// Populate the sidebar
//
// This is a script, and not included directly in the page, to control the total size of the book.
// The TOC contains an entry for each page, so if each page includes a copy of the TOC,
// the total size of the page becomes O(n**2).
class MDBookSidebarScrollbox extends HTMLElement {
    constructor() {
        super();
    }
    connectedCallback() {
        // Modify TOC to support external links
        var toc = '{{#toc}}{{/toc}}';
        // Handle both old mdbook (<div>) and new mdbook 0.5 (<span>) formats
        // External links open in new tab with external link icon
        toc = toc.replace(/<(div|span)>([^$<>]*)\$\$external:([^$<>]*)\$\$<\/(div|span)>/g, '<a class="external-link" href="$3" target="_blank" rel="noopener noreferrer">$2 ↗</a>') 
        this.innerHTML = toc
        // Set the current, active page, and reveal it if it's hidden
        let current_page = document.location.href.toString();
        if (current_page.endsWith("/")) {
            current_page += "index.html";
        }
        var links = Array.prototype.slice.call(this.querySelectorAll("a"));
        var l = links.length;
        for (var i = 0; i < l; ++i) {
            var link = links[i];
            var href = link.getAttribute("href");
            if (href && !href.startsWith("#") && !/^(?:[a-z+]+:)?\/\//.test(href)) {
                link.href = path_to_root + href;
            }
            // The "index" page is supposed to alias the first chapter in the book.
            if (link.href === current_page || (i === 0 && path_to_root === "" && current_page.endsWith("/index.html"))) {
                link.classList.add("active");
                var parent = link.parentElement;
                if (parent && parent.classList.contains("chapter-item")) {
                    parent.classList.add("expanded");
                }
                while (parent) {
                    if (parent.tagName === "LI" && parent.classList.contains("chapter-item")) {
                        parent.classList.add("expanded");
                    }
                    parent = parent.parentElement;
                }
            }
        }
        updateChapterNavigation(links);
        // Track and set sidebar scroll position
        this.addEventListener('click', function(e) {
            if (e.target.tagName === 'A') {
                sessionStorage.setItem('sidebar-scroll', this.scrollTop);
            }
        }, { passive: true });
        var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
        sessionStorage.removeItem('sidebar-scroll');
        if (sidebarScrollTop) {
            // preserve sidebar scroll position when navigating via links within sidebar
            this.scrollTop = sidebarScrollTop;
        } else {
            // scroll sidebar to current active section when navigating via "next/previous chapter" buttons
            var activeSection = document.querySelector('#sidebar .active');
            if (activeSection) {
                activeSection.scrollIntoView({ block: 'center' });
            }
        }
        // Toggle buttons (delegate to avoid navigation)
        var sidebarRoot = document.getElementById('sidebar');
        if (sidebarRoot) {
            sidebarRoot.addEventListener('click', function (ev) {
                var toggle = ev.target.closest('a.chapter-fold-toggle');
                if (!toggle) { return; }
                ev.preventDefault();
                ev.stopPropagation();
                var parentLi = toggle.closest('li.chapter-item');
                if (parentLi) {
                    parentLi.classList.toggle('expanded');
                }
            }, true);
            sidebarRoot.addEventListener('pointerdown', function (ev) {
                var toggle = ev.target.closest('a.chapter-fold-toggle');
                if (!toggle) { return; }
                ev.preventDefault();
                ev.stopPropagation();
            }, true);
        }
    }
}
window.customElements.define("mdbook-sidebar-scrollbox", MDBookSidebarScrollbox);

function normalizeChapterUrl(url) {
    try {
        var normalized = new URL(url, document.location.href);
        normalized.hash = "";
        normalized.search = "";
        if (normalized.pathname.endsWith("/")) {
            normalized.pathname += "index.html";
        }
        return normalized.href;
    } catch (_) {
        return "";
    }
}

function setChapterNavigationLink(selector, chapter) {
    var link = document.querySelector(selector);
    if (!link) {
        return;
    }

    if (!chapter) {
        link.hidden = true;
        link.removeAttribute("href");
        return;
    }

    link.href = chapter.href;
    link.hidden = false;

    var label = link.querySelector(".chapter-nav-label") || link.querySelector("span");
    if (label) {
        label.textContent = chapter.title;
    }
}

function updateChapterNavigation(links) {
    var current = normalizeChapterUrl(document.location.href);
    var seen = Object.create(null);
    var chapters = [];

    links.forEach(function (link) {
        var rawHref = link.getAttribute("href");
        if (!rawHref || rawHref.startsWith("#") || link.classList.contains("external-link")) {
            return;
        }

        var url;
        try {
            url = new URL(link.href, document.location.href);
        } catch (_) {
            return;
        }
        if (url.origin !== document.location.origin && url.protocol !== "file:") {
            return;
        }

        var normalized = normalizeChapterUrl(url.href);
        if (!normalized || seen[normalized]) {
            return;
        }
        seen[normalized] = true;

        chapters.push({
            href: link.href,
            key: normalized,
            title: link.textContent.trim()
        });
    });

    var index = chapters.findIndex(function (chapter) {
        return chapter.key === current;
    });
    var previous = index > 0 ? chapters[index - 1] : null;
    var next = index >= 0 && index < chapters.length - 1 ? chapters[index + 1] : null;

    setChapterNavigationLink(".mobile-nav-chapters.previous", previous);
    setChapterNavigationLink(".nav-chapters.previous", previous);
    setChapterNavigationLink(".mobile-nav-chapters.next", next);
    setChapterNavigationLink(".nav-chapters.next", next);
}