/**
 * Café Bach Email Generator - Form Handling & Preview Logic
 */

document.addEventListener('DOMContentLoaded', function() {
    const form = document.getElementById('emailForm');
    const previewBtn = document.getElementById('previewBtn');
    const descCount = document.getElementById('desc-count');
    const descriptionField = document.getElementById('description');

    // Character counter for description field
    if (descriptionField && descCount) {
        descriptionField.addEventListener('input', function() {
            const currentLength = this.value.length;
            const maxLength = this.maxLength;
            descCount.textContent = `${currentLength}/${maxLength}`;
            
            if (currentLength > maxLength * 0.9) {
                descCount.style.color = '#e74c3c';
            } else {
                descCount.style.color = '#95a5a6';
            }
        });
    }

    // Form submission handler
    if (form) {
        form.addEventListener('submit', async function(e) {
            e.preventDefault();
            
            if (validateForm()) {
                const formData = getFormData();
                await submitFormData(formData);
            }
        });
    }

    // Preview button handler
    if (previewBtn) {
        previewBtn.addEventListener('click', function() {
            if (validateForm()) {
                const formData = getFormData();
                showPreview(formData);
            }
        });
    }

    // Clear form handler
    const clearBtn = document.querySelector('button[type="reset"]');
    if (clearBtn) {
        clearBtn.addEventListener('click', function() {
            resetForm();
        });
    }

    // Real-time validation on blur
    const inputs = form ? form.querySelectorAll('input, textarea') : [];
    inputs.forEach(input => {
        input.addEventListener('blur', function() {
            validateField(this);
        });
    });

    // Real-time validation on input
    inputs.forEach(input => {
        if (input.required) {
            input.addEventListener('input', function() {
                if (this.classList.contains('error')) {
                    validateField(this);
                }
            });
        }
    });
});
/**
 * Validate the entire form
 */
function validateForm() {
    const form = document.getElementById('emailForm');
    const inputs = form.querySelectorAll('input[required], textarea[required]');
    let isValid = true;

    inputs.forEach(input => {
        if (!validateField(input)) {
            isValid = false;
        }
    });

    // Validate URLs if provided
    const urlFields = ['image_url', 'button_url', 'next_event_url'];
    urlFields.forEach(fieldName => {
        const field = document.getElementById(fieldName);
        if (field && field.value && !isValidUrl(field.value)) {
            showError(fieldName, 'Please enter a valid URL');
            isValid = false;
        }
    });

    return isValid;
}

/**
 * Validate a single field
 */
function validateField(field) {
    const fieldName = field.id;
    const value = field.value.trim();

    // Clear previous error
    clearError(fieldName);

    // Required field check
    if (field.required && !value) {
        showError(fieldName, 'This field is required');
        field.classList.add('error');
        return false;
    }

    // Length validation
    if (value && field.maxLength) {
        if (value.length > field.maxLength) {
            showError(fieldName, `Must be less than ${field.maxLength} characters`);
            field.classList.add('error');
            return false;
        }
    }

    field.classList.remove('error');
    return true;
}

/**
 * Show error message for a field
 */
function showError(fieldName, message) {
    const errorElement = document.getElementById(`${fieldName}-error`);
    if (errorElement) {
        errorElement.textContent = message;
    }
}

/**
 * Clear error message for a field
 */
function clearError(fieldName) {
    const errorElement = document.getElementById(`${fieldName}-error`);
    if (errorElement) {
        errorElement.textContent = '';
    }
}

/**
 * Validate URL format
 */
function isValidUrl(string) {
    try {
        new URL(string);
        return true;
    } catch (_) {
        return false;
    }
}

/**
 * Get form data as object
 */
function getFormData() {
    const form = document.getElementById('emailForm');
    const formData = new FormData(form);
    const data = {};

    for (let [key, value] of formData.entries()) {
        data[key] = value;
    }

    // Convert to JSON string for display
    data.jsonString = JSON.stringify(data, null, 2);

    return data;
}

/**
 * Submit form data to backend
 */
async function submitFormData(data) {
    try {
        const response = await fetch('/generate', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            },
            body: JSON.stringify(data)
        });

        if (response.ok) {
            const result = await response.json();
            console.log('Form submitted successfully:', result);
            alert('Email generated successfully!');
        } else {
            console.error('Submission failed');
            alert('Failed to generate email. Please try again.');
        }
    } catch (error) {
        console.error('Submission error:', error);
        alert('Network error. Please check your connection and try again.');
    }
}

/**
 * Show preview of email
 */
function showPreview(data) {
    const previewContainer = document.getElementById('emailPreview');
    
    // Format date for display
    let formattedDate = '';
    if (data.date_time) {
        const date = new Date(data.date_time);
        formattedDate = date.toLocaleString('en-US', {
            weekday: 'long',
            year: 'numeric',
            month: 'long',
            day: 'numeric',
            hour: '2-digit',
            minute: '2-digit'
        });
    }

    // Build HTML preview
    const previewHTML = `
        <div class="email-template">
            <h1>${escapeHtml(data.title)}</h1>
            
            ${data.image_url ? `<img src="${escapeHtml(data.image_url)}" alt="Event Image" class="event-image">` : ''}
            
            <div class="event-details">
                <strong>📅 Date & Time</strong>
                <p>${formattedDate || escapeHtml(data.date_time)}</p>
                
                <strong>📍 Location</strong>
                <p>${escapeHtml(data.location)}</p>
                
                <strong>📝 Description</strong>
                <p>${escapeHtml(data.description)}</p>
            </div>
            
            <a href="${escapeHtml(data.button_url)}" class="cta-button">${escapeHtml(data.button_text)}</a>
            
            ${data.next_event_text ? `
                <div class="next-event">
                    <p><strong>Next Event:</strong> ${escapeHtml(data.next_event_text)}</p>
                    ${data.next_event_url ? `<a href="${escapeHtml(data.next_event_url)}">Learn More</a>` : ''}
                </div>
            ` : ''}
        </div>
    `;

    previewContainer.innerHTML = previewHTML;

    // Scroll to preview
    previewContainer.scrollIntoView({ behavior: 'smooth', block: 'start' });
}

/**
 * Reset form to initial state
 */
function resetForm() {
    const form = document.getElementById('emailForm');
    form.reset();
    
    // Clear all error messages
    const errorMessages = document.querySelectorAll('.error-message');
    errorMessages.forEach(el => el.textContent = '');
    
    // Remove error classes
    const inputs = form.querySelectorAll('input, textarea');
    inputs.forEach(input => input.classList.remove('error'));
    
    // Reset character counter
    const descCount = document.getElementById('desc-count');
    if (descCount) {
        descCount.textContent = '0/2000';
        descCount.style.color = '#95a5a6';
    }
}

/**
 * Escape HTML to prevent XSS
 */
function escapeHtml(text) {
    if (!text) return '';
    const div = document.createElement('div');
    div.textContent = text;
    return div.innerHTML;
}

/**
 * Copy to clipboard functionality
 */
function copyToClipboard() {
    const previewContent = document.getElementById('emailPreview').innerHTML;
    
    navigator.clipboard.writeText(previewContent).then(() => {
        const btn = document.getElementById('copyBtn');
        if (btn) {
            btn.textContent = '✓ Copied to Clipboard!';
            setTimeout(() => {
                btn.textContent = 'Copy HTML to Clipboard';
            }, 2000);
        }
    }).catch(err => {
        console.error('Failed to copy:', err);
        alert('Failed to copy to clipboard. Please select and copy manually.');
    });
}

// Export functions for global access
window.copyToClipboard = copyToClipboard;