window.ph_select = function(sel) {
    if (!window.Sizzle) {
        return Array.from(document.querySelectorAll(sel));
    }

    if (sel.includes(":contains(")) {
        if (!window.Sizzle) {
            throw new Error("Using ':contains' when window.Sizzle is not available.");
        }
        return window.Sizzle(sel);
    } else {
        return Array.from(document.querySelectorAll(sel));
    }
};

window.ph_find = function(sel) {
    const els = window.ph_select(sel);
    if (els.length === 0)
        throw new Error(sel + " not found");
    if (els.length > 1)
        throw new Error(sel + " is ambiguous");
    return els[0];
};

window.ph_text = function(sel) {
    const el = window.ph_find(sel);
    if (el.textContent === undefined)
        throw new Error(sel + " can not have text");
    // 0xa0 is a non-breakable space, which is a rendering detail of Chromium
    // and awkward to handle in tests; turn it into normal spaces
    return el.textContent.replaceAll("\xa0", " ");
};

window.ph_is_visible = function(sel) {
    const el = window.ph_find(sel);
    return el.tagName === "svg" || ((el.offsetWidth > 0 || el.offsetHeight > 0) && !(el.style.visibility === "hidden" || el.style.display === "none"));
};

class PhWaitCondTimeout extends Error {
    constructor(description) {
        if (description && description.apply)
            description = description.apply();
        if (description)
            super(description);
        else
            super("condition did not become true");
    }
}

window.ph_wait_cond = function (cond, timeout, error_description) {
    return new Promise((resolve, reject) => {
        // poll every 100 ms for now;  FIXME: poll less often and re-check on mutations using
        // https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver
        let stepTimer = null;
        let last_err = null;
        const tm = window.setTimeout(() => {
            if (stepTimer)
                window.clearTimeout(stepTimer);
            reject(last_err || new PhWaitCondTimeout(error_description));
        }, timeout);
        function step() {
            try {
                if (cond()) {
                    window.clearTimeout(tm);
                    resolve();
                    return;
                }
            } catch (err) {
                last_err = err;
            }
            stepTimer = window.setTimeout(step, 100);
        }
        step();
    });
};