Lolcrypt

local function chars(str)
    local pos = 1
    return function()
        if pos <= #str  then
            local pos_was = pos
            pos = pos + 1
            return str:sub(pos_was, pos_was), pos_was
        end
    end
end

-- from lua users wiki - magic
local function unpackbits(num, width)
    local fl = {}
    local rem
    for i = 1,width do
        num,rem = math.modf(num/2)
        fl[#fl+1] = rem>=0.5
    end
    return fl
end

local function permutation(str, ix)
    local bits = unpackbits(ix, #str)
    local this = ""
    for char, idx in chars(str) do
        local newchar = char:lower()
        if bits[idx] then newchar = char:upper() end
        this = this .. newchar
    end
    return this
end

local function caps_permutations(str)
    local combinations = math.pow(2, #str) - 1
    local ret = {}
    for i = 0, combinations do
        table.insert(ret, permutation(str, i))
    end
    return ret
end

local function nybbles(byte)
    return bit.brshift(bit.band(0xF0, byte), 4), bit.band(0x0F, byte)
end

local function rpt(t, x)
    local out = {}
    for i = 1, x do
        for _, v in pairs(t) do
            table.insert(out, v)
        end
    end
    return out
end

local function invert(t)
    local out = {}
    for k, v in pairs(t) do
        out[v] = k
    end
    return out
end

local function sanify(t)
    local ix = 0
    local out = {}
    for _, v in pairs(t) do
        out[ix] = v
        ix = ix + 1
    end
    return out
end

local dictionary = caps_permutations "lol"
for k, v in pairs({
    " ",
    ".",
    "?",
    "!",
    "#",
    ",",
    ";",
    ":"
}) do table.insert(dictionary, v) end
dictionary = sanify(dictionary)
local inverse_dictionary = invert(dictionary)

local function encode(str)
    local out = ""
    for char in chars(str) do
        local hi, lo = nybbles(string.byte(char))
        out = out .. dictionary[hi] .. dictionary[lo]
    end
    return out
end

local function tokenize(str)
    local in_lol = ""
    local toks = {}
    for char, index in chars(str) do
        local lowered = char:lower()
        if in_lol ~= "" then -- if we have a current lol, push lol to the tokens stack and clear it if we get a L
            in_lol = in_lol .. char
            if lowered == "l" then
                table.insert(toks, in_lol)
                in_lol = ""
            elseif lowered == "o" then
            else error "Invalid character in LOL" end
        else
            if lowered == "l" then
                in_lol = char
            else
                table.insert(toks, char)
            end
        end
    end
    return toks
end

local function decode_one(tok)
    local d = inverse_dictionary[tok]
    if not d then error("Invalid token in loltext: " .. tostring(tok)) end
    return d
end

local function decode_pair(t1, t2)
    local hi, lo = decode_one(t1), decode_one(t2)
    local n = bit.bor(bit.blshift(hi, 4), lo)
    return string.char(n)
end

local function decode(str)
    local toks = tokenize(str)
    local out = ""
    while true do
        local t1, t2 = table.remove(toks, 1), table.remove(toks, 1)
        if not t1 or not t2 then
            break
        else
            out = out .. decode_pair(t1, t2)
        end
    end
    return out
end

local function repeat_function(f, times)
    return function(data, times_)
        local times = times_ or times
        local d = data
        for i = 1, times do
            d = f(d)
        end
        return d
    end
end

return { encode = repeat_function(encode, 1), decode = repeat_function(decode, 1) }