// ===== GLOBAL STATE =====
let currentResults = null;
let explanations = null;
let sessionId = null;

// ===== SECTION NAVIGATION (CRITICAL - MISSING IN YOUR CODE) =====
function showSection(sectionId) {
    console.log('🔄 Showing section:', sectionId);
    
    // Hide all sections
    document.querySelectorAll('.section').forEach(section => {
        section.classList.remove('active');
    });
    
    // Show target section
    const targetSection = document.getElementById(sectionId);
    if (targetSection) {
        targetSection.classList.add('active');
        targetSection.scrollIntoView({ behavior: 'smooth', block: 'start' });
    } else {
        console.error('❌ Section not found:', sectionId);
    }
}

// ===== INITIALIZATION =====
document.addEventListener('DOMContentLoaded', () => {
    console.log('✅ DOM loaded, initializing...');
    initFileUpload();
    
    // Show upload section by default
    showSection('upload-section');
});

// ===== FILE UPLOAD =====
function initFileUpload() {
    const fileInput = document.getElementById('fileInput');
    const uploadArea = document.getElementById('uploadArea');
    
    if (!fileInput || !uploadArea) {
        console.error('❌ Upload elements not found');
        return;
    }
    
    console.log('✅ Upload initialized');
    
    // Click to upload
    fileInput.addEventListener('change', handleFileSelect);
    
    // Drag and drop
    uploadArea.addEventListener('dragover', (e) => {
        e.preventDefault();
        uploadArea.classList.add('border-secondary', 'bg-blue-100');
    });
    
    uploadArea.addEventListener('dragleave', () => {
        uploadArea.classList.remove('border-secondary', 'bg-blue-100');
    });
    
    uploadArea.addEventListener('drop', (e) => {
        e.preventDefault();
        uploadArea.classList.remove('border-secondary', 'bg-blue-100');
        
        const file = e.dataTransfer.files[0];
        if (file && file.type === 'application/pdf') {
            uploadFile(file);
        } else {
            showToast('Please upload a PDF file', 'error');
        }
    });
}

function handleFileSelect(e) {
    const file = e.target.files[0];
    if (file) {
        uploadFile(file);
    }
}

async function uploadFile(file) {
    const formData = new FormData();
    formData.append('file', file);
    
    // Show progress
    document.getElementById('uploadArea').classList.add('hidden');
    document.getElementById('uploadProgress').classList.remove('hidden');
    
    try {
        console.log('📤 Uploading file:', file.name);
        
        const response = await fetch('/api/upload', {
            method: 'POST',
            body: formData
        });
        
        const data = await response.json();
        console.log('📥 Upload response:', data);
        
        if (!response.ok) {
            throw new Error(data.error || 'Upload failed');
        }
        
        // Store session ID and results
        sessionId = data.session_id;
        currentResults = data.results;
        
        console.log('✅ Session ID:', sessionId);
        console.log('✅ Results:', currentResults.length);
        
        showToast(`✓ Found ${data.count} lab results!`, 'success');
        
        // Display results immediately with template explanations
        console.log('🎨 Displaying template results...');
        displayResults();
        updateSummaryStats();
        
        // Show stats and buttons
        document.getElementById('summaryStats').classList.remove('hidden');
        document.getElementById('generateSummaryBtn').classList.remove('hidden');
        
        // Switch to results section
        setTimeout(() => {
            showSection('results-section');
        }, 500);
        
        // Fetch AI explanations in background
        console.log('🤖 Fetching AI explanations...');
        showToast('Generating AI explanations...', 'info');
        
        await generateExplanations();
        
        // Update display with AI explanations
        console.log('🔄 Updating with AI explanations...');
        displayResults();
        
        showToast('✓ AI explanations loaded!', 'success');
        
    } catch (error) {
        console.error('❌ Upload error:', error);
        showToast(error.message, 'error');
        resetUploadArea();
    }
}

async function generateExplanations() {
    try {
        console.log('🔄 Calling /api/explain with session:', sessionId);
        
        const response = await fetch('/api/explain', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ session_id: sessionId })
        });
        
        const data = await response.json();
        console.log('📥 Explanation response:', data);
        
        if (!response.ok) {
            throw new Error(data.error || 'Failed to generate explanations');
        }
        
        explanations = data.explanations;
        console.log('✅ Explanations loaded:', Object.keys(explanations).length);
        
    } catch (error) {
        console.error('❌ Explanation error:', error);
        showToast('Using basic explanations', 'info');
    }
}

function displayResults() {
    const container = document.getElementById('resultsContainer');
    
    console.log('🎯 displayResults() called');
    console.log('📊 Results:', currentResults?.length);
    console.log('💬 Explanations:', explanations ? Object.keys(explanations).length : 0);
    
    if (!currentResults || currentResults.length === 0) {
        console.log('❌ No results to display');
        container.innerHTML = '<div class="flex flex-col items-center justify-center h-full text-slate-400 py-20"><div class="text-6xl mb-4 opacity-20">📊</div><p>Upload a lab report to view results here</p></div>';
        return;
    }
    
    console.log(`✅ Displaying ${currentResults.length} results`);
    
    // Clear container
    container.innerHTML = '';
    
    // Create result cards
    currentResults.forEach((result, index) => {
        console.log(`📝 Card ${index + 1}:`, result.test_name, result.status);
        const card = createResultCard(result, index);
        container.appendChild(card);
    });
    
    // Reset upload area
    resetUploadArea();
    
    console.log('✅ All cards rendered');
}

function createResultCard(result, index) {
    const card = document.createElement('div');
    card.className = 'bg-white rounded-xl shadow-md border border-slate-200 p-6 mb-4 hover:shadow-lg transition-shadow';
    
    // Status colors
    const statusColors = {
        normal: { bg: 'bg-green-50', text: 'text-green-700', border: 'border-green-200' },
        high: { bg: 'bg-red-50', text: 'text-red-700', border: 'border-red-200' },
        low: { bg: 'bg-yellow-50', text: 'text-yellow-700', border: 'border-yellow-200' },
        unknown: { bg: 'bg-slate-50', text: 'text-slate-700', border: 'border-slate-200' }
    };
    
    const colors = statusColors[result.status] || statusColors.unknown;
    
    // Get explanation
    let explanation = '';
    
    if (explanations && explanations[result.test_name]) {
        explanation = explanations[result.test_name];
        console.log(`  ✅ Using AI explanation for ${result.test_name}`);
    } else {
        console.log(`  ⚠️ Using template for ${result.test_name}`);
        // Template explanation
        if (result.status === 'normal') {
            explanation = `✅ <strong>Good news!</strong> Your ${result.test_name} level of ${result.value} ${result.unit} is within the normal range (${result.reference_range}).<br><br>This indicates healthy levels. Keep up your current health habits!`;
        } else if (result.status === 'high') {
            explanation = `⚠️ Your ${result.test_name} level of ${result.value} ${result.unit} is <strong>above</strong> the normal range (${result.reference_range}).<br><br>This may require attention. Please consult your healthcare provider.`;
        } else if (result.status === 'low') {
            explanation = `⚠️ Your ${result.test_name} level of ${result.value} ${result.unit} is <strong>below</strong> the normal range (${result.reference_range}).<br><br>This may require attention. Please consult your healthcare provider.`;
        } else {
            explanation = `Your ${result.test_name} result is ${result.value} ${result.unit}.<br><br>Reference range: ${result.reference_range}`;
        }
    }
    
    card.innerHTML = `
        <div class="flex justify-between items-start mb-4">
            <div>
                <h3 class="text-xl font-bold text-slate-800">${escapeHtml(result.test_name)}</h3>
                <p class="text-sm text-slate-500">Reference: ${escapeHtml(result.reference_range || 'N/A')}</p>
            </div>
            <div class="text-right">
                <div class="text-2xl font-bold text-slate-800">${escapeHtml(result.value)} <span class="text-lg text-slate-500">${escapeHtml(result.unit)}</span></div>
                <span class="inline-block mt-2 px-3 py-1 rounded-full text-sm font-medium ${colors.bg} ${colors.text} border ${colors.border}">
                    ${result.status.toUpperCase()}
                </span>
            </div>
        </div>
        <div class="mt-4 p-4 bg-blue-50 rounded-lg border border-blue-100">
            <div class="font-semibold text-blue-900 mb-2">💡 What does this mean?</div>
            <div class="text-sm text-slate-700 leading-relaxed">${explanation}</div>
        </div>
    `;
    
    return card;
}

function updateSummaryStats() {
    const stats = { normal: 0, high: 0, low: 0 };
    
    currentResults.forEach(result => {
        if (result.status in stats) {
            stats[result.status]++;
        }
    });
    
    document.getElementById('normalCount').textContent = stats.normal;
    document.getElementById('highCount').textContent = stats.high;
    document.getElementById('lowCount').textContent = stats.low;
    
    console.log('📊 Stats updated:', stats);
}

function resetUploadArea() {
    document.getElementById('uploadArea').classList.remove('hidden');
    document.getElementById('uploadProgress').classList.add('hidden');
    document.getElementById('fileInput').value = '';
}

// ===== CHAT FUNCTIONALITY =====
async function askQuestion() {
    const input = document.getElementById('chatInput');
    const question = input.value.trim();
    
    if (!question) return;
    
    if (!sessionId) {
        showToast('Please upload a lab report first', 'error');
        return;
    }
    
    console.log('💬 Asking:', question);
    
    // Clear input
    input.value = '';
    
    // Add user message
    addChatMessage(question, 'user');
    
    // Add loading message
    const loadingId = addChatMessage('Thinking...', 'assistant', true);
    
    try {
        const response = await fetch('/api/ask', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ 
                question: question,
                session_id: sessionId 
            })
        });
        
        const data = await response.json();
        console.log('💬 Answer:', data);
        
        if (!response.ok) {
            throw new Error(data.error || 'Failed to get answer');
        }
        
        // Remove loading message
        document.getElementById(loadingId).remove();
        
        // Add assistant response
        addChatMessage(data.answer, 'assistant');
        
    } catch (error) {
        console.error('❌ Chat error:', error);
        document.getElementById(loadingId).remove();
        addChatMessage(`Sorry, I encountered an error: ${error.message}`, 'assistant');
        showToast(error.message, 'error');
    }
}

function addChatMessage(text, sender, isLoading = false) {
    const messagesContainer = document.getElementById('chatMessages');
    
    // Remove placeholder text if exists
    const placeholder = messagesContainer.querySelector('.text-slate-400');
    if (placeholder && placeholder.closest('.text-center')) {
        placeholder.closest('.text-center').remove();
    }
    
    const messageId = `msg-${Date.now()}-${Math.random()}`;
    const messageDiv = document.createElement('div');
    messageDiv.id = messageId;
    messageDiv.className = `mb-4 ${sender === 'user' ? 'text-right' : 'text-left'}`;
    
    const bubbleClass = sender === 'user' 
        ? 'inline-block bg-secondary text-white px-4 py-2 rounded-2xl rounded-tr-sm max-w-[80%]'
        : 'inline-block bg-slate-100 text-slate-800 px-4 py-2 rounded-2xl rounded-tl-sm max-w-[80%]';
    
    messageDiv.innerHTML = `<div class="${bubbleClass} ${isLoading ? 'animate-pulse' : ''}">${escapeHtml(text)}</div>`;
    
    messagesContainer.appendChild(messageDiv);
    messagesContainer.scrollTop = messagesContainer.scrollHeight;
    
    return messageId;
}

// ===== SUMMARY GENERATION =====
async function generateSummary() {
    if (!sessionId) {
        showToast('Please upload a lab report first', 'error');
        return;
    }
    
    console.log('📊 Generating summary...');
    
    const summaryContent = document.getElementById('summaryContent');
    summaryContent.innerHTML = '<div class="text-center py-10"><div class="inline-block animate-spin rounded-full h-8 w-8 border-4 border-blue-200 border-t-secondary"></div><p class="text-secondary mt-3">Generating summary...</p></div>';
    
    try {
        const response = await fetch('/api/summary', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({ session_id: sessionId })
        });
        
        const data = await response.json();
        console.log('📊 Summary:', data);
        
        if (!response.ok) {
            throw new Error(data.error || 'Failed to generate summary');
        }
        
        // Display summary
        summaryContent.innerHTML = `
            <div class="prose max-w-none">
                <div class="text-slate-700 leading-relaxed whitespace-pre-wrap">${escapeHtml(data.summary)}</div>
            </div>
        `;
        
        showToast('✓ Summary generated!', 'success');
        
    } catch (error) {
        console.error('❌ Summary error:', error);
        summaryContent.innerHTML = '<div class="text-center text-slate-400 py-10"><p>Error generating summary. Please try again.</p></div>';
        showToast('Error: ' + error.message, 'error');
    }
}

// ===== TOAST NOTIFICATIONS =====
function showToast(message, type = 'info') {
    const toast = document.getElementById('toast');
    
    const colors = {
        success: 'bg-green-600',
        error: 'bg-red-600',
        info: 'bg-blue-600'
    };
    
    toast.textContent = message;
    toast.className = `fixed bottom-5 right-5 ${colors[type] || colors.info} text-white px-6 py-3 rounded-lg shadow-2xl z-50 transform transition-all duration-300`;
    toast.style.transform = 'translateY(0)';
    toast.style.opacity = '1';
    
    setTimeout(() => {
        toast.style.transform = 'translateY(100px)';
        toast.style.opacity = '0';
    }, 4000);
}

// ===== UTILITY FUNCTIONS =====
function escapeHtml(text) {
    if (!text) return '';
    const div = document.createElement('div');
    div.textContent = text;
    return div.innerHTML;
}