Encmail Login Server

--Loading AES encryption functions. AES API ported to CC by SquidDev. Thanks heaps!
local apipath
if shell then apipath = fs.combine(shell.dir(),"aes") else apipath = "" end
if (not aes) and (not fs.exists(apipath)) then
    print("AES API not found! Downloading...")
    local prog = http.get("http://pastebin.com/raw/9E5UHiqv")
    if not prog then error("FAIL!") end
    local file = fs.open(apipath,"w")
    file.write(prog.readAll())
    file.close()
end
if not aes then
    local res = os.loadAPI(apipath)
    if not res then error("Didn't load AES API!") end
end

--In case I use an API that uses a different syntax than (msg, key)
local encrite = function(msg, key)
    return aes.encrypt(key, msg)
end

local decrite = function(msg, key)
    return aes.decrypt(key, msg)
end

local encode = function(txt) --converts string into a table of each character's byte code
    if type(txt) ~= "string" then return false, "requires string" end
    return {txt:byte(1,-1)}
end

local decode = function(tbl) --converts an encoded string into something useful.
    if type(tbl) ~= "table" then return false, "requires table" end
    return string.char(tableunpack(tbl))
end

local strcapsule = function(txt)
    return "\""..tostring(txt).."\""
end

local cwrite = function(txt,setY,doClearLine)
    local scr_x, scr_y = termgetSize()
    local x,y = termgetCursorPos()
    termsetCursorPos((scr_x/2)-(#txt/2),setY or y)
    if doClearLine then termclearLine() end
    write(txt)
end

local waitForModem = function()
    local mod
    while true do
        sleep(0.2)
        mod = peripheral.find("modem")
        if mod then
            return mod
        end
    end
end

if not peripheral.find("modem") then
    termsetBackgroundColor(colors.gray)
    termsetTextColor(colors.white)
    termclear()
    cwrite("Encmail requires a modem.",3)
    cwrite("Add one, or press a key.",4)
    sleep(0.1)
    local outcome = parallelwaitForAny(function() os.pullEvent("key") end, waitForModem)
    modems = {peripheral.find("modem")}
    if #modems == 0 then
        termsetBackgroundColor(colors.black)
        termsetCursorPos(1,scr_y)
        termclearLine()
        sleep(0)
        return false
    end
end

local modemOpen = function(chan)
    for a = 1, #modems do
        modems[a].open(chan)
    end
end

local modemClose = function(chan)
    for a = 1, #modems do
        modems[a].close(chan)
    end
end

local modemTransmit = function(chan,repchan,msg)
    for a = 1, #modems do
        modems[a].transmit(chan,repchan,msg)
    end
end

local tsv = function(visible)
    if termcurrent then if termcurrent().setVisible then termcurrent().setVisible(visible) return true else return false end else return false end
end


local maindir = ".encmail"
local userdir = fs.combine(maindir,"users")
local configpath = fs.combine(maindir,"config")

local readConfig = function()
    dofile(configpath)
end

local writeConfig = function() --writes current values to config, no arguments needed!
    local file = fs.open(configpath,"w")
    file.writeLine("--This config file will store any variables I want persistant.")
    file.writeLine("--Do not modify while running! It won't do a thing!")
    file.close()
end

local fenv = getfenv()
readConfig()
local newfenv = getfenv()
local newvars = {}
for k,v in pairs(newfenv) do
    if not fenv[k] then
        newvars[k] = v
    end
end

listUsers = function()
    return fs.list(userdir)
end

listMail = function(user)
    if not fs.isDir(fs.combine(userdir,user)) then
        return false, "No such user"
    end
    local output = {}
    local path = fs.list(fs.combine(userdir,user))

end