document.addEventListener('DOMContentLoaded', () => {
    const EVENTS_STORAGE_KEY = 'socialCookingEvents';
    const USERS_STORAGE_KEY = 'socialCookingUsers';
    const CURRENT_USER_KEY = 'socialCookingCurrentUser';
    const REGISTRATION_STORAGE_KEY = 'socialCookingRegistrations';

    // Zentrale DOM-Referenzen fuer klare, testbare Funktionen.
    const loggedOutState = document.getElementById('logged-out-state');
    const loggedInContent = document.getElementById('logged-in-content');
    const profileHeadline = document.getElementById('profile-headline');
    const profileSubline = document.getElementById('profile-subline');
    const logoutButton = document.getElementById('logout-button');
    const profileTabButtons = Array.from(document.querySelectorAll('[data-profile-tab]'));
    const profileTabPanels = Array.from(document.querySelectorAll('[data-profile-panel]'));

    const myEventsCount = document.getElementById('my-events-count');
    const myRegistrationsCount = document.getElementById('my-registrations-count');
    const myEventsList = document.getElementById('my-events-list');
    const myRegistrationsList = document.getElementById('my-registrations-list');

    const profileForm = document.getElementById('profile-form');
    const profileFeedback = document.getElementById('profile-feedback');
    const vornameInput = document.getElementById('vorname');
    const nachnameInput = document.getElementById('nachname');
    const emailInput = document.getElementById('email');
    const passwortInput = document.getElementById('passwort');

    let currentUser = getCurrentUser();
    let allEvents = [];

    init();

    async function init() {
        if (!currentUser) {
            renderLoggedOutState();
            return;
        }

        renderLoggedInState(currentUser);
        bindFormHandlers();
        activateProfileTab('hosting');

        allEvents = await loadAllEvents();
        renderMyEvents(allEvents, currentUser);
        renderMyRegistrations(allEvents, currentUser);
    }

    // Liest den aktuell eingeloggten Benutzer robust aus dem Storage.
    function getCurrentUser() {
        try {
            const raw = localStorage.getItem(CURRENT_USER_KEY);
            return raw ? JSON.parse(raw) : null;
        } catch (error) {
            console.error('Der aktuelle Benutzer konnte nicht geladen werden.', error);
            return null;
        }
    }

    // Liest lokal erstellte Events aus dem Storage.
    function getStoredEvents() {
        try {
            const raw = localStorage.getItem(EVENTS_STORAGE_KEY);
            return raw ? JSON.parse(raw) : [];
        } catch (error) {
            console.error('Lokale Events konnten nicht gelesen werden.', error);
            return [];
        }
    }

    // Liest den Anmeldestatus pro Benutzer-E-Mail.
    function getRegistrationMap() {
        try {
            const raw = localStorage.getItem(REGISTRATION_STORAGE_KEY);
            return raw ? JSON.parse(raw) : {};
        } catch (error) {
            console.error('Anmeldedaten konnten nicht gelesen werden.', error);
            return {};
        }
    }

    // Schreibt den gesamten Registrierungszustand in localStorage.
    function setRegistrationMap(registrationMap) {
        localStorage.setItem(REGISTRATION_STORAGE_KEY, JSON.stringify(registrationMap));
    }

    // Schreibt die lokal erstellten Events in den Storage.
    function setStoredEvents(events) {
        localStorage.setItem(EVENTS_STORAGE_KEY, JSON.stringify(events));
    }

    // Fuehrt JSON-Daten und lokal erstellte Events in einer Liste zusammen.
    async function loadAllEvents() {
        try {
            const response = await fetch('data/events.json');
            const apiEvents = await response.json();
            return [...getStoredEvents(), ...apiEvents];
        } catch (error) {
            console.error('Events konnten nicht geladen werden.', error);
            return getStoredEvents();
        }
    }

    // Schaltet in den ausgeloggten Zustand und blendet geschuetzte Inhalte aus.
    function renderLoggedOutState() {
        loggedOutState.classList.remove('hidden');
        loggedInContent.classList.add('hidden');
        logoutButton.classList.add('hidden');
        profileHeadline.textContent = 'Mein Profil';
        profileSubline.textContent = 'Bitte logge dich ein, um deinen Bereich zu sehen.';
    }

    // Fuellt Ueberschriften und Formular mit den aktuellen Benutzerdaten.
    function renderLoggedInState(user) {
        loggedOutState.classList.add('hidden');
        loggedInContent.classList.remove('hidden');
        logoutButton.classList.remove('hidden');

        profileHeadline.textContent = `Hallo ${user.vorname || 'Gast'}`;
        profileSubline.textContent = 'Hier kannst du deine Events und Anmeldungen verwalten.';

        vornameInput.value = user.vorname || '';
        nachnameInput.value = user.nachname || '';
        emailInput.value = user.email || '';
    }

    // Bindet Submit-, Input- und Logout-Verhalten an die Profilseite.
    function bindFormHandlers() {
        profileForm.addEventListener('submit', handleProfileSubmit);
        myRegistrationsList.addEventListener('click', handleRegistrationListClick);
        myEventsList.addEventListener('click', handleHostedListClick);

        profileTabButtons.forEach(button => {
            button.addEventListener('click', () => {
                const tabName = button.getAttribute('data-profile-tab');
                if (!tabName) {
                    return;
                }

                activateProfileTab(tabName);
            });
        });

        [vornameInput, nachnameInput, emailInput, passwortInput].forEach(input => {
            input.addEventListener('input', () => {
                input.parentElement.classList.remove('has-error');
                profileFeedback.textContent = '';
            });
        });

        logoutButton.addEventListener('click', () => {
            localStorage.removeItem(CURRENT_USER_KEY);
            window.location.href = 'login.html';
        });
    }

    // Reagiert auf Aktionen in der Liste "Meine Events" per Event Delegation.
    function handleHostedListClick(event) {
        const target = event.target;
        if (!(target instanceof HTMLElement)) {
            return;
        }

        const cancelButton = target.closest('[data-cancel-event-id]');
        if (cancelButton && currentUser?.email) {
            const eventId = Number(cancelButton.getAttribute('data-cancel-event-id'));
            if (Number.isFinite(eventId)) {
                cancelHostedEvent(eventId, currentUser.email);
            }
            return;
        }

        if (target.closest('a, button')) {
            return;
        }

        const card = target.closest('[data-event-id]');
        if (!card) {
            return;
        }

        const eventId = Number(card.getAttribute('data-event-id'));
        if (!Number.isFinite(eventId)) {
            return;
        }

        window.location.href = `event_detail.html?id=${eventId}`;
    }

    // Schaltet den sichtbaren Profilbereich per Tabname um.
    function activateProfileTab(tabName) {
        profileTabButtons.forEach(button => {
            const isActive = button.getAttribute('data-profile-tab') === tabName;
            button.classList.toggle('is-active', isActive);
            button.setAttribute('aria-selected', isActive ? 'true' : 'false');
        });

        profileTabPanels.forEach(panel => {
            const isActive = panel.getAttribute('data-profile-panel') === tabName;
            panel.classList.toggle('hidden', !isActive);
        });
    }

    // Reagiert auf Aktionen in der Liste "Meine Anmeldungen" per Event Delegation.
    function handleRegistrationListClick(event) {
        const target = event.target;
        if (!(target instanceof HTMLElement)) {
            return;
        }

        const unregisterButton = target.closest('[data-unregister-id]');
        if (unregisterButton) {
            if (!currentUser?.email) {
                return;
            }

            const eventId = Number(unregisterButton.getAttribute('data-unregister-id'));
            if (!Number.isFinite(eventId)) {
                return;
            }

            unregisterFromEvent(eventId, currentUser.email);
            return;
        }

        if (target.closest('a, button')) {
            return;
        }

        const card = target.closest('[data-event-id]');
        if (!card) {
            return;
        }

        const eventId = Number(card.getAttribute('data-event-id'));
        if (!Number.isFinite(eventId)) {
            return;
        }

        window.location.href = `event_detail.html?id=${eventId}`;
    }


    // Sagt ein gehostetes Event ab (aus eigener Profilansicht entfernen).
    function cancelHostedEvent(eventId, userEmail) {
        // Lokal erstellte, eigene Events werden direkt aus dem Storage geloescht.
        const storedEvents = getStoredEvents();
        const nextStoredEvents = storedEvents.filter(event => {
            const isTargetEvent = Number(event.id) === eventId;
            const isOwnedByUser = normalizeText(event.hostEmail || '') === normalizeText(userEmail)
                || normalizeText(event.host?.name || '') === normalizeText(currentUser?.vorname || '');

            return !(isTargetEvent && isOwnedByUser);
        });
        setStoredEvents(nextStoredEvents);

        // Event-ID fuer alle Benutzer aus den Anmeldungen entfernen.
        const registrationMap = getRegistrationMap();
        Object.keys(registrationMap).forEach(email => {
            const ids = Array.isArray(registrationMap[email])
                ? registrationMap[email].map(id => Number(id)).filter(Number.isFinite)
                : [];

            registrationMap[email] = ids.filter(id => id !== eventId);
        });
        setRegistrationMap(registrationMap);

        allEvents = allEvents.filter(event => Number(event.id) !== eventId);

        renderMyEvents(allEvents, currentUser);
        renderMyRegistrations(allEvents, currentUser);
        profileFeedback.textContent = 'Event wurde abgesagt und aus deinem Hosting entfernt.';
    }
    // Entfernt eine Event-ID aus der Benutzerliste und aktualisiert die UI sofort.
    function unregisterFromEvent(eventId, userEmail) {
        const registrationMap = getRegistrationMap();
        const currentIds = Array.isArray(registrationMap[userEmail]) ? registrationMap[userEmail] : [];
        const nextIds = currentIds
            .map(id => Number(id))
            .filter(id => Number.isFinite(id) && id !== eventId);

        registrationMap[userEmail] = nextIds;
        setRegistrationMap(registrationMap);

        renderMyRegistrations(allEvents, currentUser);
        profileFeedback.textContent = 'Du wurdest von dem Event abgemeldet.';
    }

    // Validiert Profildaten konsistent und liefert true/false zur Submit-Steuerung.
    function validateProfileForm() {
        let isValid = true;

        const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

        if (!vornameInput.value.trim()) {
            vornameInput.parentElement.classList.add('has-error');
            isValid = false;
        }

        if (!nachnameInput.value.trim()) {
            nachnameInput.parentElement.classList.add('has-error');
            isValid = false;
        }

        if (!emailRegex.test(emailInput.value.trim())) {
            emailInput.parentElement.classList.add('has-error');
            isValid = false;
        }

        if (passwortInput.value && passwortInput.value.length < 6) {
            passwortInput.parentElement.classList.add('has-error');
            isValid = false;
        }

        return isValid;
    }

    // Speichert Profilaenderungen lokal und synchronisiert auch den Benutzerkatalog.
    function handleProfileSubmit(event) {
        event.preventDefault();

        if (!validateProfileForm()) {
            profileFeedback.textContent = 'Bitte pruefe die markierten Felder.';
            return;
        }

        const previousEmail = currentUser.email;
        const nextUser = {
            ...currentUser,
            vorname: vornameInput.value.trim(),
            nachname: nachnameInput.value.trim(),
            email: emailInput.value.trim(),
            passwort: passwortInput.value ? passwortInput.value : currentUser.passwort,
            updatedAt: new Date().toISOString()
        };

        currentUser = nextUser;
        localStorage.setItem(CURRENT_USER_KEY, JSON.stringify(nextUser));
        syncUserInUserStore(previousEmail, nextUser);

        // Falls sich die E-Mail geaendert hat, verschieben wir bestehende Anmeldungen auf die neue E-Mail.
        migrateRegistrationEmail(previousEmail, nextUser.email);

        passwortInput.value = '';
        profileHeadline.textContent = `Hallo ${nextUser.vorname}`;
        profileFeedback.textContent = 'Profil erfolgreich gespeichert.';
    }

    // Synchronisiert einen Benutzer im zentralen User-Array.
    function syncUserInUserStore(previousEmail, nextUser) {
        let users = [];

        try {
            const raw = localStorage.getItem(USERS_STORAGE_KEY);
            users = raw ? JSON.parse(raw) : [];
        } catch (error) {
            console.error('Benutzerdaten konnten nicht gelesen werden.', error);
        }

        const nextUsers = users.filter(user => user.email !== previousEmail && user.email !== nextUser.email);
        nextUsers.unshift(nextUser);
        localStorage.setItem(USERS_STORAGE_KEY, JSON.stringify(nextUsers));
    }

    // Migriert bestehende Registrierungen, falls die E-Mail aktualisiert wurde.
    function migrateRegistrationEmail(previousEmail, nextEmail) {
        if (!previousEmail || !nextEmail || previousEmail === nextEmail) {
            return;
        }

        const map = getRegistrationMap();
        const existingRegistrations = Array.isArray(map[previousEmail]) ? map[previousEmail] : [];
        const alreadyPresent = Array.isArray(map[nextEmail]) ? map[nextEmail] : [];

        map[nextEmail] = Array.from(new Set([...alreadyPresent, ...existingRegistrations]));
        delete map[previousEmail];

        localStorage.setItem(REGISTRATION_STORAGE_KEY, JSON.stringify(map));
    }

    // Ermittelt gehostete Events aus lokal erstellten Daten des aktuellen Benutzers.
    function getMyHostedEvents(events, user) {
        const userFirstName = normalizeText(user.vorname || '');
        const userEmail = normalizeText(user.email || '');

        return events.filter(event => {
            if (event.source !== 'local') {
                return false;
            }

            const hostEmail = normalizeText(event.hostEmail || '');
            const hostName = normalizeText(event.host?.name || '');

            if (hostEmail && hostEmail === userEmail) {
                return true;
            }

            return userFirstName && hostName === userFirstName;
        });
    }

    // Ermittelt angemeldete Events ueber die Registration-Map.
    function getMyRegisteredEvents(events, user) {
        const registrationMap = getRegistrationMap();
        const registeredIds = Array.isArray(registrationMap[user.email]) ? registrationMap[user.email] : [];
        const idSet = new Set(registeredIds.map(id => Number(id)));

        return events.filter(event => idSet.has(Number(event.id)));
    }

    // Rendert gehostete Events inkl. Zaehler.
    function renderMyEvents(events, user) {
        const hostedEvents = getMyHostedEvents(events, user);
        myEventsCount.textContent = String(hostedEvents.length);
        renderEventCards(myEventsList, hostedEvents, {
            title: 'Noch kein eigenes Event',
            text: 'Starte dein erstes Dinner und lade die Community an deinen Tisch ein.',
            buttonLabel: 'Event erstellen',
            href: 'event_create.html'
        }, 'hosting');
    }

    // Rendert angemeldete Events inkl. Zaehler.
    function renderMyRegistrations(events, user) {
        const registeredEvents = getMyRegisteredEvents(events, user);
        myRegistrationsCount.textContent = String(registeredEvents.length);
        renderEventCards(myRegistrationsList, registeredEvents, {
            title: 'Noch keine Anmeldungen',
            text: 'Entdecke spannende Dinner in deiner Naehe und melde dich direkt an.',
            buttonLabel: 'Events entdecken',
            href: 'event_overview.html'
        }, 'registrations');
    }

    // Baut die Eventkarten fuer beide Listen in einheitlichem Markup.
    function renderEventCards(container, events, emptyStateConfig, mode) {
        container.innerHTML = '';

        if (events.length === 0) {
            const emptyElement = document.createElement('div');
            emptyElement.className = 'profile-empty-state';
            emptyElement.innerHTML = `
                <p class="profile-empty-kicker">Keine Treffer</p>
                <h3>${emptyStateConfig.title}</h3>
                <p>${emptyStateConfig.text}</p>
                <a class="button" href="${emptyStateConfig.href}">${emptyStateConfig.buttonLabel}</a>
            `;
            container.appendChild(emptyElement);
            return;
        }

        events.forEach(event => {
            const card = document.createElement('article');
            card.className = 'profile-event-card profile-event-card-clickable';
            card.setAttribute('data-event-id', String(event.id));
            const addressMarkup = mode === 'registrations' && event.address && isAddressVisibleWindow(event)
                ? `
                    <div class="profile-event-address-block" aria-label="Event Adresse">
                        <p class="profile-event-address-label">Adresse</p>
                        <p class="profile-event-address">${event.address}</p>
                    </div>
                `
                : '';

            const actionMarkup = mode === 'registrations'
                ? `
                    <div class="profile-event-actions">
                        <button class="profile-unregister-btn" type="button" data-unregister-id="${event.id}">Abmelden</button>
                    </div>
                `
                : `
                    <div class="profile-event-actions">
                        <button class="profile-cancel-btn" type="button" data-cancel-event-id="${event.id}">Event absagen</button>
                    </div>
                `;

            card.innerHTML = `
                <div>
                    <h3 class="profile-event-title">${event.title}</h3>
                    <p class="profile-event-meta">${event.location} | ${formatEventDate(event.date)} | ${formatEventTime(event.time)}</p>
                    ${addressMarkup}
                </div>
                ${actionMarkup}
            `;

            container.appendChild(card);
        });
    }

    // Gibt true zurueck, wenn ein Event innerhalb der naechsten 12 Stunden startet.
    function isAddressVisibleWindow(event) {
        const eventDateTime = parseEventDateTime(event);
        if (!eventDateTime || Number.isNaN(eventDateTime.getTime())) {
            return false;
        }

        const msUntilStart = eventDateTime.getTime() - Date.now();
        const twelveHoursInMs = 12 * 60 * 60 * 1000;

        return msUntilStart >= 0 && msUntilStart <= twelveHoursInMs;
    }

    // Parse fuer ISO- und lokalisierte Datumsformate aus den Eventdaten.
    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;
        let month;
        let day;

        if (isoDateMatch) {
            year = Number(isoDateMatch[1]);
            month = Number(isoDateMatch[2]);
            day = Number(isoDateMatch[3]);
        } else {
            const monthMap = {
                JAN: 1,
                FEB: 2,
                'MÄR': 3,
                MRZ: 3,
                APR: 4,
                MAI: 5,
                JUN: 6,
                JUL: 7,
                AUG: 8,
                SEP: 9,
                OKT: 10,
                NOV: 11,
                DEZ: 12
            };
            const localizedMatch = dateValue.match(/^(\d{1,2})\.\s*([A-ZÄÖÜ]{3})\.\s*(\d{4})$/);

            if (!localizedMatch) {
                return null;
            }

            day = Number(localizedMatch[1]);
            month = monthMap[localizedMatch[2]];
            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);
    }

    // Formatiert ein Eventdatum konsistent fuer die Profilkarten.
    function formatEventDate(dateString) {
        if (!dateString) {
            return 'Kein Datum';
        }

        if (/^\d{4}-\d{2}-\d{2}$/.test(dateString)) {
            const [year, month, day] = dateString.split('-');
            const monthLabel = ['Januar', 'Februar', 'Maerz', 'April', 'Mai', 'Juni', 'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'][Number(month) - 1];
            return `${Number(day)}. ${monthLabel} ${year}`;
        }

        return dateString;
    }

    // Vereinheitlicht die Zeitanzeige fuer die Profilseite.
    function formatEventTime(timeString) {
        if (!timeString) {
            return 'Keine Uhrzeit';
        }

        return timeString.includes('UHR') ? timeString.replace('UHR', 'Uhr').trim() : timeString;
    }

    // Normalisiert Vergleichswerte fuer robuste String-Matches.
    function normalizeText(value) {
        return String(value || '').trim().toLowerCase();
    }
});