import { PrismaClient } from '@prisma/client'

const globalForPrisma = globalThis as unknown as {
  prisma: PrismaClient | undefined
}

// Detect database provider from environment (default to sqlite for local development)
// Next.js automatically loads environment variables from .env, .env.development, .env.production
const databaseProvider = process.env.DATABASE_PROVIDER || 'sqlite'
const databaseUrl = process.env.DATABASE_URL

// Create PrismaClient with appropriate adapter
const createPrismaClient = () => {
  let client: PrismaClient
  
  if (databaseProvider === 'postgresql') {
    // Validate DATABASE_URL is present for PostgreSQL
    if (!databaseUrl) {
      throw new Error(
        'DATABASE_URL environment variable is required when DATABASE_PROVIDER is set to postgresql. ' +
        'Current DATABASE_PROVIDER: ' + databaseProvider
      )
    }
    
    // Use PrismaPg adapter for PostgreSQL
    const { PrismaPg } = require('@prisma/adapter-pg')
    const adapter = new PrismaPg({ connectionString: databaseUrl })
    client = new PrismaClient({ adapter })
  } else {
    // No adapter needed for SQLite
    client = new PrismaClient()
  }
  
  return client
}

export const prisma = globalForPrisma.prisma ?? createPrismaClient()

if (process.env.NODE_ENV !== 'production') globalForPrisma.prisma = prisma