// Viewer.js - Document viewer functionality

// Configuration
const DOC_MAP = {
    'USER_GUIDE': '/docs/USER_GUIDE.md',
    'E2E_TESTING_GUIDE': '/docs/E2E_TESTING_GUIDE.md',
    'IMPLEMENTATION_COMPLETE': '/docs/IMPLEMENTATION_COMPLETE.md',
    'ARCHITECTURE_GUIDE': '/docs/ARCHITECTURE_GUIDE.md',
    'QUICK_START': '/docs/QUICK_START.md',
    'DOCUMENTATION_INDEX': '/docs/DOCUMENTATION_INDEX.md',
    'IMPLEMENTATION_SUMMARY': '/docs/IMPLEMENTATION_SUMMARY.md'
};

let currentDoc = null;
let sidebarOpen = true;

// Initialize on page load
document.addEventListener('DOMContentLoaded', function() {
    initViewer();
    setupEventListeners();
    loadDocumentFromURL();
});

function initViewer() {
    // Configure marked.js
    if (typeof marked !== 'undefined') {
        marked.setOptions({
            breaks: true,
            gfm: true,
            highlight: function(code, lang) {
                if (typeof hljs !== 'undefined' && lang && hljs.getLanguage(lang)) {
                    try {
                        return hljs.highlight(code, { language: lang }).value;
                    } catch (err) {
                        console.error('Highlight error:', err);
                    }
                }
                return code;
            }
        });
    }
}

function setupEventListeners() {
    // Sidebar toggle
    const toggleBtn = document.getElementById('toggle-sidebar');
    if (toggleBtn) {
        toggleBtn.addEventListener('click', toggleSidebar);
    }

    // Document selector
    const docSelector = document.getElementById('doc-selector');
    if (docSelector) {
        docSelector.addEventListener('change', function() {
            if (this.value) {
                loadDocument(this.value);
            }
        });
    }

    // Print button
    const printBtn = document.getElementById('print-doc');
    if (printBtn) {
        printBtn.addEventListener('click', function() {
            window.print();
        });
    }

    // Download button
    const downloadBtn = document.getElementById('download-doc');
    if (downloadBtn) {
        downloadBtn.addEventListener('click', downloadCurrentDoc);
    }

    // Sidebar navigation links
    document.querySelectorAll('.sidebar-nav .nav-link').forEach(link => {
        link.addEventListener('click', function(e) {
            e.preventDefault();
            const url = this.getAttribute('href');
            const params = new URLSearchParams(url.split('?')[1]);
            const doc = params.get('doc');
            if (doc) {
                loadDocument(doc);
                updateURL(doc);
            }
        });
    });
}

function loadDocumentFromURL() {
    const params = new URLSearchParams(window.location.search);
    const doc = params.get('doc');
    if (doc && DOC_MAP[doc]) {
        loadDocument(doc);
    } else {
        showError('No document specified. Please select a document from the navigation.');
    }
}

async function loadDocument(docKey) {
    const docPath = DOC_MAP[docKey];
    if (!docPath) {
        showError(`Document "${docKey}" not found`);
        return;
    }

    currentDoc = docKey;
    showLoading();
    hideError();

    try {
        const response = await fetch(docPath);
        if (!response.ok) {
            throw new Error(`HTTP error! status: ${response.status}`);
        }

        const markdown = await response.text();
        renderMarkdown(markdown);
        generateTOC();
        updateActiveNav(docKey);
        updateDocSelector(docKey);
        updateURL(docKey);

        // Scroll to top
        window.scrollTo(0, 0);
    } catch (error) {
        console.error('Error loading document:', error);
        showError(`Failed to load document: ${error.message}`);
    } finally {
        hideLoading();
    }
}

function renderMarkdown(markdown) {
    const contentDiv = document.getElementById('content');
    if (!contentDiv) return;

    try {
        // Parse markdown to HTML
        const html = marked.parse(markdown);

        // Sanitize HTML using DOMPurify if available, otherwise use trusted content
        const safeHTML = (typeof DOMPurify !== 'undefined')
            ? DOMPurify.sanitize(html, { ADD_ATTR: ['target'] })
            : html;

        contentDiv.innerHTML = safeHTML;

        // Syntax highlighting for code blocks
        if (typeof hljs !== 'undefined') {
            contentDiv.querySelectorAll('pre code').forEach((block) => {
                hljs.highlightElement(block);
            });
        }

        // Make external links open in new tab
        contentDiv.querySelectorAll('a[href^="http"]').forEach(link => {
            link.setAttribute('target', '_blank');
            link.setAttribute('rel', 'noopener noreferrer');
        });

        // Add IDs to headings for anchor links
        contentDiv.querySelectorAll('h1, h2, h3, h4, h5, h6').forEach((heading, index) => {
            if (!heading.id) {
                heading.id = `heading-${index}`;
            }
        });

    } catch (error) {
        console.error('Error rendering markdown:', error);
        showError(`Failed to render document: ${error.message}`);
    }
}

function generateTOC() {
    const tocContent = document.getElementById('toc-content');
    const content = document.getElementById('content');

    if (!tocContent || !content) return;

    const headings = content.querySelectorAll('h2, h3');
    if (headings.length === 0) {
        tocContent.textContent = 'No headings found';
        return;
    }

    // Clear existing content
    tocContent.innerHTML = '';

    // Create TOC links using DOM methods
    headings.forEach(heading => {
        const level = heading.tagName.toLowerCase();
        const text = heading.textContent;
        const id = heading.id || `heading-${text.replace(/\s+/g, '-').toLowerCase()}`;
        heading.id = id;

        const link = document.createElement('a');
        link.href = `#${id}`;
        link.textContent = text;

        if (level === 'h3') {
            link.style.marginLeft = '1rem';
        }

        link.addEventListener('click', function(e) {
            e.preventDefault();
            const target = document.getElementById(id);
            if (target) {
                target.scrollIntoView({ behavior: 'smooth', block: 'start' });
            }
        });

        tocContent.appendChild(link);
    });
}

function toggleSidebar() {
    const sidebar = document.querySelector('.sidebar');
    const icon = document.getElementById('sidebar-icon');

    if (sidebar) {
        sidebarOpen = !sidebarOpen;
        sidebar.classList.toggle('active');
        if (icon) {
            icon.textContent = sidebarOpen ? '☰' : '✕';
        }
    }
}

function updateActiveNav(docKey) {
    document.querySelectorAll('.sidebar-nav .nav-link').forEach(link => {
        link.classList.remove('active');
        const url = link.getAttribute('href');
        if (url && url.includes(`doc=${docKey}`)) {
            link.classList.add('active');
        }
    });
}

function updateDocSelector(docKey) {
    const selector = document.getElementById('doc-selector');
    if (selector) {
        selector.value = docKey;
    }
}

function updateURL(docKey) {
    const newURL = `${window.location.pathname}?doc=${docKey}`;
    window.history.pushState({ doc: docKey }, '', newURL);
}

function downloadCurrentDoc() {
    if (!currentDoc) {
        alert('No document loaded');
        return;
    }

    const docPath = DOC_MAP[currentDoc];
    const filename = docPath.split('/').pop();

    fetch(docPath)
        .then(response => response.text())
        .then(text => {
            const blob = new Blob([text], { type: 'text/markdown' });
            const url = URL.createObjectURL(blob);
            const a = document.createElement('a');
            a.href = url;
            a.download = filename;
            document.body.appendChild(a);
            a.click();
            document.body.removeChild(a);
            URL.revokeObjectURL(url);
        })
        .catch(error => {
            console.error('Download error:', error);
            alert('Failed to download document');
        });
}

function showLoading() {
    const loading = document.getElementById('loading');
    const content = document.getElementById('content');

    if (loading) loading.style.display = 'block';
    if (content) content.style.display = 'none';
}

function hideLoading() {
    const loading = document.getElementById('loading');
    const content = document.getElementById('content');

    if (loading) loading.style.display = 'none';
    if (content) content.style.display = 'block';
}

function showError(message) {
    const error = document.getElementById('error');
    const errorMessage = document.getElementById('error-message');
    const content = document.getElementById('content');

    if (error) error.style.display = 'block';
    if (errorMessage) errorMessage.textContent = message;
    if (content) content.style.display = 'none';
}

function hideError() {
    const error = document.getElementById('error');
    if (error) error.style.display = 'none';
}

// Handle browser back/forward buttons
window.addEventListener('popstate', function(event) {
    if (event.state && event.state.doc) {
        loadDocument(event.state.doc);
    }
});

// Search functionality (future enhancement)
function searchDocumentation(query) {
    // TODO: Implement search across all documentation
    console.log('Search query:', query);
}