEMP]
  dict1[INDEX] = dict1[TEMP]
  INDEX = INDEX + 1
  i = 2
  while true do
    TEMP = PutBite()
    if TEMP == false then break end
    dict1[INDEX - 1] = dict1[INDEX - 1]..dict1[TEMP]:sub(1, 1)
    INPUT=INPUT..dict1[TEMP]
    dict1[INDEX]=dict1[TEMP]
    INDEX = INDEX + 1
    i = i + 1
  end
--  INPUT = INPUT..dict1[INDEX - 1]
end

inflate()
deflate()