Lesson 5: Send messages safely

Goal: reply to !echo text without flooding or passing along unsafe text.

--! name: Safe echo
--! description: !echo <text> with a per-nick cooldown
--! api: 1
--! permissions: send
local COOLDOWN_MS = 5000
local lastUse: {[string]: number} = {}

local function clean(text: string): string
    text = swizzin.strip(text)                -- remove IRC colours and formatting
    text = string.gsub(text, "[\r\n]+", " ")  -- one line only
    return string.sub(text, 1, 300)           -- keep it short
end

swizzin.on("message", function(e)
    if not swizzin.wildmatch("!echo *", e.text) then return end
    local last = lastUse[e.nick]
    if last ~= nil and e.time - last < COOLDOWN_MS then return end
    lastUse[e.nick] = e.time
    swizzin.send(e.target, "You said: " .. clean(string.sub(e.text, 7)))
end)

What it does

It ignores everything except !echo ..., allows one use per nick every 5 seconds (using the event’s own time), and cleans the text before sending.

Rules SwizzinIRC enforces for you

Text must be one line of 1 to 2000 characters.
Text that looks like an authentication command (IDENTIFY, LOGIN, PASS, …) is refused, and so are messages to ZNC *module users.
At most 10 messages per second (burst of 20) per script.
Without a network context an action is refused rather than guessed.

Expected result

!echo hello is answered with You said: hello. Repeating it within 5 seconds from the same nick is ignored.

Common mistakes

Echoing user text unchanged: it can be long, multi-line or try to trigger other bots.
Replying to bots, which can start message loops.
Sending from a timer in a tight loop.

Troubleshooting

A send does nothing: the reason is written to the Console (permission, empty or too-long text, line break, rate limit).