-- 将全局 SYMBOLS 字符串（192 字节）转换为表（64 个符号，每个 3 字节）
local symbol_table = {}
for i = 1, 64 do
    local start_byte = (i-1)*3 + 1
    symbol_table[i] = SYMBOLS:sub(start_byte, start_byte+2)
end
SYMBOLS = symbol_table  -- 现在 SYMBOLS 是表，可直接用数字索引

local BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"

local function randChars(len)
    local chars = "abcdefghijklmnopqrstuvwxyz0123456789"
    local s = {}
    for i = 1, len do
        s[i] = chars:sub(math.random(#chars), math.random(#chars))
    end
    return table.concat(s)
end

local function randSymbols(len)
    local s = {}
    for i = 1, len do
        s[i] = SYMBOLS[math.random(64)]  -- 直接取表元素
    end
    return table.concat(s)
end

-- 纯 Lua Base64 编码（字节级正确）
local function b64Encode(str)
    local chars = BASE64_CHARS
    local len = #str
    local result = {}
    local i = 1
    while i <= len do
        local b1 = str:byte(i)
        local b2 = str:byte(i+1) or 0
        local b3 = str:byte(i+2) or 0
        local n1 = math.floor(b1 / 4)
        local n2 = (b1 % 4) * 16 + math.floor(b2 / 16)
        local n3 = (b2 % 16) * 4 + math.floor(b3 / 64)
        local n4 = b3 % 64
        result[#result+1] = chars:sub(n1+1, n1+1)
        result[#result+1] = chars:sub(n2+1, n2+1)
        if i+1 <= len then
            result[#result+1] = chars:sub(n3+1, n3+1)
        end
        if i+2 <= len then
            result[#result+1] = chars:sub(n4+1, n4+1)
        end
        i = i + 3
    end
    local pad = (3 - (len % 3)) % 3
    if pad == 1 then
        result[#result+1] = "="
    elseif pad == 2 then
        result[#result+1] = "=="
    end
    return table.concat(result)
end

local function encryptLin(url)
    local r1 = randChars(8)
    local r2 = randChars(8)
    return "Lin" .. r1 .. r2 .. b64Encode(url)
end

local function encryptLinpro(url)
    local r1 = randSymbols(8)
    local r2 = randSymbols(8)
    local plain = url .. "||"
    local xored_bytes = {}
    for i = 1, #plain do
        xored_bytes[i] = string.char(plain:byte(i) ~ 0x5A)
    end
    local b64 = b64Encode(table.concat(xored_bytes))
    local sym = {}
    for i = 1, #b64 do
        local ch = b64:sub(i, i)
        local idx = BASE64_CHARS:find(ch, 1, true)  -- 返回 1~64 或 nil
        if idx then
            sym[#sym+1] = SYMBOLS[idx]  -- 用表索引取符号
        end
    end
    return "linpro" .. r1 .. r2 .. table.concat(sym)
end

local function Main()
    local sel = gg.choice({"免费版 Lin", "付费版 linpro", "退出"}, nil, "选择加密模式")
    if sel == nil or sel == 3 then return end
    local input = gg.prompt({"请输入Lua直链URL"}, {""}, {"text"})
    if not input or input[1] == "" then
        gg.alert("内容不能为空")
        return
    end
    local url = input[1]
    local result
    if sel == 1 then
        result = encryptLin(url)
    else
        result = encryptLinpro(url)
    end
    local c = gg.choice({"复制文本", "关闭"}, nil, result)
    if c == 1 then
        gg.copyText(result)
        gg.alert("复制成功，请粘贴到 MT 管理器或浏览器查看符号")
    end
end

Main()