import mongoose from 'mongoose'

const MONGODB_URI = process.env.MONGODB_URI || 'mongodb://localhost:27017/siliconpin'

if (!MONGODB_URI) {
  throw new Error('Please define the MONGODB_URI environment variable inside .env.local')
}

interface CachedConnection {
  conn: typeof mongoose | null
  promise: Promise<typeof mongoose> | null
}

// Global variable to cache the database connection across hot reloads in development
declare global {
  var mongoose: CachedConnection | undefined
}

let cached: CachedConnection = global.mongoose || { conn: null, promise: null }

if (!global.mongoose) {
  global.mongoose = cached
}

async function connectDB(): Promise<typeof mongoose> {
  // Skip database connection during build phase
  const isBuildTime = process.env.NEXT_PHASE === 'phase-production-build'
  if (isBuildTime) {
    throw new Error('Database connection skipped during build phase')
  }

  if (cached.conn) {
    return cached.conn
  }

  if (!cached.promise) {
    const opts = {
      bufferCommands: false,
      maxPoolSize: 10,
      minPoolSize: 5,
      socketTimeoutMS: 45000,
      connectTimeoutMS: 10000,
      serverSelectionTimeoutMS: 10000,
    }

    cached.promise = mongoose.connect(MONGODB_URI, opts)
  }

  try {
    cached.conn = await cached.promise
    console.log('Connected to MongoDB')
    return cached.conn
  } catch (error) {
    cached.promise = null
    console.error('MongoDB connection error:', error)
    throw error
  }
}

// Test MongoDB connection
export async function testMongoConnection(): Promise<boolean> {
  try {
    const connection = await connectDB()

    // Test database operations
    await connection.connection.db.admin().ping()
    console.log('✅ MongoDB connection test successful')

    // Optional: Test if we can create a test collection
    const testCollection = connection.connection.db.collection('connection_test')
    await testCollection.insertOne({ test: true, timestamp: new Date() })
    await testCollection.deleteOne({ test: true })

    console.log('✅ MongoDB read/write test successful')
    return true
  } catch (error) {
    console.error('❌ MongoDB connection test failed:', error)
    console.error('Please check:')
    console.error('1. MongoDB is running (docker-compose up -d in /mongo directory)')
    console.error('2. MONGODB_URI in .env is correct')
    console.error('3. MongoDB credentials are valid')
    return false
  }
}

export default connectDB
export { connectDB }