import { exec } from 'child_process'
import path from 'path'
import { promisify } from 'util'
import fs from 'fs/promises'

const execAsync = promisify(exec)

export async function createDatabaseBackup(): Promise<string> {
  if (!process.env.DATABASE_URL) {
    throw new Error('DATABASE_URL environment variable is required')
  }
  
  const timestamp = Date.now()
  const backupPath = path.join(process.cwd(), 'backups', `backup_${timestamp}.sql`)
  
  try {
    // Ensure backup directory exists
    await execAsync('mkdir -p backups')
    
    // Create PostgreSQL backup using pg_dump
    // Extract database name from connection string
    const url = new URL(process.env.DATABASE_URL)
    const dbName = url.pathname.substring(1) // Remove leading slash
    const host = url.hostname
    const port = url.port || '5432'
    const username = url.username
    const password = url.password
    
    // Set PGPASSWORD environment variable for pg_dump
    const env = { ...process.env, PGPASSWORD: password }
    
    await execAsync(
      `pg_dump -h ${host} -p ${port} -U ${username} -d ${dbName} --no-password > "${backupPath}"`,
      { env }
    )
    
    return backupPath
  } catch (error) {
    console.error('Backup failed:', error)
    throw new Error('Database backup failed')
  }
}

export async function restoreDatabase(backupPath: string): Promise<void> {
  if (!process.env.DATABASE_URL) {
    throw new Error('DATABASE_URL environment variable is required')
  }
  
  try {
    // Create backup of current DB first
    await createDatabaseBackup()
    
    // Extract database connection details
    const url = new URL(process.env.DATABASE_URL)
    const dbName = url.pathname.substring(1)
    const host = url.hostname
    const port = url.port || '5432'
    const username = url.username
    const password = url.password
    
    // Set PGPASSWORD environment variable for psql
    const env = { ...process.env, PGPASSWORD: password }
    
    // Restore from SQL backup
    await execAsync(
      `psql -h ${host} -p ${port} -U ${username} -d ${dbName} --no-password < "${backupPath}"`,
      { env }
    )
    
    console.log('Database restored successfully')
  } catch (error) {
    console.error('Restore failed:', error)
    throw new Error('Database restore failed')
  }
}

export async function listBackups(): Promise<string[]> {
  try {
    const backupDir = path.join(process.cwd(), 'backups')
    
    try {
      const files = await fs.readdir(backupDir)
      const sqlFiles = files.filter(file => file.endsWith('.sql'))
      
      // Get file stats for each backup
      const backupInfo = await Promise.all(
        sqlFiles.map(async (file) => {
          const filePath = path.join(backupDir, file)
          const stats = await fs.stat(filePath)
          return `${stats.mtime.toISOString()} ${file} (${Math.round(stats.size / 1024)}KB)`
        })
      )
      
      return backupInfo.sort().reverse() // Most recent first
    } catch (dirError) {
      return []
    }
  } catch {
    return []
  }
}