let currentUser = null;
let allShifts = [];
let mySignups = [];

// Initialize when DOM is loaded
document.addEventListener('DOMContentLoaded', async () => {
    await checkAuth();
    await loadShifts();
    await loadMySignups();
    setupEventListeners();
    
    // Add clear filters button handler
    const clearBtn = document.getElementById('clear-filters-btn');
    if (clearBtn) {
        clearBtn.addEventListener('click', clearFilters);
    }
});

async function checkAuth() {
    try {
        const response = await fetch('/api/auth/check');
        const data = await response.json();
        
        if (!data.authenticated) {
            window.location.href = '/login.html';
            return;
        }
        
        currentUser = data.user;
        document.getElementById('user-email').textContent = currentUser.email;
        
        // Add admin link if user is admin
        if (currentUser.isAdmin) {
            const headerActions = document.querySelector('.header-actions');
            const adminLink = document.createElement('a');
            adminLink.href = '/admin.html#shifts';
            adminLink.className = 'btn btn-secondary';
            adminLink.textContent = '⚙️ Manage Shifts';
            headerActions.insertBefore(adminLink, headerActions.firstChild);
        }
        
    } catch (error) {
        console.error('Auth check failed:', error);
        window.location.href = '/login.html';
    }
}

async function loadShifts() {
    try {
        const response = await fetch('/api/shifts');
        const data = await response.json();
        
        if (data.success) {
            allShifts = data.shifts;
            displayShifts(allShifts);
        }
    } catch (error) {
        showStatus('Failed to load shifts', 'error');
    }
}

async function loadMySignups() {
    try {
        const response = await fetch('/api/shifts/my-signups');
        const data = await response.json();
        
        if (data.success) {
            mySignups = data.signups;
            displayMySignups();
        } else {
            // Still display empty signups if the endpoint fails
            mySignups = [];
            displayMySignups();
        }
    } catch (error) {
        console.error('Failed to load signups:', error);
        // Don't show error to user, just display empty signups
        mySignups = [];
        displayMySignups();
    }
}

function displayShifts(shifts) {
    const grid = document.getElementById('shifts-grid');
    
    if (shifts.length === 0) {
        grid.innerHTML = '<p class="no-shifts">No shifts available at this time.</p>';
        return;
    }
    
    grid.innerHTML = shifts.map(shift => {
        const shiftDate = new Date(shift.Date);
        const isSignedUp = mySignups.some(s => s.shift_id === shift.ID);
        const isFull = shift['Current Volunteers'] >= shift['Max Volunteers'];
        
        return `
            <div class="shift-card ${isFull ? 'full' : ''} ${isSignedUp ? 'signed-up' : ''}">
                <h3>${escapeHtml(shift.Title)}</h3>
                <div class="shift-details">
                    <p>📅 ${shiftDate.toLocaleDateString()}</p>
                    <p>⏰ ${shift['Start Time']} - ${shift['End Time']}</p>
                    <p>📍 ${escapeHtml(shift.Location || 'TBD')}</p>
                    <p>👥 ${shift['Current Volunteers']}/${shift['Max Volunteers']} volunteers</p>
                </div>
                ${shift.Description ? `<div class="shift-description">${escapeHtml(shift.Description)}</div>` : ''}
                <div class="shift-actions">
                    ${isSignedUp 
                        ? `<button class="btn btn-danger btn-sm cancel-signup-btn" data-shift-id="${shift.ID}">Cancel Signup</button>`
                        : isFull
                            ? '<button class="btn btn-secondary btn-sm" disabled>Shift Full</button>'
                            : `<button class="btn btn-primary btn-sm signup-btn" data-shift-id="${shift.ID}">Sign Up</button>`
                    }
                </div>
            </div>
        `;
    }).join('');
    
    // Add event listeners after rendering
    setupShiftCardListeners();
}

function displayMySignups() {
    const list = document.getElementById('my-signups-list');
    
    if (mySignups.length === 0) {
        list.innerHTML = '<p>You haven\'t signed up for any shifts yet.</p>';
        return;
    }
    
    // Need to match signups with shift details
    const signupsWithDetails = mySignups.map(signup => {
        const shift = allShifts.find(s => s.ID === signup.shift_id);
        return { ...signup, shift };
    }).filter(s => s.shift);
    
    list.innerHTML = signupsWithDetails.map(signup => {
        const shiftDate = new Date(signup.shift.Date);
        return `
            <div class="signup-item">
                <div>
                    <h4>${escapeHtml(signup.shift.Title)}</h4>
                    <p>📅 ${shiftDate.toLocaleDateString()} ⏰ ${signup.shift['Start Time']} - ${signup.shift['End Time']}</p>
                </div>
                <button class="btn btn-danger btn-sm cancel-signup-btn" data-shift-id="${signup.shift.ID}">Cancel</button>
            </div>
        `;
    }).join('');
    
    // Add event listeners after rendering
    setupMySignupsListeners();
}

// New function to setup listeners for shift cards
function setupShiftCardListeners() {
    const grid = document.getElementById('shifts-grid');
    if (!grid) return;
    
    // Remove any existing listeners by cloning
    const newGrid = grid.cloneNode(true);
    grid.parentNode.replaceChild(newGrid, grid);
    
    // Add click listener for signup buttons
    newGrid.addEventListener('click', async (e) => {
        if (e.target.classList.contains('signup-btn')) {
            const shiftId = e.target.getAttribute('data-shift-id');
            await signupForShift(shiftId);
        } else if (e.target.classList.contains('cancel-signup-btn')) {
            const shiftId = e.target.getAttribute('data-shift-id');
            await cancelSignup(shiftId);
        }
    });
}

// New function to setup listeners for my signups
function setupMySignupsListeners() {
    const list = document.getElementById('my-signups-list');
    if (!list) return;
    
    // Remove any existing listeners by cloning
    const newList = list.cloneNode(true);
    list.parentNode.replaceChild(newList, list);
    
    // Add click listener for cancel buttons
    newList.addEventListener('click', async (e) => {
        if (e.target.classList.contains('cancel-signup-btn')) {
            const shiftId = e.target.getAttribute('data-shift-id');
            await cancelSignup(shiftId);
        }
    });
}

async function signupForShift(shiftId) {
    try {
        const response = await fetch(`/api/shifts/${shiftId}/signup`, {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            }
        });
        
        const data = await response.json();
        
        if (data.success) {
            showStatus('Successfully signed up for shift!', 'success');
            await loadShifts();
            await loadMySignups();
        } else {
            showStatus(data.error || 'Failed to sign up', 'error');
        }
    } catch (error) {
        console.error('Error signing up:', error);
        showStatus('Failed to sign up for shift', 'error');
    }
}

async function cancelSignup(shiftId) {
    if (!confirm('Are you sure you want to cancel your signup for this shift?')) {
        return;
    }
    
    try {
        const response = await fetch(`/api/shifts/${shiftId}/cancel`, {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            }
        });
        
        const data = await response.json();
        
        if (data.success) {
            showStatus('Signup cancelled', 'success');
            await loadShifts();
            await loadMySignups();
        } else {
            showStatus(data.error || 'Failed to cancel signup', 'error');
        }
    } catch (error) {
        console.error('Error cancelling signup:', error);
        showStatus('Failed to cancel signup', 'error');
    }
}

function setupEventListeners() {
    const dateFilter = document.getElementById('date-filter');
    if (dateFilter) {
        dateFilter.addEventListener('change', filterShifts);
    }
}

function filterShifts() {
    const dateFilter = document.getElementById('date-filter').value;
    
    if (!dateFilter) {
        displayShifts(allShifts);
        return;
    }
    
    const filtered = allShifts.filter(shift => {
        return shift.Date === dateFilter;  // Changed from shift.date to shift.Date
    });
    
    displayShifts(filtered);
}

function clearFilters() {
    document.getElementById('date-filter').value = '';
    loadShifts(); // Reload shifts without filters
}

function showStatus(message, type = 'info') {
    const container = document.getElementById('status-container');
    if (!container) return;
    
    const messageDiv = document.createElement('div');
    messageDiv.className = `status-message ${type}`;
    messageDiv.textContent = message;
    
    container.appendChild(messageDiv);
    
    setTimeout(() => {
        messageDiv.remove();
    }, 5000);
}

function escapeHtml(text) {
    if (text === null || text === undefined) {
        return '';
    }
    const div = document.createElement('div');
    div.textContent = String(text);
    return div.innerHTML;
}