using System.ComponentModel;
using trakker.Models;

namespace trakker.Data
{
    /// <summary>
    /// Provides data access methods for the <see cref="Models.Client"/> entity.
    /// This class encapsulates database operations such as upsert, delete and ad-hoc
    /// SQL execution for clients. It inherits from <see cref="DataAccess"/> which
    /// provides connection management.
    /// </summary>
    internal class ClientData(string connectionString) : DataAccess(connectionString)
    {

        public BindingList<Client> Get(string? clientId = null)
        {
            var results = new BindingList<Client>();

            string whereClause = "1 = 1";
            if (clientId != null)
            {
                whereClause = "client_id = $client_id";
            }
            
            string sql = $@"
                SELECT 
                    client_id,
                    name,
                    company,
                    email,
                    phone,
                    address_street,
                    address_city,
                    address_state,
                    address_postal,
                    notes,
                    is_active
                FROM 
                    clients
                WHERE
                    {whereClause}
                ORDER BY
                  name ASC
                ;
            ";


            using var conn = OpenConnection();
            using var cmd = conn.CreateCommand();
            cmd.CommandText = sql;

            if (clientId != null)
            {
                cmd.Parameters.AddWithValue("$client_id", clientId);
            }
            using var reader = cmd.ExecuteReader();

            var _var1 = reader.GetOrdinal("client_id");
            var _var2 = reader.GetOrdinal("name");
            var _var3 = reader.GetOrdinal("company");
            var _var4 = reader.GetOrdinal("email");
            var _var5 = reader.GetOrdinal("phone");
            var _var6 = reader.GetOrdinal("address_street");
            var _var7 = reader.GetOrdinal("address_city");
            var _var8 = reader.GetOrdinal("address_state");
            var _var9 = reader.GetOrdinal("address_postal");
            var _var10 = reader.GetOrdinal("notes");
            var _var11 = reader.GetOrdinal("is_active");

            while (reader.Read())
            {
                results.Add(new Client
                {
                    ClientId = reader.GetString(_var1),
                    Name = reader.GetString(_var2),
                    Company = reader.GetString(_var3),
                    Email = reader.GetString(_var4),
                    Phone = reader.GetString(_var5),
                    AddressStreet = reader.GetString(_var6),
                    AddressCity = reader.GetString(_var7),
                    AddressState = reader.GetString(_var8),
                    AddressPostal = reader.GetString(_var9),
                    Notes = reader.GetString(_var10),
                    IsActive = reader.GetString(_var11),
                });
            }

            return results;
        }

        /// <summary>
        /// Inserts a new client record or updates an existing one (upsert) using
        /// the provided <paramref name="client"/> model. This method executes
        /// a single SQL statement inside a transaction and will commit on
        /// success or roll back on failure.
        /// </summary>
        /// <param name="client">The <see cref="Client"/> model to insert or update. Must not be null.</param>
        /// <remarks>
        /// The SQL statement uses an ON CONFLICT clause to perform the update when a
        /// matching <c>client_id</c> already exists. Parameter names correspond to the
        /// client model property names.
        /// </remarks>
        public void Upsert(Client client) 
        { 
            const string sql = @"
                INSERT INTO clients (
                    client_id,
                    name,
                    company,
                    email,
                    phone,
                    address_street,
                    address_city,
                    address_state,
                    address_postal,
                    notes,
                    is_active
                )
                VALUES (
                    $client_id,
                    $name,
                    $company,
                    $email,
                    $phone,
                    $address_street,
                    $address_city,
                    $address_state,
                    $address_postal,
                    $notes,
                    $is_active
                )
                ON CONFLICT(client_id) DO UPDATE SET
                    name           = excluded.name,
                    company        = excluded.company,
                    email          = excluded.email,
                    phone          = excluded.phone,
                    address_street = excluded.address_street,
                    address_city   = excluded.address_city,
                    address_state  = excluded.address_state,
                    address_postal = excluded.address_postal,
                    notes          = excluded.notes,
                    is_active      = excluded.is_active,
                    updated_at     = CURRENT_TIMESTAMP;
            ";

            using var conn = OpenConnection();
            using var tx = conn.BeginTransaction();

            try
            {
                using (var cmd = conn.CreateCommand())
                {
                    cmd.Transaction = tx;
                    cmd.CommandText = sql;
                    cmd.Parameters.AddWithValue("$client_id", client.ClientId);
                    cmd.Parameters.AddWithValue("$name", client.Name);
                    cmd.Parameters.AddWithValue("$company", client.Company);
                    cmd.Parameters.AddWithValue("$email", client.Email);
                    cmd.Parameters.AddWithValue("$phone", client.Phone);
                    cmd.Parameters.AddWithValue("$address_street", client.AddressStreet);
                    cmd.Parameters.AddWithValue("$address_city", client.AddressCity);
                    cmd.Parameters.AddWithValue("$address_state", client.AddressState);
                    cmd.Parameters.AddWithValue("$address_postal", client.AddressPostal);
                    cmd.Parameters.AddWithValue("$notes", client.Notes);
                    cmd.Parameters.AddWithValue("$is_active", client.IsActive);
                    cmd.ExecuteNonQuery();
                }

                tx.Commit();
            }
            catch
            {
                tx.Rollback();
                throw;
            }

        }
        /// <summary>
        /// Deletes the client with the specified <paramref name="clientId"/> from the
        /// database.
        /// </summary>
        /// <param name="clientId">The identifier of the client to delete.</param>
        /// <returns>An optional integer representing any scalar value returned by the
        /// command executed after deletion (if applicable). May be null.</returns>
        /// <remarks>
        /// The method executes within a transaction. The current implementation attempts
        /// to read a scalar value after the delete; that value depends on surrounding
        /// database triggers or commands and may be null.
        /// </remarks>
        public int? Delete(string clientId) 
        { 
            const string sql = @"
                DELETE FROM 
                  clients
                WHERE
                  client_id = $client_id
                ;
            ";

            using var conn = OpenConnection();
            using var tx = conn.BeginTransaction();

            int? result = 0;
            try
            {
                using (var cmd = conn.CreateCommand())
                {
                    cmd.Transaction = tx;
                    cmd.CommandText = sql;
                    cmd.Parameters.AddWithValue("$client_id", clientId);
                    cmd.ExecuteNonQuery();
                }

                using var idCmd = conn.CreateCommand();
                idCmd.Transaction = tx;
                result = (int?)idCmd.ExecuteScalar() ;

                tx.Commit();
            }
            catch
            {
                tx.Rollback();
                throw;
            }

            return result;
        }

    }
}