// shared/elevation.js — admin elevation via an on-page toggle.
//
// Sudo-style model: admins behave as normal users by default; elevating
// the session turns on admin escape hatches (WORM bypass, .zddc edit
// authority, profile admin scaffolds). State is carried in a
// `zddc-elevate=1` cookie that the server reads via handler.ACLMiddleware
// → zddc.Principal{Elevated}.
//
// Two ways to arm, both gated on /.profile/access `can_elevate` so only
// real admins can flip it (a non-admin's attempt is a silent no-op):
//   1. The on-page toggle (renderToggle) — a small fixed control that we
//      render ONLY for users who can_elevate. This is the primary path.
//   2. `?admin=true|false` typed into any URL — still honoured (handy for
//      deep links / scripting), just normalised into the same state.
//
// Admin mode is EPHEMERAL — scoped to the page you turned it on:
//   * the cookie is a SESSION cookie (no Max-Age), and
//   * we clear it on `pagehide`, so navigating away / closing the tab
//     drops admin (you re-arm deliberately on the next page).
// Because of that we apply state IN PLACE (no reload — a reload's pagehide
// would race the clear). SPAs that server-render elevation-dependent data
// (e.g. browse's listing verbs) listen for the `zddc:elevationchange`
// event we emit and re-fetch. The red viewport border + banner
// (applyArmedChrome) reflect the cookie, kept in sync on every change.
(function () {
    'use strict';

    if (!window.zddc) window.zddc = {};
    if (window.zddc.elevation) return;

    var COOKIE_NAME = 'zddc-elevate';

    function isElevated() {
        var parts = document.cookie.split(';');
        for (var i = 0; i < parts.length; i++) {
            var kv = parts[i].trim().split('=');
            if (kv[0] === COOKIE_NAME && kv[1] === '1') return true;
        }
        return false;
    }

    function setElevated(on) {
        if (on) {
            // SameSite=Lax blocks cross-site form-post / image-tag CSRF
            // shapes. No Max-Age → a SESSION cookie: it dies with the tab
            // and, combined with the pagehide handler below, is cleared the
            // moment you leave the page. Admin powers never silently
            // outlive the page you armed them on.
            document.cookie = COOKIE_NAME + '=1; Path=/; SameSite=Lax';
        } else {
            document.cookie = COOKIE_NAME + '=; Path=/; SameSite=Lax; Max-Age=0';
        }
    }

    // emitChange notifies same-page listeners (SPAs that server-render
    // elevation-dependent data, e.g. browse's listing verbs / editor
    // affordances) so they can re-fetch without a full reload.
    function emitChange() {
        try {
            window.dispatchEvent(new CustomEvent('zddc:elevationchange', {
                detail: { elevated: isElevated() }
            }));
        } catch (_e) { /* CustomEvent unsupported — non-fatal */ }
    }

    // setOn / setOff are the single funnel for every arm/drop path (toggle,
    // URL param, banner button). Each flips the cookie, re-paints the armed
    // chrome, syncs the toggle checkbox, and emits the change — no reload.
    function setOn() {
        setElevated(true);
        applyArmedChrome(true);
        syncToggle();
        emitChange();
    }
    function setOff() {
        setElevated(false);
        applyArmedChrome(false);
        syncToggle();
        emitChange();
    }

    async function fetchAccess() {
        try {
            var resp = await fetch('/.profile/access', {
                headers: { 'Accept': 'application/json' },
                credentials: 'same-origin',
                cache: 'no-cache'
            });
            if (!resp.ok) return null;
            return await resp.json();
        } catch (_e) {
            return null;
        }
    }

    // ── URL toggle: ?admin=true | ?admin=false (typeable anywhere) ──────
    //
    // Admin mode is toggled via a URL query param rather than an on-screen
    // checkbox, so it's reachable from any zddc-server page. The param only
    // SETS the cookie; the cookie is the sticky state (it persists across
    // navigation for its Max-Age window and is what the server reads), so
    // there's no need to keep ?admin= in the URL once applied.

    // adminParam returns true/false for a recognised ?admin= value, or null
    // when absent / unrecognised (ignored).
    function adminParam() {
        try {
            var v = new URLSearchParams(window.location.search).get('admin');
            if (v === null) return null;
            v = v.toLowerCase();
            if (v === 'true' || v === '1' || v === 'on' || v === 'yes') return true;
            if (v === 'false' || v === '0' || v === 'off' || v === 'no') return false;
            return null;
        } catch (_e) { return null; }
    }

    // urlWithoutAdmin returns the current URL with the admin param stripped
    // (other params + hash preserved) — what we navigate/replace to so the
    // dirty param isn't bookmarked and Back doesn't re-trigger it.
    function urlWithoutAdmin() {
        var u = new URL(window.location.href);
        u.searchParams.delete('admin');
        var qs = u.searchParams.toString();
        return u.pathname + (qs ? '?' + qs : '') + u.hash;
    }

    // handleAdminParam applies a ?admin= request IN PLACE (no reload — see
    // the module header on why reloads would race the pagehide-clear).
    // Enabling is gated on can_elevate — a non-admin who types ?admin=true
    // just gets the param stripped, never a misleading red border.
    // Disabling is open (anyone may drop a cookie they somehow hold).
    // `access` (a prefetched /.profile/access, may be null) lets init reuse
    // its single fetch instead of issuing a second one.
    async function handleAdminParam(access) {
        var want = adminParam();
        if (want === null) return;
        var clean = urlWithoutAdmin();
        try { history.replaceState(history.state, '', clean); } catch (_e) {}
        if (want === isElevated()) return; // already in the requested state
        if (want === true) {
            if (access === undefined) access = await fetchAccess();
            if (!access || !access.can_elevate) return; // silent no-op
            setOn();
        } else {
            setOff();
        }
    }

    // Page-wide affordances when elevation is active. The toggle alone
    // is easy to miss — admin mode silently bypasses WORM and ACL
    // restrictions, which produces surprising "I shouldn't have been
    // able to do that" moments. A body class + a sticky banner with a
    // one-click disable make the armed state unmistakable.
    function applyArmedChrome(elevated) {
        var b = document.body;
        if (!b) return;
        if (elevated) b.classList.add('is-elevated');
        else b.classList.remove('is-elevated');

        var banner = document.getElementById('elevation-banner');
        if (elevated) {
            if (!banner) {
                banner = document.createElement('div');
                banner.id = 'elevation-banner';
                banner.className = 'elevation-banner';
                banner.setAttribute('role', 'alert');
                banner.innerHTML =
                    '<span class="elevation-banner__dot" aria-hidden="true"></span>'
                    + '<span class="elevation-banner__msg">'
                    +   'Admin mode is on — write access bypasses WORM and ACL safeguards.'
                    + '</span>'
                    + '<button type="button" class="elevation-banner__off" id="elevation-banner-off">'
                    +   'Drop admin'
                    + '</button>';
                document.body.insertBefore(banner, document.body.firstChild);
                var off = banner.querySelector('#elevation-banner-off');
                if (off) off.addEventListener('click', function () { setOff(); });
            }
        } else if (banner) {
            banner.parentNode.removeChild(banner);
        }
    }

    // renderToggle mounts the on-page admin switch — but ONLY for users the
    // server says can_elevate (i.e. who'd actually gain edit authority by
    // arming). Everyone else never sees it. It's a fixed control so it works
    // in any tool without that tool rendering a header slot for it.
    function renderToggle() {
        // Reuse the header placeholder the tool templates ship (an empty
        // `<span id="elevation-toggle" class="… hidden">`) when present —
        // dropping its `hidden` class and repopulating it; otherwise create
        // one. Either way the fixed-position CSS floats it bottom-right, so
        // it doesn't matter where in the DOM it lives.
        var el = document.getElementById('elevation-toggle');
        var created = false;
        if (!el) {
            el = document.createElement('span');
            el.id = 'elevation-toggle';
            created = true;
        }
        el.className = 'elevation-toggle'; // drops any stale `hidden`
        el.title = 'Arm admin mode for this page. Drops automatically when you leave.';
        el.innerHTML = '';
        var input = document.createElement('input');
        input.type = 'checkbox';
        input.id = 'elevation-toggle-input';
        input.className = 'elevation-toggle__input';
        input.checked = isElevated();
        input.addEventListener('change', function () {
            if (input.checked) setOn(); else setOff();
        });
        var txt = document.createElement('span');
        txt.className = 'elevation-toggle__label';
        txt.textContent = 'Admin mode';
        txt.addEventListener('click', function () { input.click(); });
        el.appendChild(input);
        el.appendChild(txt);
        if (created) document.body.appendChild(el);
    }

    // syncToggle keeps the checkbox honest when state is flipped by some
    // other path (URL param, banner "Drop admin", bfcache restore).
    function syncToggle() {
        var input = document.getElementById('elevation-toggle-input');
        if (input) input.checked = isElevated();
    }

    async function init() {
        // file:// (offline FS-Access mode) has no server to elevate against
        // — skip the access probe and the toggle entirely.
        if (window.location.protocol === 'file:') return;

        // Reflect the cookie's armed chrome on every load (a leftover from a
        // not-yet-fired pagehide, or an arrived-with ?admin link).
        applyArmedChrome(isElevated());

        // One /.profile/access probe drives both decisions: whether to show
        // the toggle (can_elevate) and whether a ?admin=true may arm.
        var access = await fetchAccess();
        if (access && access.can_elevate) renderToggle();
        await handleAdminParam(access);

        // Admin mode is per-page: clear the cookie when the page goes away
        // so it never persists past a navigation. (No UI work here — the
        // page is unloading; the next page re-derives state from scratch.)
        window.addEventListener('pagehide', function () {
            if (isElevated()) setElevated(false);
        });
        // bfcache can restore a page whose pagehide already cleared the
        // cookie — re-sync the visible state so chrome ≠ cookie can't happen.
        window.addEventListener('pageshow', function (e) {
            if (e.persisted) { applyArmedChrome(isElevated()); syncToggle(); }
        });
    }

    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', init);
    } else {
        init();
    }

    window.zddc.elevation = {
        isElevated: isElevated,
        setElevated: setElevated,
        setOn: setOn,
        setOff: setOff
    };
})();