function extract(...args) {
    let message = {
        from: "DataExtracter:Extract",
        args: args
    }
    chrome.runtime.sendMessage(message, r => {
        if (r) console.log(r);
    });
}

chrome.runtime.onMessage.addListener(
    function (request, sender, sendResponse) {
        if (!request.from) return;
        let [ext, act] = request.from.split(":");
        if (ext.toLowerCase() !== 'dataextracter') return;
        // console.log(request);
        switch (act.toLowerCase()) {
            case "extract":
                let data = extractTabData(request.itemsSelector, request.fieldSelectors);
                if (sendResponse) sendResponse(data);
                break;
            case "gotourl":
                window.location.replace(request.url);
                if (sendResponse) sendResponse(request.url);
                break;
            case "reportin":
                if (sendResponse) sendResponse(request.from);
                break;
            case "queryurl":
                if (sendResponse) sendResponse(window.location.href);
                break;
            default:
                break;
        }
    }
);

function extractTabData(itemsSelector, fieldSelectors) {
    let fieldNotFound = false;
    let results = $(itemsSelector).toArray().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 = $(item).find(cls).toArray();
                    if (!fieldVals.length) {
                        fieldNotFound = true;
                        return;
                    }
                    return fieldVals.map(find => attr ? find[attr] : find.textContent.trim()).join('\n')
                }
            )
        }
    );
    return fieldNotFound ? [] : results
}