chrome.runtime.onMessage.addListener(
    function (request, sender, sendResponse) {
        if (!request.action) return;
        // console.log("Recieved request:",request);
        switch (request.action) {
            case ACTION_EXTRACT:
                let data = extract(request.itemsSelector, request.fieldSelectors);
                if (sendResponse) sendResponse(data);
                break;
            case ACTION_GOTO_URL:
                window.location.replace(request.url);
                if (sendResponse) sendResponse(request.url);
                break;
            case ACTION_REPORT_IN:
                if (sendResponse) sendResponse(request.action);
                break;
            case ACTION_QUERY_URL:
                if (sendResponse) sendResponse(window.location.href);
                break;
            default:
                break;
        }
    }
);

function extract(itemsSelector, fieldSelectors) {
    // let fieldNotFound = false;
    let items = Array.from(document.querySelectorAll(itemsSelector));
    if (!items.length) return [];
    let results = items.map(
        item => {
            return fieldSelectors.map(
                selector => {
                    let [cls, attr] = selector.split('@').slice(0, 2);
                    // TODO: close tab to cancel task tip
                    // if (fieldNotFound) return;
                    let fieldVals = Array.from(item.querySelectorAll(cls));
                    // if (!fieldVals.length) {
                    //     fieldNotFound = true;
                    //     return;
                    // }
                    return fieldVals.map(find => attr ? find[attr] : find.textContent.trim()).join('\n')
                }
            )
        }
    );
    // return fieldNotFound ? [] : results
    return results;
}