/**
 * Migration script: SQLite to PostgreSQL
 * 
 * Migrates data from SQLite databases to PostgreSQL.
 * 
 * Usage:
 *   DATABASE_URL=postgresql://user:pass@host:port/db tsx scripts/migrate-sqlite-to-postgres.ts
 */

import Database from 'better-sqlite3';
import { Pool } from 'pg';
import { join, dirname } from 'path';
import { fileURLToPath } from 'url';
import * as fs from 'fs';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const SQLITE_CACHE_DB = join(__dirname, '../../data/cmdb-cache.db');
const SQLITE_CLASSIFICATIONS_DB = join(__dirname, '../../data/classifications.db');

async function migrate() {
  const databaseUrl = process.env.DATABASE_URL;
  if (!databaseUrl) {
    console.error('Error: DATABASE_URL environment variable is required');
    console.error('Example: DATABASE_URL=postgresql://user:pass@localhost:5432/cmdb');
    process.exit(1);
  }

  console.log('Starting migration from SQLite to PostgreSQL...');
  console.log(`PostgreSQL: ${databaseUrl.replace(/:[^:@]+@/, ':****@')}`);

  const pg = new Pool({ connectionString: databaseUrl });

  try {
    // Test connection
    await pg.query('SELECT 1');
    console.log('✓ PostgreSQL connection successful');

    // Migrate cache database
    if (fs.existsSync(SQLITE_CACHE_DB)) {
      console.log('\nMigrating cache database...');
      await migrateCacheDatabase(pg);
    } else {
      console.log('\n⚠ Cache database not found, skipping...');
    }

    // Migrate classifications database
    if (fs.existsSync(SQLITE_CLASSIFICATIONS_DB)) {
      console.log('\nMigrating classifications database...');
      await migrateClassificationsDatabase(pg);
    } else {
      console.log('\n⚠ Classifications database not found, skipping...');
    }

    console.log('\n✓ Migration completed successfully!');
  } catch (error) {
    console.error('\n✗ Migration failed:', error);
    process.exit(1);
  } finally {
    await pg.end();
  }
}

async function migrateCacheDatabase(pg: Pool) {
  const sqlite = new Database(SQLITE_CACHE_DB, { readonly: true });

  try {
    // Migrate cached_objects
    const objects = sqlite.prepare('SELECT * FROM cached_objects').all() as any[];
    console.log(`  Migrating ${objects.length} cached objects...`);

    for (const obj of objects) {
      await pg.query(
        `INSERT INTO cached_objects (id, object_key, object_type, label, data, jira_updated_at, jira_created_at, cached_at)
         VALUES ($1, $2, $3, $4, $5::jsonb, $6, $7, $8)
         ON CONFLICT (id) DO UPDATE SET
           object_key = EXCLUDED.object_key,
           label = EXCLUDED.label,
           data = EXCLUDED.data,
           jira_updated_at = EXCLUDED.jira_updated_at,
           cached_at = EXCLUDED.cached_at`,
        [
          obj.id,
          obj.object_key,
          obj.object_type,
          obj.label,
          obj.data, // Already JSON string, PostgreSQL will parse it
          obj.jira_updated_at,
          obj.jira_created_at,
          obj.cached_at,
        ]
      );
    }

    // Migrate object_relations
    const relations = sqlite.prepare('SELECT * FROM object_relations').all() as any[];
    console.log(`  Migrating ${relations.length} relations...`);

    for (const rel of relations) {
      await pg.query(
        `INSERT INTO object_relations (source_id, target_id, attribute_name, source_type, target_type)
         VALUES ($1, $2, $3, $4, $5)
         ON CONFLICT (source_id, target_id, attribute_name) DO UPDATE SET
           source_type = EXCLUDED.source_type,
           target_type = EXCLUDED.target_type`,
        [
          rel.source_id,
          rel.target_id,
          rel.attribute_name,
          rel.source_type,
          rel.target_type,
        ]
      );
    }

    // Migrate sync_metadata
    const metadata = sqlite.prepare('SELECT * FROM sync_metadata').all() as any[];
    console.log(`  Migrating ${metadata.length} metadata entries...`);

    for (const meta of metadata) {
      await pg.query(
        `INSERT INTO sync_metadata (key, value, updated_at)
         VALUES ($1, $2, $3)
         ON CONFLICT (key) DO UPDATE SET
           value = EXCLUDED.value,
           updated_at = EXCLUDED.updated_at`,
        [meta.key, meta.value, meta.updated_at]
      );
    }

    console.log('  ✓ Cache database migrated');
  } finally {
    sqlite.close();
  }
}

async function migrateClassificationsDatabase(pg: Pool) {
  const sqlite = new Database(SQLITE_CLASSIFICATIONS_DB, { readonly: true });

  try {
    // Migrate classification_history
    const history = sqlite.prepare('SELECT * FROM classification_history').all() as any[];
    console.log(`  Migrating ${history.length} classification history entries...`);

    for (const entry of history) {
      await pg.query(
        `INSERT INTO classification_history (application_id, application_name, changes, source, timestamp, user_id)
         VALUES ($1, $2, $3, $4, $5, $6)
         ON CONFLICT DO NOTHING`,
        [
          entry.application_id,
          entry.application_name,
          entry.changes,
          entry.source,
          entry.timestamp,
          entry.user_id,
        ]
      );
    }

    // Migrate session_state
    const sessions = sqlite.prepare('SELECT * FROM session_state').all() as any[];
    console.log(`  Migrating ${sessions.length} session state entries...`);

    for (const session of sessions) {
      await pg.query(
        `INSERT INTO session_state (key, value, updated_at)
         VALUES ($1, $2, $3)
         ON CONFLICT (key) DO UPDATE SET
           value = EXCLUDED.value,
           updated_at = EXCLUDED.updated_at`,
        [session.key, session.value, session.updated_at]
      );
    }

    console.log('  ✓ Classifications database migrated');
  } finally {
    sqlite.close();
  }
}

// Run migration
migrate().catch(console.error);