local shell=require("shell")
local fs=require("filesystem")

local args,options,reason=shell.parse(...)
if#args==0 then
args[1]='.'
end

local TRY=[[
Try 'du --help' for more information.]]

local VERSION=[[
du (OpenOS bin) 1.0
Written by payonel, patterned after GNU coreutils du]]

local HELP=[[
Usage: du [OPTION]... [FILE]...
Summarize disk usage of each FILE, recursively for directories.

  -h, --human-readable  print sizes in human readable format (e.g., 1K 234M 2G)
  -s, --summarize       display only a total for each argument
      --help     display this help and exit
      --version  output version information and exit]]

if options.help then
print(HELP)
return true
end

if options.version then
print(VERSION)
return true
end

local function addTrailingSlash(path)
if path:sub(-1)~='/'then
return path..'/'
else
return path
end
end

local function opCheck(shortName,longName)
local enabled=options[shortName]or options[longName]
options[shortName]=nil
options[longName]=nil
return enabled
end

local bHuman=opCheck('h','human-readable')
local bSummary=opCheck('s','summarize')

if next(options)then
for op,v in pairs(options)do
io.stderr:write(string.format("du: invalid option -- '%s'\n",op))
end
io.stderr:write(TRY..'\n')
return 1
end

local function formatSize(size)
if not bHuman then
return tostring(size)
end
local sizes={"","K","M","G"}
local unit=1
local power=options.si and 1000 or 1024
while size>power and unit<#sizes do
unit=unit+1
size=size/power
end

return math.floor(size*10)/10 ..sizes[unit]
end

local function printSize(size,rpath)
local displaySize=formatSize(size)
io.write(string.format("%s%s\n",string.format("%-12s",displaySize),rpath))
end

local function visitor(rpath)
local subtotal=0
local dirs=0
local spath=shell.resolve(rpath)

if fs.isDirectory(spath)then
local list_result=fs.list(spath)
for list_item in list_result do
local vtotal,vdirs=visitor(addTrailingSlash(rpath)..list_item)
subtotal=subtotal+vtotal
dirs=dirs+vdirs
end

if dirs==0 then
if not bSummary then
printSize(subtotal,rpath)
end
end

elseif not fs.isLink(spath)then
subtotal=fs.size(spath)
end

return subtotal,dirs
end

for i,arg in ipairs(args)do
local path=shell.resolve(arg)

if not fs.exists(path)then
io.stderr:write(string.format("du: cannot access '%s': no such file or directory\n",arg))
return 1
else
if fs.isDirectory(path)then
local total=visitor(arg)

if bSummary then
printSize(total,arg)
end
elseif fs.isLink(path)then
printSize(0,arg)
else
printSize(fs.size(path),arg)
end
end
end

return true