/**
 * Bricks SPA Router
 * 
 * 为bricks单页应用提供路由支持：
 * 1. urlwidget加载内容到sage_main_content时更新浏览器URL
 * 2. 浏览器刷新时根据URL恢复当前页面
 * 3. 支持浏览器前进/后退按钮
 * 4. 支持直接URL访问（深链接）
 *
 * URL格式: /?page=/module/index.ui
 *
 * 工作原理：
 * - 拦截bricks.buildUrlwidgetHandler，当target是sage_main_content时记录路由
 * - 使用History API (pushState/replaceState)更新URL
 * - 监听popstate事件处理前进/后退
 * - 页面加载时检查URL参数并恢复状态
 */

(function() {
    'use strict';

    // 路由配置
    var ROUTE_PARAM = 'page';
    var MAIN_CONTENT_ID = 'sage_main_content';

    // 路由状态
    var currentRoute = null;
    var isPopState = false;
    var routerReady = false;

    // ── URL 操作 ──

    function getRouteFromURL() {
        var params = new URLSearchParams(window.location.search);
        return params.get(ROUTE_PARAM) || null;
    }

    function pushRoute(route) {
        var url = new URL(window.location);
        url.searchParams.set(ROUTE_PARAM, route);
        history.pushState({ route: route }, '', url.toString());
        currentRoute = route;
    }

    function replaceRoute(route) {
        var url = new URL(window.location);
        if (route) {
            url.searchParams.set(ROUTE_PARAM, route);
        } else {
            url.searchParams.delete(ROUTE_PARAM);
        }
        history.replaceState({ route: route }, '', url.toString());
        currentRoute = route;
    }

    // ── 路由加载 ──

    function waitForApp(maxWait) {
        return new Promise(function(resolve) {
            if (bricks && bricks.app) {
                resolve(true);
                return;
            }
            var waited = 0;
            var interval = setInterval(function() {
                waited += 100;
                if ((bricks && bricks.app) || waited >= maxWait) {
                    clearInterval(interval);
                    resolve(!!(bricks && bricks.app));
                }
            }, 100);
        });
    }

    function getMainContent() {
        if (!bricks || !bricks.app) return null;
        return bricks.getWidgetById(MAIN_CONTENT_ID, bricks.app);
    }

    /**
     * 程序化加载路由：构建urlwidget并放入sage_main_content
     */
    async function loadRoute(route, pushHistory) {
        if (!route) return;

        var ready = await waitForApp(5000);
        if (!ready) {
            console.error('[SPA Router] bricks.app not ready');
            return;
        }

        var mainContent = getMainContent();
        if (!mainContent) {
            console.error('[SPA Router] #' + MAIN_CONTENT_ID + ' not found');
            return;
        }

        // 避免重复加载
        if (currentRoute === route && !isPopState) return;

        console.log('[SPA Router] Loading:', route);

        var desc = {
            widgettype: 'urlwidget',
            options: { url: route }
        };

        try {
            var widget = await bricks.widgetBuild(desc, bricks.app);
            if (widget && !(widget instanceof bricks.Popup) && !(widget instanceof bricks.NewWindow)) {
                mainContent.clear_widgets();
                mainContent.add_widget(widget);
                currentRoute = route;

                if (pushHistory && !isPopState) {
                    pushRoute(route);
                }
            }
        } catch (e) {
            console.error('[SPA Router] Load failed:', route, e);
        }

        isPopState = false;
    }

    // ── 拦截 buildUrlwidgetHandler ──

    function installInterceptor() {
        var _orig = bricks.buildUrlwidgetHandler;

        bricks.buildUrlwidgetHandler = function(w, target, rtdata, desc) {
            var url = desc && desc.options ? desc.options.url : null;
            var targetId = target ? target.id : null;

            // 只拦截目标是sage_main_content的urlwidget
            if (targetId === MAIN_CONTENT_ID && url && routerReady) {
                // 获取原始handler
                var handler = _orig(w, target, rtdata, desc);

                if (typeof handler === 'function') {
                    // 包装：执行原始handler后更新URL
                    return async function() {
                        await handler();
                        // 跳过已经是当前路由的情况
                        if (currentRoute !== url && !isPopState) {
                            console.log('[SPA Router] Route changed:', url);
                            pushRoute(url);
                        }
                    };
                }
            }

            return _orig(w, target, rtdata, desc);
        };

        console.log('[SPA Router] Interceptor installed');
    }

    // ── popstate 处理 ──

    function onPopState(event) {
        var route = (event.state && event.state.route) || getRouteFromURL();
        console.log('[SPA Router] popstate →', route);
        isPopState = true;
        if (route) {
            loadRoute(route, false);
        }
    }

    // ── 初始化 ──

    async function init() {
        console.log('[SPA Router] Initializing...');

        // 等bricks.js加载完
        if (typeof bricks === 'undefined') {
            await waitForApp(10000);
        }

        if (!bricks) {
            console.error('[SPA Router] bricks not found, aborting');
            return;
        }

        installInterceptor();
        window.addEventListener('popstate', onPopState);

        // 检查URL是否有初始路由
        var initialRoute = getRouteFromURL();

        if (initialRoute) {
            console.log('[SPA Router] Deep link:', initialRoute);
            // 等shell加载完再恢复
            await waitForApp(5000);
            await new Promise(function(r) { setTimeout(r, 300); });
            await loadRoute(initialRoute, false);
            // 用replaceState标记初始状态
            replaceRoute(initialRoute);
        } else {
            // 记录初始状态
            replaceRoute(null);
        }

        routerReady = true;
        console.log('[SPA Router] Ready');
    }

    // 启动
    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', init);
    } else {
        init();
    }

    // 调试API
    window.BricksRouter = {
        loadRoute: function(route) { return loadRoute(route, true); },
        current: function() { return currentRoute; },
        back: function() { history.back(); },
        forward: function() { history.forward(); }
    };

})();