Firefox

javascript: (function(clipboard) {
    var subKeys = {
        cf: 'CassetteFuturism',
        cm: 'cybermonk',
        dp: 'decopunk',
        it: 'ImaginaryTechnology',
        iso: 'isometric',
        iv: 'ImaginaryVehicles',
        ap: 'ApocalypsePorn',
        ss: 'Simon_Stalenhag',
        sw: 'spainwave',
        sk: 'sketches',
    };
    var args = '%s'.split(' ');
    var subreddit = args[0];
    if (!subreddit) {
        var promptText = "Type subreddit:";
        for (var shortcut in subKeys) promptText += `\n- ${shortcut}: ${subKeys[shortcut]}`;
        subreddit = prompt(promptText);
    }
    if (!subreddit) return;
    if (subKeys[subreddit]) subreddit = subKeys[subreddit];
    var data = getData();
    if (!data) return;
    data.url = encodeURIComponent(data.url);
    window.open(`https://www.reddit.com/r/${subreddit}/submit?url=${data.url}&title=${data.title}`);
    if (!data.comment) return;
    if (clipboard) clipboard.writeText(data.comment);
    showComment(data.comment);

    function getData() {
        var imgs;
        var title = document.title;
        var comment = "";
        var isArtStation = document.location.host.endsWith("artstation.com");
        var isFlickr = document.location.host.endsWith("flickr.com");
        var isDeviantArt = document.location.host.endsWith("deviantart.com");
        if (isArtStation) {
            imgs = [...document.querySelectorAll(".project-assets-list picture img")];
            if (!imgs.length) {
                imgs = [...document.querySelectorAll(".project-assets img")];
            }
        } else if (isFlickr) {
            imgs = document.getElementsByClassName("zoom-large");
            if (!imgs.length) {
                alert("No large zoom image found.");
            }
        } else if (isDeviantArt) {
            var deviantArtImgRegex = /\/w_\d+,h_\d+/;
            imgs = [...document.querySelectorAll(".ReactModalPortal img")].filter(img => !(deviantArtImgRegex.exec(img.src)));
            if (!imgs.length) {
                alert("No large zoom image found.");
            }
        } else {
            imgs = document.getElementsByTagName("img");
        }
        if (!imgs.length) return;
        var imgIdx = undefined;
        if (imgs.length > 1) {
            if (args.length > 1) imgIdx = parseInt(args[1]);
            if (imgIdx === undefined || isNaN(imgIdx) || imgIdx < 1 || imgIdx > imgs.length) {
                numberImgs();
                imgIdx = parseInt(prompt(`There are ${imgs.length} images, select index:`, 1));
            }
            if (isNaN(imgIdx) || imgIdx < 1 || imgIdx > imgs.length) return;
            url = imgs[imgIdx - 1].src;
        } else {
            url = imgs[0].src;
        }
        if (isArtStation) {
            var data = getArtStationData(imgs);
            title = data.title;
            comment = data.comment;
        } else if (isFlickr) {
            var data = getFlickrData();
            title = data.title;
            comment = data.comment;
        } else if (isDeviantArt) {
            var data = getDevianArtData();
            title = data.title;
            comment = data.comment;
        }
        return {
            title: title,
            url: url,
            comment: comment
        };
    }

    function getArtStationData(imgs) {
        var title = document.querySelector(".project-sidebar-inner h1");
        if (!title) title = document.querySelector(".artwork-info-container h1");
        if (!title) return;
        var author = document.querySelector(".project-author-name a");
        if (!author) author = document.querySelector(".artist-name-and-headline .name a");
        if (!author) return;
        var withMoreImages = imgs.length > 1 ? " **with more images**" : "";
        var comment = `Source${withMoreImages}: [${title.innerText} (by ${author.innerText} - ArtStation)](${document.location.href})`;
        var desc = document.querySelector(".project-description p:first-child");
        if (!desc) desc = document.querySelector("#project-description p:first-child");
        if (desc) comment += formatRedditCommentQuote(desc.innerText);
        return {
            title: `${title.innerText} (by ${author.innerText})`,
            comment: comment
        };
    }

    function getFlickrData() {
        var author = document.getElementsByClassName("owner-name")[0].innerText;
        var title = document.title.substr(0, document.title.length - 9);
        if (title.indexOf(author) < 0) {
            title += ` (${author})`;
        }
        var comment = `Source: [${title} (Flickr)](${document.location.href})`;
        var desc = document.querySelector(".title-desc-block h1");
        if (!desc) desc = document.querySelector(".title-desc-block h2");
        if (desc) comment += formatRedditCommentQuote(desc.innerText);
        return {
            title: title,
            comment: comment
        };
    }

    function getDevianArtData() {
        var userLinkElems = document.querySelectorAll("a.user-link");
        if (userLinkElems.length < 2) return;
        var title = document.querySelector('h1[data-hook="deviation_title"]');
        if (!title) return;
        var comment = `Source: [${title.innerText} (by ${userLinkElems[1].innerText} - DeviantArt)](${document.location.href})`;
        var desc = document.querySelector(".legacy-journal");
        if (desc) comment += formatRedditCommentQuote(desc.innerText);
        return {
            title: `${title.innerText} (${userLinkElems[1].innerText})`,
            comment: comment
        };
    }

    function showComment(comment) {
        var inpt = document.getElementById("source-code");
        if (!inpt) {
            inpt = document.createElement("textarea");
            inpt.id = "source-code";
            inpt.style.position = "fixed";
            inpt.style.color = "black";
            inpt.style.top = "72px";
            inpt.style.width = "720px";
            inpt.style.height = "120px";
            inpt.style.zIndex = "99999";
            inpt.style.lineHeight = "normal";
            inpt.ondblclick = () => inpt.select();
            document.body.appendChild(inpt);
        };
        inpt.value = comment;
        inpt.focus();
        inpt.select();
    }

    function formatRedditCommentQuote(quote) {
        while (quote.indexOf("\n\n") >= 0) quote = quote.replaceAll("\n\n", "\n");
        return `: \r\n> ${quote.replaceAll("\n", "  \n")}`;
    }

    function numberImgs() {
        var imgs;
        var isArtStation = document.location.host.endsWith("artstation.com");
        if (isArtStation) {
            imgs = [...document.querySelectorAll(".project-assets-list picture img")].concat([...document.querySelectorAll(".project-assets img")]);
        } else {
            imgs = document.getElementsByTagName("img");
        }
        for (var img = 0; img < imgs.length; img++) {
            var parent = imgs[img].parentElement;
            if (!parent) continue;
            var numberDiv = document.createElement("div");
            numberDiv.innerHTML = 1 + img;
            numberDiv.style.position = "absolute";
            numberDiv.style.padding = "2px 9px 2px 6px";
            numberDiv.style.background = "rgba(255, 0, 0, 0.5)";
            numberDiv.style.zIndex = "9999";
            parent.prepend(numberDiv);
        }
    }
})(navigator.clipboard)