Itch.io Web Integration

Shows if an Itch.io link has been claimed or not
当前为 2020-06-06 提交的版本，查看最新版本。
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// ==UserScript==
// @name        Itch.io Web Integration
// @namespace   Lex@GreasyFork
// @match       *://*/*
// @grant       GM_xmlhttpRequest
// @grant       GM_getValue
// @grant       GM_setValue
// @version     0.1.3
// @author      Lex
// @description Shows if an Itch.io link has been claimed or not
// @connect     itch.io
// ==/UserScript==

// TODO
// Add ability to claim the game with one click

(function(){
    'use strict';
    
    const INVALIDATION_TIME = 5*60*60*1000; // 5 hour cache time
    const ITCH_GAME_CACHE_KEY = 'ItchGameCache';
    var ItchGameCache;
    
    // Promise wrapper for GM_xmlhttpRequest
    const Request = details => new Promise((resolve, reject) => {
        details.onerror = details.ontimeout = reject;
        details.onload = resolve;
        GM_xmlhttpRequest(details);
    });
    
    function loadItchCache() {
        ItchGameCache = JSON.parse(GM_getValue(ITCH_GAME_CACHE_KEY) || '{}');
    }
    
    function _saveItchCache() {
        if (ItchGameCache === undefined) return;
        GM_setValue(ITCH_GAME_CACHE_KEY, JSON.stringify(ItchGameCache));
    }
    
    function setItchGameCache(key, game) {
        loadItchCache(); // refresh our cache in case another tab has edited it
        ItchGameCache[key] = game;
        _saveItchCache();
    }
    
    function deleteItchGameCache(key) {
        if (key === undefined) return;
        loadItchCache();
        delete ItchGameCache[key];
        _saveItchCache();
    }
    
    function getItchGameCache(link) {
        if (!ItchGameCache) loadItchCache();
        if (Object.prototype.hasOwnProperty.call(ItchGameCache, link)) {
            return ItchGameCache[link];
        }
        return null;
    }
    
    // Sends an XHR request and parses the results into a game object
    async function fetchItchGame(url) {
        const response = await Request({method: "GET",
                                 url: url});
        const parser = new DOMParser();
        const dom = parser.parseFromString(response.responseText, 'text/html');
        // Gets the inner text of an element if it can be found otherwise returns undefined
        const txt = query => { const e = dom.querySelector(query); return e && e.innerText.trim(); };
        
        const game = {};
        
        game.cachetime = (new Date()).getTime();
        game.url = url;
        
        const h2 = dom.querySelector(".purchase_banner_inner .key_row .ownership_reason");
        game.isOwned = h2 !== null;
        
        game.isClaimable = [...dom.querySelectorAll(".buy_btn")].filter(e => e.innerText == "Download or claim").length > 0;
        game.isFree = [...dom.querySelectorAll("span[itemprop=price]")].filter(e => e.innerText == "$0.00 USD").length > 0;
        game.original_price = txt("span.original_price");
        game.price = txt("span[itemprop=price]");
        game.saleRate = txt(".sale_rate");
        
        return game;
    }
    
    // Loads an itch game from cache or fetches the page if needed
    async function getItchGame(url) {
        let game = getItchGameCache(url);
        if (game !== null) {
            const isExpired = (new Date()).getTime() - game.cachetime > INVALIDATION_TIME;
            if (isExpired) {
                game = null;
            }
        }
        if (game === null) {
            game = await fetchItchGame(url);
            setItchGameCache(url, game);
        }
        return game;
    }
    
    // Appends the isOwned tag to an anchor link
    function appendTags(a, game) {
        const div = document.createElement("div");
        a.after(div);
        let ownMark = '';
        if (game.isOwned) {
            ownMark = `<span title="Game is already claimed on itch.io">✔️</span>`;
        } else {
            if (!game.isClaimable) {
                let tooltip = game.price ? `🛒 Game costs ${game.price}` : `Game is not free`;
                ownMark = `<span title="${tooltip}">⛔</span>`;
            } else {
                const origPrice = game.original_price ? ` 🛒 Original price: ${game.original_price} 💸 Current Price: ${game.price}` : '';
                ownMark = `<span title="Game is claimable but you haven't claimed it.${origPrice}">❌</span>`;
            }
        }
        div.outerHTML = `<div style="margin-left: 5px; background:rgb(200,200,200); border-radius: 5px; display: inline-block;">${ownMark}</div>`;
    }
    
    function addClickHandler(a) {
        a.addEventListener('mouseup', event => {
            deleteItchGameCache(event.target.href);
        });
    }

    // Handles an itch.io link on a page
    async function handleLink(a) {
        addClickHandler(a);
        const game = await getItchGame(a.href);
        appendTags(a, game);
    }
    
    // Finds all the itch.io links on the current page
    function getItchLinks() {
        let links = [...document.querySelectorAll("a[href*='itch.io/']")];
        links = links.filter(a => /^https:\/\/[^.]+\.itch\.io\/[^/]+$/.test(a.href));
        links = links.filter(a => !a.classList.contains("return_link"));
        links = links.filter(a => { const t = a.textContent.trim(); return t !== "" && t !== "GIF"; });
        return links;
    }
    
    function handlePage() {
        const as = getItchLinks();
        as.forEach(handleLink);
    }
    
    handlePage();
})();