// Main application script
document.addEventListener('DOMContentLoaded', function() {
    // Handle login form submission
    const loginForm = document.getElementById('loginForm');
    if (loginForm) {
        loginForm.addEventListener('submit', function(e) {
            e.preventDefault();
            const username = document.getElementById('username').value;
            const password = document.getElementById('password').value;
            
            // Simple validation (in production, use proper authentication)
            if (username && password) {
                localStorage.setItem('isAuthenticated', 'true');
                window.location.href = 'dashboard.html';
            } else {
                alert('Please enter both username and password');
            }
        });
    }

    // Check authentication on dashboard pages
    const isAuthenticated = localStorage.getItem('isAuthenticated');
    if (!isAuthenticated && !window.location.pathname.includes('login.html')) {
        window.location.href = 'login.html';
    }

    // PDF Upload Functionality
    const pdfUploadForms = document.querySelectorAll('.pdf-upload-form');
    pdfUploadForms.forEach(form => {
        form.addEventListener('submit', function(e) {
            e.preventDefault();
            const department = this.querySelector('select[name="department"]').value;
            const startDate = this.querySelector('input[name="start_date"]').value;
            const endDate = this.querySelector('input[name="end_date"]').value;
            const pdfFile = this.querySelector('input[name="pdf_file"]').files[0];
            
            if (pdfFile) {
                const reader = new FileReader();
                reader.onload = function(e) {
                    const pdfData = e.target.result;
                    // Store in localStorage (in production, use backend)
                    localStorage.setItem(`pdf_${department}_${startDate}_${endDate}`, pdfData);
                    alert('PDF uploaded successfully!');
                };
                reader.readAsDataURL(pdfFile);
            }
        });
    });

    // Generate trend chart from PDF data (mock implementation)
    function generateTrendChart(department, startDate, endDate) {
        // In a real app, you would parse the PDF and extract data
        // This is a mock implementation with random data
        const ctx = document.getElementById('trendChart');
        if (!ctx) return;
        
        const labels = [];
        const start = new Date(startDate);
        const end = new Date(endDate);
        const diffTime = Math.abs(end - start);
        const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24)); 
        
        for (let i = 0; i <= diffDays; i += 7) {
            labels.push(`Week ${i/7 + 1}`);
        }
        
        const randomData = labels.map(() => Math.floor(Math.random() * 100));
        
        new Chart(ctx, {
            type: 'line',
            data: {
                labels: labels,
                datasets: [{
                    label: `${department} Performance Trend`,
                    data: randomData,
                    borderColor: '#f97316',
                    backgroundColor: 'rgba(249, 115, 22, 0.1)',
                    borderWidth: 2,
                    tension: 0.3,
                    fill: true
                }]
            },
            options: {
                responsive: true,
                scales: {
                    y: {
                        beginAtZero: true,
                        max: 100
                    }
                }
            }
        });
    }

    // Initialize trend chart when viewing a PDF
    const urlParams = new URLSearchParams(window.location.search);
    const department = urlParams.get('department');
    const startDate = urlParams.get('start_date');
    const endDate = urlParams.get('end_date');
    
    if (department && startDate && endDate) {
        generateTrendChart(department, startDate, endDate);
    }
});
// Theme toggle functionality
function toggleTheme() {
    const html = document.documentElement;
    if (html.classList.contains('dark')) {
        html.classList.remove('dark');
        localStorage.setItem('theme', 'light');
    } else {
        html.classList.add('dark');
        localStorage.setItem('theme', 'dark');
    }
}

// Check for saved theme preference
if (localStorage.getItem('theme') === 'dark' || (!localStorage.getItem('theme') && window.matchMedia('(prefers-color-scheme: dark)').matches)) {
    document.documentElement.classList.add('dark');
} else {
    document.documentElement.classList.remove('dark');
}