BD_empresa/Data/AccessService.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.OleDb;
using System.Linq;
using System.Threading.Tasks;

namespace BD_empresa.Data
{
    public class AccessService(string connectionString) : IClienteRepository
    {
        private readonly string _connectionString = connectionString;

        public async Task<List<ClienteSmart>> SearchClientesAsync(string query)
        {
            return await Task.Run(() =>
            {
                var clientes = new List<ClienteSmart>();
                using (var connection = new OleDbConnection(_connectionString))
                {
                    connection.Open();
                    string sql = @"SELECT Gestao, Cliente, Unidade, CNPJ_CPF, Codigo_Instalacao, Razao_Social FROM Dados_cadastrais WHERE CNPJ_CPF LIKE ? OR Codigo_Instalacao LIKE ? OR Razao_Social LIKE ? OR Cliente LIKE ?";
                    using var cmd = new OleDbCommand(sql, connection);
                    string likeQuery = $"%{query}%";
                    cmd.Parameters.AddWithValue("?", likeQuery);
                    cmd.Parameters.AddWithValue("?", likeQuery);
                    cmd.Parameters.AddWithValue("?", likeQuery);
                    cmd.Parameters.AddWithValue("?", likeQuery);
                    using var reader = cmd.ExecuteReader();
                    while (reader.Read())
                    {
                        clientes.Add(new ClienteSmart
                        {
                            Gestao = reader["Gestao"].ToString(),
                            Cliente = reader["Cliente"].ToString(),
                            Unidade = reader["Unidade"].ToString(),
                            CNPJ_CPF = reader["CNPJ_CPF"].ToString(),
                            Codigo_Instalacao = reader["Codigo_Instalacao"].ToString(),
                            Razao_Social = reader["Razao_Social"].ToString()
                        });
                    }
                }
                // Unifica clientes por CNPJ, retorna no máximo 3
                return clientes
                    .GroupBy(c => c.CNPJ_CPF)
                    .Select(g => g.First())
                    .Take(3)
                    .ToList();
            });
        }

        public async Task<List<ClienteSmart>> GetAllClientesAsync()
        {
            return await Task.Run(() =>
            {
                var clientes = new List<ClienteSmart>();
                using (var connection = new OleDbConnection(_connectionString))
                {
                    connection.Open();
                    string sql = "SELECT Gestao, Cliente, Unidade, CNPJ_CPF, Codigo_Instalacao, Razao_Social FROM Dados_cadastrais";
                    using var cmd = new OleDbCommand(sql, connection);
                    using var reader = cmd.ExecuteReader();
                    while (reader.Read())
                    {
                        clientes.Add(new ClienteSmart
                        {
                            Gestao = reader["Gestao"].ToString(),
                            Cliente = reader["Cliente"].ToString(),
                            Unidade = reader["Unidade"].ToString(),
                            CNPJ_CPF = reader["CNPJ_CPF"].ToString(),
                            Codigo_Instalacao = reader["Codigo_Instalacao"].ToString(),
                            Razao_Social = reader["Razao_Social"].ToString()
                        });
                    }
                }
                // Unifica clientes por CNPJ
                return clientes
                    .GroupBy(c => c.CNPJ_CPF)
                    .Select(g => g.First())
                    .Take(3)
                    .ToList();
            });
        }
    }
}