redirect-to-cache.js

const KEY_REDIRECT = "neurowhai-OTAC-redirect";


let flagRedirect = true;

function setRedirectFlag(flag) {
    flagRedirect = flag;

    chrome.browserAction.setBadgeText({ text: (flag ? "ON" : "OFF") });
    chrome.browserAction.setBadgeBackgroundColor({
        color: (flag ? [66, 133, 244, 200] : [112, 146, 190, 200])
    });
}

// Get first data
chrome.storage.local.get(KEY_REDIRECT, function(items) {
    var data = items[KEY_REDIRECT];

    setRedirectFlag(data != "0");
})

// Change flag
chrome.browserAction.onClicked.addListener(function(tab) {
    chrome.storage.local.get(KEY_REDIRECT, function(items) {
        var data = items[KEY_REDIRECT];

        setRedirectFlag(data == "0");
            
        var newData = {};
        newData[KEY_REDIRECT] = (flagRedirect ? "1" : "0");
            
        chrome.storage.local.set(newData);
    })
});


function redirect(tabId, url) {
    chrome.tabs.update(tabId, {
        url: url,
        active: false
    });
}

function redirectToCache(tabId, url) {
    redirect(tabId, "http://webcache.googleusercontent.com/search?q=cache:" + url);
}

function redirectToWayback(tabId, url) {
    url = "https://web.archive.org/save/" + url;

    chrome.tabs.executeScript(tabId, {
        code: "location.replace(\'" + encodeURI(url) + "\')"
    });
}

function needRedirect(url) {
    var matches = url.match(/^http:\/\/([\d\w\-\_]+)\.tistory\.com/);
    return (matches !== null && matches[1] != 'www');
}

chrome.webNavigation.onBeforeNavigate.addListener(function(details) {
    if (flagRedirect === false) {
        return;
    }
    
    
    // If only main window navigation
    if (details.frameId === 0 && needRedirect(details.url)) {
        // Redirect to Google web cache
        redirectToCache(details.tabId, details.url);
    }
}, {
    url: [{urlMatches: "^http:\\/\\/[\\d\\w\\-\\_]+\\.tistory\\.com"}]
});

chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab) {
    if (flagRedirect === false) {
        return;
    }
    
    
    var url = changeInfo.url || tab.url;
    var title = changeInfo.title || tab.title;

    var matches = url.match(/^https?:\/\/webcache\.googleusercontent\.com\/search\?q=cache:(http:\/\/[\d\w\-\_]+\.tistory\.com.*)/);

    // Redirect to Archive if there is no cache
    if (matches !== null && title == "Error 404 (Not Found)!!1") {
        redirectToWayback(tabId, matches[1]);
    }
});