PageScrollHistory UserScript

PageScrollHistory.js

// ==UserScript==
// @name         Page Scroll History
// @namespace    http://tampermonkey.net/
// @version      1.2.2
// @description  Page Scroll History
// @author       Tyler Sedlar
// @match        *://www.tdev.top/eBooks/*
// @grant        GM.registerMenuCommand
// @grant        GM.getValue
// @grant        GM.setValue
// @grant        GM.listValues
// @grant        GM.xmlHttpRequest
// ==/UserScript==

(function() {
    'use strict';

    var storageService = 'https://keyvalue.immanuel.co/api/KeyVal';
    var storageApiKey = 'YOUR_KEY_HERE, GET @ https://keyvalue.immanuel.co/api/KeyVal/GetAppKey';

    function getPageID() {
        var minTitle = document.title
            .toLowerCase()
            .replace(/ /g, '_')
            .replace(/-/g, '_')
            .replace(/:/g, '_')
            .replace(/__/g, '_')
            .replace(/\./g, '')
            .replace(/,/g, '');
        var divCount = document.querySelectorAll('div').length;
        var pCount = document.querySelectorAll('p').length;
        var imgCount = document.querySelectorAll('img').length;
        var spanCount = document.querySelectorAll('span').length;
        var blockquoteCount = document.querySelectorAll('blockquote').length;
        var aCount = document.querySelectorAll('a').length;
        return minTitle + `_${divCount}d${pCount}p${imgCount}i${spanCount}s${blockquoteCount}b${aCount}a`;
    }

    function contentElement(callback) {
        callback(document.body);
    }

    function updateBookmark(element) {
        if (element) {
            var pageID = getPageID();
            var currentParagraph = topmostContent();
            GM.setValue(pageID, currentParagraph);
            GM.xmlHttpRequest({
                url: `${storageService}/UpdateValue/${storageApiKey}/${pageID}/${currentParagraph}`,
                method: 'POST',
                onload: function(response) {
                    if (response.readyState == 4 && response.status == 200) {
                        alert(`Bookmark updated to ${currentParagraph}`);
                    } else {
                        alert('Bookmaked locally, but failed to set remotely.');
                    }
                },
                onerror: function(response) {
                    alert('Bookmaked locally, but failed to set remotely.');
                }
            });
        }
    }

    function scrollToBookmark(element) {
        if (element) {
            var pageID = getPageID();
            console.log(`scrollToBookmark(${pageID})`);
            GM.getValue(pageID).then(function(localParagraph) {
                Promise.resolve(new Promise(function(resolve, reject) {
                    GM.xmlHttpRequest({
                        url: `${storageService}/GetValue/${storageApiKey}/${pageID}`,
                        method: 'GET',
                        onload: function(response) {
                            if (response.readyState == 4 && response.status == 200 && response.responseText.replace(/"/g, '').length > 0) {
                                resolve(parseInt(response.responseText.replace(/"/g, '')));
                            } else {
                                resolve(-1);
                            }
                        },
                        onerror: function(response) {
                            resolve(-1);
                        }
                    });
                })).then(function(remoteParagraph) {
                    var latestParagraph = localParagraph;
                    if (latestParagraph) {
                        if (remoteParagraph > latestParagraph) {
                            latestParagraph = remoteParagraph;
                            GM.setValue(pageID, latestParagraph);
                        } else if (latestParagraph > remoteParagraph && remoteParagraph != -1) {
                            contentElement(function(e) { updateBookmark(e); });
                        }
                    } else if (remoteParagraph >= 0) {
                        latestParagraph = remoteParagraph;
                        GM.setValue(pageID, latestParagraph);
                    }

                    if (latestParagraph !== undefined && latestParagraph >= 0) {
                        console.log('scrolling to bookmark ' + latestParagraph);
                        scrollToPos(latestParagraph);
                    }
                });
            });
        }
    }

    function checkVisible(elm) {
        var rect = elm.getBoundingClientRect();
        var viewHeight = Math.max(document.documentElement.clientHeight, window.innerHeight);
        return !(rect.bottom < 0 || rect.top - viewHeight >= 0);
    }

    function topmostContent() {
        var paragraphs = document.querySelectorAll('p');
        var idx = 0;
        for (var p of paragraphs) {
            if (checkVisible(p)) {
                return idx;
            }
            idx++;
        }
        return 0;
    }

    function scrollToPos(pos) {
        var paragraphs = document.querySelectorAll('p');
        if (paragraphs.length >= pos) {
            paragraphs[pos].scrollIntoView({ behavior: "smooth", block: "start", inline: "nearest" });
        }
    }

    GM.registerMenuCommand('Go To Bookmark', function() { contentElement(function(e) { scrollToBookmark(e); }); }, 'g');
    GM.registerMenuCommand('Update Bookmark', function() { contentElement(function(e) { updateBookmark(e); }); }, 'u');
    GM.registerMenuCommand('Download Bookmarks', function() {
        function downloadString(text, fileType, fileName) {
            var blob = new Blob([text], { type: fileType });

            var a = document.createElement('a');
            a.download = fileName;
            a.href = URL.createObjectURL(blob);
            a.dataset.downloadurl = [fileType, a.download, a.href].join(':');
            a.style.display = "none";
            document.body.appendChild(a);
            a.click();
            document.body.removeChild(a);

            setTimeout(function() { URL.revokeObjectURL(a.href); }, 1500);
        }

        GM.listValues().then(function(keys) {
            Promise.all(keys.map(function(k) {
                return GM.getValue(k).then(function(v) {
                    return { key: k, value: v };
                });
            })).then(function(dataList) {
                var bookmarks = {};
                for (let data of dataList) {
                    bookmarks[data.key] = data.value;
                }
                downloadString(JSON.stringify(bookmarks, null, 2), 'json', 'page-scroll-history-storage.json');
            });
        });
    }, 'd');

    window.onbeforeunload = function(e) {
        if (confirm('Would you like to save your position?')) {
            contentElement(function(e) { updateBookmark(e); });
        }
    };

    setTimeout(function() {
        contentElement(function(e) { scrollToBookmark(e); });
    }, 2000);
})();