local component=require("component")
local fs=require("filesystem")
local internet=require("internet")
local shell=require("shell")
local text=require("text")

if not component.isAvailable("internet")then
io.stderr:write("This program requires an internet card to run.")
return
end

local args,options=shell.parse(...)
options.q=options.q or options.Q

if#args<1 then
io.write("Usage: wget [-fq] <url> [<filename>]\n")
io.write(" -f: Force overwriting existing files.\n")
io.write(" -q: Quiet mode - no status messages.\n")
io.write(" -Q: Superquiet mode - no error messages.")
return
end

local url=text.trim(args[1])
local filename=args[2]
if not filename then
filename=url
local index=string.find(filename,"/[^/]*$")
if index then
filename=string.sub(filename,index+1)
end
index=string.find(filename,"?",1,true)
if index then
filename=string.sub(filename,1,index-1)
end
end
filename=text.trim(filename)
if filename==""then
if not options.Q then
io.stderr:write("could not infer filename, please specify one")
end
return nil,"missing target filename"
end
filename=shell.resolve(filename)

local preexisted
if fs.exists(filename)then
preexisted=true
if not options.f then
if not options.Q then
io.stderr:write("file already exists")
end
return nil,"file already exists"
end
end

local f,reason=io.open(filename,"a")
if not f then
if not options.Q then
io.stderr:write("failed opening file for writing: "..reason)
end
return nil,"failed opening file for writing: "..reason
end
f:close()
f=nil

if not options.q then
io.write("Downloading... ")
end
local result,response=pcall(internet.request,url,nil,{["user-agent"]="Wget/OpenComputers"})
if result then
local result,reason=pcall(function()
for chunk in response do
if not f then
f,reason=io.open(filename,"wb")
assert(f,"failed opening file for writing: "..tostring(reason))
end
f:write(chunk)
end
end)
if not result then
if not options.q then
io.stderr:write("failed.\n")
end
if f then
f:close()
if not preexisted then
fs.remove(filename)
end
end
if not options.Q then
io.stderr:write("HTTP request failed: "..reason.."\n")
end
return nil,reason
end
if not options.q then
io.write("success.\n")
end

if f then
f:close()
end

if not options.q then
io.write("Saved data to "..filename.."\n")
end
else
if not options.q then
io.write("failed.\n")
end
if not options.Q then
io.stderr:write("HTTP request failed: "..response.."\n")
end
return nil,response
end
return true