/**
 * Automated Table of Contents Generator
 * Scans document for headings and generates TOC with REAL page numbers from PDF
 */

class TOCGenerator {
    constructor() {
        this.tocContainer = null;
        this.headings = [];
        this.pageNumbers = {};
        this.totalPages = 0;
    }

    /**
     * Initialize the TOC generator
     */
    async init() {
        console.log('🚀 TOC Generator initializing...');
        
        // Find the TOC container
        this.tocContainer = document.querySelector('.toc-auto');
        if (!this.tocContainer) {
            console.error('❌ TOC container not found. Looking for .toc-auto class.');
            return;
        }
        
        console.log('✅ TOC container found:', this.tocContainer);

        // Load real page numbers from PDF analysis
        await this.loadPageNumbers();
        
        // Generate TOC
        this.generateTOC();
        
        // Add event listener for dynamic updates
        this.setupDynamicUpdates();
        
        console.log('✅ TOC Generator initialized successfully');
    }

    /**
     * Load real page numbers from the JSON file generated by PDF analysis
     */
    async loadPageNumbers() {
        try {
            // Try to load page numbers from the JSON file
            const response = await fetch('../page_numbers.json');
            if (response.ok) {
                this.pageNumbers = await response.json();
                console.log('✅ Loaded real page numbers from PDF analysis');
                
                // Calculate total pages from the highest page number
                this.totalPages = Math.max(...Object.values(this.pageNumbers));
                console.log(`📊 Total pages from PDF analysis: ${this.totalPages}`);
                
                                        // Update CSS variable immediately
                if (this.totalPages) {
                    document.documentElement.style.setProperty('--total-pages', this.totalPages);
                    console.log(`🎨 CSS variable --total-pages set to: ${this.totalPages}`);
                } else {
                    console.error('❌ Cannot set CSS variable: totalPages is null');
                }
            } else {
                console.error('❌ Page numbers file not found or empty');
                this.pageNumbers = {};
                this.totalPages = null; // No hardcoded value!
            }
        } catch (error) {
            console.error('❌ ERROR: Cannot load page numbers from JSON file!');
            console.error('   This usually means:');
            console.error('   1. The HTML file is opened directly (file://) instead of through a web server');
            console.error('   2. The page_numbers.json file is missing or corrupted');
            console.error('   3. CORS policy is blocking the request');
            console.error('   Solution: Run the HTML through a local web server or fix the JSON file path');
            console.error('   Original error:', error);
            
            // Show error in TOC container instead of hardcoded values
            this.tocContainer.innerHTML = `
                <div style="color: red; padding: 20px; border: 2px solid red; background: #ffe6e6;">
                    <h2>❌ Fehler beim Laden der Seitennummern</h2>
                    <p><strong>Problem:</strong> Die Datei page_numbers.json kann nicht geladen werden.</p>
                    <p><strong>Mögliche Ursachen:</strong></p>
                    <ul>
                        <li>HTML-Datei wird direkt geöffnet (file://) statt über Webserver</li>
                        <li>page_numbers.json fehlt oder ist beschädigt</li>
                        <li>CORS-Richtlinie blockiert den Zugriff</li>
                    </ul>
                    <p><strong>Lösung:</strong> Führen Sie main.py aus, um PDF zu generieren und zu analysieren.</p>
                </div>
            `;
            
            this.pageNumbers = {};
            this.totalPages = null; // No hardcoded value!
            
            // Still try to generate TOC with estimated numbers
            console.log('🔄 Attempting to generate TOC with estimated numbers...');
            this.generateTOC();
        }
    }

    /**
     * Generate the complete TOC
     */
    generateTOC() {
        console.log('🔄 Generating TOC...');
        
        // Clear existing content
        this.tocContainer.innerHTML = '<h1 class="toc-title">Inhaltsverzeichnis</h1>';
        
        // Find all headings with specific classes
        this.headings = [];
        
        // Try different selectors to find headings
        const headingSelectors = [
            'h1.content-heading.heading-level-1',
            'h2.content-heading.heading-level-2', 
            'h3.content-heading.heading-level-3',
            'h1.heading-level-1',
            'h2.heading-level-2',
            'h3.heading-level-3',
            'h1.content-heading',
            'h2.content-heading',
            'h3.content-heading'
        ];
        
        console.log('🔍 Looking for headings with selectors:', headingSelectors);
        
        let foundAny = false;
        
        headingSelectors.forEach(selector => {
            const elements = document.querySelectorAll(selector);
            console.log(`📋 Found ${elements.length} elements for selector: ${selector}`);
            
            if (elements.length > 0) {
                foundAny = true;
            }
            
            elements.forEach(element => {
                // Get the text content WITH the numbering
                const text = element.textContent.trim();
                const level = element.classList.contains('heading-level-1') ? 1 : 
                             element.classList.contains('heading-level-2') ? 2 : 3;
                
                console.log(`📝 Heading: "${text}" (Level ${level})`);
                
                // Only add if we don't already have this text
                if (!this.headings.some(h => h.text === text)) {
                    this.headings.push({
                        element: element,
                        text: text,
                        level: level,
                        page: this.estimatePageNumber(element)
                    });
                }
            });
        });

        if (!foundAny) {
            console.log('⚠️ No headings found with any selector. Trying generic h1, h2, h3...');
            const genericHeadings = document.querySelectorAll('h1, h2, h3');
            console.log(`📋 Found ${genericHeadings.length} generic headings`);
            
            genericHeadings.forEach((element, index) => {
                const text = element.textContent.trim();
                const level = element.tagName === 'H1' ? 1 : element.tagName === 'H2' ? 2 : 3;
                
                console.log(`📝 Generic Heading: "${text}" (Level ${level})`);
                
                this.headings.push({
                    element: element,
                    text: text,
                    level: level,
                    page: 3 + Math.floor(index / 2) // Simple page estimation
                });
            });
        }

        console.log(`📊 Total headings found: ${this.headings.length}`);

        // Sort headings by their position in the document
        this.headings.sort((a, b) => {
            const posA = a.element.getBoundingClientRect().top;
            const posB = b.element.getBoundingClientRect().top;
            return posA - posB;
        });

        // Generate TOC entries
        this.headings.forEach(heading => {
            const entry = this.createTOCEntry(heading);
            this.tocContainer.appendChild(entry);
        });
        
        // Update total pages based on actual content
        if (this.headings.length > 0) {
            const maxPage = Math.max(...this.headings.map(h => h.page));
            this.totalPages = maxPage;
            console.log(`📊 Total pages calculated: ${this.totalPages}`);
            
                    // Update CSS variable for footers
        document.documentElement.style.setProperty('--total-pages', this.totalPages);
        
        // Update footer text to show total pages
        this.updateFooterText();
        }
        
        console.log('✅ TOC generation complete');
    }

    /* Removed getRealPageNumber function - using direct estimation instead */

    /**
     * Estimate page number (fallback method)
     */
    estimatePageNumber(element) {
        try {
            if (!element) return 3;
            
            const rect = element.getBoundingClientRect();
            const scrollTop = window.pageYOffset || document.documentElement.scrollTop;
            const absoluteTop = rect.top + scrollTop;
            
            // A4 page height in pixels (assuming 96 DPI)
            // A4 = 210mm x 297mm, 1 inch = 25.4mm, 1 inch = 96 pixels
            const pageHeightPixels = (297 * 96) / 25.4; // ~1123 pixels per page
            
            // Account for margins and spacing - use actual content height
            const effectivePageHeight = pageHeightPixels - 150; // More realistic margin
            
            // Calculate page number (start from page 3 since pages 1-2 are title and TOC)
            let pageNumber = Math.floor(absoluteTop / effectivePageHeight) + 3;
            
            // Don't clamp - let it go to actual page count
            console.log(`📄 Element "${element.textContent.trim()}" at position ${absoluteTop}px = page ${pageNumber}`);
            
            return pageNumber;
        } catch (error) {
            console.warn('Error estimating page number:', error);
            return 3; // Default fallback
        }
    }

    /**
     * Create a TOC entry element
     */
    createTOCEntry(heading) {
        const entry = document.createElement('div');
        entry.className = `toc-entry toc-level-${heading.level}`;
        
        // Create the text content
        const textSpan = document.createElement('span');
        textSpan.className = 'toc-text';
        textSpan.textContent = heading.text;
        
        // Create the dots area (now just spacing)
        const dotsSpan = document.createElement('span');
        dotsSpan.className = 'dots';
        
        // Create the page number
        const pageSpan = document.createElement('span');
        pageSpan.className = 'toc-page';
        pageSpan.textContent = heading.page;
        
        // Assemble the entry
        entry.appendChild(textSpan);
        entry.appendChild(dotsSpan);
        entry.appendChild(pageSpan);
        
        // Add click functionality to jump to heading
        entry.addEventListener('click', () => {
            heading.element.scrollIntoView({ behavior: 'smooth' });
        });
        
        return entry;
    }

    /**
     * Setup dynamic updates
     */
    setupDynamicUpdates() {
        // Refresh TOC when window is resized
        window.addEventListener('resize', () => {
            setTimeout(() => this.refresh(), 100);
        });
        
        // Refresh TOC when content changes
        const observer = new MutationObserver(() => {
            this.refresh();
        });
        
        // Observe the main content area
        const mainContent = document.querySelector('.main-content');
        if (mainContent) {
            observer.observe(mainContent, { 
                childList: true, 
                subtree: true,
                characterData: true 
            });
        }
    }

    /**
     * Refresh the TOC
     */
    async refresh() {
        await this.loadPageNumbers();
        this.generateTOC();
    }

    /**
     * Estimate page number based on element position
     */
    estimatePageNumber(element) {
        const pageHeightPixels = 1123; // A4 height in pixels at 96 DPI
        const absoluteTop = element.offsetTop;
        const estimatedPage = Math.floor(absoluteTop / pageHeightPixels) + 1;
        console.log(`📍 Element "${element.textContent.trim()}" at position ${absoluteTop}px -> estimated page ${estimatedPage}`);
        return estimatedPage;
    }

    /**
     * Get total page count for footer updates
     */
    getTotalPages() {
        return this.totalPages;
    }
}

// Initialize when DOM is loaded
document.addEventListener('DOMContentLoaded', function() {
    console.log('🚀 TOC Generator: DOM loaded, starting...');
    
    // Wait for numbering script to finish
    setTimeout(() => {
        console.log('🔄 TOC Generator: Creating instance...');
        window.tocGenerator = new TOCGenerator();
        window.tocGenerator.init();
    }, 100);
});

// Also try immediate execution as fallback
console.log('📜 TOC Generator script loaded');

// Simple test - if this shows up, JavaScript is working
document.addEventListener('DOMContentLoaded', function() {
    console.log('🧪 SIMPLE TEST: JavaScript is working!');
    
    // Test if we can find the TOC container
    const tocContainer = document.querySelector('.toc-auto');
    if (tocContainer) {
        console.log('✅ Found TOC container:', tocContainer);
        // Don't overwrite the TOC content - just log that we found it
    } else {
        console.log('❌ TOC container NOT found');
    }
});