const { Pool } = require('pg');
const BaseStorage = require('@gofynd/fdk-extension-javascript/express/storage/base_storage');

const DEFAULT_TABLE_NAME = 'fdk session storage';

function normalizeText(value) {
  return typeof value === 'string' ? value.trim() : '';
}

function quoteIdentifier(value) {
  return `"${String(value).replace(/"/g, '""')}"`;
}

function coerceJsonValue(value) {
  if (!value) return null;
  if (typeof value === 'object') return value;

  try {
    return JSON.parse(value);
  } catch {
    return null;
  }
}

class PostgresFdkStorage extends BaseStorage {
  constructor(connectionString, prefixKey = 'sms_extension_', tableName = DEFAULT_TABLE_NAME) {
    super(prefixKey);
    this.pool = new Pool({ connectionString });
    this.tableName = quoteIdentifier(tableName);
  }

  getFullKey(key) {
    return `${this.prefixKey}${key}`;
  }

  async get(key) {
    const fullKey = this.getFullKey(key);
    const result = await this.pool.query(
      `SELECT value, expires_at
         FROM ${this.tableName}
        WHERE storage_key = $1
        ORDER BY updated_at DESC NULLS LAST, id DESC
        LIMIT 1`,
      [fullKey]
    );

    if (!result.rows.length) return null;

    const row = result.rows[0];
    const expiresAt = row.expires_at ? new Date(row.expires_at) : null;

    if (expiresAt && expiresAt.getTime() <= Date.now()) {
      await this.del(key);
      return null;
    }

    return coerceJsonValue(row.value);
  }

  async set(key, value) {
    return this.save(key, value, null);
  }

  async setex(key, value, ttl) {
    const ttlSeconds = Number(ttl);
    const expiresAt = Number.isFinite(ttlSeconds) && ttlSeconds > 0
      ? new Date(Date.now() + ttlSeconds * 1000)
      : null;

    return this.save(key, value, expiresAt);
  }

  async save(key, value, expiresAt) {
    const fullKey = this.getFullKey(key);
    const serializedValue = JSON.stringify(value || {});
    const client = await this.pool.connect();

    try {
      await client.query('BEGIN');

      const updateResult = await client.query(
        `UPDATE ${this.tableName}
            SET value = $2,
                expires_at = $3,
                updated_at = NOW()
          WHERE storage_key = $1`,
        [fullKey, serializedValue, expiresAt]
      );

      if (updateResult.rowCount === 0) {
        await client.query(
          `INSERT INTO ${this.tableName} (storage_key, value, expires_at)
           VALUES ($1, $2, $3)`,
          [fullKey, serializedValue, expiresAt]
        );
      }

      await client.query('COMMIT');
      return 'OK';
    } catch (error) {
      await client.query('ROLLBACK');
      throw error;
    } finally {
      client.release();
    }
  }

  async del(key) {
    const fullKey = this.getFullKey(key);
    await this.pool.query(`DELETE FROM ${this.tableName} WHERE storage_key = $1`, [fullKey]);
  }
}

function createFdkStorage(connectionString) {
  const normalizedConnectionString = normalizeText(connectionString);
  if (!normalizedConnectionString) return null;

  return new PostgresFdkStorage(normalizedConnectionString);
}

module.exports = {
  createFdkStorage,
  PostgresFdkStorage,
};