/**
 * Database Migration System
 * Handles reading and executing SQL migrations
 */

import { readdir, readFile } from 'fs/promises';
import { join } from 'path';
import { query } from './connection';

/**
 * Run all pending migrations
 */
export async function runMigrations(): Promise<void> {
  console.log('Starting database migrations...');

  try {
    // Ensure schema_migrations table exists
    await query(`
      CREATE TABLE IF NOT EXISTS schema_migrations (
        version INTEGER PRIMARY KEY,
        name VARCHAR(255) NOT NULL,
        executed_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
      )
    `);

    // Get all migration files
    const migrationsDir = join(__dirname, 'migrations');
    const files = await readdir(migrationsDir);
    const migrationFiles = files
      .filter((f) => f.endsWith('.sql'))
      .sort();

    if (migrationFiles.length === 0) {
      console.log('No migration files found');
      return;
    }

    // Get executed migrations
    const executedResult = await query<{ version: number }>(
      'SELECT version FROM schema_migrations ORDER BY version'
    );
    const executedVersions = new Set(executedResult.rows.map((r) => r.version));

    // Execute pending migrations
    let executedCount = 0;
    for (const file of migrationFiles) {
      const match = file.match(/^(\d+)_/);
      if (!match) continue;

      const version = parseInt(match[1], 10);
      if (executedVersions.has(version)) {
        console.log(`✓ Migration ${version} already executed`);
        continue;
      }

      try {
        const filePath = join(migrationsDir, file);
        const sqlContent = await readFile(filePath, 'utf-8');

        // Split into individual statements (simple approach)
        const statements = sqlContent
          .split(';')
          .map((s) => s.trim())
          .filter((s) => s && !s.startsWith('--'));

        for (const statement of statements) {
          await query(statement + ';');
        }

        console.log(`✓ Migration ${version} executed: ${file}`);
        executedCount++;
      } catch (error) {
        console.error(`✗ Migration ${version} failed:`, error);
        throw error;
      }
    }

    console.log(
      `✓ Database migrations completed (${executedCount} new migrations executed)`
    );
  } catch (error) {
    console.error('Migration failed:', error);
    throw error;
  }
}

/**
 * Get migration status
 */
export async function getMigrationStatus(): Promise<{
  executed: number;
  total: number;
  pending: string[];
}> {
  try {
    const migrationsDir = join(__dirname, 'migrations');
    const files = await readdir(migrationsDir);
    const migrationFiles = files.filter((f) => f.endsWith('.sql')).sort();

    const executedResult = await query<{ version: number; name: string }>(
      'SELECT version, name FROM schema_migrations ORDER BY version'
    );
    const executedVersions = new Set(executedResult.rows.map((r) => r.version));

    const pending: string[] = [];
    for (const file of migrationFiles) {
      const match = file.match(/^(\d+)_/);
      if (!match) continue;

      const version = parseInt(match[1], 10);
      if (!executedVersions.has(version)) {
        pending.push(file);
      }
    }

    return {
      executed: executedResult.rows.length,
      total: migrationFiles.length,
      pending,
    };
  } catch (error) {
    console.error('Failed to get migration status:', error);
    return {
      executed: 0,
      total: 0,
      pending: [],
    };
  }
}