local fs=require("filesystem")
local unicode=require("unicode")
local process=require("process")

local shell={}




local shells=setmetatable({},{__mode="v"})

function shell.getShell()
local shellPath=os.getenv("SHELL")or"/bin/sh"
local shellName,reason=shell.resolve(shellPath,"lua")
if not shellName then
return nil,"cannot resolve shell `"..shellPath.."': "..reason
end
if shells[shellName]then
return shells[shellName]
end
local sh,load_reason=loadfile(shellName,nil,setmetatable({},{__index=_G}))
if sh then
shells[shellName]=sh
end
return sh,load_reason
end



function shell.prime()
local data=process.info().data
for _,key in ipairs({'aliases','vars'})do

local raw=rawget(data,key)
if not raw then

local current=data[key]
data[key]={}
if current then
for k,v in pairs(current)do
data[key][k]=v
end
end
end
end
end

function shell.getAlias(alias)
return process.info().data.aliases[alias]
end

function shell.setAlias(alias,value)
checkArg(1,alias,"string")
checkArg(2,value,"string","nil")
process.info().data.aliases[alias]=value
end

function shell.getWorkingDirectory()

return os.getenv("PWD")or"/"
end

function shell.setWorkingDirectory(dir)
checkArg(1,dir,"string")


dir=fs.canonical(dir):gsub("^$","/"):gsub("(.)/$","%1")
if fs.isDirectory(dir)then
os.setenv("PWD",dir)
return true
else
return nil,"not a directory"
end
end

function shell.resolve(path,ext)
checkArg(1,path,"string")

local dir=path
if dir:find("/")~=1 then
dir=fs.concat(shell.getWorkingDirectory(),dir)
end
local name=fs.name(path)
dir=fs[name and"path"or"canonical"](dir)
local fullname=fs.concat(dir,name or"")

if not ext then
return fullname
elseif name then
checkArg(2,ext,"string")


local search_in=path:find("/")and dir or os.getenv("PATH")
for search_path in string.gmatch(search_in,"[^:]+")do

local search_name=fs.concat(shell.resolve(search_path),name)
if not fs.exists(search_name)then
search_name=search_name.."."..ext
end

if fs.exists(search_name)and not fs.isDirectory(search_name)then
return search_name
end
end
end

return nil,"file not found"
end

function shell.parse(...)
local params=table.pack(...)
local args={}
local options={}
local doneWithOptions=false
for i=1,params.n do
local param=params[i]
if not doneWithOptions and type(param)=="string"then
if param=="--"then
doneWithOptions=true
elseif param:sub(1,2)=="--"then
local key,value=param:match("%-%-(.-)=(.*)")
if not key then
key,value=param:sub(3),true
end
options[key]=value
elseif param:sub(1,1)=="-"and param~="-"then
for j=2,unicode.len(param)do
options[unicode.sub(param,j,j)]=true
end
else
table.insert(args,param)
end
else
table.insert(args,param)
end
end
return args,options
end



require("package").delay(shell,"/lib/core/full_shell.lua")

return shell