// =============================================
// Dynamische Navigation
// Je nach Login-Status wird die Kopfzeile für
// alle Seiten mit passendem Markup aufgebaut.
// =============================================

document.addEventListener('DOMContentLoaded', () => {
    const CURRENT_USER_KEY = 'socialCookingCurrentUser';
    const REGISTRATION_STORAGE_KEY = 'socialCookingRegistrations';
    const EVENTS_STORAGE_KEY = 'socialCookingEvents';
    const navcontainers = document.querySelectorAll('.nav-tab-links');
    const currentPage = (window.location.pathname.split('/').pop() || 'index.html').toLowerCase();

    // Beendet früh, falls auf einer Seite keine Hauptnavigation vorhanden ist.
    if (!navcontainers.length) {
        return;
    }

    // Liest den aktiven Benutzer robust aus localStorage.
    function getCurrentUser() {
        try {
            const stored = localStorage.getItem(CURRENT_USER_KEY);
            return stored ? JSON.parse(stored) : null;
        } catch (error) {
            console.error('Aktueller Benutzer konnte nicht gelesen werden.', error);
            return null;
        }
    }

    // Logout-Funktion
    window.logout = function() {
        localStorage.removeItem(CURRENT_USER_KEY);
        window.location.href = 'index.html';
    };

    // Hilfsfunktionen für Datumsberechnungen
    function parseEventDateTime(event) {
        if (!event?.date) return null;
        const dateValue = String(event.date).trim();
        const isoDateMatch = dateValue.match(/^(\d{4})-(\d{2})-(\d{2})$/);
        let year, month, day;

        if (isoDateMatch) {
            year = Number(isoDateMatch[1]);
            month = Number(isoDateMatch[2]);
            day = Number(isoDateMatch[3]);
        } else {
            const monthMap = {
                jan: 1, januar: 1,
                feb: 2, februar: 2,
                'mär': 3, mrz: 3, mar: 3, maerz: 3, märz: 3,
                apr: 4, april: 4,
                mai: 5,
                jun: 6, juni: 6,
                jul: 7, juli: 7,
                aug: 8, august: 8,
                sep: 9, sept: 9, september: 9,
                okt: 10, oktober: 10,
                nov: 11, november: 11,
                dez: 12, dezember: 12
            };
            const localizedMatch = dateValue.match(/^(\d{1,2})\.\s*([A-Za-zÄÖÜäöü]{3,9})\.?\s*(\d{4})$/);
            if (!localizedMatch) return null;
            day = Number(localizedMatch[1]);
            month = monthMap[String(localizedMatch[2]).toLowerCase()];
            year = Number(localizedMatch[3]);
            if (!month) return null;
        }

        const timeMatch = String(event.time || '').match(/(\d{1,2}):(\d{2})/);
        const hours = timeMatch ? Number(timeMatch[1]) : 0;
        const minutes = timeMatch ? Number(timeMatch[2]) : 0;
        return new Date(year, month - 1, day, hours, minutes, 0, 0);
    }

    function isAddressVisibleWindow(event) {
        const eventDateTime = parseEventDateTime(event);
        if (!eventDateTime || Number.isNaN(eventDateTime.getTime())) return false;
        const now = Date.now();
        const start = eventDateTime.getTime();
        const revealStart = start - (24 * 60 * 60 * 1000);
        const revealEnd = start + (1 * 60 * 60 * 1000);
        return now >= revealStart && now <= revealEnd;
    }

    async function hasUnreadNotifications(user) {
        if (!user || !user.email) return false;
        
        let events = [];
        try {
            const rawStored = localStorage.getItem(EVENTS_STORAGE_KEY);
            const storedEvents = rawStored ? JSON.parse(rawStored) : [];
            
            const response = await fetch('data/events.json');
            const apiEvents = await response.json();
            events = [...storedEvents, ...apiEvents];
        } catch (err) {
            console.error('Fehler beim Laden der Events für Benachrichtigungen', err);
            return false;
        }

        let map = {};
        try {
            const rawReg = localStorage.getItem(REGISTRATION_STORAGE_KEY);
            map = rawReg ? JSON.parse(rawReg) : {};
        } catch (err) {}

        let seenAddresses = [];
        try {
            const rawSeen = localStorage.getItem('socialCookingSeenAddresses');
            seenAddresses = rawSeen ? JSON.parse(rawSeen) : [];
        } catch (err) {}

        const registeredIds = Array.isArray(map[user.email]) ? map[user.email] : [];
        const idSet = new Set(registeredIds.map(id => Number(id)));

        const myRegisteredEvents = events.filter(e => idSet.has(Number(e.id)));
        
        // Unread = address visible AND NOT marked as seen
        return myRegisteredEvents.some(e => isAddressVisibleWindow(e) && !seenAddresses.includes(Number(e.id)));
    }

    // Baut die Navigation für ausgeloggte Besucher.
    function buildLoggedOutNavigation() {
        const loginIsActive = currentPage === 'login.html';
        const signupIsActive = currentPage === 'signup.html';
        const isIndex = currentPage === 'index.html' || currentPage === '';

        // Auf der Startseite, Login und Signup nur Login anzeigen.
        if (isIndex || loginIsActive || signupIsActive) {
            return `
                <a
                    class="button-small"
                    href="login.html"
                    aria-label="Login"
                >
                    Login
                </a>
            `;
        }

        return `
            <a
                class="button-small auth-nav-button ${loginIsActive ? 'auth-nav-button--active' : 'auth-nav-button--default'}"
                href="login.html"
                aria-label="Login"
                ${loginIsActive ? 'aria-current="page"' : ''}
            >
                Login
            </a>
            <a
                class="button-small auth-nav-button ${signupIsActive ? 'auth-nav-button--active' : 'auth-nav-button--default'}"
                href="signup.html"
                aria-label="Signup"
                ${signupIsActive ? 'aria-current="page"' : ''}
            >
                Signup
            </a>
        `;
    }

    // Baut die Navigation für eingeloggte Benutzer.
    function buildLoggedInNavigation(user, hasNotifications) {
        const initial = (user.vorname || 'U').charAt(0).toUpperCase();
        const isEventOverview = currentPage === 'event_overview.html';
        const isEventCreate = currentPage === 'event_create.html';
        const notificationMarkup = hasNotifications ? '<span class="notification-dot"></span>' : '';

        return `
            <a
                class="nav-tab${isEventCreate ? ' nav-tab--active' : ''}"
                href="event_create.html"
                ${isEventCreate ? 'aria-current="page"' : ''}
            >
                Event erstellen
            </a>
            <a
                class="nav-tab${isEventOverview ? ' nav-tab--active' : ''}"
                href="event_overview.html"
                ${isEventOverview ? 'aria-current="page"' : ''}
            >
                Event finden
            </a>
            <button
                class="button-small logout-button"
                onclick="logout()"
                aria-label="Logout"
            >
                Logout
            </button>
            <a
                class="profile-pill"
                href="my_profil.html"
                aria-label="Mein Profil"
                title="${user.vorname || 'Profil'}"
            >
                ${initial}
                ${notificationMarkup}
            </a>
        `;
    }

    async function initNavigation() {
        const currentUser = getCurrentUser();
        let nextMarkup;

        if (currentUser) {
            const hasNotifications = await hasUnreadNotifications(currentUser);
            nextMarkup = buildLoggedInNavigation(currentUser, hasNotifications);
        } else {
            nextMarkup = buildLoggedOutNavigation();
        }

        // Wendet das passende Markup auf alle vorhandenen Kopf-Navigationen an.
        navcontainers.forEach(container => {
            container.innerHTML = nextMarkup;
        });
    }

    initNavigation();
});