local shell = require "shell"
local mtar = require "libmtar"
local fs = require "filesystem"

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

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

local function cleanPath(path)
 local pt = {}
 for segment in path:gmatch("[^/]+") do
  if segment == ".." then
   pt[#pt] = nil
  elseif segment ~= "." then
   pt[#pt+1] = segment
  end
 end
 return table.concat(pt,"/")
end

function unarchive(stream,dest,verbose,csize)
 csize = csize or 2048
 function vwrite(...)
  if verbose then
   io.write(...)
  end
 end
 for fname, read, len in mtar.iter(stream) do
  local written = 0
  fname = cleanPath(fname)
  vwrite(string.format("%s %i... ",fname,len))
  local dir = fname:match("(.+)/.*%.?.+")
  if dir then
   if dir:sub(1,1) ~= "/" then
    dir = os.getenv("PWD").."/"..dir
   end
   fs.makeDirectory(dest.."/"..dir)
  end
  local f = io.open(dest.."/"..fname,"wb")
  if f then
   repeat
    local rb = read(csize)
    written = written + rb:len()
    f:write(rb)
    vwrite(written)
    vwrite(" ")
   until written == len
   f:close()
   vwrite("done\n")
  else
   vwrite("failed to open "..fname.."\n")
  end
 end
end

function open(fn,mode)
 local f
 if opts.z then
  f = lz16.open(fn, mode)
  if mode == "w" and tonumber(opts.csize) then
   f.bufferSize = tonumber(opts.csize)
  end
 else
  f = io.open(fn, mode)
 end
 return f
end

if opts.x then
 local f = open(args[1],"rb")
 if not f then error("unable to open file") end
 local w, r = unarchive(f,args[2] or ".",opts.v)
 f:close()
elseif opts.t then
 local f = open(args[1],"rb")
 if not f then error("unable to open file") end
 for name, _, fsize in mtar.iter(f) do
  print(name..": "..tostring(fsize))
 end
 f:close()
elseif opts.c then
 local mode = (opts.r and "ab") or "wb"
 local f = open(args[1],mode)
 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] [--csize=blocksize]
Operations:
 x: extract archive
 c: create archive
 t: list contents of archive
Flags:
 v: be verbose
 z: use LZSS compression (requires liblz16)
 r: append rather than overwrite
Extended options:
 csize: compression input block size]])
end