根据 https://forum.smart-teach.cn/d/2764-yi-si-zhao-dao-liao-lun-tan-sou-suo-de-ke-yong-fang-fa/16 发现的bug
作用：移除url末尾空格；拦截论坛的 pushState / replaceState 路由跳转；屏蔽“已解决主题帖”；修复下拉菜单中的搜索结果预览
// ==UserScript==
// @name         智教联盟论坛搜索修复
// @namespace    https://forum.smart-teach.cn/
// @version      2.4.0
// @description  修复实时主题搜索预览、搜索链接并提供已解决主题显示开关
// @match        https://forum.smart-teach.cn/*
// @match        http://forum.smart-teach.cn/*
// @run-at       document-start
// @grant        GM_getValue
// @grant        GM_registerMenuCommand
// @grant        GM_setValue
// ==/UserScript==

(() => {
    'use strict';

    const CONFIG = Object.freeze({
        searchParam: 'q',
        apiLimit: 8,
        hideSolvedKey: 'hideSolvedPreview',
    });
    const state = {
        previewRequest: 0,
        hideSolved: GM_getValue(CONFIG.hideSolvedKey, false),
    };
    const searchSelector = '[role="search"] input[type="search"]';
    // Flarum 用空格分隔搜索语法，只清理首尾空白，不改动内部空格。
    const trimQuery = value => typeof value === 'string' ? value.trim() : value;

    const fixUrl = url => {
        try {
            const target = new URL(url, location.href);
            const query = target.searchParams.get(CONFIG.searchParam);
            const fixed = trimQuery(query);
            if (query !== null && fixed !== query) {
                target.searchParams.set(CONFIG.searchParam, fixed);
                return target.href;
            }
        } catch {}
        return url;
    };

    // Flarum 用 pushState/replaceState 完成搜索跳转。
    // 在路由写入地址前修正 q，避免地址栏重新变成 ?q=关键词%20。
    for (const method of ['pushState', 'replaceState']) {
        const original = history[method];
        history[method] = function (state, title, url, ...args) {
            return original.call(this, state, title, typeof url === 'string' ? fixUrl(url) : url, ...args);
        };
    }

    const isSolvedQuery = query =>
        /(?:^|\s)is:solved(?:\s|$)/i.test(query || '');

    const getSearchMenu = () => document.querySelector('.Search-results');

    const registerSettingsMenu = () => {
        GM_registerMenuCommand(
            `${state.hideSolved ? '显示' : '隐藏'}已解决主题帖预览`,
            () => {
                GM_setValue(CONFIG.hideSolvedKey, !state.hideSolved);
                location.reload();
            },
        );
    };

    const escapeHtml = value => String(value ?? '').replace(/[&<>"']/g, character => ({
        '&': '&amp;',
        '<': '&lt;',
        '>': '&gt;',
        '"': '&quot;',
        "'": '&#39;',
    }[character]));

    const findSectionHeader = (menu, title) =>
        [...menu.querySelectorAll(':scope > li.Dropdown-header')]
            .find(item => item.textContent.trim() === title);

    const renderDiscussionPreview = results => {
        const menu = getSearchMenu();
        if (!menu) return;

        menu.querySelectorAll('[data-stcn-preview]').forEach(item => item.remove());
        if (!results.length) return;

        const themeHeader = findSectionHeader(menu, '主题');
        if (!themeHeader) return;

        const nextHeader = [...menu.children]
            .find(child =>
                child.classList.contains('Dropdown-header') &&
                themeHeader.compareDocumentPosition(child) &
                Node.DOCUMENT_POSITION_FOLLOWING
            );
        const fragment = document.createDocumentFragment();

        for (const discussion of results) {
            const item = document.createElement('li');
            item.dataset.stcnPreview = 'true';
            const link = document.createElement('a');
            link.className = 'hasIcon';
            link.href = fixUrl(discussion.url);
            link.innerHTML =
                `<i aria-hidden="true" class="icon fas fa-search Button-icon"></i>` +
                `<span class="Button-label">${escapeHtml(discussion.title)}</span>`;
            item.append(link);
            fragment.append(item);
        }

        (nextHeader || null)?.before(fragment);
        if (!nextHeader) menu.append(fragment);
    };

    const loadDiscussionPreview = async query => {
        const request = ++state.previewRequest;
        const normalized = trimQuery(query);
        if (!normalized) {
            renderDiscussionPreview([]);
            return;
        }

        try {
            const params = new URLSearchParams({
                'filter[q]': normalized,
                'page[limit]': String(CONFIG.apiLimit),
            });
            const response = await fetch(`/api/discussions?${params}`);
            if (!response.ok) return;
            const payload = await response.json();
            if (request !== state.previewRequest) return;

            const results = (payload.data || [])
                .map(item => {
                    const attributes = item.attributes || {};
                    const slug = attributes.slug || item.id;
                    return {
                        title: attributes.title,
                        url: `/d/${item.id}-${slug}`,
                    };
                })
                .filter(item => item.title && item.url)
            renderDiscussionPreview(results);
        } catch {
            // API 不可用时保留 Flarum 自己的搜索入口。
        }
    };

    // 搜索预览按钮是动态生成的，提交前直接修正其 href。
    const fixSearchLink = event => {
        const link = event.target.closest?.('.Search-results a[href]');
        if (link) link.href = fixUrl(link.href);
    };
    document.addEventListener('pointerdown', fixSearchLink, true);
    document.addEventListener('click', fixSearchLink, true);

    // 在页面上下文拦截论坛自己的搜索预览请求。
    const patch = document.createElement('script');
    patch.textContent = `(${(param => {
        const trim = value => typeof value === 'string' ? value.replace(/\s+$/, '') : value;
        const url = value => {
            try {
                const target = new URL(value, location.href);
            const query = target.searchParams.get(param);
                const fixed = trim(query);
                if (query !== null && fixed !== query) {
                    target.searchParams.set(param, fixed);
                    return target.href;
                }
            } catch {}
            return value;
        };
        const body = value => {
            if (value instanceof URLSearchParams) {
                const query = value.get(param);
                const fixed = trim(query);
                if (query !== null && fixed !== query) {
                    const copy = new URLSearchParams(value);
                    copy.set(param, fixed);
                    return copy;
                }
                return value;
            }
            if (typeof value !== 'string') return value;
            try {
                const params = new URLSearchParams(value);
                if (params.has(param)) {
                    const query = params.get(param);
                    const fixed = trim(query);
                    if (fixed !== query) {
                        params.set(param, fixed);
                        return params.toString();
                    }
                }
            } catch {}
            return value;
        };

        const fetch = window.fetch;
        window.fetch = (input, init) => {
            if (input instanceof Request) {
                input = new Request(url(input.url), input);
                if (input.method !== 'GET' && input.method !== 'HEAD') {
                    input = new Request(input, { body: body(input.body) });
                }
            }
            else {
                input = url(input);
                if (init) init = { ...init, body: body(init.body) };
            }
            return fetch.call(this, input, init);
        };

        const open = XMLHttpRequest.prototype.open;
        XMLHttpRequest.prototype.open = function (method, target, ...args) {
            return open.call(this, method, url(target), ...args);
        };
        const send = XMLHttpRequest.prototype.send;
        XMLHttpRequest.prototype.send = function (value) {
            return send.call(this, body(value));
        };

        for (const method of ['pushState', 'replaceState']) {
            const original = history[method];
            history[method] = function (state, title, target, ...args) {
                return original.call(
                    this,
                    state,
                    title,
                    typeof target === 'string' ? url(target) : target,
                    ...args
                );
            };
        }
    }).toString()})(${JSON.stringify(CONFIG.searchParam)});`;
    const injectPatch = () => {
        const root = document.documentElement || document.head;
        if (!root) {
            requestAnimationFrame(injectPatch);
            return;
        }
        root.append(patch);
        patch.remove();
    };
    injectPatch();

    // 修复当前地址、链接和表单提交。
    const fixCurrentUrl = () => {
        const fixed = fixUrl(location.href);
        if (fixed !== location.href) history.replaceState(history.state, '', fixed);
    };
    fixCurrentUrl();
    addEventListener('popstate', fixCurrentUrl);
    addEventListener('pageshow', fixCurrentUrl);
    document.addEventListener('submit', event => {
        const input = event.target.querySelector?.(
            `input[name="${CONFIG.searchParam}"]`,
        );
        if (input) input.value = trimQuery(input.value);
    }, true);

    // Flarum 的搜索框没有 name="q"，必须在其原生 oninput 前修正值。
    document.addEventListener('input', event => {
        const input = event.target;
        if (input.matches?.(searchSelector)) {
            const fixed = trimQuery(input.value);
            if (fixed !== input.value) input.value = fixed;
            loadDiscussionPreview(input.value);
        }
    }, true);

    document.addEventListener('keydown', event => {
        const input = event.target;
        if (event.key === 'Enter' && input.matches?.(searchSelector)) {
            const fixed = trimQuery(input.value);
            if (fixed !== input.value) input.value = fixed;

            if (state.hideSolved) {
                filterSolvedPreview();
                event.preventDefault();
                event.stopImmediatePropagation();
                const target = new URL(location.href);
                target.search = '';
                target.searchParams.set(CONFIG.searchParam, fixed);
                location.assign(target.href);
            }
        }
    }, true);

    const filterSolvedPreview = () => {
        const menu = getSearchMenu();
        if (!menu) return;

        const solvedHeader = findSectionHeader(menu, '已解决');
        if (!solvedHeader) return;

        solvedHeader.hidden = state.hideSolved;
        let sibling = solvedHeader.nextElementSibling;
        while (sibling && !sibling.classList.contains('Dropdown-header')) {
            sibling.hidden = state.hideSolved;
            sibling = sibling.nextElementSibling;
        }
    };

    const refreshPreview = () => {
        filterSolvedPreview();
    };

    const previewObserver = new MutationObserver(refreshPreview);
    previewObserver.observe(document, { childList: true, subtree: true });
    document.addEventListener('input', event => {
        if (event.target.matches?.(searchSelector)) {
            queueMicrotask(refreshPreview);
        }
    }, true);

    registerSettingsMenu();
})();