// public/public.js (for index.html)

// Convert time string (e.g., '9:30am' or '2:00pm') to minutes since midnight
function timeToMinutes(timeStr) {
    const match = timeStr.match(/([0-9]{1,2}):([0-9]{2})(am|pm)/i);
    if (!match) {
        console.error('Invalid time format:', timeStr);
        return 0;
    }
    const [_, hours, minutes, period] = match;
    let totalHours = parseInt(hours);
    if (period.toLowerCase() === 'pm' && totalHours !== 12) totalHours += 12;
    if (period.toLowerCase() === 'am' && totalHours === 12) totalHours = 0;
    return totalHours * 60 + parseInt(minutes);
}

// Get UID from URL path
function getUidFromPath() {
    const path = window.location.pathname.substring(1); // Remove leading slash
    return path || null;
}

// Validate UID format
function isValidUid(uid) {
    return /^[a-z0-9-]+$/.test(uid);
}

document.addEventListener('DOMContentLoaded', async () => {
    // Add custom CSS for the current date to make it more distinguishable
    const style = document.createElement('style');
    style.textContent = `
        .date-item.current {
            border: 2px solid #ffc107 !important; /* Yellow border */
            background-color: rgba(255, 193, 7, 0.1) !important; /* Light yellow background */
            font-weight: bold !important;
            color: #212529 !important; /* Ensure text is visible */
        }
        
        /* Ensure current date styling takes precedence but doesn't interfere with selection */
        .date-item.current.selected {
            border: 2px solid #0d6efd !important; /* Blue border for selected */
            background-color: #0d6efd !important; /* Dark blue background when selected */
            color: white !important; /* White text for better contrast */
            font-weight: bold !important;
        }
    `;
    document.head.appendChild(style);
    
    const uid = getUidFromPath();
    const mainContent = document.getElementById('mainContent');
    const uidError = document.getElementById('uidError');

    // Check if we have a valid UID
    if (!uid || !isValidUid(uid)) {
        mainContent.style.display = 'none';
        uidError.style.display = 'block';
        return;
    }

    // Hide error, show main content
    uidError.style.display = 'none';
    mainContent.style.display = 'block';

    const calendarDates = document.getElementById('calendarDates');
    const monthYear = document.getElementById('monthYear');
    const prevMonthBtn = document.getElementById('prevMonth');
    const nextMonthBtn = document.getElementById('nextMonth');
    const currentTimeElement = document.getElementById('currentTime');
    const timeSlotsContainer = document.getElementById('timeSlots');

    // Check if navigation buttons exist before adding event listeners
    if (!prevMonthBtn || !nextMonthBtn) {
        console.error('Navigation buttons (prevMonth or nextMonth) not found in the DOM');
        return;
    }

    let currentDate = new Date();
    let currentMonth = currentDate.getMonth();
    let currentYear = currentDate.getFullYear();
    let selectedDate = null; // Track selected date

    const months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];

    // Fetch available dates from the API
    async function fetchAvailability() {
        try {
            const response = await fetch(`/api/availability/${uid}`);
            if (response.status === 404) {
                // UID doesn't exist, show error page
                mainContent.style.display = 'none';
                uidError.style.display = 'block';
                return null;
            }
            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }
            const availability = await response.json();
            console.log('Fetched availability for UID:', uid, availability);
            return availability;
        } catch (error) {
            console.error('Error fetching availability:', error);
            return {};
        }
    }

    // Render the calendar with available dates highlighted and automatically select/display the current date
    async function renderCalendar(month, year) {
        const availability = await fetchAvailability();
        if (availability === null) return; // UID doesn't exist

        calendarDates.innerHTML = '';
        monthYear.textContent = `${months[month]} ${year}`;

        const firstDay = new Date(year, month, 1).getDay();
        const daysInMonth = new Date(year, month + 1, 0).getDate();
        const today = new Date();
        const currentMinutes = today.getHours() * 60 + today.getMinutes();

        // Create blank cells for days before the first day of the month
        for (let i = 0; i < firstDay; i++) {
            const blank = document.createElement('div');
            blank.classList.add('date-item', 'p-2', 'rounded-pill', 'text-center', 'text-muted');
            calendarDates.appendChild(blank);
        }

        // Populate the calendar with days
        for (let i = 1; i <= daysInMonth; i++) {
            const day = document.createElement('div');
            day.classList.add('date-item', 'p-2', 'rounded-pill', 'text-center');
            day.textContent = i;
            const date = new Date(year, month, i);
            const dateStr = date.toISOString().split('T')[0];
            
            // Start of today (midnight)
            const startOfToday = new Date(today.getFullYear(), today.getMonth(), today.getDate());
            
            // Check if date is in the past
            const isPastDate = date < startOfToday;
            const isToday = date.toDateString() === today.toDateString();

            if (isToday) {
                day.classList.add('current');
            }
            
            // Check if the date has available time slots
            let hasAvailableTimes = false;
            if (availability[dateStr]) {
                let times = [];
                if (typeof availability[dateStr] === 'string') {
                    times = availability[dateStr].split(',').map(t => t.trim());
                } else if (Array.isArray(availability[dateStr])) {
                    times = availability[dateStr].map(t => t.trim());
                }
                
                // For today, filter out past times
                if (isToday) {
                    times = times.filter(time => timeToMinutes(time) > currentMinutes);
                }
                
                // Only mark as available if there are valid times
                hasAvailableTimes = times.length > 0;
            }
            
            // Only add 'available' class if the date is not in the past AND has available times
            if (hasAvailableTimes && !isPastDate) {
                day.classList.add('available');
            }
            
            if (isPastDate) {
                day.classList.add('disabled');
            } else {
                day.addEventListener('click', () => selectDate(date, firstDay));
            }
            calendarDates.appendChild(day);
        }

        // Auto-select today if we're in the current month/year
        if (today.getMonth() === month && today.getFullYear() === year) {
            await selectDate(today, firstDay);
            // Also update time slots directly since we're on today's date
            await updateTimeSlots(today);
        }
    }

    // Handle date selection
    async function selectDate(date, firstDay) {
        // Check if the date is in the past
        const today = new Date();
        const startOfToday = new Date(today.getFullYear(), today.getMonth(), today.getDate());
        if (date < startOfToday) {
            console.warn('Attempted to select a past date');
            return;
        }

        selectedDate = date;
        const dateItems = document.querySelectorAll('#calendarDates .date-item');
        dateItems.forEach(item => item.classList.remove('selected')); // Ensure only one date is selected
        // Find the exact date item for the clicked or auto-selected date
        const selectedDay = Array.from(dateItems).find(item => {
            const dayText = item.textContent;
            const itemDate = new Date(currentYear, currentMonth, parseInt(dayText));
            return itemDate.toDateString() === date.toDateString();
        });
        if (selectedDay) selectedDay.classList.add('selected');
        await updateTimeSlots(date); // Update time slots based on selected date, ensuring async completion
    }

    // Update time slots based on selected date
    async function updateTimeSlots(date) {
        const availability = await fetchAvailability();
        const dateStr = date.toISOString().split('T')[0];
        console.log('Looking for date:', dateStr);
        console.log('Available dates:', Object.keys(availability));
        let times = [];
        if (availability[dateStr]) {
            console.log('Found times for date:', availability[dateStr]);
            // Ensure availability[dateStr] is a string or array before processing
            if (typeof availability[dateStr] === 'string') {
                times = availability[dateStr].split(',').map(t => t.trim());
            } else if (Array.isArray(availability[dateStr])) {
                times = availability[dateStr].map(t => t.trim());
            } else {
                console.warn(`Unexpected data format for date ${dateStr}:`, availability[dateStr]);
            }

            // Filter out past times if it's today
            const today = new Date();
            const isToday = date.toDateString() === today.toDateString();
            console.log('Time filtering - Today:', today.toDateString());
            console.log('Time filtering - Selected:', date.toDateString());
            console.log('Is today?', isToday);
            if (isToday) {
                const currentMinutes = today.getHours() * 60 + today.getMinutes();
                console.log('Current minutes:', currentMinutes);
                console.log('Times before filtering:', times);
                times = times.filter(time => {
                    const timeMin = timeToMinutes(time);
                    console.log(`Time ${time} = ${timeMin} minutes`);
                    return timeMin > currentMinutes;
                });
                console.log('Times after filtering:', times);
            }

            // Sort times chronologically
            times.sort((a, b) => timeToMinutes(a) - timeToMinutes(b));
        }

        // Clear existing time slots or message
        timeSlotsContainer.innerHTML = '';

        if (times.length === 0) {
            // Display "No availability on selected date." if no times are available
            const noAvailabilityMsg = document.createElement('p');
            noAvailabilityMsg.classList.add('text-muted', 'text-center', 'fw-bold', 'fs-5', 'py-3');
            noAvailabilityMsg.textContent = 'No availability on selected date.';
            timeSlotsContainer.appendChild(noAvailabilityMsg);
        } else {
            // Populate time slots dynamically if times are available
            times.forEach(time => {
                const button = document.createElement('button');
                button.classList.add('time-slot', 'btn', 'rounded-pill', 'w-100', 'mb-2');
                button.classList.add('btn-outline-primary', 'available');
                button.textContent = time;
                button.addEventListener('click', () => {
                    const allTimeSlots = timeSlotsContainer.querySelectorAll('.time-slot');
                    allTimeSlots.forEach(s => s.classList.remove('selected'));
                    button.classList.add('selected');
                    
                    // Format date as MM/DD/YY
                    const [year, month, day] = dateStr.split('-');
                    const formattedDate = `${month}/${day}/${year.slice(2)}`;
                    
                    // Show booking modal
                    document.getElementById('selectedTime').value = time;
                    document.getElementById('selectedDate').value = dateStr;
                    document.getElementById('bookingModalLabel').textContent = `Confirm Appointment for ${formattedDate} at ${time} EST`;
                    
                    // Clear previous form data
                    document.getElementById('bookingForm').reset();
                    
                    // Show modal
                    const bookingModal = new bootstrap.Modal(document.getElementById('bookingModal'));
                    bookingModal.show();
                });
                timeSlotsContainer.appendChild(button);
            });
        }
    }

    // Navigate to previous month
    prevMonthBtn.addEventListener('click', () => {
        currentMonth--;
        if (currentMonth < 0) {
            currentMonth = 11;
            currentYear--;
        }
        renderCalendar(currentMonth, currentYear);
    });

    // Navigate to next month
    nextMonthBtn.addEventListener('click', () => {
        currentMonth++;
        if (currentMonth > 11) {
            currentMonth = 0;
            currentYear++;
        }
        renderCalendar(currentMonth, currentYear);
    });

    // Update current time in Eastern Time (US & Canada)
    function updateCurrentTime() {
        const options = {
            timeZone: 'America/New_York',
            hour: '2-digit',
            minute: '2-digit',
            hour12: true
        };
        const time = new Date().toLocaleTimeString('en-US', options);
        currentTimeElement.textContent = time;
    }

    // Update time every second
    setInterval(updateCurrentTime, 1000);
    updateCurrentTime(); // Initial call

    // Form validation and submission
    const form = document.getElementById('bookingForm');
    const submitBtn = document.getElementById('submitBooking');

    // Email validation function
    function isValidEmail(email) {
        const re = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
        return re.test(email);
    }

    // Phone validation function (optional field)
    function isValidPhone(phone) {
        if (!phone) return true; // Optional field
        const re = /^[0-9]{3}-[0-9]{3}-[0-9]{4}$/;
        return re.test(phone);
    }

    // Format phone number as user types
    document.getElementById('phone').addEventListener('input', (e) => {
        let value = e.target.value.replace(/\D/g, ''); // Remove non-digits
        if (value.length >= 3) {
            value = value.slice(0, 3) + '-' + value.slice(3);
            if (value.length >= 7) {
                value = value.slice(0, 7) + '-' + value.slice(7);
            }
        }
        e.target.value = value.slice(0, 12); // Limit to XXX-XXX-XXXX
    });

    // Validate fields on blur
    document.getElementById('name').addEventListener('blur', (e) => {
        if (!e.target.value.trim()) {
            e.target.classList.add('is-invalid');
        } else {
            e.target.classList.remove('is-invalid');
        }
    });

    document.getElementById('email').addEventListener('blur', (e) => {
        const email = e.target.value.trim();
        if (!email || !isValidEmail(email)) {
            e.target.classList.add('is-invalid');
        } else {
            e.target.classList.remove('is-invalid');
        }
    });

    document.getElementById('phone').addEventListener('blur', (e) => {
        const phone = e.target.value.trim();
        if (phone && !isValidPhone(phone)) {
            e.target.classList.add('is-invalid');
        } else {
            e.target.classList.remove('is-invalid');
        }
    });

    submitBtn.addEventListener('click', async (e) => {
        e.preventDefault();

        const name = document.getElementById('name').value.trim();
        const email = document.getElementById('email').value.trim();
        const phone = document.getElementById('phone').value.trim();
        const notes = document.getElementById('notes').value.trim();
        const selectedTime = document.getElementById('selectedTime').value;
        const selectedDate = document.getElementById('selectedDate').value;

        // Clear previous validation state
        form.querySelectorAll('.is-invalid').forEach(el => el.classList.remove('is-invalid'));

        // Validate required fields
        let hasErrors = false;
        
        if (!name) {
            document.getElementById('name').classList.add('is-invalid');
            hasErrors = true;
        }
        
        if (!email || !isValidEmail(email)) {
            document.getElementById('email').classList.add('is-invalid');
            hasErrors = true;
        }

        // Validate phone if provided
        if (phone && !isValidPhone(phone)) {
            document.getElementById('phone').classList.add('is-invalid');
            hasErrors = true;
        }

        if (hasErrors) {
            return;
        }

        // Prepare booking data
        const bookingData = {
            name,
            email,
            phone: phone || null,
            notes: notes || null,
            date: selectedDate,
            time: selectedTime
        };

        try {
            const response = await fetch('/api/book', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json'
                },
                body: JSON.stringify(bookingData)
            });

            if (!response.ok) {
                throw new Error('Booking failed');
            }

            // Close modal and show success message
            const modal = bootstrap.Modal.getInstance(document.getElementById('bookingModal'));
            modal.hide();
            alert('Appointment scheduled successfully!');

            // Refresh the calendar
            await renderCalendar(currentMonth, currentYear);
        } catch (error) {
            console.error('Error booking appointment:', error);
            alert('Failed to schedule appointment. Please try again.');
        }
    });

    // Initial render and setup
    await renderCalendar(currentMonth, currentYear);
    
    // Force an immediate update of time slots for today's date
    const today = new Date();
    selectedDate = today; // Ensure selectedDate is set
    await updateTimeSlots(today);
    
    // Double-check that time slots are updated
    if (!timeSlotsContainer.hasChildNodes()) {
        const noAvailabilityMsg = document.createElement('p');
        noAvailabilityMsg.classList.add('text-muted', 'text-center', 'fw-bold', 'fs-5', 'py-3');
        noAvailabilityMsg.textContent = 'No availability on selected date.';
        timeSlotsContainer.appendChild(noAvailabilityMsg);
    }
});