const fs = require('fs');
const path = require('path');
const { executeQuery, executeTransaction } = require('../database');

/**
 * Run all database migrations
 */
async function runMigrations() {
    console.log('🚀 Starting database migrations...');
    
    try {
        // Create migrations table to track what's been run
        await executeQuery(`
            CREATE TABLE IF NOT EXISTS migrations (
                id SERIAL PRIMARY KEY,
                filename VARCHAR(255) NOT NULL UNIQUE,
                executed_at BIGINT NOT NULL DEFAULT EXTRACT(epoch FROM NOW()) * 1000
            );
        `);
        
        // Get list of executed migrations
        const executedMigrations = await executeQuery(
            'SELECT filename FROM migrations ORDER BY executed_at'
        );
        const executedFiles = new Set(executedMigrations.map(m => m.filename));
        
        // Read migration files
        const migrationsDir = path.join(__dirname);
        const migrationFiles = fs.readdirSync(migrationsDir)
            .filter(file => file.endsWith('.sql'))
            .sort();
        
        console.log(`📁 Found ${migrationFiles.length} migration files`);
        
        for (const file of migrationFiles) {
            if (executedFiles.has(file)) {
                console.log(`⏭️  Skipping ${file} (already executed)`);
                continue;
            }
            
            console.log(`🔄 Executing ${file}...`);
            
            const filePath = path.join(migrationsDir, file);
            const sql = fs.readFileSync(filePath, 'utf8');
            
            await executeTransaction(async (client) => {
                // Execute the migration SQL
                if (process.env.USE_NEON_SERVERLESS === 'true') {
                    // For Neon serverless, split by statements and execute individually
                    const statements = sql
                        .split(';')
                        .map(s => s.trim())
                        .filter(s => s.length > 0);
                    
                    for (const statement of statements) {
                        if (statement.trim()) {
                            await client(statement);
                        }
                    }
                } else {
                    await client.query(sql);
                }
                
                // Record that this migration was executed
                if (process.env.USE_NEON_SERVERLESS === 'true') {
                    await client('INSERT INTO migrations (filename) VALUES ($1)', [file]);
                } else {
                    await client.query('INSERT INTO migrations (filename) VALUES ($1)', [file]);
                }
            });
            
            console.log(`✅ Completed ${file}`);
        }
        
        console.log('🎉 All migrations completed successfully!');
        
    } catch (error) {
        console.error('❌ Migration failed:', error);
        throw error;
    }
}

/**
 * Create a new migration file
 * @param {string} name - Migration name
 */
function createMigration(name) {
    const timestamp = new Date().toISOString().replace(/[:.]/g, '-').split('T')[0];
    const filename = `${timestamp}_${name}.sql`;
    const filepath = path.join(__dirname, filename);
    
    const template = `-- Migration: ${filename}
-- Description: ${name}

-- Add your SQL here

`;
    
    fs.writeFileSync(filepath, template);
    console.log(`📝 Created migration: ${filename}`);
    return filename;
}

// Run migrations if this file is executed directly
if (require.main === module) {
    const command = process.argv[2];
    
    if (command === 'create') {
        const name = process.argv[3];
        if (!name) {
            console.error('❌ Please provide a migration name: npm run db:migrate create migration_name');
            process.exit(1);
        }
        createMigration(name);
    } else {
        runMigrations()
            .then(() => {
                console.log('🏁 Migration process completed');
                process.exit(0);
            })
            .catch(error => {
                console.error('💥 Migration process failed:', error);
                process.exit(1);
            });
    }
}

module.exports = {
    runMigrations,
    createMigration
};