// Putting a described value on the clipboard.
//
// `c3e145e0`. An `Act` can say that pressing it copies a value, and this is the
// browser's half. It replaces seven `window.<name>` globals across 14 sites on
// the MNW server, six of which scraped the text back off the DOM at press time
// and one of which read an element by id.
//
// It reads one attribute the node emitter writes and nothing else:
// `data-copies` carries the value. An ordinary escaped attribute, so nothing
// here is a program built out of app text -- the same rule that makes this a
// script rather than an emitted _hyperscript program. A licence key reading
// `"; alert(1); "` is a value in an attribute here and could not be one in a
// program.
//
// What it does NOT do is say "Copied!". Every shipped site relabelled its own
// button and reverted, six at 1500ms and one at 2000ms, and that is a temporary
// label rather than a copy: it belongs to `makeover-timing` and to mnw-server
// `033c722f`. Splitting them is deliberate -- a host with no notion of a
// reverting label still needs to be told the act copies something.
(() => {
    "use strict";

    /** The value to put on the clipboard. */
    const VALUE = "data-copies";

    /**
     * Write `text` to the clipboard, preferring the async API.
     *
     * `navigator.clipboard` is unavailable on an insecure origin and can be
     * refused by permissions policy, and neither is an error worth surfacing to
     * a reader who pressed a copy button. The fallback is the old selection
     * dance, which works in both cases and is why it is still here.
     */
    const write = async (text) => {
        try {
            if (navigator.clipboard?.writeText) {
                await navigator.clipboard.writeText(text);
                return;
            }
        } catch {
            // Fall through: refused, or no permission. The fallback below does
            // not ask for one.
        }

        const carrier = document.createElement("textarea");
        carrier.value = text;
        // Off-screen rather than hidden: a `display: none` element cannot be
        // selected, and selecting is the whole mechanism here.
        carrier.setAttribute("readonly", "");
        carrier.style.position = "fixed";
        carrier.style.top = "-9999px";
        document.body.appendChild(carrier);
        carrier.select();
        try {
            document.execCommand("copy");
        } catch {
            // Nothing left to try. The reader sees no change, which is the
            // same outcome as a page that never described the copy at all.
        }
        carrier.remove();
    };

    // One delegated listener rather than one per control, for `FILL_JS`'
    // reason: these controls arrive in swaps, so binding per element would mean
    // rebinding on every swap.
    document.addEventListener("click", (event) => {
        const control = event.target?.closest?.(`[${VALUE}]`);
        if (!control) {
            return;
        }
        void write(control.getAttribute(VALUE) ?? "");
    });
})();