local shell = require "shell"
local mtar = require "libmtar"

local args, opts = shell.parse(...)

local w, lz16 = pcall(require, "liblz16")
if not w then lz16 = nil end

local function toint(s)
 s = s or "\0"
 local n = 0
 local i = 1
 for p in s:gmatch(".") do
  n = n << 8
  n = n | string.byte(p)
  i=i+1
 end
 return n
end

local function vw(s)
 if opts.v and s then
  io.write(tostring(s))
 end
end

local function vp(...)
 for k,v in ipairs({...}) do
  vw(tostring(v).."\n")
 end
end

if opts.x then
 local f
 if opts.z then
  f = lz16.open(args[1],"rb")
 else
  f = io.open(args[1],"rb")
 end
 if not f then error("unable to open file") end
 local w, r = mtar.unarchive(f,args[2] or ".",opts.v)
 f:close()
elseif opts.t then
 local f
 if opts.z then
  f = lz16.open(args[1],"rb")
 else
  f = io.open(args[1],"rb")
 end
 if not f then error("unable to open file") end
 while true do
  local nlen = toint(f:read(2))
  if nlen == 0 then
   break
  end
  local name = f:read(nlen)
  local fsize = toint(f:read(2) or "\0\0")
  f:read(fsize)
  print(name..": "..tostring(fsize))
 end
 f:close()
elseif opts.c then
 local mode = (opts.r and "ab") or "wb"
 local f
 if opts.z then
  f = lz16.open(args[1],mode)
 else
  f = io.open(args[1],mode)
 end
 if not f then error("unable to open file") end
 table.remove(args,1)
 local fs = require "filesystem"
 for k,v in pairs(args) do
  local ap = true
  if v:sub(1,1) ~= "/" then
   ap = false
   v = os.getenv("PWD") .. "/" .. v
  end
  v=fs.canonical(v)
  vw(v.."... ")
  if fs.isDirectory(v) then
   vp("directory.")
   for file in fs.list(v) do
    if ap then
     args[#args+1] = v.."/"..file
    else
     args[#args+1] = v:sub(os.getenv("PWD"):len()+2).."/"..file
    end
   end
  else
   local fsize = fs.size(v)
   local inputf = io.open(v,"rb")
   if fsize and inputf then
    local c = 0
    if ap then
     f:write(mtar.genHeader(v,fsize))
    else
     f:write(mtar.genHeader(v:sub(os.getenv("PWD"):len()+2),fsize))
    end
    while true do
     local ib = inputf:read(4096)
     if ib then
      c=c+ib:len()
      f:write(ib)
     else
      break
     end
    end
    vp(c)
   else
    vp("failed to open.")
   end
  end
 end
 f:close()
else
 print([[Usage:
 mtar -[crtxvz] <archivefile> [otherfile] [otherfile]
Operations:
 x: extract archive
 c: create archive
 t: list contents of archive
Flags:
 v: be verbose
 z: use LZSS compression (requires liblz16)]])
end