// ==UserScript==
// @name Google Books Wiktionary Citation
// @version  1
// @include https://www.google.com/search*&tbm=bks&*
// @include https://www.google.com/search?tbm=bks&*
// @grant GM.xmlHttpRequest
// ==/UserScript==

function addCiteLinksBooks() {
    var results = document.getElementsByClassName("Yr5TG");

    for (var i = 0; i < results.length; i++) {
        var line = results[i].getElementsByClassName("N96wpd")[0];
        var button = document.createElement('button');
        var buttonText = document.createTextNode("[cite]");
        button.appendChild(buttonText);
        button.onclick = displayCitationBooks;
        line.appendChild(button);
    }
}

function displayCitationBooks() {
    var result = this.closest(".Yr5TG");

    var target = result.getElementsByTagName("a")[0].href.split("&hl=")[0];
    var id = /\?id=(.*?)&/.exec(target)[1];

    var snippet = result.getElementsByClassName("ETWPw");
    var page = null;
    if (snippet.length) {
        snippet = snippet[0].getElementsByTagName("span")[0].textContent;
        page = result.getElementsByClassName("VNSPub")[0].textContent;
        page = /Page (\d+)/.exec(page);
        if (page) page = page[1];
    } else snippet = false;

    var request = GM.xmlHttpRequest({
        method: "GET",
        url: "https://www.googleapis.com/books/v1/volumes/" + id,

        onload: function(response) {
            volumeInfo = JSON.parse(response.responseText)["volumeInfo"];

            var title = volumeInfo["title"] && (volumeInfo["title"] + (volumeInfo["subtitle"] && (": " + volumeInfo["subtitle"]) || "")).replace("|", "&#124;");

            var publisher = volumeInfo["publisher"] && volumeInfo["publisher"].replace("|", "&#124;");

            var date = volumeInfo["publishedDate"];
            var dateType = date && date.includes("-") && "date" || "year";

            var lang = volumeInfo["language"];

            var isbn, issn;
            var identifiers = volumeInfo["industryIdentifiers"];
            if (identifiers) {
                isbn = identifiers.find(function(x) {
                    return x.type == "ISBN_13"
                }) || identifiers.find(function(x) {
                    return x.type == "ISBN_10"
                });
                issn = identifiers.find(function(x) {
                    return x.type == "ISSN"
                });
                if (isbn) isbn = isbn["identifier"];
                if (issn) issn = issn["identifier"];
            }

            var author = volumeInfo["authors"] && volumeInfo["authors"].join(", ").replace("|", "&#124;");

            var citation = "{{quote-book|" +
                lang +
                (target && ("\n|url=" + target) || "") +
                (title && ("\n|title=" + title) || "") +
                (author && ("\n|author=" + author) || "") +
                (publisher && ("\n|publisher=" + publisher) || "") +
                (isbn && ("\n|isbn=" + isbn) || "") +
                (issn && ("\n|issn=" + issn) || "") +
                (date && ("\n|" + dateType + "=" + date) || "") +
                (page && ("\n|page=" + page) || "") +
                (snippet && ("\n|passage=" + snippet) || "") +
                (snippet && (lang != "en") && ("\n|t=") || "") +
                "\n}}";

            var textarea = document.createElement("textarea");
            var button = document.createElement('button');
            var buttonText = document.createTextNode("[minify]");
            button.appendChild(buttonText);
            button.onclick = minify;
            textarea.setAttribute('rows', 10);
            textarea.setAttribute('cols', 80);
            textarea.value = citation;

            var line = result.getElementsByClassName("N96wpd")[0];
            line.insertBefore(button, this.nextSibling);
            line.insertBefore(textarea, button);
        }
    });
}

function minify() {
    var textarea = this.parentNode.getElementsByTagName('textarea')[0];
    textarea.value = textarea.value.replace(/\n/g, "");
}

addCiteLinksBooks();