// ==UserScript==
// @name         Fanfiction.net: Not-Crossover Link
// @namespace    https://greasyfork.org/en/users/163551-vannius
// @version      1.0
// @description  Add link to not-Crossover page to Fanfiction.net.
// @author       Vannius
// @match        https://www.fanfiction.net/crossovers/*
// @include      https://www.fanfiction.net/*Crossovers/*
// @grant        none
// @downloadURL none
// ==/UserScript==

(function () {
        // Functions
        // Replace and delete prohibited characters.
        function deleteProhibitedCharacter(text){
            return text.replace(/['|\.|\/| & | - | + ]+/g, ' ').replace(/[,\+!:;\|☆★！？]+/g, '');
        }

        // Return imgTag with click event
        function addClickToNotCrossover(imgTag, url){
            imgTag.addEventListener('click', function(e) {
                e.preventDefault();
                fetch(url, { method: 'GET',
                                 mode: 'same-origin',
                                 cache: 'default' })
                    .then(response => response.text())
                    .then(body => {
                        const doc = document.implementation.createHTMLDocument('myBody');
                        doc.documentElement.innerHTML = body;
                        const content = doc.getElementById('content_wrapper_inner');

                        const list = content.getElementsByClassName('z-list');
                        if (list.length) window.location.href = url; // Bingo

                        const candidates = content.querySelectorAll('.gui_normal a');
                        if (candidates.length == 1) window.location.href = candidates[0].href;
                        else if (candidates.length > 1) window.location.href = url; // There can be sevaral candidates for same fandom
                 }).catch(error=> console.log(error));
            });
            return imgTag;
        }

        // Main
        const splitPath = window.location.href.split('/');

        if (/^.+[-\_]and[-\_].+[-\_]Crossovers$/.test(splitPath[3])){
            // Scrape each fandom link
            const divTag = document.getElementById('content_wrapper_inner');
            const titleTags = [divTag.children[1], divTag.children[2]];

            for (let titleTag of titleTags){
                // Make joinTitle by replacing and deleting prohibited symbols
                const joinTitle = deleteProhibitedCharacter(titleTag.textContent).split(' ').join('-');
                const url = [window.location.origin, 'anime', joinTitle, ''].join('/');

                // Make link to Not-Crossover
                const imgTag = document.getElementById('content_wrapper_inner').children[0];
                const addImgTag = addClickToNotCrossover(imgTag.cloneNode(false), url);
                addImgTag.title = "Not-Crossover";
                addImgTag.style.transform = "scale(-1, 1)";

                // Add link and place adjustment
                imgTag.parentNode.insertBefore(addImgTag, titleTag);
                imgTag.parentNode.insertBefore(document.createTextNode(' '), titleTag);
            }
        }else if (splitPath[3] == 'crossovers' || /^.+[-\_]Crossovers$/.test(splitPath[3])){
            // Make title and url by splitPath[4] or splitPath[3]
            const title = (splitPath[3] == 'crossovers') ? splitPath[4] : splitPath[3].slice(0, - "-Crossovers".length);
            const url = [window.location.origin, 'anime', title, ''].join('/');

            // Make link to Not-Crossover
            const divTag = document.getElementById('content_wrapper_inner');
            const imgTag = (splitPath[3] == 'crossovers') ? divTag.children[2]: divTag.children[0];
            const addImgTag = addClickToNotCrossover(imgTag.cloneNode(false), url);
            addImgTag.title = "Not-Crossover";
            addImgTag.style.transform = "scale(-1, 1)";

            // Add link and place adjustment
            imgTag.parentNode.insertBefore(addImgTag, imgTag.nextSibling);
            imgTag.parentNode.insertBefore(document.createTextNode(' '), imgTag.nextSibling);
        }
})();