/**
 * Hot Reload Client for Development
 * Connects to SSE stream and handles reload events
 */
export class HotReload {
    constructor(options = {}) {
        this.url = options.url || '/dev/hot-reload';
        this.reconnectDelay = options.reconnectDelay || 5000;
        this.maxReconnectAttempts = options.maxReconnectAttempts || 10;
        this.debug = options.debug || false;
        
        this.eventSource = null;
        this.reconnectAttempts = 0;
        this.reconnectTimer = null;
        
        // Only enable in development
        if (this.isDevelopment()) {
            this.connect();
            this.setupVisibilityHandlers();
        }
    }

    /**
     * Check if we're in development mode
     */
    isDevelopment() {
        return window.location.hostname === 'localhost' 
            || window.location.hostname === '127.0.0.1'
            || window.location.hostname.includes('.local');
    }

    /**
     * Connect to SSE stream
     */
    connect() {
        if (this.eventSource) {
            return;
        }

        this.log('Connecting to Hot Reload server...');
        
        this.eventSource = new EventSource(this.url);
        
        // Connection opened
        this.eventSource.addEventListener('open', () => {
            this.log('Hot Reload connected');
            this.reconnectAttempts = 0;
            this.showNotification('Hot Reload Connected', 'success');
        });

        // Handle reload events
        this.eventSource.addEventListener('reload', (event) => {
            const data = JSON.parse(event.data);
            this.handleReload(data);
        });

        // Handle heartbeat
        this.eventSource.addEventListener('heartbeat', () => {
            this.log('Heartbeat received');
        });

        // Handle close
        this.eventSource.addEventListener('close', () => {
            this.log('Server requested close');
            this.disconnect();
        });

        // Handle errors
        this.eventSource.addEventListener('error', (error) => {
            this.log('Connection error', error);
            this.disconnect();
            this.scheduleReconnect();
        });
    }

    /**
     * Disconnect from SSE stream
     */
    disconnect() {
        if (this.eventSource) {
            this.eventSource.close();
            this.eventSource = null;
        }
        
        if (this.reconnectTimer) {
            clearTimeout(this.reconnectTimer);
            this.reconnectTimer = null;
        }
    }

    /**
     * Schedule reconnection attempt
     */
    scheduleReconnect() {
        if (this.reconnectAttempts >= this.maxReconnectAttempts) {
            this.log('Max reconnection attempts reached');
            this.showNotification('Hot Reload disconnected', 'error');
            return;
        }

        this.reconnectAttempts++;
        const delay = Math.min(this.reconnectDelay * this.reconnectAttempts, 30000);
        
        this.log(`Reconnecting in ${delay}ms (attempt ${this.reconnectAttempts})`);
        
        this.reconnectTimer = setTimeout(() => {
            this.connect();
        }, delay);
    }

    /**
     * Handle reload event from server
     */
    handleReload(data) {
        this.log('Reload event received', data);
        
        switch (data.type) {
            case 'css':
                this.reloadCSS(data.file);
                break;
            
            case 'hmr':
                this.handleHMR(data);
                break;
            
            case 'partial':
                this.reloadPartial(data);
                break;
            
            case 'full':
            default:
                this.reloadPage();
                break;
        }
    }

    /**
     * Reload CSS without page refresh
     */
    reloadCSS(file) {
        this.log('Reloading CSS:', file);
        
        const links = document.querySelectorAll('link[rel="stylesheet"]');
        const timestamp = new Date().getTime();
        
        links.forEach(link => {
            const href = link.getAttribute('href');
            if (href) {
                // Remove existing timestamp
                const cleanHref = href.split('?')[0];
                
                // Add new timestamp to force reload
                link.setAttribute('href', `${cleanHref}?t=${timestamp}`);
            }
        });
        
        this.showNotification('CSS updated', 'info', 2000);
    }

    /**
     * Handle Hot Module Replacement
     */
    handleHMR(data) {
        this.log('HMR not yet implemented, falling back to full reload');
        this.reloadPage();
    }

    /**
     * Reload partial content
     */
    reloadPartial(data) {
        this.log('Partial reload not yet implemented, falling back to full reload');
        this.reloadPage();
    }

    /**
     * Reload the entire page
     */
    reloadPage() {
        this.log('Reloading page...');
        this.showNotification('Reloading...', 'info', 500);
        
        setTimeout(() => {
            window.location.reload();
        }, 500);
    }

    /**
     * Show notification to user
     */
    showNotification(message, type = 'info', duration = 3000) {
        // Remove existing notification
        const existing = document.getElementById('hot-reload-notification');
        if (existing) {
            existing.remove();
        }

        // Create notification element
        const notification = document.createElement('div');
        notification.id = 'hot-reload-notification';
        notification.textContent = message;
        notification.className = `hot-reload-notification hot-reload-notification--${type}`;
        
        // Style the notification
        notification.style.cssText = `
            position: fixed;
            bottom: 20px;
            right: 20px;
            padding: 12px 20px;
            border-radius: 6px;
            font-family: system-ui, -apple-system, sans-serif;
            font-size: 14px;
            font-weight: 500;
            z-index: 999999;
            transition: opacity 0.3s ease;
            pointer-events: none;
            max-width: 300px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        `;

        // Type-specific styles
        switch(type) {
            case 'success':
                notification.style.backgroundColor = '#10b981';
                notification.style.color = '#ffffff';
                break;
            case 'error':
                notification.style.backgroundColor = '#ef4444';
                notification.style.color = '#ffffff';
                break;
            case 'warning':
                notification.style.backgroundColor = '#f59e0b';
                notification.style.color = '#ffffff';
                break;
            default:
                notification.style.backgroundColor = '#3b82f6';
                notification.style.color = '#ffffff';
        }

        document.body.appendChild(notification);

        // Auto-remove after duration
        if (duration > 0) {
            setTimeout(() => {
                notification.style.opacity = '0';
                setTimeout(() => {
                    notification.remove();
                }, 300);
            }, duration);
        }
    }

    /**
     * Setup visibility handlers for reconnection
     */
    setupVisibilityHandlers() {
        // Reconnect when tab becomes visible
        document.addEventListener('visibilitychange', () => {
            if (!document.hidden && !this.eventSource) {
                this.log('Tab became visible, reconnecting...');
                this.connect();
            }
        });

        // Disconnect when window is closed
        window.addEventListener('beforeunload', () => {
            this.disconnect();
        });
    }

    /**
     * Debug logging
     */
    log(...args) {
        if (this.debug) {
            console.log('[HotReload]', ...args);
        }
    }
}

// Auto-initialize if in development
if (typeof window !== 'undefined') {
    window.addEventListener('DOMContentLoaded', () => {
        // Only initialize if not already initialized
        if (!window.__hotReload) {
            window.__hotReload = new HotReload({
                debug: true // Enable debug in development
            });
        }
    });
}