import {
  ConnectionTestResult,
  cacheConnectionWithConfiguration,
  generateSourceOptionsHash,
  getCachedConnection,
  QueryService,
  QueryResult,
  QueryError,
  getTooljetEdition,
} from '@tooljet-plugins/common';
import { SourceOptions, QueryOptions } from './types';
import knex, { Knex } from 'knex';
import { isEmpty } from '@tooljet-plugins/common';
import { Client } from 'ssh2';
import { URL } from 'url';
import net from 'net';

  async function createLocalSSHTunnel(
    sourceOptions: SourceOptions,
    targetHost: string,
    targetPort: number
  ): Promise<{
    sshClient: Client;
    server: net.Server;
    localPort: number;
  }> {
    return new Promise((resolve, reject) => {
      const ssh = new Client();
      ssh.on('ready', () => {
        

        const server = net.createServer((localSocket) => {
          ssh.forwardOut(
            localSocket.remoteAddress || '127.0.0.1',
            localSocket.remotePort || 0,
            targetHost,
            targetPort,
            (err, remoteStream) => {
              if (err) {
                localSocket.destroy();
                return;
              }

              localSocket.pipe(remoteStream).pipe(localSocket);

              remoteStream.on('error', () => {
                localSocket.destroy();
              });

              localSocket.on('error', () => {
                remoteStream.destroy();
              });
            }
          );
        });

        server.listen(0, '127.0.0.1', () => {
          const addr = server.address() as net.AddressInfo;
          resolve({
            sshClient: ssh,
            server,
            localPort: addr.port,
          });
        });
      });

      ssh.on('error', (e) => {
        reject(e);
      });

      const sshConfig: any = {
        host: sourceOptions.ssh_host,
        port: Number(sourceOptions.ssh_port) || 22,
        username: sourceOptions.ssh_username,
        readyTimeout: 20000, // recommended
      };

      if (sourceOptions.ssh_auth_type === 'private_key') {
        if (
          !sourceOptions.ssh_private_key ||
          sourceOptions.ssh_private_key.trim() === ''
        ) {
          return reject(
            new Error('SSH private key is required for private_key auth type')
          );
        }
        sshConfig.privateKey = Buffer.from(
          sourceOptions.ssh_private_key
        );
        if (
          sourceOptions.ssh_passphrase &&
          sourceOptions.ssh_passphrase.trim() !== ''
        ) {
          sshConfig.passphrase =
            sourceOptions.ssh_passphrase;
        }

      } else if (sourceOptions.ssh_auth_type === 'password') {
        if (
          !sourceOptions.ssh_password ||
          sourceOptions.ssh_password.trim() === ''
        ) {
          return reject(
            new Error('SSH password is required for password auth type')
          );
        }
        sshConfig.password =
          sourceOptions.ssh_password;

      } else {
        return reject(
          new Error(
            `Unsupported SSH auth type: ${sourceOptions.ssh_auth_type}`
          )
        );
      }
      ssh.connect(sshConfig);
    });
  }

export default class PostgresqlQueryService implements QueryService {
  private static _instance: PostgresqlQueryService;
  private STATEMENT_TIMEOUT;
  private tooljet_edition: string;

  constructor() {
    this.tooljet_edition = getTooljetEdition();
    // Default 120 secs
    this.STATEMENT_TIMEOUT =
      process.env?.PLUGINS_SQL_DB_STATEMENT_TIMEOUT && !isNaN(Number(process.env?.PLUGINS_SQL_DB_STATEMENT_TIMEOUT))
        ? Number(process.env.PLUGINS_SQL_DB_STATEMENT_TIMEOUT)
        : 120000;

    if (PostgresqlQueryService._instance) {
      return PostgresqlQueryService._instance;
    }
    PostgresqlQueryService._instance = this;
    return PostgresqlQueryService._instance;
  }

  async invokeMethod(
    methodName: string,
    context: { user?: any; app?: any },
    sourceOptions: SourceOptions,
    args?: any
  ): Promise<any> {
    if (methodName === 'getTables') {
      const dataSourceId = args?.dataSourceId || '';
      const dataSourceUpdatedAt = args?.dataSourceUpdatedAt || '';
      const result = await this.listTables(
        sourceOptions,
        dataSourceId,
        dataSourceUpdatedAt
      );

      // safely unwrap possible structures
      const tables =
        (result as any)?.data?.data ??
        (result as any)?.data ??
        [];

      const formattedTables = tables.map((row:any)=>({
        label: String(row.table_name),
        value: String(row.table_name),
      }));

      return {
        status:'ok',
        data: formattedTables,
      };
    }

    throw new QueryError(
      'Method not found',
      `Method ${methodName} is not supported for PostgreSQL plugin`,
      { availableMethods: ['getTables'] }
    );
  }

  async run(
    sourceOptions: SourceOptions,
    queryOptions: QueryOptions,
    dataSourceId: string,
    dataSourceUpdatedAt: string
  ): Promise<QueryResult> {
    let pgPool, pgConnection, checkCache, knexInstance;

    if (sourceOptions['allow_dynamic_connection_parameters']) {
      if (sourceOptions.connection_type === 'manual') {
        sourceOptions['host'] = queryOptions['host'] ? queryOptions['host'] : sourceOptions['host'];
        sourceOptions['database'] = queryOptions['database'] ? queryOptions['database'] : sourceOptions['database'];
      } else if (sourceOptions.connection_type === 'string') {
        const modifiedConnectionString = new URL(sourceOptions.connection_string);
        if (queryOptions['host']) modifiedConnectionString.hostname = queryOptions['host'];
        if (queryOptions['database']) modifiedConnectionString.pathname = `/${queryOptions['database']}`;
        sourceOptions['connection_string'] = modifiedConnectionString.toString();
      }
    }

    try {
      // If dynamic connection parameters is toggled on - We don't cache the connection also destroy the connection created.
      checkCache = sourceOptions['allow_dynamic_connection_parameters'] ? false : true;
      knexInstance = await this.getConnection(sourceOptions, {}, checkCache, dataSourceId, dataSourceUpdatedAt);

      switch (queryOptions.mode) {
        case 'sql': {
          if (this.isSqlParametersUsed(queryOptions)) {
            return await this.handleRawQuery(knexInstance, queryOptions);
          } else {
            pgPool = knexInstance.client.pool;
            pgConnection = await pgPool.acquire().promise;
            const query = queryOptions.query;
            let result = { rows: [] };

            result = await pgConnection.query(query);
            return {
              status: 'ok',
              data: result.rows,
            };
          }
        }
        case 'gui': {
          return await this.handleGuiQuery(knexInstance, queryOptions);
        }
        default:
          throw new Error("Invalid query mode. Must be either 'sql' or 'gui'.");
      }
    } catch (err) {
      const errorMessage = err.message || 'An unknown error occurred';
      const errorDetails: any = {};
      if (err && err instanceof Error) {
        const postgresError = err as any;
        const { code, detail, hint, routine } = postgresError;
        errorDetails.code = code || null;
        errorDetails.detail = detail || null;
        errorDetails.hint = hint || null;
        errorDetails.routine = routine || null;
      }
      throw new QueryError('Query could not be completed', errorMessage, errorDetails);
    } finally {
      if (pgPool && pgConnection) pgPool.release(pgConnection);
      if (!checkCache && knexInstance) {
        const tunnel = (knexInstance as any).__sshTunnel;
        await knexInstance.destroy();
        if (tunnel) {
          tunnel.server.close();
          tunnel.sshClient.end();
        }
      }
    }
  }

  async testConnection(
    sourceOptions: SourceOptions
  ): Promise<ConnectionTestResult> {
    let knexInstance: Knex | undefined;
    try {
      knexInstance =
        await this.getConnection(sourceOptions, {}, false);

      await knexInstance
        .raw('SELECT version();')
        .timeout(this.STATEMENT_TIMEOUT);

      return { status: 'ok' };

    } catch (err: any) {
      let message = 'Connection test failed';
      let details: any = {};
      //  PostgreSQL driver errors
      if (err?.code || err?.detail || err?.hint) {
        message = err.message;
        details = {
          code: err.code ?? null,
          detail: err.detail ?? null,
          hint: err.hint ?? null,
          routine: err.routine ?? null,
        };
      }
      //  Invalid connection string
      else if (
        err instanceof TypeError &&
        err.message?.includes('Invalid URL')
      ) {
        message = 'Invalid PostgreSQL connection string';
      }

      //  SSH errors
      else if (err?.message?.includes('SSH')) {

        message = `SSH connection failed : ${err.message}`;

      }

      //  Knex timeout
      else if (err?.name === 'KnexTimeoutError') {
        message =
          'Database connection timeout. Please check host/port/firewall';
      }

      //  fallback
      else if (err?.message) {
        message = err.message;
      }

      throw new QueryError(
        'Connection test failed',
        message,
        details
      );

    } finally {
      //  Always cleanup SSH tunnel + knex
      if (knexInstance) {
        const tunnel =
          (knexInstance as any).__sshTunnel;
        await knexInstance.destroy();
        if (tunnel) {
          tunnel.server.close();
          tunnel.sshClient.end();
        }
      }
    }
  }

  async listTables(
    sourceOptions: SourceOptions,
    dataSourceId: string,
    dataSourceUpdatedAt: string
  ): Promise<QueryResult> {
    let knexInstance;
    try {
      knexInstance = await this.getConnection(sourceOptions, {}, true, dataSourceId, dataSourceUpdatedAt);

      const { rows } = await knexInstance.raw(`
      SELECT table_name 
      FROM information_schema.tables 
      WHERE table_schema = 'public' 
      AND table_type = 'BASE TABLE'
      ORDER BY table_name;
    `);

      return {
        status: 'ok',
        data: rows,
      };
    } catch (err) {
      const errorMessage = err.message || 'An unknown error occurred';
      throw new QueryError('Could not fetch tables', errorMessage, {});
    }
  }

  private async handleGuiQuery(knexInstance: Knex, queryOptions: QueryOptions): Promise<any> {
    if (queryOptions.operation !== 'bulk_update_pkey') {
      return { rows: [] };
    }

    const query = this.buildBulkUpdateQuery(queryOptions);
    return await this.executeQuery(knexInstance, query);
  }

  private isSqlParametersUsed(queryOptions: QueryOptions): boolean {
    const { query_params } = queryOptions;
    const queryParams = query_params || [];
    const sanitizedQueryParams: string[][] = queryParams.filter(([key]) => !isEmpty(key));
    return !!sanitizedQueryParams.length;
  }

  private async handleRawQuery(knexInstance: Knex, queryOptions: QueryOptions): Promise<QueryResult> {
    const { query, query_params } = queryOptions;
    const queryParams = query_params || [];
    const sanitizedQueryParams: Record<string, any> = Object.fromEntries(queryParams.filter(([key]) => !isEmpty(key)));
    const result = await this.executeQuery(knexInstance, query, sanitizedQueryParams);

    return { status: 'ok', data: result };
  }

  private async executeQuery(knexInstance: Knex, query: string, sanitizedQueryParams: Record<string, any> = {}) {
    if (isEmpty(query)) throw new Error('Query is empty');
    const { rows } = await knexInstance.raw(query, sanitizedQueryParams);
    return rows;
  }

  private connectionOptions(sourceOptions: SourceOptions) {
    const _connectionOptions = (sourceOptions.connection_options || []).filter((o) => o.some((e) => !isEmpty(e)));
    const connectionOptions = Object.fromEntries(_connectionOptions);
    Object.keys(connectionOptions).forEach((key) =>
      connectionOptions[key] === '' ? delete connectionOptions[key] : {}
    );
    return connectionOptions;
  }

  private async buildConnection(sourceOptions: SourceOptions): Promise<Knex> {
    let connectionConfig: any;
    let tunnel: Awaited<ReturnType<typeof createLocalSSHTunnel>> | null = null;

    // Resolve the base connection parameters depending on connection_type
    let resolvedHost: string = sourceOptions.host;
    let resolvedPort: number | undefined = Number(sourceOptions.port) || undefined;
    let resolvedUser: string = sourceOptions.username;
    let resolvedPass: string = sourceOptions.password;
    let resolvedDb: string = sourceOptions.database;

    if (sourceOptions.connection_type === 'string' && sourceOptions.connection_string) {
      const parsedUrl = new URL(sourceOptions.connection_string);

      const connUser = decodeURIComponent(parsedUrl.username || '');
      const connPass = decodeURIComponent(parsedUrl.password || '');
      const connHost = parsedUrl.hostname || '';
      const connPort: number = parsedUrl.port ? Number(parsedUrl.port) : 5432;
      const connDb = parsedUrl.pathname ? parsedUrl.pathname.replace('/', '') : '';
      const sslmode =
      parsedUrl.searchParams.get('sslmode') ||
      parsedUrl.searchParams.get('ssl') ||
      '';

      let connSslEnabled: 'enabled' | 'disabled' | undefined;

      if (
        sslmode === 'require' ||
        sslmode === 'verify-full' ||
        sslmode === 'verify-ca' ||
        sslmode === 'true'
      ) {
        connSslEnabled = 'enabled';
      } else if (
        sslmode === 'disable' ||
        sslmode === 'false'
      ) {
        connSslEnabled = 'disabled';
      }
      // Explicit UI values override connection string values
      resolvedUser = sourceOptions.username || connUser;
      resolvedPass = sourceOptions.password || connPass;
      // Only override if user explicitly changed away from the default
      resolvedHost = (sourceOptions.host && sourceOptions.host !== 'localhost') 
        ? sourceOptions.host 
        : connHost;

      resolvedPort =
          sourceOptions.port &&
          Number(sourceOptions.port) !== 5432
            ? Number(sourceOptions.port)
            : connPort;

      resolvedDb = sourceOptions.database || connDb;

          // SSL Autofill
    if ((!sourceOptions.ssl_enabled ||
          sourceOptions.ssl_enabled === 'disabled') &&
          connSslEnabled) {
          sourceOptions.ssl_enabled = connSslEnabled;
        }
    }

    // --- SSL config ---
    const sslConfig = this.getSslConfig(sourceOptions);

    // Set up SSH tunnel if enabled — pass targetHost/targetPort explicitly to avoid type conflicts
    if (sourceOptions.ssh_enabled === 'enabled') {
      tunnel = await createLocalSSHTunnel(sourceOptions, resolvedHost, resolvedPort ?? 5432);

      connectionConfig = {
        host: '127.0.0.1',
        port: tunnel.localPort,
        user: resolvedUser,
        password: resolvedPass,
        database: resolvedDb,
        ssl: sslConfig,
        ...(this.tooljet_edition !== 'cloud' ? { statement_timeout: this.STATEMENT_TIMEOUT } : {}),
      };
    } else {
      connectionConfig = {
        host: resolvedHost,
        port: resolvedPort,
        user: resolvedUser,
        password: resolvedPass,
        database: resolvedDb,
        ssl: sslConfig,
        ...(this.tooljet_edition !== 'cloud' ? { statement_timeout: this.STATEMENT_TIMEOUT } : {}),
      };
    }
    const knexInstance = knex({
      client: 'pg',
      connection: connectionConfig,
      pool: { min: 0, max: 10, acquireTimeoutMillis: 10000 },
      acquireConnectionTimeout: 60000,
      ...this.connectionOptions(sourceOptions),
    });
    // Attach tunnel reference for cleanup in run()/testConnection()
    if (tunnel) {
      (knexInstance as any).__sshTunnel = tunnel;
    }
    return knexInstance;
  }

  private getSslConfig(sourceOptions: SourceOptions) {
    // ssl_enabled is stored as string "enabled"/"disabled" from the toggle-flip widget
    if (sourceOptions.ssl_enabled !== 'enabled') return false;

    return {
      rejectUnauthorized: (sourceOptions.ssl_certificate ?? 'none') !== 'none',
      ca: sourceOptions.ssl_certificate === 'ca_certificate' ? sourceOptions.ca_cert : undefined,
      key: sourceOptions.ssl_certificate === 'self_signed' ? sourceOptions.client_key : undefined,
      cert: sourceOptions.ssl_certificate === 'self_signed' ? sourceOptions.client_cert : undefined,
    };
  }

  async getConnection(
    sourceOptions: SourceOptions,
    options: any,
    checkCache: boolean,
    dataSourceId?: string,
    dataSourceUpdatedAt?: string
  ): Promise<Knex> {
    if (checkCache) {
      const optionsHash = generateSourceOptionsHash(sourceOptions);
      const enhancedCacheKey = `${dataSourceId}_${optionsHash}`;
      const cachedConnection = await getCachedConnection(enhancedCacheKey, dataSourceUpdatedAt);
      if (cachedConnection) return cachedConnection;

      const connection = await this.buildConnection(sourceOptions);
      cacheConnectionWithConfiguration(dataSourceId, enhancedCacheKey, connection);
      return connection;
    }

    return await this.buildConnection(sourceOptions);
  }

  buildBulkUpdateQuery(queryOptions: QueryOptions): string {
    let queryText = '';

    const { table: tableName, primary_key_column: primaryKey, records } = queryOptions;

    for (const record of records) {
      const primaryKeyValue = typeof record[primaryKey] === 'string' ? `'${record[primaryKey]}'` : record[primaryKey];

      queryText = `${queryText} UPDATE ${tableName} SET`;

      for (const key of Object.keys(record)) {
        if (key !== primaryKey) {
          queryText = ` ${queryText} ${key} = ${record[key] === null ? null : `'${record[key]}'`},`;
        }
      }

      queryText = queryText.slice(0, -1);
      queryText = `${queryText} WHERE ${primaryKey} = ${primaryKeyValue};`;
    }

    return queryText.trim();
  }
}