/* AutoFirmer Capture — MV3 service worker.
 *
 * Loop: every tick, scrape the tab you are looking at and POST it to
 * /api/autobuyer/capture. The dashboard's AutoBuyer page renders whatever
 * landed there.
 *
 * Nothing here has a switch. Capture is scoped instead: only the ACTIVE tab of
 * the last-focused window, and only when that tab is one of the firm sites in
 * host_permissions. Sit on any other page and nothing is read or sent.
 *
 * The locate queue is served whenever clicks are waiting. The AutoBuyer is
 * ready at all times; a run happens because someone asked for one.
 */

const DEFAULTS = {
    apiBase: 'http://localhost:3000',
    pollSeconds: 3,
    // Optional CSS selector — matching elements get their on-screen position
    // measured alongside the HTML.
    elementSelector: '',
};

let timer = null;
let pendingLocate = 0;

// ── Config / state ──────────────────────────────────────────────────────────

async function getConfig() {
    const stored = await chrome.storage.local.get(Object.keys(DEFAULTS));
    const cfg = { ...DEFAULTS, ...stored };
    cfg.apiBase = String(cfg.apiBase).replace(/\/+$/, '');
    return cfg;
}

/** Mirror the worker's status into storage so the popup can render it. */
async function setState(patch) {
    const { state: prev } = await chrome.storage.local.get('state');
    await chrome.storage.local.set({ state: { ...(prev || {}), ...patch, updatedAt: Date.now() } });
}

/** `!` when the dashboard is unreachable, blank otherwise. A blank badge is the
 *  working state — there is nothing to switch on, so nothing to advertise. */
function setBadge(connected) {
    chrome.action.setBadgeText({ text: connected ? '' : '!' });
    chrome.action.setBadgeBackgroundColor({ color: '#ef4444' });
}

// ── The injected scraper ────────────────────────────────────────────────────

/** Runs in the page's own world. Must be self-contained — nothing from this
 *  file's scope is available inside it. */
function pageCapture(selector) {
    // getBoundingClientRect() measures from the top-left of the viewport, so
    // rect.left / rect.top ARE the element's position relative to the window.
    // + scrollX/scrollY  -> position within the document
    // + screenX/screenY and the chrome height -> absolute desktop coordinates,
    //   which is what an OS-level clicker needs.
    const chromeHeight = window.outerHeight - window.innerHeight;

    const elements = selector
        ? Array.from(document.querySelectorAll(selector)).slice(0, 200).map((el, index) => {
            const r = el.getBoundingClientRect();
            return {
                index,
                tag: el.tagName.toLowerCase(),
                id: el.id || null,
                text: (el.textContent || '').trim().slice(0, 80),
                // Off-screen or display:none elements still return a rect — all zeroes.
                visible: r.width > 0 && r.height > 0,
                inViewport: r.top < window.innerHeight && r.bottom > 0 && r.left < window.innerWidth && r.right > 0,
                viewport: { x: r.left, y: r.top, width: r.width, height: r.height },
                page: { x: r.left + window.scrollX, y: r.top + window.scrollY },
                // Centre of the element in desktop coordinates (CSS pixels —
                // multiply by devicePixelRatio for physical pixels on HiDPI).
                screen: {
                    x: window.screenX + r.left + r.width / 2,
                    y: window.screenY + chromeHeight + r.top + r.height / 2,
                },
            };
        })
        : [];

    return {
        url: location.href,
        title: document.title,
        html: document.documentElement.outerHTML,
        viewport: {
            scrollX: window.scrollX,
            scrollY: window.scrollY,
            innerWidth: window.innerWidth,
            innerHeight: window.innerHeight,
            outerWidth: window.outerWidth,
            outerHeight: window.outerHeight,
            screenX: window.screenX,
            screenY: window.screenY,
            chromeHeight,
            devicePixelRatio: window.devicePixelRatio,
        },
        elements,
    };
}

// ── Capture pipeline ────────────────────────────────────────────────────────

/** The sites this extension is allowed to touch, taken from the manifest rather
 *  than from a setting.
 *
 *  These are the same hosts host_permissions grants, so they cannot drift out of
 *  sync with what the extension can actually read, and adding a firm — which
 *  means adding its host to the manifest anyway — scopes capture automatically.
 *  localhost is filtered out: that is the dashboard, and capturing it would just
 *  mirror our own output back. */
function firmPatterns() {
    return chrome.runtime.getManifest().host_permissions
        .filter((p) => !/\/\/(localhost|127\.0\.0\.1)/.test(p));
}

/** The firm tab you are actually looking at, or nothing.
 *
 *  Deliberately no fallback to "some other firm tab that happens to be open":
 *  capture should report the page in front of you, not a stale background tab
 *  you left on a broker site hours ago. Chrome does the pattern matching, so a
 *  tab outside host_permissions cannot be selected here at all.
 */
async function pickTab() {
    const [tab] = await chrome.tabs.query({
        active: true,
        lastFocusedWindow: true,
        url: firmPatterns(),
    });
    return tab && /^https?:/.test(tab.url || '') ? tab : undefined;
}

async function captureAndSend(cfg) {
    const tab = await pickTab();
    if (!tab) {
        await setState({ connected: true, error: null, waiting: 'Not on a firm page — nothing captured' });
        return;
    }

    const [injection] = await chrome.scripting.executeScript({
        target: { tabId: tab.id },
        func: pageCapture,
        args: [cfg.elementSelector || ''],
    });
    const result = injection?.result;
    if (!result) throw new Error('Injection returned nothing');

    const res = await fetch(`${cfg.apiBase}/api/autobuyer/capture`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
            ...result,
            // Stamp the build so the dashboard side can tell which version of this
            // worker is actually live — Chrome keeps running the old one until the
            // extension is reloaded, which is invisible from the server otherwise.
            viewport: { ...result.viewport, extVersion: chrome.runtime.getManifest().version },
            capturedAt: Date.now(),
        }),
    });
    if (!res.ok) throw new Error(`Capture POST failed: HTTP ${res.status}`);

    await setState({
        connected: true,
        error: null,
        waiting: null,
        lastCapture: { url: result.url, title: result.title, bytes: result.html.length, at: Date.now() },
    });
}

/** Which browser is hosting this extension.
 *
 *  The clicker has to raise *this* browser before clicking, and picking by list
 *  order gets it wrong the moment two are installed — it would raise Edge while
 *  the coordinates came from a tab in Chrome, landing every click in the wrong
 *  window. So the answer travels with the measurement.
 */
function detectBrowser() {
    const ua = navigator.userAgent || '';
    if (/\bEdg\//.test(ua)) return 'edge';
    if (/\bOPR\//.test(ua)) return 'opera';
    if (/\bVivaldi\//.test(ua)) return 'vivaldi';
    try {
        if (navigator.brave) return 'brave';   // Brave otherwise reports as Chrome
    } catch { /* not Brave */ }
    return 'chrome';
}

// ── Locate: turn a CSS selector into desktop coordinates ────────────────────

/** Runs in the page. Scrolls the element into view, then reports where it ended up. */
function pageLocate(selector, index) {
    const matches = document.querySelectorAll(selector);
    if (matches.length === 0) return { error: `No element matches ${selector}` };
    const el = matches[index];
    if (!el) return { error: `Selector ${selector} matched ${matches.length} element(s), no index ${index}` };

    // Centre it in the viewport first — an element scrolled off-screen has a rect,
    // but clicking those coordinates would hit whatever is actually displayed there.
    el.scrollIntoView({ block: 'center', inline: 'center', behavior: 'instant' });

    const r = el.getBoundingClientRect();
    if (r.width === 0 || r.height === 0) {
        return { error: `Element ${selector} has zero size (hidden or display:none)` };
    }
    if (r.bottom <= 0 || r.top >= window.innerHeight || r.right <= 0 || r.left >= window.innerWidth) {
        return { error: `Element ${selector} is outside the viewport even after scrolling` };
    }

    const chromeHeight = window.outerHeight - window.innerHeight;
    const cx = r.left + r.width / 2;
    const cy = r.top + r.height / 2;

    // What sits at that point? If it's not our element (or a descendant), something
    // is covering it — a cookie banner, a modal — and the click would hit that instead.
    const atPoint = document.elementFromPoint(cx, cy);
    const covered = atPoint && atPoint !== el && !el.contains(atPoint);

    // Enough to identify it. A bare tag name — the common case for a modal
    // backdrop or a captcha overlay, neither of which carries an id — says
    // nothing about which overlay is in the way. SVG's className is an object,
    // not a string, hence the guard.
    const describeNode = (node) => {
        if (!node) return null;
        const classes = typeof node.className === 'string'
            ? node.className.trim().split(/\s+/).filter(Boolean).slice(0, 4).map((c) => `.${c}`).join('')
            : '';
        return `${node.tagName.toLowerCase()}${node.id ? `#${node.id}` : ''}${classes}`;
    };

    // Current contents, so the caller can confirm afterwards that what it typed
    // actually landed — a field that silently ignored the keystrokes (masked,
    // read-only, or never focused) is otherwise indistinguishable from success.
    const isField = el.tagName === 'INPUT' || el.tagName === 'TEXTAREA';
    const value = isField ? el.value : (el.isContentEditable ? el.innerText : null);

    return {
        tag: el.tagName.toLowerCase(),
        text: (el.textContent || '').trim().slice(0, 80),
        matchCount: matches.length,
        value,
        editable: (isField || el.isContentEditable) && !el.disabled && !el.readOnly,
        inputType: isField ? (el.type || null) : null,
        covered: !!covered,
        coveredBy: covered ? describeNode(atPoint) : null,
        viewport: { x: r.left, y: r.top, width: r.width, height: r.height },
        // Desktop coordinates of the element's centre, in CSS pixels.
        screen: { x: window.screenX + cx, y: window.screenY + chromeHeight + cy },
        // Lets the Python side work out whether the OS uses a different pixel
        // scale than CSS does (Windows display scaling, some Linux setups).
        screenSize: { width: window.screen.width, height: window.screen.height },
        devicePixelRatio: window.devicePixelRatio,
        chromeHeight,
        url: location.href,
    };
}

/** Runs in the page. Answers "is this element there, and can it be seen?" —
 *  no scrolling, no measuring, no error when it is missing. pageLocate cannot
 *  answer this: absent and hidden both come back as errors there, and a wait
 *  gate has to tell those two apart from a broken pipeline. */
function pageVisible(selector, index) {
    const matches = document.querySelectorAll(selector);
    const el = matches[index];
    if (!el) {
        return {
            op: 'visible', present: false, visible: false, matchCount: matches.length,
            reason: matches.length ? `matched ${matches.length} element(s), no index ${index}` : 'no element matches',
        };
    }

    // checkVisibility covers what CSS can do to make an element invisible while
    // leaving it in the DOM — display, visibility, content-visibility, opacity —
    // including when the property sits on an ancestor. Both spellings of the
    // options are passed: Chrome renamed them, and unknown keys are ignored.
    const rendered = typeof el.checkVisibility === 'function'
        ? el.checkVisibility({
            checkVisibilityCSS: true, checkOpacity: true,
            visibilityProperty: true, opacityProperty: true,
            contentVisibilityAuto: true,
        })
        : true;

    // Size is not part of that check, and a container collapsed to nothing is
    // just as invisible as one that was hidden outright.
    const r = el.getBoundingClientRect();
    const sized = r.width > 0 && r.height > 0;

    return {
        op: 'visible',
        present: true,
        visible: rendered && sized,
        matchCount: matches.length,
        tag: el.tagName.toLowerCase(),
        text: (el.textContent || '').trim().slice(0, 80),
        viewport: { x: r.left, y: r.top, width: r.width, height: r.height },
        reason: rendered ? (sized ? null : 'zero size') : 'hidden by CSS',
        url: location.href,
    };
}

/** Is the tab already showing this page? Compares origin and path only —
 *  query strings and hashes shouldn't force a reload. */
function alreadyAt(current, target) {
    try {
        const a = new URL(current);
        const b = new URL(target);
        return a.origin === b.origin && a.pathname.replace(/\/$/, '') === b.pathname.replace(/\/$/, '');
    } catch {
        return false;
    }
}

/** Resolve after the tab reports `complete`. A tab that has only just been
 *  created has no DOM to inject into yet. */
function waitForTabLoad(tabId, timeoutMs = 15000) {
    return new Promise((resolve, reject) => {
        const started = Date.now();
        const check = async () => {
            let tab;
            try {
                tab = await chrome.tabs.get(tabId);
            } catch {
                return reject(new Error('the tab was closed while loading'));
            }
            if (tab.status === 'complete') return resolve(tab);
            if (Date.now() - started > timeoutMs) {
                return reject(new Error(`the page did not finish loading within ${timeoutMs / 1000}s`));
            }
            setTimeout(check, 200);
        };
        check();
    });
}

/** Runs in the page. Scrolls until the list stops growing, then reports what it
 *  ended up with.
 *
 *  The scrolling element is often NOT the window — lists like this usually live
 *  in a div with its own overflow, and scrolling the document does nothing at
 *  all. So walk up from a matched item looking for the ancestor that actually
 *  scrolls, and let the caller name one outright when the guess is wrong.
 */
async function pageScrollToLoad(selector, containerSelector, maxScrolls, settleMs, stableRounds) {
    const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
    const count = () => document.querySelectorAll(selector).length;

    function scroller() {
        if (containerSelector) {
            const named = document.querySelector(containerSelector);
            if (!named) return { error: `No element matches container ${containerSelector}` };
            return { el: named };
        }

        // An ancestor that can actually scroll: overflow allows it, and there is
        // more content than fits.
        let node = document.querySelector(selector)?.parentElement ?? null;
        while (node && node !== document.body) {
            const overflow = getComputedStyle(node).overflowY;
            if (/(auto|scroll)/.test(overflow) && node.scrollHeight > node.clientHeight + 4) {
                return { el: node };
            }
            node = node.parentElement;
        }
        return { el: document.scrollingElement || document.documentElement, isDocument: true };
    }

    const found = scroller();
    if (found.error) return { error: found.error };
    const el = found.el;

    const before = count();
    let last = before;
    let stable = 0;
    let scrolls = 0;

    while (scrolls < maxScrolls) {
        const wasAtBottom = el.scrollTop + el.clientHeight >= el.scrollHeight - 4;
        el.scrollTop = el.scrollHeight;
        scrolls++;
        await sleep(settleMs);

        const now = count();
        // Nothing new AND we were already pinned to the bottom: the list is done
        // growing, not merely slow.
        stable = (now > last) ? 0 : stable + (wasAtBottom ? 1 : 0);
        last = now;
        if (stable >= stableRounds) break;
    }

    return {
        before,
        after: last,
        scrolls,
        exhausted: stable >= stableRounds,
        container: found.isDocument ? 'document' : (el.className || el.tagName || 'element').toString().slice(0, 60),
        url: location.href,
    };
}

// ── Captcha: read the widget, then hand a solved token back to the page ─────

/** Runs in the page's MAIN world. Describes the captcha widget well enough for
 *  2captcha to solve it, or reports that there isn't one yet.
 *
 *  Three sources, best first: the render hook (the only one that sees
 *  programmatically-passed parameters), the widget's own data- attributes, and
 *  finally the challenge iframe, whose URL carries the sitekey when nothing else
 *  does. */
function pageCaptchaInfo(scopeSelector, wanted) {
    const root = scopeSelector ? document.querySelector(scopeSelector) : document;
    if (!root) return { error: `No element matches ${scopeSelector}` };

    const KINDS = {
        turnstile: { cls: '.cf-turnstile', frame: 'challenges.cloudflare.com' },
        recaptcha: { cls: '.g-recaptcha', frame: '/recaptcha/' },
        hcaptcha: { cls: '.h-captcha', frame: 'hcaptcha.com' },
    };
    const want = (kind) => !wanted || wanted === 'auto' || wanted === kind;
    const enterprise = !!document.querySelector('script[src*="recaptcha/enterprise"]');

    // Cloudflare's iframe has no sitekey parameter — it is a path segment, and
    // every Turnstile key starts with 0x.
    const fromFrameUrl = (kind, src) => {
        try {
            const url = new URL(src, location.href);
            if (kind === 'recaptcha') return url.searchParams.get('k');
            if (kind === 'hcaptcha') return url.searchParams.get('sitekey');
            return url.pathname.split('/').find((part) => /^0x[A-Za-z0-9_-]{8,}$/.test(part)) || null;
        } catch {
            return null;
        }
    };

    // Newest first. A page that renders a fresh widget per modal leaves the
    // earlier ones in the registry — they are never unregistered — and the one
    // that matters is the one just rendered, not the first ever seen.
    for (const widget of [...(window.__autofirmerCaptcha?.widgets || [])].reverse()) {
        const params = widget.params || {};
        if (!want(widget.kind) || !params.sitekey) continue;
        return {
            provider: widget.kind,
            sitekey: params.sitekey,
            pageurl: location.href,
            action: params.action || '',
            data: params.cData || '',
            pagedata: params.chlPageData || '',
            invisible: params.size === 'invisible',
            enterprise,
            userAgent: navigator.userAgent,
            source: 'render hook',
        };
    }

    for (const kind of Object.keys(KINDS)) {
        if (!want(kind)) continue;
        const el = root.querySelector(`${KINDS[kind].cls}[data-sitekey]`);
        if (!el) continue;
        return {
            provider: kind,
            sitekey: el.getAttribute('data-sitekey'),
            pageurl: location.href,
            action: el.getAttribute('data-action') || '',
            data: el.getAttribute('data-cdata') || '',
            pagedata: '',
            invisible: el.getAttribute('data-size') === 'invisible',
            enterprise,
            userAgent: navigator.userAgent,
            source: 'data-sitekey',
        };
    }

    const frames = Array.from(root.querySelectorAll('iframe'));
    for (const kind of Object.keys(KINDS)) {
        if (!want(kind)) continue;
        for (const frame of frames) {
            const src = frame.getAttribute('src') || '';
            if (!src.includes(KINDS[kind].frame)) continue;
            const sitekey = fromFrameUrl(kind, src);
            if (!sitekey) continue;
            return {
                provider: kind,
                sitekey,
                pageurl: location.href,
                action: '',
                data: '',
                pagedata: '',
                invisible: false,
                enterprise,
            userAgent: navigator.userAgent,
                source: 'challenge iframe',
            };
        }
    }

    return { error: 'No captcha widget on the page yet' };
}

/** Runs in the page's MAIN world. Puts a solved token where the page looks for
 *  it, then tells the page it arrived.
 *
 *  Both halves matter. The hidden response field is what the form posts, but
 *  most pages enable their submit button from the widget's callback and never
 *  read the field until then — so filling it alone leaves the page looking
 *  unsolved. Only the FIRST callback found is fired: they are the page's own
 *  submit handlers, and calling several would risk sending the form twice. */
function pageCaptchaSubmit(token, provider) {
    const FIELDS = {
        turnstile: ['cf-turnstile-response', 'g-recaptcha-response'],
        recaptcha: ['g-recaptcha-response'],
        hcaptcha: ['h-captcha-response', 'g-recaptcha-response'],
    };

    const targets = new Set();
    for (const name of (FIELDS[provider] || FIELDS.recaptcha)) {
        document.querySelectorAll(`[name="${name}"], #${name}`).forEach((el) => targets.add(el));
    }
    // Turnstile names its hidden input per widget: cf-chl-widget-<id>_response.
    document.querySelectorAll('input[name^="cf-chl-widget-"]').forEach((el) => targets.add(el));

    let filled = 0;
    const fieldIds = [];
    for (const el of targets) {
        el.value = token;
        el.dispatchEvent(new Event('input', { bubbles: true }));
        el.dispatchEvent(new Event('change', { bubbles: true }));
        fieldIds.push(el.id || `(${el.getAttribute('name')})`);
        filled++;
    }

    // reCAPTCHA numbers its response fields by widget id: the first widget gets
    // #g-recaptcha-response, the second #g-recaptcha-response-1, and so on. That
    // suffix is the only reliable link from the field the open modal is actually
    // showing back to the client object holding ITS callback.
    //
    // Guessing wrong is invisible from the outside and looks exactly like the
    // site ignoring a good token: the callback runs, but on a widget belonging
    // to a modal that has already closed, so nothing stores the token and the
    // confirm button never enables.
    let liveWidgetId = null;
    for (const el of targets) {
        const match = /^g-recaptcha-response(?:-(\d+))?$/.exec(el.id || '');
        if (match) { liveWidgetId = Number(match[1] || 0); break; }
    }

    let called = null;
    const invoke = (fn, where) => {
        if (called || typeof fn !== 'function') return false;
        try {
            fn(token);
            called = where;
            return true;
        } catch (err) {
            // The page's own handler threw. That is its business, but the token
            // did reach it, so don't go looking for another one to call.
            called = `${where} (threw: ${err.message})`;
            return true;
        }
    };

    // Newest first, for the same reason detection is: firing the callback of a
    // widget belonging to a modal that has already closed hands the token to
    // nobody, and the live widget never hears that it was solved — which looks
    // from the outside like the site simply ignoring a correct token.
    const hookWidgets = [...(window.__autofirmerCaptcha?.widgets || [])].reverse();
    let candidates = 0;
    let clientKeys = [];
    for (const widget of hookWidgets) {
        if (provider && provider !== 'auto' && widget.kind !== provider) continue;
        candidates++;
        if (called) continue;
        const cb = (widget.params || {}).callback;
        if (typeof cb === 'function') invoke(cb, `${widget.kind} render callback`);
        else if (typeof cb === 'string') invoke(window[cb], cb);
    }

    if (!called) {
        for (const el of document.querySelectorAll('[data-callback]')) {
            const name = el.getAttribute('data-callback');
            if (invoke(window[name], `data-callback ${name}`)) break;
        }
    }

    // reCAPTCHA rendered declaratively keeps its callback in a private config
    // object and nowhere else. The keys around it are minified; `callback` is not.
    if (window.___grecaptcha_cfg?.clients) {
        // Clients accumulate: reCAPTCHA adds one per render and removes none, so
        // after the second modal there are two and only one is live. Try the one
        // the response field named, then the rest newest-first as a fallback.
        const all = Object.entries(window.___grecaptcha_cfg.clients);
        clientKeys = all.map(([key]) => key);
        candidates += all.length;

        const ordered = all
            .sort(([a], [b]) => Number(b) - Number(a))
            .sort(([a], [b]) => (Number(a) === liveWidgetId ? -1 : Number(b) === liveWidgetId ? 1 : 0));

        for (const [key, client] of ordered) {
            if (called) break;
            // Depth-limited walk: the keys around it are minified, `callback`
            // is not.
            const seen = new Set();
            const queue = [client];
            let budget = 2000;
            while (queue.length && !called && budget-- > 0) {
                const node = queue.shift();
                if (!node || typeof node !== 'object' || seen.has(node)) continue;
                seen.add(node);
                for (const [prop, value] of Object.entries(node)) {
                    if (typeof value === 'function') {
                        if (/callback/i.test(prop) && invoke(value, `grecaptcha ${prop} (widget ${key})`)) break;
                    } else if (value && typeof value === 'object') {
                        queue.push(value);
                    }
                }
            }
        }
    }

    if (!filled && !called) {
        return { error: 'nowhere to put the token — no response field and no callback on the page' };
    }
    // `candidates` is the diagnostic that matters when a token is accepted and
    // the page does nothing: more than one means the page has stale widgets, and
    // the token went to whichever this picked.
    return {
        filled,
        called,
        candidates,
        // The diagnostic that matters when a token is accepted and the page does
        // nothing: which field carried it, and which widgets were on offer.
        fieldIds,
        liveWidgetId,
        clientKeys,
        provider,
        url: location.href,
    };
}

async function resolveLocateTab(cfg, request) {
    // Every step carries its firm's pattern; the manifest hosts are the fallback
    // for a bare request (the CLI's locate without --url).
    const pattern = request.urlPattern || firmPatterns();
    if (pattern) {
        const tabs = await chrome.tabs.query({ url: pattern });
        const tab = tabs.find((t) => /^https?:/.test(t.url || ''));
        if (tab) return { tab, opened: false };

        // Nothing matching is open. Open it rather than failing the run — but only
        // to the URL the firm declared, never to something a request supplied that
        // we have no host permission for.
        if (request.openUrl) {
            const created = await chrome.tabs.create({ url: request.openUrl, active: true });
            await waitForTabLoad(created.id);
            return { tab: await chrome.tabs.get(created.id), opened: true };
        }

        throw new Error(`No open tab matches ${pattern}, and no URL is configured to open`);
    }

    const [tab] = await chrome.tabs.query({ active: true, lastFocusedWindow: true });
    if (!tab || !/^https?:/.test(tab.url || '')) throw new Error('No eligible active tab');
    return { tab, opened: false };
}

/** Hand an answer — or a failure — back to whoever queued the request. */
async function postLocateResult(cfg, id, result, error) {
    await fetch(`${cfg.apiBase}/api/autobuyer/locate/result`, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ id, result, error }),
    });
}

/** Returns true if a request was handled, false if the queue was empty. */
async function serveLocateRequest(cfg) {
    const claim = await fetch(`${cfg.apiBase}/api/autobuyer/locate/claim`, { method: 'POST' });
    if (!claim.ok) throw new Error(`Claim failed: HTTP ${claim.status}`);
    const { request } = await claim.json();
    if (!request) return false;

    let result = null;
    let error = null;
    try {
        let { tab, opened } = await resolveLocateTab(cfg, request);

        // A navigate step points the tab at a specific page first. Skip it when we
        // are already there — reloading would throw away page state for nothing,
        // and the common case is that the tab is on the right page already.
        if (request.navigateUrl && !alreadyAt(tab.url, request.navigateUrl)) {
            await chrome.tabs.update(tab.id, { url: request.navigateUrl });
            await waitForTabLoad(tab.id);
            tab = await chrome.tabs.get(tab.id);
            opened = true;   // treat as a cold load: the app still has to mount
        }

        // The reported coordinates are only worth anything if that tab is the one
        // actually visible: raise its window and bring the tab to the front.
        // Only un-minimise — passing state:'normal' unconditionally would drop a
        // maximised or fullscreen window out of that state on every single click.
        const win = await chrome.windows.get(tab.windowId);
        const focus = win.state === 'minimized'
            ? { focused: true, state: 'normal' }
            : { focused: true };
        await chrome.windows.update(tab.windowId, focus);
        await chrome.tabs.update(tab.id, { active: true });
        await new Promise((r) => setTimeout(r, 250));   // let the OS finish raising it

        // A scroll request is a different operation on the same channel: no
        // element is measured, the page is just walked to the bottom.
        if (request.options && request.options.op === 'scrollToLoad') {
            const [scrolled] = await chrome.scripting.executeScript({
                target: { tabId: tab.id },
                func: pageScrollToLoad,
                args: [
                    request.selector,
                    request.options.containerSelector || '',
                    Number(request.options.maxScrolls) || 25,
                    Number(request.options.settleMs) || 800,
                    Number(request.options.stableRounds) || 2,
                ],
            });
            const out = scrolled?.result;
            if (!out) throw new Error('Scroll injection returned nothing');
            if (out.error) throw new Error(out.error);
            result = { ...out, tabId: tab.id, windowId: tab.windowId, browser: detectBrowser() };

            await postLocateResult(cfg, request.id, result, null);
            return true;
        }

        // Captcha ops are the same shape: no element is measured, the page is
        // read for its widget parameters or handed a token 2captcha solved.
        // Both run in the page's MAIN world — the isolated world cannot see the
        // page's own `turnstile` / `grecaptcha` objects, nor the render hook's
        // registry, and those hold the callbacks a token has to be given to.
        // allFrames because the widget is often in a same-origin sub-frame;
        // Chrome skips frames outside host_permissions, so the challenge iframe
        // itself is never touched.
        if (request.options && (request.options.op === 'captchaInfo' || request.options.op === 'captchaToken')) {
            const isInfo = request.options.op === 'captchaInfo';
            const injections = await chrome.scripting.executeScript({
                target: { tabId: tab.id, allFrames: true },
                world: 'MAIN',
                func: isInfo ? pageCaptchaInfo : pageCaptchaSubmit,
                args: isInfo
                    ? [request.options.scopeSelector || '', request.options.provider || 'auto']
                    : [String(request.options.token || ''), request.options.provider || 'auto'],
            });
            const answers = injections.map((i) => i?.result).filter(Boolean);
            const found = answers.find((a) => !a.error);
            if (!found) {
                throw new Error(answers[0]?.error || 'Captcha injection returned nothing');
            }
            result = { ...found, tabId: tab.id, windowId: tab.windowId, browser: detectBrowser() };

            await postLocateResult(cfg, request.id, result, null);
            return true;
        }

        // A visibility probe is a read, not a lookup: it reports on the element
        // instead of failing when there isn't one, so it never retries and never
        // errors on a missing selector — being missing is the answer.
        if (request.options && request.options.op === 'visible') {
            const [probe] = await chrome.scripting.executeScript({
                target: { tabId: tab.id },
                func: pageVisible,
                args: [request.selector, request.index || 0],
            });
            const out = probe?.result;
            if (!out) throw new Error('Visibility injection returned nothing');
            result = { ...out, tabId: tab.id, windowId: tab.windowId, browser: detectBrowser() };

            await postLocateResult(cfg, request.id, result, null);
            return true;
        }

        // `complete` only means the document loaded — a React app still has to
        // mount and paint. Retry briefly rather than declaring the element missing,
        // with a longer budget when we just opened the page from cold.
        const deadline = Date.now() + (opened ? 8000 : 2500);
        let out;
        for (;;) {
            const [injection] = await chrome.scripting.executeScript({
                target: { tabId: tab.id },
                func: pageLocate,
                args: [request.selector, request.index || 0],
            });
            out = injection?.result;
            if (!out) throw new Error('Injection returned nothing');
            if (!out.error) break;
            if (Date.now() >= deadline) throw new Error(out.error);
            await new Promise((r) => setTimeout(r, 350));
        }
        result = {
            ...out,
            tabId: tab.id,
            windowId: tab.windowId,
            openedTab: opened,
            browser: detectBrowser(),
        };
    } catch (err) {
        error = err.message;
    }

    await postLocateResult(cfg, request.id, result, error);
    return true;
}

async function tick() {
    const cfg = await getConfig();

    let status;
    try {
        const res = await fetch(`${cfg.apiBase}/api/autobuyer/status`, { cache: 'no-store' });
        if (!res.ok) throw new Error(`HTTP ${res.status}`);
        status = await res.json();
        pendingLocate = Number(status.pendingLocate) || 0;
    } catch (err) {
        setBadge(false);
        await setState({ connected: false, error: `Cannot reach ${cfg.apiBase} — ${err.message}` });
        return;
    }

    setBadge(true);
    await setState({ connected: true });

    // Only when nothing is queued: a reload mid-run drops the locate the runner
    // is blocked on. There is no hurry — the next tick is seconds away.
    if (!pendingLocate) {
        try {
            await maybeSelfUpdate(status.extensionVersion);
        } catch (err) {
            await setState({ connected: true, error: `Self-update check: ${err.message}` });
        }
    }

    // Serve queued clicks before capturing — the Python side is waiting on these,
    // and a capture of a megabyte page shouldn't sit in front of them.
    // Failures inside a request are reported back to the caller; a failure of the
    // queue plumbing itself lands here, and must not take the capture loop down.
    try {
        for (let i = 0; i < pendingLocate; i++) {
            if (!(await serveLocateRequest(cfg))) break;
        }
    } catch (err) {
        await setState({ connected: true, error: `Locate queue: ${err.message}` });
    }

    try {
        await captureAndSend(cfg);
    } catch (err) {
        await setState({ connected: true, error: err.message });
    }
}

// ── Keeping ourselves current ───────────────────────────────────────────────

/** -1 / 0 / 1 over dotted numeric versions; missing parts count as zero. */
function compareVersions(a, b) {
    const pa = String(a).split('.').map(Number);
    const pb = String(b).split('.').map(Number);
    for (let i = 0; i < Math.max(pa.length, pb.length); i++) {
        const diff = (pa[i] || 0) - (pb[i] || 0);
        if (diff) return diff < 0 ? -1 : 1;
    }
    return 0;
}

/** How we were installed: 'admin' when Chrome policy pulled us from the update
 *  server, 'development' when somebody loaded the folder unpacked. getSelf is
 *  the one chrome.management call that needs no permission. */
async function installType() {
    try {
        const self = await chrome.management.getSelf();
        return self.installType || 'development';
    } catch {
        return 'development';
    }
}

/** chrome.runtime.requestUpdateCheck as a promise; null if the call is not
 *  available at all. */
function requestUpdateCheck() {
    return new Promise((resolve) => {
        try {
            chrome.runtime.requestUpdateCheck((result) => {
                if (chrome.runtime.lastError) return resolve(null);
                resolve(result?.status || 'no_update');
            });
        } catch {
            resolve(null);
        }
    });
}

/** Get onto the newer build the dashboard is advertising.
 *
 *  Two different mechanisms, because there are two ways this extension gets
 *  installed. A policy install has a real update channel: Chrome polls the CRX
 *  on the droplet on its own schedule, and all we add is "check now" so a
 *  release lands in seconds rather than within five hours.
 *
 *  An unpacked load has no channel at all — Chrome reads the folder once and
 *  never looks again — but chrome.runtime.reload() re-reads it from disk, which
 *  the update check has already pulled into. That can only ever run code that is
 *  already there, so a dashboard ahead of this machine's pull would have us
 *  reload into the same version forever. Hence one attempt per version pair:
 *  come back unchanged and it says so and waits. A dashboard that is *behind* is
 *  left alone either way — downgrading is not something we can do. */
async function maybeSelfUpdate(expected) {
    const running = chrome.runtime.getManifest().version;
    const { updateAttempt } = await chrome.storage.local.get('updateAttempt');

    if (!expected || compareVersions(expected, running) <= 0) {
        // Nothing to do — and if we got here off the back of a reload, that
        // reload worked, so clear the note it left in the popup.
        if (updateAttempt) {
            await chrome.storage.local.remove('updateAttempt');
            await setState({ error: '' });
        }
        return;
    }

    if ((await installType()) !== 'development') {
        const status = await requestUpdateCheck();
        // Chrome swaps the extension out from under us when the CRX arrives, so
        // there is nothing to do afterwards but say what was asked for.
        await setState({
            error: status === 'throttled'
                ? `Running v${running}, v${expected} is published — Chrome is rate-limiting `
                  + `update checks and will pick it up shortly.`
                : `Running v${running}, asked Chrome to fetch v${expected} (${status || 'no answer'}).`,
        });
        return;
    }

    if (updateAttempt && updateAttempt.expected === expected && updateAttempt.running === running) {
        await setState({
            error: `Running v${running}, the dashboard ships v${expected}. Reloaded once and `
                 + `the files on disk were still the old ones — waiting for the next pull. `
                 + `If this sticks, pull and reload the card in chrome://extensions.`,
        });
        return;
    }

    // Recorded *before* the reload: the worker does not come back from this call,
    // so anything written after it would never be written at all.
    await chrome.storage.local.set({ updateAttempt: { expected, running, at: Date.now() } });
    await setState({ error: `Reloading to pick up v${expected} (running v${running})` });
    chrome.runtime.reload();
}

// ── Scheduling ──────────────────────────────────────────────────────────────

async function restart() {
    if (timer) clearInterval(timer);
    const cfg = await getConfig();
    // Re-check after the await: restart() is called from several places at startup,
    // and without this a concurrent call leaks an untracked interval — two polling
    // loops in one worker, capturing everything twice.
    if (timer) clearInterval(timer);
    const ms = Math.max(1, Number(cfg.pollSeconds) || DEFAULTS.pollSeconds) * 1000;
    timer = setInterval(tick, ms);
    tick();
}

chrome.runtime.onInstalled.addListener(restart);
chrome.runtime.onStartup.addListener(restart);

// The setInterval above only survives while the worker is alive. Each tick makes
// an extension API call, which resets the idle timer, so in practice the loop
// keeps itself running — this alarm is the safety net that revives it if Chrome
// tears the worker down anyway. 30s is the shortest period Chrome honours.
chrome.alarms.create('keepalive', { periodInMinutes: 0.5 });
chrome.alarms.onAlarm.addListener(() => {
    if (timer) tick(); else restart();
});

chrome.storage.onChanged.addListener((changes, area) => {
    if (area !== 'local') return;
    if (Object.keys(DEFAULTS).some((k) => k in changes)) restart();
});

chrome.runtime.onMessage.addListener((msg, _sender, sendResponse) => {
    if (msg?.type !== 'capture-now') return;
    getConfig()
        .then(captureAndSend)
        .then(() => sendResponse({ ok: true }))
        .catch((err) => sendResponse({ ok: false, error: err.message }));
    return true;   // keep the message channel open for the async response
});

restart();