local lz = require "lzss"
local shell = pcall(require,shell)

local tA, tO = {}, {}
if shell then
 tA, tO = shell.parse(...)
else
 tA, tO = {...}, {}
end
tO.bsize = tO.bsize or 16384

local function cint(n,l)
 local t={}
 for i = 0, 7 do
  t[i+1] = (n >> (i * 8)) & 0xFF
 end
 return string.reverse(string.char(table.unpack(t)):sub(1,l))
end
local function toint(s)
 s=s or ""
 local n = 0
 local i = 1
 while true do
  local p = s:sub(i,i)
  if p == "" then break end
  local b = string.byte(p)
  n = n << 8
  n = n | b
  i=i+1
 end
 return n
end

local function cfile(fn)
 local fi = io.open(fn,"rb")
 if not fi then return false end
 local fo = io.open(fn..".lss","wb")
 if not fo then fi:close() return false end
 fo:write("lz16") -- write header
 while true do
  local rblock = fi:read(tO.bsize)
  if rblock == "" or not rblock then break end
  local cblock = lz.compress(rblock)
  fo:write(cint(cblock:len(),2)..cblock)
 end
 fi:close()
 fo:close()
 return true
end
local function xfile(fn)
 local fi = io.open(fn,"rb")
 if not fi then return false, "unable to open input file" end
 if fi:read(4) ~= "lz16" and not tO.f then
  return false, "not an lz16 archive"
 end
 local fo = io.open(fn:sub(1,-5),"wb")
 if not fo then fi:close() return false, "unable to open output file" end
 while true do
  local len = toint(fi:read(2) or "\0\0")
  if len < 1 then
   break
  end
  fo:write(lz.decompress(fi:read(len)))
 end
 fi:close()
 fo:close()
 return true
end

if tO.x then -- extract
 for k,v in pairs(tA) do
  io.write(v.."...")
  local s,r = xfile(v)
  if s then
   print(" done")
  else
   print(" failed: "..r)
  end
 end
else -- create
 for k,v in pairs(tA) do
  io.write(v.."...")
  if cfile(v) then
   print(" done.")
  else
   print(" failed.")
  end
 end
end