import { BadRequestException, Injectable } from '@nestjs/common';
import { OracleDBService } from 'src/db/db.service';
import { AuthLoginDTO } from './auth.dto';
import * as oracledb from 'oracledb';

@Injectable()
export class AuthService {
  constructor(private readonly oracleDBService: OracleDBService) { }

  async login(body: AuthLoginDTO) {
    let connection;
    let rows = [];
    try {
      connection = await this.oracleDBService.getConnection();
      if (!connection) {
        throw new Error('No DB Connected');
      }

      const result = await connection.execute(
        `BEGIN
                    USERLOGIN_PKG.ValidateUser(:p_emailaddr,:p_password,:p_login_cursor);
                END;`,
        {
          p_emailaddr: {
            val: body.p_emailaddr,
            type: oracledb.DB_TYPE_NVARCHAR,
          },
          p_password: {
            val: body.p_password,
            type: oracledb.DB_TYPE_NVARCHAR,
          },
          p_login_cursor: {
            type: oracledb.CURSOR,
            dir: oracledb.BIND_OUT,
          },
        },
        {
          outFormat: oracledb.OUT_FORMAT_OBJECT,
        },
      );

      if (result.outBinds && result.outBinds.p_login_cursor) {
        const cursor = result.outBinds.p_login_cursor;
        let rowsBatch;

        do {
          rowsBatch = await cursor.getRows(100);
          rows = rows.concat(rowsBatch);
        } while (rowsBatch.length > 0);

        await cursor.close();
      } else {
        throw new BadRequestException({
          Error: 'Error executing request try after some time!',
        });
      }

      if (rows[0]['ERRORMESG']) {
        throw new BadRequestException({ error: 'Invalid username or password!' });
      }
      return { msg: 'Logged in successfully' };
    } catch (err) {
      console.error('Error fetching users: ', err.message);
      throw new BadRequestException({ error: 'Invalid username or password' });
    }
    finally {
      if (connection) {
        try {
          await connection.close();
        } catch (closeErr) {
          console.error('Failed to close connection:', closeErr);
        }
      }
    }
  }
}