/**
 * Unified Theme Manager für MYP Platform
 * =====================================
 * 
 * Konsolidiert alle Dark/Light Mode JavaScript-Implementierungen
 * Ersetzt: dark-mode.js, verschiedene inline Scripts
 * 
 * Author: Till Tomczak - MYP Team
 * Zweck: Einheitliches Theme-Management und Behebung von Inkonsistenzen
 */

class UnifiedThemeManager {
    constructor() {
        // Einheitlicher Storage Key (konsolidiert alle verschiedenen Keys)
        this.storageKey = 'myp-dark-mode';
        this.oldStorageKeys = ['darkMode', 'theme', 'dark-theme']; // Legacy Keys für Migration
        
        // DOM Elemente
        this.htmlElement = document.documentElement;
        this.toggleButtons = [];
        this.themeIndicators = [];
        
        // Event Callbacks
        this.callbacks = [];
        
        // Debug Modus
        this.debug = false;
        
        // Initialisierung
        this.init();
        
        // Globale Instanz für Legacy-Kompatibilität
        window.themeManager = this;
    }
    
    /**
     * Initialisiert den Theme Manager
     */
    init() {
        this.log('🎨 Unified Theme Manager initialisiert');
        
        // Legacy Storage Keys migrieren
        this.migrateLegacyStorage();
        
        // Theme aus Storage laden oder System-Präferenz verwenden
        this.loadTheme();
        
        // Event Listener registrieren
        this.setupEventListeners();
        
        // DOM-Elemente suchen und registrieren
        this.findThemeElements();
        
        // Initial UI aktualisieren
        this.updateUI();
        
        // CSS Custom Properties setzen
        this.updateCSSProperties();
    }
    
    /**
     * Migriert alte Storage Keys zum einheitlichen System
     */
    migrateLegacyStorage() {
        for (const oldKey of this.oldStorageKeys) {
            const oldValue = localStorage.getItem(oldKey);
            if (oldValue && !localStorage.getItem(this.storageKey)) {
                // Normalisiere den Wert
                const isDark = oldValue === 'true' || oldValue === 'dark';
                localStorage.setItem(this.storageKey, isDark.toString());
                localStorage.removeItem(oldKey); // Alten Key entfernen
                this.log(`🔄 Migriert ${oldKey}: ${oldValue} → ${this.storageKey}: ${isDark}`);
            }
        }
    }
    
    /**
     * Lädt das Theme aus Storage oder verwendet System-Präferenz
     */
    loadTheme() {
        let theme = localStorage.getItem(this.storageKey);
        
        if (theme === null) {
            // Keine gespeicherte Präferenz → System-Präferenz verwenden
            const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
            theme = prefersDark ? 'true' : 'false';
            this.log(`🌟 Keine gespeicherte Präferenz → System: ${prefersDark ? 'Dark' : 'Light'} Mode`);
        }
        
        const isDark = theme === 'true';
        this.setTheme(isDark, false); // Ohne Storage-Update da bereits aus Storage geladen
    }
    
    /**
     * Event Listener für System-Präferenz-Änderungen und Keyboard-Shortcuts
     */
    setupEventListeners() {
        // System-Präferenz-Änderungen
        const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
        mediaQuery.addEventListener('change', (e) => {
            // Nur reagieren wenn keine manuelle Präferenz gesetzt wurde
            const storedTheme = localStorage.getItem(this.storageKey);
            if (storedTheme === null) {
                this.setTheme(e.matches);
                this.log(`🔄 System-Präferenz geändert: ${e.matches ? 'Dark' : 'Light'} Mode`);
            }
        });
        
        // Keyboard Shortcut (Ctrl/Cmd + Shift + D)
        document.addEventListener('keydown', (e) => {
            if ((e.ctrlKey || e.metaKey) && e.shiftKey && e.key === 'D') {
                e.preventDefault();
                this.toggle();
                this.log('⌨️ Theme per Keyboard-Shortcut umgeschaltet');
            }
        });
        
        // Page Visibility API für Theme-Synchronisation zwischen Tabs
        document.addEventListener('visibilitychange', () => {
            if (!document.hidden) {
                this.syncThemeFromStorage();
            }
        });
        
        // Storage Event für Cross-Tab-Synchronisation
        window.addEventListener('storage', (e) => {
            if (e.key === this.storageKey && e.newValue !== null) {
                const isDark = e.newValue === 'true';
                this.setTheme(isDark, false); // Ohne Storage-Update
                this.log(`🔄 Theme aus anderem Tab synchronisiert: ${isDark ? 'Dark' : 'Light'} Mode`);
            }
        });
        
        // CSS-Transition Event für sanfte Übergänge
        this.htmlElement.addEventListener('transitionend', this.handleTransitionEnd.bind(this));
    }
    
    /**
     * Sucht und registriert alle Theme-bezogenen DOM-Elemente
     */
    findThemeElements() {
        // Toggle Buttons finden
        const toggleSelectors = [
            '[data-theme-toggle]',
            '.theme-toggle',
            '.dark-mode-toggle',
            '#theme-toggle',
            '#darkModeToggle'
        ];
        
        this.toggleButtons = [];
        toggleSelectors.forEach(selector => {
            const elements = document.querySelectorAll(selector);
            elements.forEach(element => {
                this.registerToggleButton(element);
            });
        });
        
        // Theme Indikatoren finden
        const indicatorSelectors = [
            '[data-theme-indicator]',
            '.theme-indicator',
            '.dark-mode-indicator'
        ];
        
        this.themeIndicators = [];
        indicatorSelectors.forEach(selector => {
            const elements = document.querySelectorAll(selector);
            elements.forEach(element => {
                this.themeIndicators.push(element);
            });
        });
        
        this.log(`🔍 Gefunden: ${this.toggleButtons.length} Toggle-Buttons, ${this.themeIndicators.length} Indikatoren`);
    }
    
    /**
     * Registriert einen Toggle-Button
     */
    registerToggleButton(element) {
        if (this.toggleButtons.includes(element)) return;
        
        element.addEventListener('click', (e) => {
            e.preventDefault();
            this.toggle();
        });
        
        // Accessibility
        element.setAttribute('role', 'button');
        element.setAttribute('aria-label', 'Theme umschalten');
        
        this.toggleButtons.push(element);
    }
    
    /**
     * Theme umschalten
     */
    toggle() {
        const currentTheme = this.isDarkMode();
        const newTheme = !currentTheme;
        
        this.setTheme(newTheme);
        this.log(`🔄 Theme umgeschaltet: ${currentTheme ? 'Dark' : 'Light'} → ${newTheme ? 'Dark' : 'Light'} Mode`);
        
        // Animation für visuelles Feedback
        this.triggerToggleAnimation();
    }
    
    /**
     * Theme setzen
     */
    setTheme(isDark, updateStorage = true) {
        const previousTheme = this.isDarkMode();
        
        // HTML Klasse setzen/entfernen
        this.htmlElement.classList.toggle('dark', isDark);
        
        // Storage aktualisieren
        if (updateStorage) {
            localStorage.setItem(this.storageKey, isDark.toString());
        }
        
        // CSS Custom Properties aktualisieren
        this.updateCSSProperties();
        
        // UI-Elemente aktualisieren
        this.updateUI();
        
        // Meta Theme-Color aktualisieren
        this.updateMetaThemeColor(isDark);
        
        // Callbacks ausführen
        this.executeCallbacks(isDark, previousTheme);
        
        // Custom Event dispatchen
        this.dispatchThemeEvent(isDark);
        
        this.log(`🎨 Theme gesetzt: ${isDark ? 'Dark' : 'Light'} Mode`);
    }
    
    /**
     * Aktueller Theme-Status
     */
    isDarkMode() {
        return this.htmlElement.classList.contains('dark');
    }
    
    /**
     * Theme als String
     */
    getTheme() {
        return this.isDarkMode() ? 'dark' : 'light';
    }
    
    /**
     * UI-Elemente aktualisieren
     */
    updateUI() {
        const isDark = this.isDarkMode();
        const themeText = isDark ? 'Dark' : 'Light';
        
        // Toggle Buttons aktualisieren
        this.toggleButtons.forEach(button => {
            // Icon aktualisieren
            const iconElement = button.querySelector('.theme-icon') || button.querySelector('i') || button;
            if (iconElement) {
                // Entferne alle Theme-Icon-Klassen
                iconElement.classList.remove('fa-sun', 'fa-moon', 'fa-lightbulb', 'fa-moon-o');
                
                // Füge entsprechendes Icon hinzu
                if (isDark) {
                    iconElement.classList.add('fa-sun');
                    iconElement.title = 'Zu Light Mode wechseln';
                } else {
                    iconElement.classList.add('fa-moon');
                    iconElement.title = 'Zu Dark Mode wechseln';
                }
            }
            
            // Text aktualisieren (falls vorhanden)
            const textElement = button.querySelector('.theme-text');
            if (textElement) {
                textElement.textContent = isDark ? 'Light Mode' : 'Dark Mode';
            }
            
            // Aria-Label aktualisieren
            button.setAttribute('aria-label', `Zu ${isDark ? 'Light' : 'Dark'} Mode wechseln`);
            
            // Data-Attribute für CSS-Styling
            button.setAttribute('data-theme', this.getTheme());
        });
        
        // Theme Indikatoren aktualisieren
        this.themeIndicators.forEach(indicator => {
            indicator.textContent = `${themeText} Mode`;
            indicator.setAttribute('data-theme', this.getTheme());
        });
        
        // Body-Klassen für Legacy-Kompatibilität
        document.body.classList.toggle('dark-mode', isDark);
        document.body.classList.toggle('light-mode', !isDark);
    }
    
    /**
     * CSS Custom Properties aktualisieren
     */
    updateCSSProperties() {
        const isDark = this.isDarkMode();
        
        // Zusätzliche CSS Properties für JavaScript-basierte Komponenten
        this.htmlElement.style.setProperty('--theme-mode', isDark ? 'dark' : 'light');
        this.htmlElement.style.setProperty('--theme-multiplier', isDark ? '-1' : '1');
        
        // Für Chart.js und andere Libraries
        this.htmlElement.style.setProperty('--chart-text-color', isDark ? '#ffffff' : '#111827');
        this.htmlElement.style.setProperty('--chart-grid-color', isDark ? '#374151' : '#e5e7eb');
    }
    
    /**
     * Meta Theme-Color für Mobile Browser aktualisieren
     */
    updateMetaThemeColor(isDark) {
        let metaThemeColor = document.querySelector('meta[name="theme-color"]');
        
        if (!metaThemeColor) {
            metaThemeColor = document.createElement('meta');
            metaThemeColor.name = 'theme-color';
            document.head.appendChild(metaThemeColor);
        }
        
        metaThemeColor.content = isDark ? '#000000' : '#ffffff';
    }
    
    /**
     * Theme-Synchronisation aus Storage
     */
    syncThemeFromStorage() {
        const storedTheme = localStorage.getItem(this.storageKey);
        if (storedTheme !== null) {
            const isDark = storedTheme === 'true';
            if (this.isDarkMode() !== isDark) {
                this.setTheme(isDark, false);
            }
        }
    }
    
    /**
     * Toggle-Animation auslösen
     */
    triggerToggleAnimation() {
        // CSS-Klasse für Animation hinzufügen
        this.htmlElement.classList.add('theme-transitioning');
        
        // Animation nach kurzer Zeit entfernen
        setTimeout(() => {
            this.htmlElement.classList.remove('theme-transitioning');
        }, 300);
    }
    
    /**
     * Transition End Handler
     */
    handleTransitionEnd(event) {
        if (event.propertyName === 'background-color' && event.target === this.htmlElement) {
            this.log('🎨 Theme-Transition abgeschlossen');
        }
    }
    
    /**
     * Custom Event dispatchen
     */
    dispatchThemeEvent(isDark) {
        const event = new CustomEvent('themeChanged', {
            detail: {
                theme: this.getTheme(),
                isDark: isDark,
                timestamp: Date.now()
            }
        });
        
        document.dispatchEvent(event);
    }
    
    /**
     * Callback registrieren
     */
    onThemeChange(callback) {
        if (typeof callback === 'function') {
            this.callbacks.push(callback);
        }
    }
    
    /**
     * Callback entfernen
     */
    offThemeChange(callback) {
        const index = this.callbacks.indexOf(callback);
        if (index > -1) {
            this.callbacks.splice(index, 1);
        }
    }
    
    /**
     * Alle Callbacks ausführen
     */
    executeCallbacks(isDark, previousTheme) {
        this.callbacks.forEach(callback => {
            try {
                callback(isDark, previousTheme);
            } catch (error) {
                console.error('Theme Callback Fehler:', error);
            }
        });
    }
    
    /**
     * Debug-Logging
     */
    log(message) {
        if (this.debug || localStorage.getItem('myp-theme-debug') === 'true') {
            console.log(`[ThemeManager] ${message}`);
        }
    }
    
    /**
     * Debug-Modus aktivieren/deaktivieren
     */
    setDebug(enabled) {
        this.debug = enabled;
        localStorage.setItem('myp-theme-debug', enabled.toString());
    }
    
    /**
     * System-Präferenz abfragen
     */
    getSystemPreference() {
        return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
    }
    
    /**
     * Theme auf System-Präferenz zurücksetzen
     */
    resetToSystemPreference() {
        localStorage.removeItem(this.storageKey);
        const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
        this.setTheme(prefersDark, false);
        this.log(`🔄 Theme auf System-Präferenz zurückgesetzt: ${prefersDark ? 'Dark' : 'Light'} Mode`);
    }
    
    /**
     * Theme-Status für APIs
     */
    getStatus() {
        return {
            currentTheme: this.getTheme(),
            isDarkMode: this.isDarkMode(),
            systemPreference: this.getSystemPreference(),
            storageKey: this.storageKey,
            toggleButtons: this.toggleButtons.length,
            indicators: this.themeIndicators.length,
            callbacks: this.callbacks.length
        };
    }
}

// ===== LEGACY COMPATIBILITY =====

// Globale Funktionen für Legacy-Kompatibilität
window.toggleDarkMode = function() {
    if (window.themeManager) {
        window.themeManager.toggle();
    }
};

window.setDarkMode = function(enabled) {
    if (window.themeManager) {
        window.themeManager.setTheme(enabled);
    }
};

window.isDarkMode = function() {
    return window.themeManager ? window.themeManager.isDarkMode() : false;
};

// ===== AUTO-INITIALIZATION =====

// Theme Manager automatisch initialisieren wenn DOM bereit ist
if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', () => {
        new UnifiedThemeManager();
    });
} else {
    new UnifiedThemeManager();
}

// ===== CSS TRANSITION SUPPORT =====

// CSS für sanfte Theme-Übergänge hinzufügen
const style = document.createElement('style');
style.textContent = `
.theme-transitioning,
.theme-transitioning * {
    transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease !important;
}

.theme-toggle {
    transition: transform 0.2s ease;
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.theme-toggle:active {
    transform: scale(0.95);
}
`;
document.head.appendChild(style);

console.log('🎨 Unified Theme Manager geladen');

// Export für Module
if (typeof module !== 'undefined' && module.exports) {
    module.exports = UnifiedThemeManager;
}