const mongoose = require('mongoose');
require('./models'); // Load all schemas

/**
 * Connect to MongoDB with reconnection logic
 * @param {string} uri - MongoDB connection URI (from process.env.MONGODB_URI)
 * @param {object} options - Optional Mongoose connection options
 * @returns {Promise<void>}
 */
async function connectMongoDB(uri, options = {}) {
    if (!uri) {
        throw new Error('MONGODB_URI is required. Add it to your .env file.');
    }

    const defaultOptions = {
        serverSelectionTimeoutMS: 5000,
        socketTimeoutMS: 45000,
        ...options
    };

    try {
        await mongoose.connect(uri, defaultOptions);
        console.log('✓ Connected to MongoDB');
        
        // Handle connection events
        mongoose.connection.on('error', (err) => {
            console.error('MongoDB connection error:', err);
        });

        mongoose.connection.on('disconnected', () => {
            console.warn('MongoDB disconnected. Attempting to reconnect...');
        });

        mongoose.connection.on('reconnected', () => {
            console.log('✓ MongoDB reconnected');
        });

    } catch (err) {
        console.error('Failed to connect to MongoDB:', err.message);
        console.error('Stack:', err.stack);
        throw err;
    }
}

/**
 * Gracefully close MongoDB connection
 * @returns {Promise<void>}
 */
async function closeMongoDB() {
    try {
        await mongoose.connection.close();
        console.log('MongoDB connection closed');
    } catch (err) {
        console.error('Error closing MongoDB:', err);
    }
}

module.exports = {
    connectMongoDB,
    closeMongoDB,
    mongoose
};