/**
 * GoingsOn - Router Module
 * URL routing with History API for bookmarking, back button, and deep links.
 *
 * URL Structure:
 * /projects           -> Projects list
 * /project/{id}       -> Project dashboard
 * /tasks              -> Tasks list
 * /events             -> Events list
 * /emails             -> Emails list
 * /day-plan           -> Day planning
 */

(function() {
    'use strict';

    // Flag to prevent recursive URL pushes when handling popstate
    let suppressPush = false;

    // Standard view mappings
    const VIEW_ROUTES = {
        'work': 'tasks',           // tab alias
        'time': 'day-plan',        // tab alias
        'messages': 'emails',      // tab alias
        'projects': 'projects',
        'tasks': 'tasks',
        'events': 'events',
        'emails': 'emails',
        'contacts': 'contacts',
        'day-plan': 'day-plan',
        'weekly-review': 'weekly-review',
        'monthly-review': 'monthly-review',
    };

    /**
     * Navigate to a URL, optionally replacing current history entry.
     * @param {string} path - The path to navigate to (e.g., '/tasks')
     * @param {boolean} replace - If true, replace current entry instead of push
     */
    function navigate(path, replace = false) {
        if (suppressPush) return;

        const method = replace ? 'replaceState' : 'pushState';
        history[method]({ path }, '', path);
    }

    /**
     * Handle a route change (from URL or popstate event).
     * @param {string} pathname - The URL pathname
     * @param {string} search - The URL search string (query params)
     */
    function handleRoute(pathname, search) {
        suppressPush = true;
        try {
            // Remove leading slash and get base path
            const path = pathname.replace(/^\//, '') || 'tasks';
            const query = Object.fromEntries(new URLSearchParams(search));

            // Project dashboard: /project/{id}
            if (path.startsWith('project/')) {
                const id = path.split('/')[1];
                if (id && typeof GoingsOn.projects?.open === 'function') {
                    GoingsOn.projects.open(id);
                }
                return;
            }

            // Standard views
            const viewName = VIEW_ROUTES[path];
            if (viewName) {
                if (typeof GoingsOn.navigation?.switchView === 'function') {
                    GoingsOn.navigation.switchView(viewName);
                }
                return;
            }

            // Unknown route - redirect to tasks
            navigate('/tasks', true);
            if (typeof GoingsOn.navigation?.switchView === 'function') {
                GoingsOn.navigation.switchView('tasks');
            }
        } finally {
            suppressPush = false;
        }
    }

    /**
     * Initialize the router - handle current URL on page load.
     */
    function init() {
        handleRoute(location.pathname, location.search);
    }

    // Listen for browser back/forward navigation
    window.addEventListener('popstate', (e) => {
        handleRoute(location.pathname, location.search);
    });

    // ============ Populate GoingsOn.router Namespace ============

    GoingsOn.router = {
        navigate,
        init,
        get suppressPush() { return suppressPush; },
    };

})();