Module:Base64

Documentation for this module may be created at Module:Base64/doc

-- Made by [[User:Celeste]] - Licensed under GPLv3

local p = {}

local yesno = require('Module:Yesno') -- invoke Yesno

local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/' -- You will need this for encoding/decoding

function p.base64(frame)
	local args
	local data
	local encode
	if frame == mw.getCurrentFrame() then
    	args = frame.args
	else
    	args = frame
	end
	data = args.data
	encode = args.encode
	yesno(encode, false)

local index_table = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'

function to_binary(integer)
    local remaining = tonumber(integer)
    local bin_bits = ''

    for i = 7, 0, -1 do
        local current_power = 2 ^ i

        if remaining >= current_power then
            bin_bits = bin_bits .. '1'
            remaining = remaining - current_power
        else
            bin_bits = bin_bits .. '0'
        end
    end

    return bin_bits
end

function from_binary(bin_bits)
    return tonumber(bin_bits, 2)
end


function to_base64(to_encode)
    local bit_pattern = ''
    local encoded = ''
    local trailing = ''

    for i = 1, string.len(to_encode) do
        bit_pattern = bit_pattern .. to_binary(string.byte(string.sub(to_encode, i, i)))
    end

    -- Check the number of bytes. If it's not evenly divisible by three,
    -- zero-pad the ending & append on the correct number of ``=``s.
    if string.len(bit_pattern) % 3 == 2 then
        trailing = '=='
        bit_pattern = bit_pattern .. '0000000000000000'
    elseif string.len(bit_pattern) % 3 == 1 then
        trailing = '='
        bit_pattern = bit_pattern .. '00000000'
    end

    for i = 1, string.len(bit_pattern), 6 do
        local byte = string.sub(bit_pattern, i, i+5)
        local offset = tonumber(from_binary(byte))
        encoded = encoded .. string.sub(index_table, offset+1, offset+1)
    end

    local result = string.sub(encoded, 1, -1 - string.len(trailing)) .. trailing
    return(result)
end


function from_base64(to_decode)
    local padded = to_decode:gsub("%s", "")
    local unpadded = padded:gsub("=", "")
    local bit_pattern = ''
    local decoded = ''

    for i = 1, string.len(unpadded) do
        local char = string.sub(to_decode, i, i)
        local offset, _ = string.find(index_table, char)
        if offset == nil then
             error("Invalid character '" .. char .. "' found.")
        end

        bit_pattern = bit_pattern .. string.sub(to_binary(offset-1), 3)
    end

    for i = 1, string.len(bit_pattern), 8 do
        local byte = string.sub(bit_pattern, i, i+7)
        decoded = decoded .. string.char(from_binary(byte))
    end

    local padding_length = padded:len()-unpadded:len()

    if (padding_length == 1 or padding_length == 2) then
        decoded = decoded:sub(1,-2)
    end
    return decoded
end


if (encode == true) then
		to_base64(data)
	else
		from_base64(data)
		local result = data
		return(result)
end
end

return p